U.S. patent application number 11/765262 was filed with the patent office on 2009-04-30 for gene reporter assay, kit, and cells for determining the presence and/or the level of a molecule that activates signal transduction activity of a cell surface protein.
This patent application is currently assigned to Le Centre Nationale de la Recherche Scientifique. Invention is credited to Christophe Lallemand, Michael G. Tovey.
Application Number | 20090111178 11/765262 |
Document ID | / |
Family ID | 32230199 |
Filed Date | 2009-04-30 |
United States Patent
Application |
20090111178 |
Kind Code |
A1 |
Tovey; Michael G. ; et
al. |
April 30, 2009 |
GENE REPORTER ASSAY, KIT, AND CELLS FOR DETERMINING THE PRESENCE
AND/OR THE LEVEL OF A MOLECULE THAT ACTIVATES SIGNAL TRANSDUCTION
ACTIVITY OF A CELL SURFACE PROTEIN
Abstract
The present invention relates to a commercializable cell and to
a gene reporter assay method and a kit which use this cell to
determine the presence and/or the level of a molecule that
activates signal transduction activity of a cell surface protein.
This cell is treated in such a manner that it will have a
sufficiently long shelf life for its intended purpose, whereupon at
the end of its useful shelf life or at the end of its use, i.e., in
an assay, the cell undergoes cellular death.
Inventors: |
Tovey; Michael G.; (Paris,
FR) ; Lallemand; Christophe; (Paris, FR) |
Correspondence
Address: |
BROWDY AND NEIMARK, P.L.L.C.;624 NINTH STREET, NW
SUITE 300
WASHINGTON
DC
20001-5303
US
|
Assignee: |
Le Centre Nationale de la Recherche
Scientifique
Paris Cedex
FR
|
Family ID: |
32230199 |
Appl. No.: |
11/765262 |
Filed: |
June 19, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10677777 |
Oct 3, 2003 |
7470536 |
|
|
11765262 |
|
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|
60415818 |
Oct 4, 2002 |
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Current U.S.
Class: |
435/374 |
Current CPC
Class: |
G01N 33/5005
20130101 |
Class at
Publication: |
435/374 |
International
Class: |
C12N 5/06 20060101
C12N005/06 |
Claims
1. A method for commercializing a cell line having a desired
biological activity, comprising: treating the cell line such that
the cell line will maintain the desired biological activity for no
more than about 30 days at a temperature above freezing, but cannot
be propagated or maintained thereafter; freezing the treated cell
line at a temperature and under conditions such that it will resume
the required biological activity after thawing; and selling or
distributing the frozen treated cell line whereby said cells will
be available for a limited time but cannot be propagated and
maintained indefinitely for multiple uses.
2. A method in accordance with claim 1, wherein said treating step
comprises treating the cell line such that the cell line will
maintain the desired biological activity for at least about 8
hours, but no more than about 30 days at a temperature above
freezing.
3. A method in accordance with claim 2, further comprising the step
of suspending the treated cell line in a solution containing a
cryopreservative before said freezing step.
4. A method in accordance with claim 3, wherein the
cryopreservative is a combination of DMSO and glycerol and the
solution contains 2.5% DMSO and 10% glycerol.
5. A method in accordance with claim 3, wherein the solution
comprises RPMI medium and 40% fetal bovine serum.
6. A method in accordance with claim 2, wherein said treating step
treats the cell line with an agent, which is anti-mitotic and
pro-apoptotic, in a sufficient amount and for a sufficient time
such that the cell line will maintain the desired biological
activity for at least about 8 hours, but will lose said signal
transduction activity and undergo cellular death in no more than
about 30 days at a temperature above freezing.
7. A method in accordance with claim 6, wherein the anti-mitotic
and pro-apoptotic agent is vinblastine.
8. A method in accordance with claim 6, wherein the anti-mitotic
and pro-apoptotic agent is 5-fluorouracil.
9. A method in accordance with claim 1, wherein, in said freezing
step, the temperature is about -80.degree. C.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional of application Ser.
No. 10/677,777, filed Oct. 3, 2003, which claims the benefit of
priority from U.S. provisional application No. 60/415,818, filed
Oct. 4, 2002, the entire content of these applications are herein
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a gene reporter assay and a
kit for determining the presence and/or the level in a sample of a
molecule that activates the signal transduction activity of a cell
surface protein. The present invention further relates to a cell
which can be used in such an assay and to a method for preparing
such a cell.
[0004] 2. Description of the Related Art
[0005] Cell surface proteins permit intracellular transduction of
extracellular signals. Cell surface proteins provide eukaryotic, as
well as prokaryotic, cells a means to detect extracellular signals
and transduce such signals intracellularly in a manner that
ultimately results in a cellular response or a concerted tissue or
organ response. Cell surface proteins, by intracellularly
transmitting information regarding the extracellular environment
via specific intracellular pathways induce an appropriate response
to a particular stimulus. The response may be immediate and
transient, slow and sustained, or some mixture thereof. By virtue
of an array of varied membrane surface proteins, eukaryotic cells
are exquisitely sensitive to their environment.
[0006] Extracellular signal molecules, such as cytokines, growth
factors, hormones, vasodilators and neurotransmitters, exert their
effects, at least in part, via interaction with cell surface
proteins. For example, some extracellular signal molecules cause
changes in transcription of target gene via changes in the levels
of secondary messengers, such as cAMP. Other signals, indirectly
alter gene expression by activating the expression of genes, such
as immediate-early genes that encode regulatory proteins, which in
turn activate expression of other genes that encode transcriptional
regulatory proteins. Other extracellular signal molecules cause
activation of latent cytoplasmic signal transducers and activators
of transcription (STAT) protein that enhance the transcription of
specific sets of genes.
[0007] Cell surface receptors and ion channels are among the cell
surface proteins that respond to extracellular signals and initiate
the events that lead to this varied gene expression and response.
Ion channels and cell surface-localized receptors are ubiquitous
and physiologically important cell surface membrane proteins. They
play a central role in regulating intracellular levels of various
ions and chemicals, many of which are important for cell viability
and function.
Cell Surface Receptors
[0008] Cell surface-localized receptors are membrane spanning
proteins that bind extracellular signalling molecules or changes in
the extracellular environment and transmit the signal via signal
transduction pathways to effect a cellular response. Cell surface
receptors bind circulating signal molecules, such as cytokines,
growth factors and hormones, etc., as the initiating step in the
induction of numerous intracellular pathways. Receptors are
classified on a structural basis or on the basis of the particular
type of pathway that is induced. Among these classes of receptors
are classes of cytokine receptors which include those that bind
growth factors and have intrinsic tyrosine kinase activity, such as
the heparin binding growth factor (HBGF) receptors, the
immunoglobulin receptor superfamily, the hematopoietin/cytokine
receptor superfamily, the nerve-growth factor receptor superfamily,
other receptor tyrosine or serine kinases, and those that couple to
effector proteins through guanine nucleotide binding regulatory
proteins, which are referred to as G protein coupled receptors and
G proteins, respectively.
[0009] Cytokines are intercellular messengers which coordinate
communication between cells within a particular tissue, for
example, antibody and T cell immune system interactions, and serve
to modulate or modify the biological response. They are pleiotropic
and have a broad spectrum of biological effects on more than one
type of cell or tissue. The receptors for cytokines are broadly
grouped into two classes, where the Class I cytokine receptors
include receptors that bind various interleukins (IL-2, IL-3, IL-4,
IL-6, IL-7, IL-9, IL-11, IL-12, IL-15), erythropoietin (EPO),
growth hormone (GH), granulocyte colony stimulating factor (G-CSF),
granulocyte macrophage colony stimulating factor (GM-CSF), leukemia
inhibitory factor (LIF), and ciliary neurotrophic factor (CNTF),
and the Class II cytokine receptors include receptors that bind
interferon (IFN) .alpha./.beta., IFN.gamma., and IL-10.
Interferon Receptors
[0010] Human interferons (IFNs) are a family of homologous helical
cytokines composed of four distinct species: .alpha., .beta.,
.gamma. and .omega. based on nucleotide and amino acid sequence
homology. The Type I IFNS, .alpha., .beta., and .omega., are
encoded by at least 12 functional IFN.alpha. genes, an IFN.omega.
gene, and a more distantly related IFN.beta. gene. Type II IFN, or
IFN.gamma., is encoded by an unrelated gene and binds to a distinct
cell surface receptor (De Maeyer et al., 1988; Pestka et al., 1987
and Diaz et al., 1993).
[0011] Type I IFNs bind to a common receptor, as shown by their
ability to cross-compete for receptor binding (Pestka et al., 1987;
Branca et al., 1981; and Merlin et al., 1985). The Type 1
interferon receptor has the largest number of natural ligands, some
14 in all, of all known cytokine receptors. Binding of interferons
to their cell surface receptor represents the initial and probably
most specific step in the IFN signaling pathway.
[0012] The Type I IFN receptor is composed of two transmembrane
glycoproteins, IFNAR1 and IFNAR2 (Uze et al., 1990; Novick et al.,
1994; Lutfalla et al., 1995; Domanski et al., 1995), which are
rapidly tyrosine-phosphorylated following IFN binding (Platanias et
al., 1994; Constantinescu et al., 1994; and Abramovich et al.,
1994). Both subunits belong to the class II cytokine receptor
superfamily (Bazan et al., 1990 and Thoreau et al., 1990) and are
required for high affinity ligand binding and the establishment of
biological activity (Langer et al., 1996 and Domanski et al.,
1996). Class II cytokine receptors are distinguished from Class I
receptors on the basis of the pattern of the conserved pairs of
cysteine residues that are thought to form disulfide bonds.
[0013] In contrast to other cytokine receptors, particularly the
IFN-.gamma. receptor, neither IFNAR1 nor IFNAR2 alone bind to
IFN.alpha. or IFN.beta. with an affinity comparable to the
heterodimer. Despite the fact that IFNAR2 plays a prominent role in
ligand binding, IFNAR1 contributes to IFN binding by increasing the
affinity of the receptor complex (4-10 fold) relative to that of
IFNAR2 alone. IFNAR1 also modulates the specificity of ligand
binding relative to that observed with IFNAR2 alone (Cohen et al.,
1995; Russell-Harde et al., 1995; Cutrone et al., 1997; and Cook et
al., 1996). IFNAR1 has a larger extracellular domain than most
other class II cytokine receptors, composed of 4
immunoglobulin-like subdomains separated by di- or tri-proline
motifs which can be divided into two tandem repeats (Novick et al.,
1994; Lutfalla et al., 1992; and Uze et al., 1995).
[0014] Human, murine and bovine IFNAR1 have been cloned and
expressed in human and murine cells. Studies performed with
transfected cells show that IFNAR1 plays a central role in ligand
binding, cellular responses to IFNs and in the induction of the
biological activities of the Type I interferons (Novick et al.,
1994; Abramovich et al., 1994; Uze et al., 1992; Mouchel-Vielh et
al., 1992; Lim et al., 1993; Cleary et al., 1994; Constantinescu et
al., 1995; Hwang et al., 1995; Vandenbroek et al., 1995; and
Colamonici et al., 1994). Furthermore, the intracellular domain of
IFNAR1 has been shown to play a key role in the transduction of the
signal initiated at the cell surface by binding of Type I
interferons to the nucleus (Basu et al., 1998). Targeted disruption
of the IFNAR1 gene results in the loss of the antiviral response to
Type I IFNs demonstrating that this receptor polypeptide is an
essential component of the receptor complex and that both IFNAR1
and IFNAR2 subunits are required for IFN.alpha. and IFN.beta.
signaling (Vandenbroek et al., 1995; Muller et al., 1994; Fiette et
al., 1995; Steinhoff et al., 1995; and van den Broek et al.,
1995).
[0015] Binding of type I interferon to the receptor complex
activates two Janus kinases, Tyk2 and JAK1, which mediate the
tyrosine phosphorylation and activation of two latent cytoplasmic
transcription factors STAT1 and STAT2 which form a complex with a
p48 DNA binding protein, interferon responsive protein 9 (IRF 9),
which is translocated to the nucleus to promote specific gene
transcription (Fu et al., 1992; Schindler et al., 1992; Darnell et
al., 1994; Ihle et al, 1995; and Taniguchi, 1995). Both Tyk2 and
STAT2 are constitutively associated with the membrane proximal
region of the IFNAR1 chain, while JAK1 and STAT1 are physically
associated with IFNAR2 and all four factors are rapidly activated
during IFN.alpha. stimulation (Lutfalla et al., 1995; Bazan, 1990;
Basu et al., 1998; Barbieri et al., 1994; Velazquez et al., 1995;
Uddin et al., 1995; Yan et al., 1996(a) and 1996(b).
G-Coupled Receptors
[0016] The G protein transmembrane signaling pathways consist of
three proteins: receptors, G proteins and effectors. G proteins,
which are the intermediaries in transmembrane signaling pathways,
are heterodimers and consist of .alpha., .beta. and .gamma.
subunits. Among the members of a family of G proteins the .alpha.
subunits differ. Functions of G proteins are regulated by the
cyclic association of GTP with the .alpha. subunit followed by
hydrolysis of GTP to GDP and dissociation of GDP.
[0017] G protein coupled receptors are a diverse class of receptors
that mediate signal transduction by binding to G proteins. Signal
transduction is initiated via ligand binding to the cell membrane
receptor, which stimulates binding of the receptor to the G
protein. The receptor G protein interaction releases GDP, which is
specifically bound to the G protein, and permits the binding of
GTP, which activates the G protein. Activated G protein dissociates
from the receptor and activates the effector protein, which
regulates the intracellular levels of specific second messengers.
Examples of such effector proteins include adenyl cyclase, guanyl
cyclase, phospholipase C, and others.
Growth Factors and Growth Factor Receptors
[0018] Polypeptide growth factors are modulators of cell
proliferation and differentiation whose biological functions are
mediated by the interaction of the growth factor with cell surface
receptors and subsequent alterations in gene expression. Growth
factors bind to specific receptors and appear to induce tyrosine
phosphorylation and c-fos mRNA synthesis. In addition, at least
some growth factors, such as platelet-derived growth factor (Yeh et
al., 1987) and heparin-binding growth factor-2 or basic fibroblast
growth factor (Bouche et al., 1987), are translocated to the
nucleus.
[0019] Activation of growth factor receptors by interaction with
specific growth factors or with agents such as phorbol mistric
acetate (PMA) activates protein kinase C, which is a family of
phospholipid- and calcium-activated protein kinases. This
activation results in the transcription of an array of
proto-oncogene transcription factor encoding genes, including
c-fos, c-myc and c-jun, proteases, protease inhibitors, including
collagenase type I and plasminogen activator inhibitor, and
adhesion molecules, including intercellular adhesion molecule I.
Protein kinase C activation antagonizes growth factor activity by
the rapid phosphorylation of growth factor receptors, which thereby
decreases tyrosine kinase activity. Growth factors and other
mitogens that induce cell proliferation and cell growth are
believed to play a role in tumor growth, which often carry
identifiable cell surface receptors specific for growth factors and
other extracellular signals.
[0020] The interaction of nerve growth factor (NGF) with its
receptor is typical of the array of responses such an extracellular
signal induces. NGF is a polypeptide growth hormone that is
necessary for differentiation and growth of the neural
crest-derived sensory neuron. NGF binds to its specific cell
surface receptor and is retrogradely transported to the cell body
(Changelian et al., 1989). This initiates a cascade of
intracellular events, culminating in a differentiated phenotype.
PC12 cells, which are a rat pheochromocytoma cell line, are used as
a model for the study of NGF-mediated differentiation. When treated
with NGF, PC12 cells change from replicating
adrenal-chromaffin-like cells to nonreplicating, electrically
excitable sympathetic-neuron-like cells.
[0021] Concomitant with the phenotypic changes, there is induction
and expression of specific genes. Binding of NGF to PC12 cells
induces the immediate and rapid expression of certain genes,
including the c-fos, NGF1-A and NGF1-.gamma.genes, which are
referred to as early genes. Such early genes are believed to encode
transcriptional regulators. The NGF-1A gene product contains
tandemly repeated "zinc finger" domains that are characteristic of
DNA-binding proteins, and the NGF1-B protein is homologous to
members of the glucocorticoid receptor family and, thus, may
function as a ligand-dependent modulator of transcription. The
c-fos gene product, FOS appears to function as a transcriptional
regulatory molecule.
The c-fos Gene and Related Genes
[0022] As discussed above, induction of expression of the c-fos
gene is an event that is common to a number of response pathways
that are initiated by the activity of a variety of cell surface
proteins.
[0023] The c-fos gene product, FOS, associates with the
transcription activator JUN, which is the product of the c-jun
gene, to form a complex that forms a transcription activation
complex, AP-1. Transcription of both c-fos and c-jun is induced
rapidly and transiently following stimulation. The induced mRNAs
accumulate for 1-2 hours in the cytoplasm where the FOS and JUN
proteins, which are short-lived, are translated and then
translocated to the nucleus to form a heterodimeric protein complex
that binds to the DNA regulatory element, AP-1 binding site.
[0024] The c-fos and c-jun genes are members of gene families that
encode proteins that participate in the formation of heterodimeric
complexes that interact with AP-1 binding sites. Transcription
factor AP-1 is composed of several protein complexes whose
concentrations change upon cell stimulation. These complexes
specifically interact with a seven-base core nucleotide sequence
motif, that is known to be a relatively common constituent of both
positive and negative transcriptional regulatory elements and that
is required for both basal and induced levels of gene
expression.
[0025] The gene products, FOS and JUN cooperate in the regulation
of target genes that underlie many cellular and adaptive responses
to the environment. They are involved in a number of
neurophysiological processes.
[0026] Thus, c-fos induction involves distinct second messenger
pathways that act via separate regulatory elements and that
differentially modify, the resulting gene product, FOS, which in
turn interacts in different ways with differentially modified JUN
protein. Therefore, a multitude of extracellular events induce
expression of a small number of inducible proteins that form an
array of protein complexes that can differentially bind to DNA
regulatory elements that contain AP-1 binding sites. Therefore,
numerous cell surface proteins can act via overlapping transduction
pathways and transduce extracellular signals that ultimately induce
a variety of responses.
[0027] There are many assays that may rely on in vivo activity in a
living cell line. One example is a cell line having an Interferon
Stimulatory Response Element (ISRE) connected to a luciferase gene,
or another reporter gene, so that when the cell line is subjected
to the presence of interferon as an extracellular signal, the
signal transduction activity of endogenous interferon cell surface
receptors produces a signal that activates the ISRE, which then
causes transcription of the luciferase gene. Thus, the activity of
luciferase in creating light can be measured and is related to the
amount of interferon which is present in the sample, and which is
proportional to the amount of interferon over a particular range
(Lallemand et al., 1996).
[0028] Lleonart et al. (1990) described a reporter gene assay for
Type I interferon based on monkey Vero cells transfected with Type
I interferon inducible mouse Mx promoter linked to the human growth
hormone (hGH) gene as the reporter gene. This Type I interferon
assay was developed further by transfecting monkey Vero cells with
a plasmid carrying the luciferase reporter gene under the control
of the Type I interferon inducible mouse Mx1 promoter (Canosi et
al., 1996).
[0029] A further type of interferon reporter gene assay was
developed by Hammerling et al. (1998) who used a human glioblastoma
cell line transfected with a reporter gene construct of glial
fibrillary acidic protein (GFAP) promoter and an E. coli
.beta.-galactosidase (lacZ) reporter gene. In this particular
assay, it is the reduction/inhibition of .delta.-galactosidase
expression by either human Type I or Type II interferon in a
selective and dose dependent manner that is measured.
[0030] With the types of cell lines which can be used in such
assays, there is a problem in commercializing them in that once the
cell line is shipped for use in a single assay, the end user can
grow the cells and then use their own stock of such cells for
future assays without the need to order more cells from the
supplier.
[0031] Citation of any document herein is not intended as an
admission that such document is pertinent prior art, or considered
material to the patentability of any claim of the present
application. Any statement as to content or a date of any document
is based on the information available to applicant at the time of
filing and does not constitute an admission as to the correctness
of such a statement.
SUMMARY OF THE INVENTION
[0032] It is an object of the present invention to develop a way to
make a desirable cell line an essentially "one time use" commercial
cell line with a sufficiently long shelf life for its intended
purpose so that whenever a user uses this commercial cell line,
such as in an assay, this user must purchase cells of this
commercial cell line from a supplier.
[0033] Thus, the present invention provides a cell transformed with
a reporter gene construct in which the expression of the reporter
gene product is regulated by the signal transduction activity of a
cell surface protein in response to an extracellular signal. This
cell according to the present invention has been treated so that it
will maintain signal transduction activity for at least about 1
hour, but no more than 30 days at a temperature above freezing,
before losing that ability. Such a treated cell has acquired the
commercial advantage of having a sufficiently long shelf life for
its purpose by maintaining the cell in a state or by inhibiting
cell division, whereupon at the end of its useful shelf life or at
the end of its use the cell undergoes cellular death such as by
apoptosis.
[0034] The present invention also provides a cell based assay kit
for determining the level in a sample of a molecule that activates
the signal transduction activity of a cell surface protein. Such a
kit includes a testing device with multiple wells and a reagent
containing a plurality of the cell of the present invention.
[0035] Further provided by the present invention is a method for
preparing the cell of the present invention, which loses signal
transduction within 30 days. This method involves transforming a
host cell with a reporter gene construct described above for the
cell of the present invention and then treating the transformed
cell so that the treated transformed cell will maintain signal
transduction activity for at least about 1 hour but no more than
about 30 days at a temperature above freezing before losing the
signal transduction activity.
[0036] Another aspect of the present invention is directed to a
method for determining the presence and/or the level in a sample of
a molecule that activates the signal transduction activity of a
cell surface protein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 shows a schematic representation of a luciferase
reporter gene construct where luciferase expression is under the
control of a chimeric promoter containing an interferon sensitive
response element (ISRE) from the ISG15 gene and a minimal SV40
promoter.
[0038] FIG. 2 shows a schematic representation of an enhanced green
fluorescent protein (EGFP-1) reporter gene construct where EGFP-1
expression is under the control of a chimeric promoter containing
an ISRE from the ISG15 gene and a minimal SV40 promoter.
[0039] FIG. 3 shows the standard curves of luciferase activity in
PIL5 cells in the presence of different amounts of each of the
various isotypes of human Type I interferon.
[0040] FIG. 4 is a graph showing luciferase activity in PIL5 cells
four days after different doses of .gamma. radiation and incubation
at 37.degree. C.
[0041] FIG. 5 is a graph showing the percentage of viable PIL5
cells at various times after 6 Grays (Gy) of .gamma. radiation and
incubation at 37.degree. C.
[0042] FIG. 6 is a graph showing luciferase activity in PIL5 cells
at various times after 6 Gy of .gamma. radiation and incubation at
room temperature.
[0043] FIG. 7 is a graph showing luciferase activity in PIL5 cells
eight days after 6 Gy of .gamma. radiation and incubation at
4.degree. C. or room temperature.
[0044] FIG. 8 is a graph showing luciferase activity in PIL5 cells
five days after 6 Gy of .gamma. radiation and incubation at
37.degree. C. in culture medium containing 0%, 1%, or 10% fetal
bovine serum (FBS).
[0045] FIG. 9 is a graph showing luciferase activity in different
cell concentrations of PIL5 cells thirteen days after 6 Gy of
.gamma. radiation and incubation at 37.degree. C. in culture medium
containing 10% or 20% fetal bovine serum (FBS).
[0046] FIG. 10 is a graph showing luciferase activity in PIL5 cells
fourteen days after 6 Gy of .gamma. radiation and treatment with
aurintricarboxylic acid at room temperature.
[0047] FIG. 11 is a graph showing luciferase activity in PIL5 cells
24 hours after thawing from 1 month storage at -20.degree. C. in
10% DMSO. The PIL5 were treated for 1 hour with different
concentrations of anti-mitotic and pro-apoptotic agents,
vinblastine (Vin) or 5-fluorouracil (5Fu), prior to freezing and
storage at -20.degree. C.
[0048] FIG. 12 is a graph showing the effect of vinblastine or
5-fluorouracil on interferon sensitivity of frozen cells. PIL5
cells were treated for 1 hour at 37.degree. C. with 1.0, 10, or 100
.infin.M vinblastine, or 10, 100 .mu.M, or 1.0 mM 5-fluorouracil,
centrifuged, and suspended in 50 .mu.l of RPMI 1640 medium with 20%
fetal bovine serum (FBS) and 10% dimethlysulfoxide (DMSO), and
2.times.10.sup.5 cells were distributed into each well of a
micro-titer culture plate and frozen at -80.degree. C. After
storage at -80.degree. C. and subsequent storage at -20.degree. C.,
the plate was thawed rapidly and a standard preparation of human
IFN .alpha. was titrated in the luciferase gene reporter assay
procedure described above.
[0049] FIG. 13 is a graph showing the effect of vinblastine on
interferon sensitivity of frozen cells. PIL5 cells were treated for
10 minutes at 37.degree. C. with 0.1, or 1.0 .mu.g/ml of
vinblastine, centrifuged, and suspended in 25 .mu.l of RPMI 1640
medium with 40% FBS and 10% glycerol, and 2.times.10.sup.5 cells
were distributed into each well of a micro-titer culture plate and
frozen at -80.degree. C. After storage at -80.degree. C. and
subsequent storage at -20.degree. C., the plate was thawed rapidly
and a standard preparation of human IFN .alpha. was titrated in the
luciferase gene reporter assay procedure described above.
[0050] FIG. 14 is a graph showing the effect of time of treatment
with vinblastine on interferon sensitivity of frozen cells. PIL5
cells were treated for 10, 20, 30, or 40 minutes at 37.degree. C.
with 1.0 .mu.g/ml vinblastine, centrifuged, and suspended in 50
.mu.l of RPMI 1640 medium with 20% FBS and 10% DMSO, and
2.times.10.sup.5 cells were distributed into each well of a
micro-titer culture plate and frozen at -80.degree. C. After
storage at -80.degree. C. and subsequent storage at -20.degree. C.,
the plate was thawed rapidly and a standard preparation of human
IFN .alpha. was titrated in the luciferase gene reporter assay
procedure described above.
[0051] FIG. 15 is a graph showing the effect of glycerol
concentration on interferon sensitivity of frozen cells. PIL5 cells
were treated for 10 minutes at 37.degree. C. with 100 .mu.M
vinblastine, centrifuged, and suspended in 25 .mu.l of RPMI 1640
medium with 40% FBS and 5, or 10% glycerol, and 2.times.10.sup.5
cells were distributed into each well of a micro-titer culture
plate and frozen at -80.degree. C. After storage at -80.degree. C.
and subsequent storage at -20.degree. C., the plate was thawed
rapidly and a standard preparation of human IFN .alpha. was
titrated in the luciferase gene reporter assay procedure described
above.
[0052] FIG. 16 is a graph showing the effect of glycerol
concentration on the interferon sensitivity of frozen cells. PIL5
cells were treated for 10 minutes at 37.degree. C. with 100 .mu.M
vinblastine, centrifuged, and suspended in 25 .mu.l of RPMI 1640
medium with 40% FBS and 5, 10, 15, 20% glycerol, or 5% glycerol and
5% DMSO and 2.times.10.sup.5 cells were distributed into each well
of a micro-titer culture plate and frozen at -80.degree. C. After
storage at -80.degree. C. and subsequent storage at -20.degree. C.,
the plate was thawed rapidly and a standard preparation of human
IFN .alpha. was titrated in the luciferase gene reporter assay
procedure described above.
[0053] FIG. 17 is a graph showing the effect of glycerol in the
presence or absence of DMSO on the interferon sensitivity of frozen
cells. PIL5 cells were treated for 10 minutes at 37.degree. C. with
100 .mu.M vinblastine, centrifuged, and suspended in 25 .mu.l of
RPMI 1640 medium with 40% FBS and 10% glycerol, with or without
2.5% DMSO, and 2.times.10.sup.5 cells were distributed into each
well of a micro-titer culture plate and frozen at -80.degree. C.
After storage at -80.degree. C. and subsequent storage at
-20.degree. C., the plate was thawed rapidly and a standard
preparation of human IFN .alpha. was titrated in the luciferase
gene reporter assay procedure described above.
[0054] FIG. 18 is a graph showing the effect of cell density on the
interferon sensitivity of frozen cells. PIL5 cells were treated for
10 minutes at 37.degree. C. with 100 .mu.M vinblastine,
centrifuged, and 2.times.10.sup.5 cells suspended in 10, 25, or 50
.mu.l of RPMI 1640 medium with 40% FBS and 10% DMSO, and
distributed into the wells of a micro-titer culture plate and
frozen at -80.degree. C. After storage at -80.degree. C. and
subsequent storage at -20.degree. C., the plate was thawed rapidly
and a standard preparation of human IFN .alpha. was titrated in the
luciferase gene reporter assay procedure described above.
[0055] FIG. 19 is a graph showing the effect of cell density on the
interferon sensitivity of frozen cells. PIL5 cells were treated for
10 minutes at 37.degree. C. with 100 .mu.M vinblastine,
centrifuged, and 2.times.10.sup.5 cells suspended in 25 or 50 .mu.l
of RPMI 1640 medium with 40% FBS and 10% DMSO, and distributed into
the wells of a micro-titer culture plate and frozen at -80.degree.
C. After storage at -80.degree. C. and subsequent storage at
-20.degree. C., the plate was thawed rapidly and a standard
preparation of human IFN .alpha. was titrated in the luciferase
gene reporter assay procedure described above.
[0056] FIG. 20 is a graph showing the effect of cell density on the
interferon sensitivity of frozen cells. PIL5 cells were treated for
10 minutes at 37.degree. C. with 100 .mu.M vinblastine,
centrifuged, and 2.times.10.sup.5 cells suspended in 10, 25, or 50
.mu.l of RPMI 1640 medium with 40% FBS and 10% glycerol, and
distributed into the wells of a micro-titer culture plate and
frozen at -80.degree. C. After storage at -80.degree. C. and
subsequent storage at -20.degree. C., the plate was thawed rapidly
and a standard preparation of human IFN .alpha. was titrated in the
luciferase gene reporter assay procedure described above.
[0057] FIG. 21 is a graph showing the effect of cell number on
interferon sensitivity following freezing. PIL5 cells were treated
for 10 minutes at 37.degree. C. with 100 .mu.M vinblastine,
centrifuged, and 0.5, 1.0, or 2.times.10.sup.5 cells suspended in
10 .mu.l of RPMI 1640 medium with 40% FBS and 10% glycerol, and
distributed into the wells of a micro-titer culture plate and
frozen at -80.degree. C. After storage at -80.degree. C. and
subsequent storage at -20.degree. C., the plate was thawed rapidly
and a standard preparation of human IFN .alpha. was titrated in the
luciferase gene reporter assay procedure described above.
[0058] FIG. 22 is a graph showing the effect of cell number on
interferon sensitivity following freezing. PIL5 cells were treated
for 10 minutes at 37.degree. C. with 100 .mu.M vinblastine,
centrifuged, and 0.5, 1.0, or 2.times.10.sup.5 cells suspended in
10 .mu.l of 40% FBS and distributed into the wells of a micro-titer
culture plate and frozen at -80.degree. C. After storage at
-80.degree. C. and subsequent storage at -20.degree. C., the plate
was thawed rapidly and a standard preparation of human IFN a was
titrated in the luciferase gene reporter assay procedure described
above.
[0059] FIG. 23 is a graph showing the effect of freezing in a
cryo-preservation ampoule or micro-titer plate on interferon
sensitivity. PIL5 cells were treated for 10 minutes at 37.degree.
C. with 1.0 .mu.g/ml of vinblastine, centrifuged, and suspended of
RPMI 1640 medium with 40% FBS, 10% glycerol, and 2.5% DMSO. The
cells were then distributed into each well of a micro-titer culture
plate (2.times.10.sup.5 cells in 25 .mu.l/well) or added to a
cryo-preservation ampoule (2.times.10.sup.7 cells in 1.0 ml) and
frozen at -80.degree. C. After storage at -80.degree. C. and
subsequent storage at -20.degree. C., the micro-titer plate and
cryo-preservation ampoule were thawed rapidly and a standard
preparation of human IFN a was titrated in the micro-titer plate,
or the contents of the cryo-preservation ampoule (2.times.10.sup.7
cells in 1.0 ml) were diluted in 6.5 ml of RPMI 1640 medium and 75
.mu.l of cell suspension was then distributed into each well of a
micro-titer culture plate and a standard preparation of human IFN a
was titrated in the micro-titer plate in the luciferase gene
reporter assay procedure described above.
[0060] FIG. 24 is a graph showing the titration of a standard
interferon preparation on PIL5 cells following freezing. PIL5 cells
were treated for 10 minutes at 37.degree. C. with 1.0 .mu.g/ml of
vinblastine, centrifuged, and suspended at a concentration of
2.times.10.sup.5 cells/25 .mu.l in RPMI 1640 medium with 40% FBS,
10% glycerol, and 2.5% DMSO, and distributed into each well of a
micro-titer culture plate and frozen at -80.degree. C. After
storage at -80.degree. C. and subsequent storage at -20.degree. C.,
the plate was thawed rapidly and a standard preparation of human
IFN a was titrated in the luciferase gene reporter assay procedure
described above.
DETAILED DESCRIPTION OF THE INVENTION
[0061] The present invention is directed to a cell transformed with
a reporter gene construct comprising a nucleotide sequence encoding
a reporter gene product operatively linked to one or more
transcriptional control elements that is regulated by the signal
transduction activity of a cell surface protein in response to an
extracellular signal. This cell of the present invention has been
treated in such a way that it will maintain the signal transduction
activity of the cell surface protein for at least about 1 hour but
no more than about 30 days at a temperature above freezing before
losing the signal transduction activity. Thus, not only does the
cell of the present invention have a sufficient shelf life by
inhibiting cell division or by maintaining the cell in a frozen
state for the purpose desired by an end user, such as for
conducting an assay, but it has been treated in such a manner that
the cells can be frozen, or even kept at room temperature, allowing
storage for extended periods and transportation in a frozen state
or at room temperature. The cell of the present invention also has
the commercial advantage to a supplier of being a one time use cell
that cannot be propagated by the end user for possible further use.
Instead, the cell, preferably as part of a kit, must be purchased
from the supplier for each single use.
[0062] The cell according to the present invention may be any
eukaryotic or prokaryotic cell. Mammalian and avian cells are
however preferred, with human cells most preferred. Non-limiting
examples of other suitable cells include other vertebrate cells,
plant protoplasts, fungal and yeast cells, and bacterial cells.
[0063] The cell surface protein from which its signal transduction
activity, in response to an extracellular signal, regulates the
expression of a reporter gene product can be any cell surface
protein that is known to those of skill in the art or that may be
identified by those of skill in the art. Exemplary cell surface
proteins include, but are not limited to, cell surface receptors
and ion channels. Non-limiting examples of cell surface receptors
include cytokine receptors (e.g., receptors for Type I interferon,
Type II interferon, interleukins, growth hormone, erythropoietin
(EPO), granulocyte colony stimulating factor (G-CSF), granulocyte
macrophage colony stimulating factor (GM-CSF), leukemia inhibitory
factor (LIF), ciliary neurotrophic factor (CNTF), etc.), growth
factor receptors, hormone receptors, T cell receptors, antigen
receptors, complement receptors, and neuroreceptors. The reference
text, J. M. Cruse and Robert E. Lewis, Atlas of Immunology, CRC
Press, Washington, D.C., 1999, which discloses many receptors
involved in immune response and immune system interactions is
entirely incorporated herein by reference. Cell surface receptors
also include, but are not limited to, muscarinic receptors (e.g.,
human M2 (GenBank accession #M16404); rat M3 (GenBank accession
#M16407); human M4 (GenBank accession #M16405); human M5 (Bonner et
al., 1988); and the like); neuronal nicotinic acetylcholine
receptors (e.g., the .alpha.2, .alpha.3 and .beta.2 subtypes); the
rat .alpha.2 subunit (Wada et al., 1988); the rat .alpha.3 subunit
(Boulter et al., 1986); the rat .alpha.4 subunit (Goldman et al.,
1987); the rat .alpha.5 subunit (Boulter et al., 1990); the rat
.beta.2 subunit (Deneris et al., 1988); the rat .beta.3 subunit
(Deneris et al., 1989); the rat .beta.4 subunit (Duvoisin et al.,
1989); combinations of the rat .alpha. subunits, .beta. subunits
and .alpha. and .beta. subunits; GABA receptors (e.g., the bovine
.alpha.1 and .beta.1 subunits (Schofield et al., 1987); the bovine
.alpha.2 and .alpha.3 subunits (Levitan et al., 1988); the
.gamma.-subunit (Pritchett et al., 1989); the 92 and .beta.3
subunits (Ymer et al., 1989); the 5 subunit (Shivers, B. D., 1989);
and the like); glutamate receptors (e.g., receptor isolated from
rat brain (Hollmann et al., 1989); and the like); adrenergic
receptors (e.g., human .beta.1 (Frielle et al., 1987); human
.alpha.2 (Kobilka et al., 1987); hamster .beta.2 (Dixon et al.,
1986); and the like); dopamine receptors (e.g., human D2 (Stormann
et al., 1990); rat (Bunzow et al., 1988); and the like); NGF
receptors (e.g., human NGF receptors (Johnson et al., 1986); and
the like); serotonin receptors (e.g., human 5HT1a (Kobilka et al.,
1987); rat 5HT2 (Julius et al., 1990); rat 5HTlc (Julius et al.,
1988); and the like).
[0064] Ion channels include, but are not limited to, calcium ion
channels (e.g., human neuronal .alpha.2 subunit (see W089/09834);
rabbit skeletal muscle .alpha.1 subunit (Tanabe et al. 1987);
rabbit skeletal muscle .alpha.2 subunit (Ellis et al., 1988);
rabbit skeletal muscle .beta. subunit (Ruth et al., 1989); rabbit
skeletal muscle .gamma. subunit (Jay et al., 1990); and the like);
potassium ion channels (e.g., rat brain (BK2) (McKinnon, D., 1989);
mouse brain (BK1) (Tempel et al., 1988); and the like); sodium ion
channels (e.g., rat brain I and II (Noda et al., 1986); rat brain
III (Kayano et al., 1988); and others).
[0065] It will be appreciated by those of skill in the art that the
cell surface protein discussed above is preferably endogenous to
the cell of the present invention. However, it will also be
appreciated that the cell surface protein may be expressed from
cloned DNA, such as to supplement the number of the cell surface
protein at the surface of the cell, or the cell surface protein may
be expressed from cloned DNA but is a cell surface protein that is
heterologous to the host cell.
[0066] For signal transduction, the intracellular signal that is
transduced is initiated by the specific interaction of an
extracellular signal, i.e., a molecule or a change in environment,
with a receptor or ion channel present on the cell surface. This
interaction sets in motion a cascade of intracellular events, the
ultimate consequence of which is a rapid and detectable change in
the expression of a gene product, which in the cell of the present
invention is a reporter gene product. The extracellular signal or
effector molecule is any compound or substance that in some manner
specifically alters the activity of a cell surface protein.
Examples of such signals include, but are not limited to, molecules
such as cytokines (i.e., interferons), growth factors, hormones,
endorphins, neurotransmitters, acetylcholine, and mitogenic
substances, such as phorbol mistric acetate (PMA), that bind to
cell surface receptors and ion channels and modulate the activity
of such receptors and channels. For example, antagonists are
extracellular signals that block or decrease the activity of cell
surface protein and agonists are examples of extracellular signals
that potentiate, induce or otherwise enhance the activity of cell
surface proteins.
[0067] The reporter gene construct carried by the cell of the
present invention is a DNA molecule that includes a nucleotide
sequence encoding a reporter gene product operatively linked to
transcriptional control elements/sequences. Transcription of the
reporter gene is controlled by these sequences. The activity of at
least one or more of these control sequences is directly or
indirectly regulated by the cell surface protein. The
transcriptional control sequences include but are not limited to
promoters and other regulatory regions, such as enhancer sequences
and repressor and activator binding sites, that modulate the
activity of the promoter, or control sequences that modulate the
activity or efficiency of the RNA polymerase that recognizes the
promoter, or control sequences that are recognized by effector
molecules, including those that are specifically induced by
interaction of an extracellular signal with a cell surface protein.
For example, modulation of the activity of the promoter may be
effected by altering the RNA polymerase binding to the promoter
region, or, alternatively, by interfering with initiation of
transcription or elongation of the mRNA. Such sequences are herein
collectively referred to as transcriptional control elements or
sequences. In addition, the construct may include sequences of
nucleotides that alter translation of the resulting mRNA, thereby
altering the amount of reporter gene product expressed.
[0068] A promoter that is regulated or mediated by the activity of
a cell surface protein is a promoter whose activity changes when a
cell is exposed to a particular extracellular signal by virtue of
the presence of cell surface proteins whose activities are affected
by the extracellular signal. For example, the c-fos promoter is
specifically activated upon the specific interaction of certain
extracellular signals, such as growth hormones, with a cell surface
protein, such as a growth hormone receptor. In particular, the
regulation of such promoters by the cell surface protein, though
indirect, occurs within minutes of the interaction of the cell
surface protein with the extracellular signal. As used herein,
operative linkage refers to the linkage of a transcriptional
control element, i.e., promoter, to a nucleotide coding sequence
such that the transcriptional control element is properly
positioned for its activity of binding RNA polymerase and
initiating transcription of the nucleotide coding sequence. Thus, a
nucleotide coding sequence in operative linkage with a promoter is
downstream, with respect to the direction of transcription, from
the promoter, is in the correct reading frame with respect to the
transcription initiation site and is inserted in a manner such that
transcription elongation proceeds through the nucleotide coding
sequence.
[0069] Suitable transcriptional control elements may be obtained or
derived from the transcriptional regulatory regions of genes whose
expression is rapidly induced, generally within minutes, of contact
between the cell surface protein and the effector protein that
modulates the activity of the cell surface protein. Examples of
such genes include, but are not limited to, the immediate early
genes (Sheng et al., 1990), such as c-fos. Immediate early genes
are genes that are rapidly induced upon binding of a ligand to a
cell surface protein. The transcriptional control elements that are
preferred for use in the reporter gene constructs include
transcriptional control elements from immediate early genes,
elements derived from other genes that exhibit some or all of the
characteristics of the immediate early genes, or synthetic elements
that are constructed such that genes in operative linkage therewith
exhibit such characteristics. The characteristics of preferred
genes from which the transcriptional control elements are derived
include, but are not limited to, low or undetectable expression in
quiescent cells, rapid induction at the transcriptional level
within minutes of extracellular simulation, induction that is
transient and independent of new protein synthesis, subsequent
shut-off of transcription requires new protein synthesis, and mRNAs
transcribed from these genes have a short half-life. It is not
necessary for all of these properties to be present.
[0070] Suitable promoters and transcriptional control elements
include, but are not limited to, the vasoactive intestinal peptide
(VIP) gene promoter (cAMP responsive; Fink et al., 1988); the
somatostatin gene promoter (cAMP responsive; Montminy et al.,
1986); the proenkephalin promoter (responsive to cAMP, nicotinic
agonists, and phorbol esters; Comb et al. 1986); the
phosphoenolpyruvate carboxy-kinase gene promoter (cAMP responsive;
Short et al., 1986); the NGFI-A gene promoter (responsive to NGF,
cAMP, and serum; Changelian et al., 1989); the transcriptional
control elements obtained or derived from the c-fos gene; and
others that may be known to or prepared by those of skill in the
art.
[0071] The c-fos proto oncogene is the cellular homologue of the
transforming gene of FBJ osteosarcoma virus. It encodes a nuclear
protein that is most likely involved in normal cellular growth and
differentiation. Transcription of c-fos is transiently and rapidly
activated by growth factors and by inducers of other cell surface
proteins, including hormones, differentiation-specific agents,
stress, mitogens and other known inducers of cell surface proteins.
Activation is protein synthesis independent. The c-fos regulatory
elements include a TATA box that is required for transcription
initiation, two upstream elements for basal transcription, and an
enhancer, which includes an element with dyad symmetry and which is
required for induction by TPA, serum, EGF, and PMA. The 20 bp
transcriptional enhancer element located between -317 and -298 bp
upstream from the c-fos mRNA cap site, which is essential for serum
induction in serum starved NIH 3T3 cells. One of the two upstream
elements is located at -63 to -57 and it resembles the consensus
sequence for cAMP regulation.
[0072] Transcriptional control elements, particularly as they
relate to a preferred embodiment of the present invention where
Type I and/or Type II interferon is the extracellular signal, are
preferably an interferon stimulatory response element (ISRE) and/or
a gamma activated sequence (GAS). There are a number of ISREs
characterized from different human genes responsive to Type I
interferon and a consensus sequence, ggraaagwGAAActg (SEQ ID NO:6;
capital letters denote core sequence; underlines denote high
conservation), to which the STAT1/STAT2/IRF9 complex binds, was
identified for ISRE (Levy et al., 1988). A preferred ISRE is from
the human ISG15 gene and is presented as SEQ ID NO:5 where
nucleotides 41-55 correspond to the consensus ISRE sequence. ISRE
is also highly conserved among species. For example, a sequence
present in the promoter region of the interferon inducible chicken
Mx gene (Schumacher et al., 1994) is similar to that found in
primates and conforms to the ISRE consensus sequence for mammalian
interferon responsive genes including rodents and cows (see FIG. 2
of Perry et al., 1999).
[0073] Regarding GAS, to which the STAT1 homodimer binds in genes
responsive to Type II interferon, a consensus sequence,
nnnsanttccgGGAAntgnsn (SEQ ID NO:7; capital letters denote core
sequence; underlines denote high conservation), from many selected
binding sequences was identified (Horvath et al., 1995).
[0074] In the embodiment of the present invention where Type I
interferon (see Example presented hereinbelow) and/or Type II
interferon is the extracellular signal, a preferred combination of
transcriptional control elements is an interferon responsive
chimeric promoter in which an ISRE and/or GAS controls a SV40
minimal promoter operatively linked to a nucleotide sequence
encoding a reporter gene product.
[0075] The reporter gene product, whose level is a measure of the
presence and/or the level of a molecule that activates the signal
transduction activity of a cell surface protein, may be RNA or
protein, as long as it is readily detectable. For instance, firefly
luciferase, enhanced green fluorescent protein (EGFP) and jellyfish
aequorin are most preferred embodiments of reporter gene products
used according to the present invention. In the case of the enzyme
firefly luciferase (deWet et al., 1987) and jellyfish aequorin
(Rider et al., 2003), the result of its enzymatic activity, light,
is detected and measured using a luminometer, whereas in the case
of EGFP, a fluorescence activated cell sorter or analyzer (FACS)
can be used at an appropriate wavelength to detect and quantify the
amount of EGFP expressed in a cell. The distribution curve of the
amount of luciferase, aequorin or EGFP expressed in a sample of
cells will be determined by the amount of ligand (within a given
range) to which the cell is exposed. Non-limiting examples of other
suitable reporter gene products include dsRED, chloramphenicol
acetyl transferase (CAT) (Alton et al., 1979) other enzyme
detection systems, such as .beta.-galactosidase, bacterial
luciferase (Engebrecht et al., 1984 and Baldwin et al. 1984),
alkaline phosphatase (Toh et al. 1989 and Hall et al. 1983), and
bacterial or humanized S-lactamase (Zlokarnik et al., 1998).
[0076] In order to provide the cell of the present invention, which
is a one time use cell that cannot be propagated for further use,
the cell transformed with a reporter gene construct is treated in
such a way that it will maintain the signal transduction activity
of the cell surface protein for at least about 1 hour but no more
than about 30 days at a temperature above freezing before losing
the signal transduction activity. Thus, according to one aspect of
the present invention, which is a method for preparing a cell
transformed with a reporter gene construct that loses signal
transduction activity within about 30 days, a cell is transformed
with a reporter gene construct containing a nucleotide sequence
encoding a reporter gene product operatively linked to one or more
transcriptional control elements that is regulated by the signal
transduction activity of a cell surface protein in response to an
extracellular signal. The transformed cell is then treated so that
it will maintain the signal transduction activity of the cell
surface protein for at least 1 hour but no more than about 30 days
at a temperature above freezing before losing this activity.
[0077] One preferred embodiment of the present invention is where
the transformed cell is treated by irradiating with
.beta.-radiation at an intensity and for a sufficient time such the
irradiated cell maintains the signal transduction activity of the
cell surface protein for a period of at least about 7 days but no
more than 30 days at a temperature above freezing following
irradiation, after which period of time the irradiated cell
immediately undergoes cellular death (i.e., apoptosis).
[0078] It is known that .gamma.-irradiation at a high dose causes a
cell to lose its signal transduction activity. Irradiation at a
somewhat lower dose causes a cell to cease replication and undergo
cellular death. The present inventors have now discovered that it
is possible to determine a dose which inhibits replication but
still allows a cell to maintains its signal transduction activity
for a period of time before undergoing cell death. For example,
.gamma.-irradiation at about 9 Grays allows a cell to retain signal
transduction activity for 14 days, after which the cells undergo
cell death. However, during those 14 days, the signal transduction
activity in response to, for example, Type I interferon that is
being assayed functions as well as in a non-irradiated control.
This is shown in the experiments using a luciferase gene reporter
assay for Type I interferon that are presented in the Example
hereinbelow. Thus, by irradiating a cell with y radiation, the
present invention provides a treated cell with a 14-day shelf life,
but which becomes inactive (undergoes cellular death) after a
period of about 14 days so that it cannot be maintained and
reproduced by an end user.
[0079] According to the irradiation embodiment of the present
invention, the dose (intensity and duration) of .gamma. radiation
to which the transformed cell is treated is preferably about 6 to
12 Grays (Gy). As the experiments in the Example presented
hereinbelow demonstrate, the temperature above freezing, at which
the cell is kept or stored, affects the shelf-life of the cell.
Preferably, this temperature is room temperature, which
advantageously maintains maximum interferon sensitivity while
providing for ease of storage and shipping of the commercial one
time use cell of the present invention.
[0080] A second preferred embodiment of the present invention is
where the transformed cell is treated with an anti-mitotic and
pro-apoptotic agent such as vinblastine, 5-fluorouracil (5-Fu), or
cisplatin in a sufficient amount and for a sufficient time such
that the treated cell maintains the signal transduction activity of
the cell surface protein for a period of at least about 1 hour but
no more than about 30 days at a temperature above freezing
following treatment with the agent, after which period of time the
treated cell immediately undergoes cellular death. An anti-mitotic
and pro-apoptotic agent will affect a treated cell when it begins
to replicate, thereby inducing apoptosis and killing the cell.
Thus, cells which have been treated with an anti-mitotic and
pro-apoptotic agent, such as the human promonocytic cells
transformed with a luciferase reporter gene construct exemplified
in the Example hereinbelow, will have a shelf life of about 24
hours during which the signal transduction assay can be conducted
and after which period of time the cells will die. It will be
appreciated that a cell having only a 24 hour shelf life is not
desirable from a commercial standpoint. In order to extend the
shelf life, the treated cells may be immediately frozen, in which
state they will have a much longer shelf life, depending upon the
manner of freezing and thawing. Once thawed, however, they must be
used within 24 hours, after which they will undergo cellular death
(i.e., apoptosis).
[0081] It should be understood that conventional wisdom is that
cryopreservation of cells requires a special freezing and thawing
process (and equipment) in which the cells are frozen at a rate of
1.degree. C. per minute until it reaches -80.degree. C. or liquid
nitrogen temperatures of about -200.degree. C., where it may be
stored indefinitely, and after which it must be thawed very
rapidly. Often, dimethyl sulfoxide (DMSO) or another
cryopreservative is also used in order to help protect the cells.
If the cells are treated with an anti-mitotic and pro-apoptotic
agent, they can be frozen with this cumbersome cryopreservation
technique for an indefinite period of time and then be used for a
purpose, such as a gene reporter assay for signal transduction
activity, for 24 hours after being thawed. However, this is
considered a less commercially viable technique as it would greatly
increase the manufacturing/processing cost.
[0082] As most laboratories do not have storage facilities at
-200.degree. C. or even -80.degree. C., it would be useful to allow
freezing of the cells to occur at -20.degree. C. However, it is
known that cell viability is poor when cells are frozen at
-20.degree. C. and then thawed. In the course of the
experimentation leading to the present invention, it was
unexpectedly discovered by the present inventors that DMSO will
protect the cells even when frozen at -20.degree. C. without any
special freezing or thawing techniques or equipment. While
glycerol, a known cryopreservative compound, will protect cells at
-20.degree. C., there is the possibility that it may prevent
protein ligands from interacting with surface receptors at the high
percentage (50%) of glycerol conventionally used for
cryopresevation. However, a low percentage of glycerol (much less
than the 50% conventionally used) can be used. DMSO does not have
this disadvantage. It is a discovery of the present invention that
DMSO will protect cells frozen at -20.degree. C. without any
special freezing or thawing techniques or equipment being required
and without adversely affecting their sensitivity to IFN as
demonstrated in the Example hereinbelow (see FIG. 11). Thus, it is
another surprising and inventive aspect of the present invention
that after treating with an anti-mitotic and pre-apoptotic agent, a
cell may achieve a long shelf life even at standard freezer
temperatures of -20.degree. C. if further treated with DMSO and
that once thawed such a cell will remain active, i.e., for signal
transduction assays, for approximately 24 hours until it undergoes
apoptosis as a result of being treated with an anti-mitotic and
pro-apoptotic agent. Any anti-mitotic and pro-apoptotic agent which
kills cells during the process of replication by inducing
apoptosis, such as vinbastine, 5-FU and cisplatin, can be used for
this purpose as it would be expected that the cells will remain
biologically active during a quiescent period and until such time
the treated cells start to die.
[0083] Thus, according to a second preferred embodiment of the
present invention, the treated transformed cell is frozen at a
temperature and under conditions such that it will resume signal
transduction after thawing. While the cell is preferably frozen at
a temperature between -20.degree. C. and -200.degree. C., more
preferably at -80.degree. C., and subsequently stored at
-20.degree. C., a commonly available freezer temperature in almost
all laboratories, it is intended that other suitable temperatures
for cryopreservation of cells, such as the liquid nitrogen
temperature of about -200.degree. C., be encompassed by the present
invention. It is further preferred that the treated transformed
cell be resuspended in a solution containing a cryopreservative
before freezing the cell. Dimethyl sulfoxide (DMSO) is the
preferred cryopreservative although other suitable
cryopreservatives which have a high bonding affinity to water, such
as ethylene glycol, polyethylene glycol, propylene glycol,
glycerol, butane diol, propanediol, and formamide, may be used so
long as they do not interfere with the use of the cell after
thawing. When DMSO is used alone as the cryopreservative, the
solution containing DMSO preferably contains about 10% DMSO. More
preferably, 2.5% DMSO is used in combination with 10% glycerol as
the cryopreservative.
[0084] Another aspect of the present invention is directed to an
assay kit for determining the level in a sample of a molecule that
activates the signal transduction activity of a cell surface
protein. This assay kit includes a plurality of the cell of the
present invention (as a reagent) and a testing device having a
plurality of wells. Preferably, the testing device is a multi-well
microtiter plate, but can also be any type of receptacle, such as
petri dishes or plates, with a plurality of wells in which an assay
can be conducted to determine the level of a molecule in a sample.
It is preferred that the cells as a component or reagent of the
assay kit be disposed in the wells of the testing device, although
it will be appreciated that such cells can instead be dispensed in
the wells of the testing device by the end user just prior to
conducting the assay. The kit may further include a set of
instructions for using the kit to conduct the intended assay for
determining the level of a molecule that activates the signal
transduction activity in a sample.
[0085] The present invention further provides an assay method for
determining the presence and/or the level in a sample, by reference
to a standard included in the assay, of a molecule that activates
the signal transduction activity of a cell surface protein,
preferably a cell surface receptor. This assay method uses the cell
of the present invention and can include the method of preparing
such a cell according to the present invention as its initial step
or steps. If the prepared cell is frozen according to a preferred
embodiment of the present invention, then the cell must be thawed
before proceeding to incubate it with a sample in which the
presence and/or the level of a molecule that activates the signal
transduction activity of a cell surface protein is sought to be
determined. In one preferred embodiment where the cell is
irradiated with .gamma. radiation, the cell is preferably
maintained and stored at room temperature until use. As the cell is
not frozen, a thawing step is unnecessary. After incubation, the
level of expression of a reporter gene product, encoded in the
reporter gene construct carried by the prepared cell, is determined
in the sample. This level of expression as determined by the method
according to the present invention is used to then qualitatively
determine the presence and/or quantitatively determine the level in
a sample of the molecule that activates the signal transduction
activity of a cell surface protein.
[0086] A gene reporter assay for Type I interferon is a most
preferred embodiment of the present invention. The reporter gene
product is preferably firefly luciferase, jellyfish aequorin, or or
enhanced green fluorescent protein (EGFP) and is preferably under
the control of an interferon sensitive chimeric promoter containing
the ISRE from ISG15 and a minimal SV40 promoter. Examples of such
reporter gene constructs are presented in FIGS. 1 and 2. FIG. 1 is
a schematic representation of a luciferase gene reporter construct
in an ISRE-luc vector (SEQ ID NO:1), where the ISRE from ISG15 (SEQ
ID NO:5) is positioned at nucleotides 38-97 of SEQ ID NO:1, the
SV40 minimal promoter is positioned at nucleotides 103-288 of SEQ
ID NO:1, and the coding sequence of the luciferase reporter gene
having the amino acid sequence of SEQ ID NO:2 is positioned at
nucleotides 328-1980 of SEQ ID NO:1. Similarly, FIG. 2 is a
schematic representation of a EGFP gene reporter construct in an
ISRE-EGFP vector (SEQ ID NO:3), where the ISRE from ISG15 is
positioned at nucleotides 30-89 of SEQ ID NO:3, the SV40 minimal
promoter is positioned at nucleotides 95-290 of SEQ ID NO:3, and
the coding sequence of the EGFP reporter gene having the amino acid
sequence of SEQ ID NO:4 is positioned at nucleotides 358-1077 of
SEQ ID NO:3.
[0087] As for the cell used in the preferred gene reporter assay
for Type I interferon embodiment of the present invention, the cell
is preferably a mammalian or avian cell, more preferably a human
cell, and most preferably a human promonocytic cell. A preferred
human promonocytic cell carrying the ISRE-luc vector containing the
luciferase gene reporter construct is a PIL5 cell. The cell is
treated to make a commercial cell line that has the commercially
desirable properties of a sufficient shelf life for the purpose of
the assay and of being a one time use cell that cannot be
propagated for possible further use. Preferably, the cell is
treated either 1) by irradiating with 6 to 12 Gy of .gamma.
radiation, more preferably about 9 Gy, and storage at room
temperature for up to 14 days after irradiation or 2) by exposure
to an anti-mitotic and pro-apoptotic agent, such as vinblastine,
cisplatin, or 5-fluorouracil, most preferably vinblastine, for 10
minutes at 37.degree. C. prior to resuspending in a solution
containing 40% fetal bovine serum (FBS) and 2.5% DMSO+10% glycerol
and freezing at -80.degree. C.
[0088] In order to optimize the method of obtaining a cell with an
indefinite shelf life during frozen storage, but which will die
approximately 24 hours after being thawed (once thawed, however,
the product has excellent sensitivity, and precision as well as
selectivity), the parameters which can be varied in the course of
such optimization include:
[0089] 1) Concentration of FBS. Besides FBS, most any serum could
be used as it acts as a toxic sink to protect the cells from
toxins, such as while being thawed or while being treated with an
anti-mitotic and pro-apoptotic agent. The concentration of FBS can
cause the results to vary.
[0090] 2) Time is a variable. The amount of time of exposure to
vinblastine before the cells are centrifuged out and washed to
remove vinblastine.
[0091] 3) The formulation of the vinblastine makes a difference.
Presently, soluble vinblastine in a proprietary prebuffered
formulation sold by Eli Lilly under the name Velbe in France is
preferably used. A different formulation may require slightly
different combination of parameters.
[0092] 4) The concentration of vinblastine.
[0093] 5) Cell concentration during the vinblastine treatment.
[0094] 6) The amount of cryopreservative or combination of
cryopreservatives.
[0095] All of these parameters can be varied empirically and the
results after freezing tested for sensitivity and precision,
assuming that the cells stay alive for approximately 24 hours after
being thawed. This can be readily determined by one of ordinary
skill in the art without undue experimentation, particularly in
view of the guidance provided in the experiments shown in FIGS.
11-24 for PIL5 cells, in order to arrive at a product having
substantially the same sensitivity as the untreated live cells for
a period of at least one hour, preferably 8 hours, following
thawing but having a viability of no more than 30 days.
[0096] A most preferred embodiment of the present invention is
exemplified below in the form of a procedure for conducting a
luciferase gene reporter assay for Type I interferon using PIL5
cells treated with the anti-mitotic and pro-apoptotic agent 1
.mu.g/ml vinblastine for 10 minutes at 37.degree. C. prior to
frozen storage at -20.degree. C. and thawing at a later time for
purposes of conducting the assay.
Protocol for Luciferase Gene Reporter Assay for Type I Interferon
Using Treated PIL5 cells
Preparation of Microtiter Assay Plates
[0097] 1. PIL5 cells at a concentration of about 2.times.10.sup.5
to 7.times.10.sup.5 cells/ml in RMPI 1640 medium with 10% fetal
bovine serum (FBS) are treated with a fresh solution of 1 .mu.g/ml
vinblastine (commercially available from Eli Lilly under the
pre-buffered formulation VELBE), diluted from 1 mg/ml in H.sub.2O,
for 10 minutes at 37.degree. C. in an atmosphere of 5% CO.sub.2 in
air. A CO.sub.2 incubator can be used for convenience. [0098] 2.
The PIL5 cells are centrifuged at 800.times.g for 10 minutes at
4.degree. C., and washed once with the same volume of RPMI 1640
medium with 10% FBS to remove the vinblastine. [0099] 3. The PIL5
cells are re-suspended at a concentration of 2.times.10.sup.7
cells/ml in RMPI 1640 medium with 40% fetal bovine serum (FBS) and
2.5% dimethylsulfoxide+10% glycerol. [0100] 4. The cell suspension
is dispensed into the wells of a flat-bottom micro-plate to give
300,000 cells per well (equivalent to 25 .mu.l of cell suspension
per well). [0101] 5. The micro-plate is frozen at -80.degree. C. in
an aluminum bag sealed under vacuum with the cover uppermost.
[0102] 6. The micro-plates can be subsequently stored at
-20.degree. C. until use.
Preparation of Cryopreservation Ampoules/Vials
[0102] [0103] 1. PIL5 cells at a concentration of about
2.times.10.sup.5 to 7.times.10.sup.5 cells/ml in RMPI 1640 medium
with 10% fetal bovine serum (FBS) are treated with a fresh solution
of 1 .mu.g/ml vinblastine (commercially available from Eli Lilly
under the prebuffered formulation VELBE), diluted from 1 mg/ml in
H.sub.2O for 10 minutes at 37.degree. C. in an atmosphere of 5%
CO.sub.2 in air. A CO.sub.2 incubator can be used for convenience.
[0104] 2. The PIL5 cells are centrifuged at 80.times.g for 10
minutes at 4.degree. C., and washed once with the same volume of
RPMI 1640 medium with 10% FBS to remove the vinblastine. [0105] 3.
The PIL5 cells are re-suspended at a concentration of
2.times.10.sup.7 cells/ml in RMPI 1640 medium with 40% fetal bovine
serum (FBS) and 2.5% dimethylsulfoxide+10% glycerol. [0106] 4. The
cell suspension (1 ml) is dispensed into a cryopreservation vial
and frozen at -80%. [0107] 5. The cryopreservation vial can be
subsequently stored at -20.degree. C. until use.
[0108] The assay procedure described below is directed to using the
microtiter assay plates prepared above. However, in case the end
user elects to obtain the treated PIL5 cells in cryopreservation
vials instead of in microtiter plates as predispensed aliquots, the
end user may dispense 75 .mu.l of the treated PIL5 cells into each
well of a microtiter plate of his/her choice following dilution of
the cells 1:6 in RPMI 1640 medium with 10% FBS or into some other
receptacles, i.e., Eppendorf microfuge tubes, and conduct the assay
in a similar fashion as described below.
Assay Procedure
Preparation of Standard Curve
[0109] 1. Remove protective cover from the sample preparation
micro-plate (Plate A). [0110] 2. Add 100 .mu.l of the diluent (RPMI
1640 medium without serum) to wells A1 through A6 and B1 through B6
of the sample preparation plate (Plate A). [0111] 3. Add 100 .mu.l
of the interferon (IFN) reference preparation to wells A1 and B1 of
Plate A containing 100 .mu.l of diluent. [0112] 4. Carry out serial
two-fold dilutions of the IFN reference preparation in Plate A from
wells A1 and B1 through wells A6 and B6 using a multi-channel
micro-pipette.
Sample Preparation
[0112] [0113] 1. Add 100 .mu.l of the diluent to the wells of the
sample preparation plate (Plate A) where required. [0114] 2. Dilute
samples to be tested if the estimated IFN titer of the samples is
greater than 100 IU/ml. [0115] 3. Dilute samples appropriately in
the sample preparation micro-plate (Plate A)
Assay Procedure
[0115] [0116] 1. Rapidly thaw the 96-well PIL5 assay micro-plate
(Plate B) on a flat surface with the cover uppermost. A water-bath
set at 37.degree. C. can be used for convenience. [0117] 2. Dry
protective cover with a paper hand towel, taking care to maintain
the label uppermost. [0118] 3. Carefully remove protective cover
from the PIL5 assay micro-plate (Plate B) while maintaining the
cover uppermost. [0119] 4. Add 75 .mu.l of each of the serial
two-fold dilutions of the reference preparation to wells A1 and B1
through wells A6 and B6 of the PIL5 assay micro-plate (Plate B)
using a multi-channel micro-pipette. [0120] 5. Add 75 .mu.l of each
undiluted or appropriately diluted sample to the PIL assay
micro-plate (Plate A). [0121] 6.Incubate the PIL5 assay micro-plate
(Plate B) overnight at 37.degree. C. in an atmosphere of 5%
CO.sub.2 in air. A CO.sub.2 incubator can be used for convenience.
[0122] 7.Add 100 .mu.l of LUCLIT PLUS (Packard Biosciences, Inc.,
now part of PerkinElmer Life Sciences, Boston, Mass., catalog
#6016961) to each well of the PIL5 assay micro-plate (Plate B)
using a multi-channel micro-pipette. [0123] 8. Determine the
luminescence of the samples using a micro-plate luminometer
(LUMICOUNT, Packard).
Calculation of International Units
[0123] [0124] 1. Plot standard curve from the mean of the
luminescence readings for each dilution of the IFN reference
preparation calibrated against the NIH international reference
standard for HuIFN-.alpha. (G-023-901-527) using Microsoft EXCEL.
[0125] 2. The equation describing the stand curve is obtained using
the EXCEL function "interpolation of the curve" using the option
"exponentionel curve". This equation is then used to calculate the
IFN titer of each sample expressed in international units (IU).
[0126] While the present invention is directed to commercializing
any cell engineered for signal transduction assays, such as those
described in U.S. Pat. Nos. 5,436,128 and 5,401,629, the entire
contents of which are incorporated herein by reference, there are
specific and important utilities for the most preferred embodiments
of a gene reporter assay for Type I interferon and the cell used in
such an assay. For example, the cell in the interferon gene
reporter assay can serve as a surrogate marker for viral infection.
It is known that circulating interferon is indicative of a virus
infection but circulating interferon does not usually appear in a
person who has a bacterial infection. Thus, if a person is
suspected of having an infection and one wants to determine whether
the infection is viral or bacterial so that treatment can be
efficacious and specifically targeted to either a viral or
bacterial infection, this interferon gene reporter assay would be
extremely useful. In HIV patients, it is known that the circulating
interferon level becomes detectable towards the end of the
asymptomatic period. Thus, interferon monitoring indicative of
disease progression is another utility.
[0127] The cell in the interferon gene reporter assay can also be
used as a surrogate marker for detecting viral infections caused by
bioterrorism in a susceptible population. If random blood samples
are taken in a susceptible population, this simple gene reporter
assay allows a relatively fast and inexpensive determination of
ubiquitous viral infection which would be an indication of a
possible bioterrorism attack.
[0128] Furthermore, rat cell lines, bovine cell lines, avian cell
lines, etc., can be created which have the reporter gene under the
control of an ISRE in order to determine if animals are infected
with a virus, such as to detect bubonic plague in rats, West Nile
virus in birds (i.e., crows), hoof and mouth disease in cattle,
etc. The presence of West Nile virus in humans can be readily
distinguished from most other viral infections because it is one of
only a few viral infections that cause a titer of Type I
interferons to quickly reach into the tens or hundreds of thousands
of units in humans.
[0129] Another utility is to monitor interferon therapy in patients
to see how much interferon is actually entering the bloodstream
(i.e., from sub-lingual administration) and to determine patient
compliance if doses of interferon are self administered.
[0130] As a further utility, the cell and interferon reporter assay
can be used to detect autoimmune diseases, such as systemic lupus
erythematosus (SLE), Type I diabetes, multiple sclerosis,
psoriasis, or rheumatoid arthritis (RA), which are characterized by
the presence of interferon in the peripheral circulation or in
other body fluids, such as synovial fluids in the case of RA, or to
determine the stage of an autoimmune disease. Often these diseases
have stages of exacerbation and remission which manifest within the
diseased tissue with an increase in circulating interferon
immediately prior to an exacerbation phase. Thus, this assay can be
used to detect when a patient may be about to enter an exacerbation
stage and may offer an opportunity for treatment to prevent or
ameliorate the exacerbation stage.
[0131] The present interferon reporter assay recognizes any Type I
interferon which binds to a Type I interferon receptor. It is
possible, however, to determine which isotype(s) of interferon is
being detected by using a parallel monoclonal antibody treatment.
Thus, a monoclonal antibody for a specific isotype of interferon
will prevent that isotype of interferon from causing signal
transduction. If the signal disappears in the presence of antibody,
then it is known that the particular interferon being detected is
the isotype to which the antibody is specific. The standard
activity curve for different isotypes of interferon differ in any
given reporter cell line such as for the PIL5 cell line shown in
FIG. 3. Such standard activity curves can be generated for each
type of interferon in a given reporter cell line. Using such
standard curves, one can accurately quantitate the level of
interferon present in a sample once it is known what isotype of
interferon is being detected.
[0132] Finally, the present invention in general provides a method
for commercializing cells having a desired biological activity.
This commercial method involves treating cells such that the cells
will maintain the desired biological activity for no more than 30
days at a temperature above freezing, and then freezing the treated
cells at a temperature and under conditions such that they will
resume the required biological activity after thawing. The frozen
treated cells, which are available for a limited time but cannot be
propagated and maintained indefinitely for multiple uses, are
subsequently sold or distributed. The cells are preferably treated
with an anti-mitotic and pro-apoptotic agent in a sufficient amount
and for a sufficient time such that the treated cells will maintain
the desired biological activity for at least 8 hours, but no more
than about 30 days at a temperature above freezing. It is preferred
that the temperature at which the cells are frozen be about
-80.degree. C. and that the cells are resuspended in RPMI 1640
medium with 40% FBS containing cryopreservatives, preferably 2.5%
DMSO+10% glycerol, prior to freezing.
[0133] Having now generally described the invention, the same will
be more readily understood through reference to the following
example which is provided by way of illustration and is not
intended to be limiting of the present invention.
EXAMPLE
[0134] The present inventors have overcome the disadvantages of
current methods of quantifying interferons by developing a highly
sensitive and reproducible method for quantifying IFN activity
based on the establishment of a human cell line transfected with
the luciferase reporter gene placed under the control of an IFN
responsive chimeric promoter. This method of the present invention
allows IFN activity to be determined in a few hours rather than in
the 3 to 4 days required for a bioassay. Briefly, the interferon
stimulatory response element (ISRE) from the ISG15 gene controlling
a SV40 minimal promoter was cloned upstream of the luciferase
reporter gene in a 5849 bp ISRE-luc vector (FIG. 1; SEQ ID NO:1).
Alternatively, the ISRE from the ISG15 gene controlling a SV40
minimal promoter is cloned upstream of an enhanced green florescent
protein (EGFP-1) reporter gene in a 4412 bp ISRE-EGFP vector (FIG.
2; SEQ ID NO:3). Human promonocytic U937 cells were transfected
with the IFN regulated gene reporter construct and stable
transfectants were isolated and cloned. A human cell line PIL5
carrying the luciferase reporter gene under the control of an IFN
responsive chimeric promoter was thus established and provides the
basis of an assay which allows IFN activity to be determined more
rapidly and with greater precision than the standard antiviral
bioassay (Lallemand et al., 1996). Table 1 presents the advantages
of the luciferase gene reporter assay for interferon using PIL5
cells over the standard antiviral bioassay and Table 2 presents a
comparison between the luciferase gene reporter assay for
interferon using PIL5 cells and the standard antiviral bioassay on
sensitivity to interferon produced as a result of infection by
various viruses.
TABLE-US-00001 TABLE 1 GENE REPORTER ASSAY BIOASSAY Sensitivity 0.1
IU 1 to 5 IU Response time 4-8 hrs 3 to 4 days Use General
Restricted Cost Reagent and labour costs High reagent costs low
>90% gross margin Labour intensive
TABLE-US-00002 TABLE 2 Gene Reporter Assay Bioassay IU/ml IU/ml
Etiology >50 25 Adenovirus 17 6 IFN treatment >50 37
Influenza B >50 25 Para Influenza I 30 9 HIV 45 12 HIV >50 37
Rotavirus 2 Undetected HCV 4 Undetected HCV
[0135] The gene reporter assay using PIL5 cells is highly sensitive
(less than 1.0 IU/ml of IFN.alpha. or IFN.beta. can be detected
routinely), reproducible (standard error +/-10%), and can detect
IFN activity over a wide range of concentrations (0.1 to 100
IU/ml). The method is also highly specific and can for example even
detect low levels of Type I IFNs (IFN.alpha. or IFN.beta.) in the
presence of high levels of IFN.gamma. which is not possible using a
conventional antiviral bioassay. The method is ideally suited for
the determination of IFN activity in biological fluids such as
human serum, cerebrospinal fluid, or urine as the method is less
subject to non-specific interference at low dilutions than the
conventional anti-viral bioassay. Human serum and other biological
fluids often contain non-specific inhibitors of virus-replication
unrelated to IFN which can affect virus replication at low
dilutions giving rise to false positives.
[0136] The PIL5 gene-reporter IFN assay recognizes any Type I
interferon which binds to a Type I interferon receptor. It also
provides a means of distinguishing between one IFN.alpha. sub-type
and another due to the ability to detect differences in the dose
response (standard) curves characteristic of individual IFN.alpha.
sub-types. This is of considerable value in distinguishing between
different virus infections. Paramyxo viruses such as Sendai induce
mainly IFN.alpha.1, IFN.alpha.2, and IFN.beta., while Lentiviruses
such as HIV-1 induces mainly IFN.alpha.5 (Lallemand et al., 1996).
Standard curves of luciferase activity in PIL5 cells in the
presence of different amounts of each of the various isotypes of
interferon is presented in FIG. 3.
[0137] Thus, a method has been developed for the determination of
IFN levels in biological fluids which has been used experimentally
to analyze numerous clinical samples from virus infected
individuals. The method is rapid, inexpensive, robust, does not
require specialized personnel or equipment, and is readily
automated. The PIL5 gene-reporter assay is based, however, on the
use of live cells which limits commercialization in its present
form, due to a severely limited shelf life and the ability of a
customer to retain and cultivate the PIL5 cell line thereby
obviating the necessity to purchase further kits. The experiments
presented below were conducted to develop a modified form of the
PIL5 gene reporter assay amenable to commercialization in a kit
format, where the PIL5 cells are treated so as to have a
sufficiently long shelf life as part of a commercial assay, and
whereupon at the end of its useful shelf life or at the end of its
use in a PIL5 gene reporter assay, the treated PIL5 cells undergo
cellular death such as by apoptosis. The experimental approach
adopted as described below is based on the use of fractionated
doses of .gamma. irradiation or on the use of anti-mitotic and
pro-apoptotic agents to prevent cell multiplication and to induce
delayed cellular death (i.e., apoptosis) while retaining a
functional IFN signal transduction pathway.
Effect of .gamma. Irradiation on IFN Sensitivity
[0138] PIL5 cells were subjected to increasing doses of .gamma.
irradiation (0.32 to 25 Gy) and then tested at various times
thereafter for their ability to detect increasing doses of Type I
interferons. The results of preliminary experiments indicated that
PIL5 cells retain full IFN sensitivity when incubated at 37.degree.
C. for up to 4 days after doses of .gamma. irradiation between 0.32
and 12 Gy (FIG. 4), and that apoptosis is induced in 100% of the
cell population exposed to doses of .gamma. irradiation of 6 to 25
Gy (Table 3). Thus, these results validated the experimental
approach adopted and suggested that the potential shelf life of the
PIL5 gene reporter assay could be extended significantly beyond 4
days by exposing cells to fractionated doses of .gamma. irradiation
within the range of 6 to 12 Gy while inducing 100% (or nearly 100%
for 6 Gy) apoptosis of the cell population (FIG. 5 and Table
3).
TABLE-US-00003 TABLE 3 Percentage of Cells Viable after Irradiation
Time After Irradiation 25 Gy 12 Gy 6 Gy 3 Gy 1.5 Gy 0.75 Gy 0.32 Gy
Control Day 1 100 100 100 100 100 100 100 100 Day 2 60 100 100 100
100 100 100 100 Day 3 40 80 100 100 100 100 100 100 Day 4 30 50 80
100 100 100 100 100 Day 8 0 0 0 50 50 100 100 100 Day 21 0 0 100
100 100 100 100 100
Effect of Temperature on IFN Sensitivity
[0139] The results of a series of experiments have established that
PIL5 cells can indeed be stored in RPMI 1640 medium with 10% fetal
calf serum for up to 13 days at room temperature following exposure
to a dose of .gamma. irradiation of 6 Gy and still retain full IFN
sensitivity (FIG. 6). That is provided that the PIL5 cells are
subsequently incubated with the test samples or IFN standard at
37.degree. C., prior to assaying luciferase activity. In contrast,
it has been unexpectedly shown that incubation of PIL5 cells at
4.degree. C. in RPMI 1640 medium with 10% fetal calf serum
following exposure of the cells to a dose of .gamma. irradiation of
6 Gy induced cell death. This resulted in a marked loss of IFN
sensitivity after only 8 days incubation at 4.degree. C. (FIG.
7).
Effect of Serum Concentration on IFN Sensitivity
[0140] In an additional series of experiments, the serum content of
the culture medium was varied between 1 and 10% in order to
modulate exposure of cells to serum growth factors, the signalling
of which is known to counter the induction of apoptosis by .gamma.
irradiation. The results of these experiments showed that induction
of apoptosis in PIL5 cells is more rapid when the cells are
incubated in culture medium containing 1% fetal bovine serum
(indicated as FBS in FIG. 8) serum than in culture medium
containing 10% serum (FIG. 8). Furthermore, increasing the serum
concentration from 10 to 20% did not affect significantly cell
viability.
Effect of Cell Concentration on Ifn Sensitivity
[0141] It was expected that the sensitivity of the present PIL5 IFN
gene reporter assay could be increased significantly simply by
increasing the number of PIL5 cells used in the assay. Such a super
high sensitivity (SHS) version of the PIL5 gene reporter assay
would find wide application for the determination of very low
levels of IFN in biological fluids such as cerebro-spinal fluid.
Thus, PIL5 cells were incubated at concentrations of 0.1 to
1.0.times.10.sup.6 cells/ml at room temperature in culture medium
containing 10% fetal bovine serum following exposure to a dose of 6
Gy of .gamma. irradiation and then tested at various times
thereafter for their ability to detect increasing doses of IFN
.alpha.. The results of these experiments showed that, although
interferon sensitivity was indeed increased initially, incubation
of PIL5 cells at high cell density induced cellular death more
rapidly than at a concentration of 0.1.times.10.sup.6 cells/ml,
most probably due to depletion of growth factors in the culture
medium or production of toxic metabolites (FIG. 9).
Effect of the Inhibitors of Apoptosis Phenylarsine Oxide and
Aurintricarboxylic Acid on IFN Sensitivity
[0142] In an attempt to extend the shelf-life of the PIL5 IFN
assay, PIL5 cells were subjected to 6 Gy of .gamma. irradiation and
then treated with increasing concentrations (0, 0.1, 1.0, 10, and
100 .mu.M) of aurintricarboxylic acid or phenylarsine in order to
modulate the induction of apoptosis. The cells were then tested at
different times thereafter (0, 5, 10, 15, 20 days etc) for IFN
sensitivity.
[0143] The results of these studies showed that the addition of
increasing concentrations of aurintricarboxylic acid did not extend
the shelf life of PIL-5 gene reporter following exposure of cells
to a dose of 6 Gy of .gamma. irradiation (FIG. 10).
Effect of Treatment with an Anti-Mitotic Agent and Subsequent
Freezing on IFN Sensitivity
[0144] PIL5 cells were suspended at a concentration of
2.times.10.sup.6 cells/ml in RPMI 1640 medium plus 10% fetal bovine
serum (FBS) and incubated at 37.degree. C. for 1.0 hour in the
presence of 100 .mu.M vinblastine. The cells were then centrifuged
at 800.times.g for 10 minutes, washed once with the same volume of
RPMI 1640 medium with 10% FBS to remove vinblastine, and
re-suspended in RPMI 1640 medium plus 40% fetal bovine serum, 10%
glycerol and 2.5% dimethylsulfoxide (DMSO). The cell suspension
(10.sup.5 cells in a volume of 25 .mu.l) is then distributed into
the wells of a micro-titer plate (CulturePlate-96, Packard
Biosciences, Inc., now part of PerkinElmer Life Sciences, Boston,
Mass.) and stored at -20.degree. C. until use. The micro-titer
plates containing the frozen cells are then removed from the
-20.degree. C. freezer, thawed rapidly, preferably using a
waterbath preset at 37.degree. C., and 75 .mu.l of the sample to be
tested, or the IFN standard without serum, or negative control
sample without serum, is added to a well of the micro-titer plate
and incubated overnight at 37.degree. C. One hundred micro-liters
of LUCLIT PLUS (Packard Biosciences, Inc., Catalog #6016961, U.S.
Pat. Nos. 5,283,179; 5,641,641; 5,650,289; and 5,814,471) or a
similar reagent, which contains luciferin
(D-(-)-2-(6'-hydroxy-2'-benzothiazolyl)-.DELTA..sup.2-thiazoline-4-carbox-
ylic acid), ATP, buffer, Mg.sup.+2, and preferably coenzyme A fr
enhancing the activity of luciferase and a thiol reagent/sulfhydryl
compound for stabilizing luciferase, is added to each well of the
micro-titer plate and the samples are read on a plate reading
luminometer (LUMICOUNT, Packard BioSciences, Inc.). PIL5 cells were
found to retain full IFN sensitivity at one month after treatment
with 100 .mu.M vinblastine and freezing at -20.degree. C. (FIG.
11). The results of this study have established a method for the
development of the PIL5 IFN gene reporter assay in a commercially
viable kit format with a current shelf-life of at least one month
at -20.degree. C. without loss of IFN sensitivity.
[0145] Studies on the effects of a variety of parameters, i.e.,
concentration of vinblastine, time of treatment with vinblastine,
fetal bovine serum (FBS) concentration, glycerol concentration in
the presence or absence of DMSO, SMSO concentration; cell density,
on interferon sensitivity of frozen cells were conducted to
determine optimal conditions. See FIGS. 12-20. It may not be
apparent from the results shown in FIG. 12 why vinblastine instead
of 5-FU was chosen as the more preferred anti-mitotic and
pro-apoptotic agent for treatment of PIL5 cells prior to freezing.
The reason is that although 5-FU was superior to vinblastine in
terms of maintaining interferon sensitivity, 5-FU was not found to
be sufficiently effective in preventing cell replication at the
doses tested.
[0146] FIGS. 21 and 22 show the effect of cell number on interferon
sensitivity of the treated PIL5 cells following freezing, and FIG.
23 is a study on the effect of freezing in either a microtiter
plate or in a cryopreservation ampoule/vial on interferon
sensitivity of thawed treated PIL5 cells. A titration curve of a
standard interferon preparation on treated PIL5 cells following
freezing is presented in FIG. 24.
[0147] Having now fully described this invention, it will be
appreciated by those skilled in the art that the same can be
performed within a wide range of equivalent parameters,
concentrations, and conditions without departing from the spirit
and scope of the invention and without undue experimentation.
[0148] While this invention has been described in connection with
specific embodiments thereof, it will be understood that it is
capable of further modifications. This application is intended to
cover any variations, uses, or adaptations of the inventions
following, in general, the principles of the invention and
including such departures from the present disclosure as come
within known or customary practice within the art to which the
invention pertains and as may be applied to the essential features
hereinbefore set forth as follows in the scope of the appended
claims.
[0149] All references cited herein, including journal articles or
abstracts, published or corresponding U.S. or foreign patent
applications, issued U.S. or foreign patents, or any other
references, are entirely incorporated by reference herein,
including all data, tables, figures, and text presented in the
cited references. Additionally, the entire contents of the
references cited within the references cited herein are also
entirely incorporated by reference.
[0150] Reference to known method steps, conventional methods steps,
known methods or conventional methods is not in any way an
admission that any aspect, description or embodiment of the present
invention is disclosed, taught or suggested in the relevant
art.
[0151] The foregoing description of the specific embodiments will
so fully reveal the general nature of the invention that others
can, by applying knowledge within the skill of the art (including
the contents of the references cited herein), readily modify and/or
adapt for various applications such specific embodiments, without
undue experimentation, without departing from the general concept
of the present invention. Therefore, such adaptations and
modifications are intended to be within the meaning and range of
equivalents of the disclosed embodiments, based on the teaching and
guidance presented herein. It is to be understood that the
phraseology or terminology herein is for the purpose of description
and not of limitation, such that the terminology or phraseology of
the present specification is to be interpreted by the skilled
artisan in light of the teachings and guidance presented herein, in
combination with the knowledge of one of ordinary skill in the
art.
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Sequence CWU 1
1
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Thr Leu Ile Asp Lys Tyr Asp Leu Ser Asn Leu His Glu Ile Ala 300 305
310tct ggg ggc gca cct ctt tcg aaa gaa gtc ggg gaa gcg gtt gca aaa
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315 320 325cgc ttc cat ctt cca ggg ata cga caa gga tat ggg ctc act
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aagtaggcat aacagttata atcataacat actgtttttt cttactccac
2640acaggcatag agtgtctgct attaataact atgctcaaaa attgtgtacc
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cactcaaagg cggtaatacg gttatccaca gaatcagggg ataacgcagg
3240aaagaacatg tgagcaaaag gccagcaaaa ggccaggaac cgtaaaaagg
ccgcgttgct 3300ggcgtttttc cataggctcc gcccccctga cgagcatcac
aaaaatcgac gctcaagtca 3360gaggtggcga aacccgacag gactataaag
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ccctgccgct taccggatac ctgtccgcct ttctcccttc 3480gggaagcgtg
gcgctttctc aatgctcacg ctgtaggtat ctcagttcgg tgtaggtcgt
3540tcgctccaag ctgggctgtg tgcacgaacc ccccgttcag cccgaccgct
gcgccttatc 3600cggtaactat cgtcttgagt ccaacccggt aagacacgac
ttatcgccac tggcagcagc 3660cactggtaac aggattagca gagcgaggta
tgtaggcggt gctacagagt tcttgaagtg 3720gtggcctaac tacggctaca
ctagaaggac agtatttggt atctgcgctc tgctgaagcc 3780agttaccttc
ggaaaaagag ttggtagctc ttgatccggc aaacaaacca ccgctggtag
3840cggtggtttt tttgtttgca agcagcagat tacgcgcaga aaaaaaggat
ctcaagaaga 3900tcctttgatc ttttctacgg ggtctgacgc tcagtggaac
gaaaactcac gttaagggat 3960tttggtcatg agattatcaa aaaggatctt
cacctagatc cttttaaatt aaaaatgaag 4020ttttaaatca atctaaagta
tatatgagta aacttggtct gacagttacc aatgcttaat 4080cagtgaggca
cctatctcag cgatctgtct atttcgttca tccatagttg cctgactccc
4140cgtcgtgtag ataactacga tacgggaggg cttaccatct ggccccagtg
ctgcaatgat 4200accgcgagac ccacgctcac cggctccaga tttatcagca
ataaaccagc cagccggaag 4260ggccgagcgc agaagtggtc ctgcaacttt
atccgcctcc atccagtcta ttaattgttg 4320ccgggaagct agagtaagta
gttcgccagt taatagtttg cgcaacgttg ttgccattgc 4380tacaggcatc
gtggtgtcac gctcgtcgtt tggtatggct tcattcagct ccggttccca
4440acgatcaagg cgagttacat gatcccccat gttgtgcaaa aaagcggtta
gctccttcgg 4500tcctccgatc gttgtcagaa gtaagttggc cgcagtgtta
tcactcatgg ttatggcagc 4560actgcataat tctcttactg tcatgccatc
cgtaagatgc ttttctgtga ctggtgagta 4620ctcaaccaag tcattctgag
aatagtgtat gcggcgaccg agttgctctt gcccggcgtc 4680aatacgggat
aataccgcgc cacatagcag aactttaaaa gtgctcatca ttggaaaacg
4740ttcttcgggg cgaaaactct caaggatctt accgctgttg agatccagtt
cgatgtaacc 4800cactcgtgca cccaactgat cttcagcatc ttttactttc
accagcgttt ctgggtgagc 4860aaaaacagga aggcaaaatg ccgcaaaaaa
gggaataagg gcgacacgga aatgttgaat 4920actcatactc ttcctttttc
aatattattg aagcatttat cagggttatt gtctcatgag 4980cggatacata
tttgaatgta tttagaaaaa taaacaaata ggggttccgc gcacatttcc
5040ccgaaaagtg ccacctgacg cgccctgtag cggcgcatta agcgcggcgg
gtgtggtggt 5100tacgcgcagc gtgaccgcta cacttgccag cgccctagcg
cccgctcctt tcgctttctt 5160cccttccttt ctcgccacgt tcgccggctt
tccccgtcaa gctctaaatc gggggctccc 5220tttagggttc cgatttagtg
ctttacggca cctcgacccc aaaaaacttg attagggtga 5280tggttcacgt
agtgggccat cgccctgata gacggttttt cgccctttga cgttggagtc
5340cacgttcttt aatagtggac tcttgttcca aactggaaca acactcaacc
ctatctcggt 5400ctattctttt gatttataag ggattttgcc gatttcggcc
tattggttaa aaaatgagct 5460gatttaacaa aaatttaacg cgaattttaa
caaaatatta acgtttacaa tttcccattc 5520gccattcagg ctgcgcaact
gttgggaagg gcgatcggtg cgggcctctt cgctattacg 5580ccagcccaag
ctaccatgat aagtaagtaa tattaaggta cgtggaggtt ttacttgctt
5640taaaaaacct cccacacctc cccctgaacc tgaaacataa aatgaatgca
attgttgttg 5700ttaacttgtt tattgcagct tataatggtt acaaataaag
caatagcatc acaaatttca 5760caaataaagc atttttttca ctgcattcta
gttgtggttt gtccaaactc atcaatgtat 5820cttatggtac tgtaactgag
ctaacataa 58492550PRTArtificialSynthetic 2Met Glu Asp Ala Lys Asn
Ile Lys Lys Gly Pro Ala Pro Phe Tyr Pro1 5 10 15Leu Glu Asp Gly Thr
Ala Gly Glu Gln Leu His Lys Ala Met Lys Arg 20 25 30Tyr Ala Leu Val
Pro Gly Thr Ile Ala Phe Thr Asp Ala His Ile Glu 35 40 45Val Asn Ile
Thr Tyr Ala Glu Tyr Phe Glu Met Ser Val Arg Leu Ala 50 55 60Glu Ala
Met Lys Arg Tyr Gly Leu Asn Thr Asn His Arg Ile Val Val65 70 75
80Cys Ser Glu Asn Ser Leu Gln Phe Phe Met Pro Val Leu Gly Ala Leu
85 90 95Phe Ile Gly Val Ala Val Ala Pro Ala Asn Asp Ile Tyr Asn Glu
Arg 100 105 110Glu Leu Leu Asn Ser Met Asn Ile Ser Gln Pro Thr Val
Val Phe Val 115 120 125Ser Lys Lys Gly Leu Gln Lys Ile Leu Asn Val
Gln Lys Lys Leu Pro 130 135 140Ile Ile Gln Lys Ile Ile Ile Met Asp
Ser Lys Thr Asp Tyr Gln Gly145 150 155 160Phe Gln Ser Met Tyr Thr
Phe Val Thr Ser His Leu Pro Pro Gly Phe 165 170 175Asn Glu Tyr Asp
Phe Val Pro Glu Ser Phe Asp Arg Asp Lys Thr Ile 180 185 190Ala Leu
Ile Met Asn Ser Ser Gly Ser Thr Gly Leu Pro Lys Gly Val 195 200
205Ala Leu Pro His Arg Thr Ala Cys Val Arg Phe Ser His Ala Arg Asp
210 215 220Pro Ile Phe Gly Asn Gln Ile Ile Pro Asp Thr Ala Ile Leu
Ser Val225 230 235 240Val Pro Phe His His Gly Phe Gly Met Phe Thr
Thr Leu Gly Tyr Leu 245 250 255Ile Cys Gly Phe Arg Val Val Leu Met
Tyr Arg Phe Glu Glu Glu Leu 260 265 270Phe Leu Arg Ser Leu Gln Asp
Tyr Lys Ile Gln Ser Ala Leu Leu Val 275 280 285Pro Thr Leu Phe Ser
Phe Phe Ala Lys Ser Thr Leu Ile Asp Lys Tyr 290 295 300Asp Leu Ser
Asn Leu His Glu Ile Ala Ser Gly Gly Ala Pro Leu Ser305 310 315
320Lys Glu Val Gly Glu Ala Val Ala Lys Arg Phe His Leu Pro Gly Ile
325 330 335Arg Gln Gly Tyr Gly Leu Thr Glu Thr Thr Ser Ala Ile Leu
Ile Thr 340 345 350Pro Glu Gly Asp Asp Lys Pro Gly Ala Val Gly Lys
Val Val Pro Phe 355 360 365Phe Glu Ala Lys Val Val Asp Leu Asp Thr
Gly Lys Thr Leu Gly Val 370 375 380Asn Gln Arg Gly Glu Leu Cys Val
Arg Gly Pro Met Ile Met Ser Gly385 390 395 400Tyr Val Asn Asn Pro
Glu Ala Thr Asn Ala Leu Ile Asp Lys Asp Gly 405 410 415Trp Leu His
Ser Gly Asp Ile Ala Tyr Trp Asp Glu Asp Glu His Phe 420 425 430Phe
Ile Val Asp Arg Leu Lys Ser Leu Ile Lys Tyr Lys Gly Tyr Gln 435 440
445Val Ala Pro Ala Glu Leu Glu Ser Ile Leu Leu Gln His Pro Asn Ile
450 455 460Phe Asp Ala Gly Val Ala Gly Leu Pro Asp Asp Asp Ala Gly
Glu Leu465 470 475 480Pro Ala Ala Val Val Val Leu Glu His Gly Lys
Thr Met Thr Glu Lys 485 490 495Glu Ile Val Asp Tyr Val Ala Ser Gln
Val Thr Thr Ala Lys Lys Leu 500 505 510Arg Gly Gly Val Val Phe Val
Asp Glu Val Pro Lys Gly Leu Thr Gly 515 520 525Lys Leu Asp Ala Arg
Lys Ile Arg Glu Ile Leu Ile Lys Ala Lys Lys 530 535 540Gly Gly Lys
Ser Lys Leu545 55034412DNAArtificialSynthetic 3tagttattac
tagcgctacc ggactcagac tcgggaaagg gaaaccgaaa ctgaagcccc 60tcgggaaagg
gaaaccgaaa ctgaagcccg atctgcatct caattagtca gcaaccatag
120tcccgcccct aactccgccc atcccgcccc taactccgcc cagttccgcc
cattctccgc 180cccatggctg actaattttt tttatttatg cagaggccga
ggccgcctcg gcctctgagc 240tattccagaa gtagtgagga ggcttttttg
gaggcctagg cttttgcaaa tctcgagctc 300aagcttcgaa ttctgcagtc
gacggtaccg cgggcccggg atccaccggt cgccacc 357atg gtg agc aag ggc gag
gag ctg ttc acc ggg gtg gtg ccc atc ctg 405Met Val Ser Lys Gly Glu
Glu Leu Phe Thr Gly Val Val Pro Ile Leu1 5 10 15gtc gag ctg gac ggc
gac gta aac ggc cac aag ttc agc gtg tcc ggc 453Val Glu Leu Asp Gly
Asp Val Asn Gly His Lys Phe Ser Val Ser Gly 20 25 30gag ggc gag ggc
gat gcc acc tac ggc aag ctg acc ctg aag ttc atc 501Glu Gly Glu Gly
Asp Ala Thr Tyr Gly Lys Leu Thr Leu Lys Phe Ile 35 40 45tgc acc acc
ggc aag ctg ccc gtg ccc tgg ccc acc ctc gtg acc acc 549Cys Thr Thr
Gly Lys Leu Pro Val Pro Trp Pro Thr Leu Val Thr Thr 50 55 60ctg acc
tac ggc gtg cag tgc ttc agc cgc tac ccc gac cac atg aag 597Leu Thr
Tyr Gly Val Gln Cys Phe Ser Arg Tyr Pro Asp His Met Lys65 70 75
80cag cac gac ttc ttc aag tcc gcc atg ccc gaa ggc tac gtc cag gag
645Gln His Asp Phe Phe Lys Ser Ala Met Pro Glu Gly Tyr Val Gln Glu
85 90 95cgc acc atc ttc ttc aag gac gac ggc aac tac aag acc cgc gcc
gag 693Arg Thr Ile Phe Phe Lys Asp Asp Gly Asn Tyr Lys Thr Arg Ala
Glu 100 105 110gtg aag ttc gag ggc gac acc ctg gtg aac cgc atc gag
ctg aag ggc 741Val Lys Phe Glu Gly Asp Thr Leu Val Asn Arg Ile Glu
Leu Lys Gly 115 120 125atc gac ttc aag gag gac ggc aac atc ctg ggg
cac aag ctg gag tac 789Ile Asp Phe Lys Glu Asp Gly Asn Ile Leu Gly
His Lys Leu Glu Tyr 130 135 140aac tac aac agc cac aac gtc tat atc
atg gcc gac aag cag aag aac 837Asn Tyr Asn Ser His Asn Val Tyr Ile
Met Ala Asp Lys Gln Lys Asn145 150 155 160ggc atc aag gtg aac ttc
aag atc cgc cac aac atc gag gac ggc agc 885Gly Ile Lys Val
Asn Phe Lys Ile Arg His Asn Ile Glu Asp Gly Ser 165 170 175gtg cag
ctc gcc gac cac tac cag cag aac acc ccc atc ggc gac ggc 933Val Gln
Leu Ala Asp His Tyr Gln Gln Asn Thr Pro Ile Gly Asp Gly 180 185
190ccc gtg ctg ctg ccc gac aac cac tac ctg agc acc cag tcc gcc ctg
981Pro Val Leu Leu Pro Asp Asn His Tyr Leu Ser Thr Gln Ser Ala Leu
195 200 205agc aaa gac ccc aac gag aag cgc gat cac atg gtc ctg ctg
gag ttc 1029Ser Lys Asp Pro Asn Glu Lys Arg Asp His Met Val Leu Leu
Glu Phe 210 215 220gtg acc gcc gcc ggg atc act ctc ggc atg gac gag
ctg tac aag taa 1077Val Thr Ala Ala Gly Ile Thr Leu Gly Met Asp Glu
Leu Tyr Lys225 230 235agcggccgcg actctagatc ataatcagcc ataccacatt
tgtagaggtt ttacttgctt 1137taaaaaacct cccacacctc cccctgaacc
tgaaacataa aatgaatgca attgttgttg 1197ttaacttgtt tattgcagct
tataatggtt acaaataaag caatagcatc acaaatttca 1257caaataaagc
atttttttca ctgcattcta gttgtggttt gtccaaactc atcaatgtat
1317cttaaggcgt aaattgtaag cgttaatatt ttgttaaaat tcgcgttaaa
tttttgttaa 1377atcagctcat tttttaacca ataggccgaa atcggcaaaa
tcccttataa atcaaaagaa 1437tagaccgaga tagggttgag tgttgttcca
gtttggaaca agagtccact attaaagaac 1497gtggactcca acgtcaaagg
gcgaaaaacc gtctatcagg gcgatggccc actacgtgaa 1557ccatcaccct
aatcaagttt tttggggtcg aggtgccgta aagcactaaa tcggaaccct
1617aaagggagcc cccgatttag agcttgacgg ggaaagccgg cgaacgtggc
gagaaaggaa 1677gggaagaaag cgaaaggagc gggcgctagg gcgctggcaa
gtgtagcggt cacgctgcgc 1737gtaaccacca cacccgccgc gcttaatgcg
ccgctacagg gcgcgtcagg tggcactttt 1797cggggaaatg tgcgcggaac
ccctatttgt ttatttttct aaatacattc aaatatgtat 1857ccgctcatga
gacaataacc ctgataaatg cttcaataat attgaaaaag gaagagtcct
1917gaggcggaaa gaaccagctg tggaatgtgt gtcagttagg gtgtggaaag
tccccaggct 1977ccccagcagg cagaagtatg caaagcatgc atctcaatta
gtcagcaacc aggtgtggaa 2037agtccccagg ctccccagca ggcagaagta
tgcaaagcat gcatctcaat tagtcagcaa 2097ccatagtccc gcccctaact
ccgcccatcc cgcccctaac tccgcccagt tccgcccatt 2157ctccgcccca
tggctgacta atttttttta tttatgcaga ggccgaggcc gcctcggcct
2217ctgagctatt ccagaagtag tgaggaggct tttttggagg cctaggcttt
tgcaaagatc 2277gatcaagaga caggatgagg atcgtttcgc atgattgaac
aagatggatt gcacgcaggt 2337tctccggccg cttgggtgga gaggctattc
ggctatgact gggcacaaca gacaatcggc 2397tgctctgatg ccgccgtgtt
ccggctgtca gcgcaggggc gcccggttct ttttgtcaag 2457accgacctgt
ccggtgccct gaatgaactg caagacgagg cagcgcggct atcgtggctg
2517gccacgacgg gcgttccttg cgcagctgtg ctcgacgttg tcactgaagc
gggaagggac 2577tggctgctat tgggcgaagt gccggggcag gatctcctgt
catctcacct tgctcctgcc 2637gagaaagtat ccatcatggc tgatgcaatg
cggcggctgc atacgcttga tccggctacc 2697tgcccattcg accaccaagc
gaaacatcgc atcgagcgag cacgtactcg gatggaagcc 2757ggtcttgtcg
atcaggatga tctggacgaa gagcatcagg ggctcgcgcc agccgaactg
2817ttcgccaggc tcaaggcgag catgcccgac ggcgaggatc tcgtcgtgac
ccatggcgat 2877gcctgcttgc cgaatatcat ggtggaaaat ggccgctttt
ctggattcat cgactgtggc 2937cggctgggtg tggcggaccg ctatcaggac
atagcgttgg ctacccgtga tattgctgaa 2997gagcttggcg gcgaatgggc
tgaccgcttc ctcgtgcttt acggtatcgc cgctcccgat 3057tcgcagcgca
tcgccttcta tcgccttctt gacgagttct tctgagcggg actctggggt
3117tcgaaatgac cgaccaagcg acgcccaacc tgccatcacg agatttcgat
tccaccgccg 3177ccttctatga aaggttgggc ttcggaatcg ttttccggga
cgccggctgg atgatcctcc 3237agcgcgggga tctcatgctg gagttcttcg
cccaccctag ggggaggcta actgaaacac 3297ggaaggagac aataccggaa
ggaacccgcg ctatgacggc aataaaaaga cagaataaaa 3357cgcacggtgt
tgggtcgttt gttcataaac gcggggttcg gtcccagggc tggcactctg
3417tcgatacccc accgagaccc cattggggcc aatacgcccg cgtttcttcc
ttttccccac 3477cccacccccc aagttcgggt gaaggcccag ggctcgcagc
caacgtcggg gcggcaggcc 3537ctgccatagc ctcaggttac tcatatatac
tttagattga tttaaaactt catttttaat 3597ttaaaaggat ctaggtgaag
atcctttttg ataatctcat gaccaaaatc ccttaacgtg 3657agttttcgtt
ccactgagcg tcagaccccg tagaaaagat caaaggatct tcttgagatc
3717ctttttttct gcgcgtaatc tgctgcttgc aaacaaaaaa accaccgcta
ccagcggtgg 3777tttgtttgcc ggatcaagag ctaccaactc tttttccgaa
ggtaactggc ttcagcagag 3837cgcagatacc aaatactgtc cttctagtgt
agccgtagtt aggccaccac ttcaagaact 3897ctgtagcacc gcctacatac
ctcgctctgc taatcctgtt accagtggct gctgccagtg 3957gcgataagtc
gtgtcttacc gggttggact caagacgata gttaccggat aaggcgcagc
4017ggtcgggctg aacggggggt tcgtgcacac agcccagctt ggagcgaacg
acctacaccg 4077aactgagata cctacagcgt gagctatgag aaagcgccac
gcttcccgaa gggagaaagg 4137cggacaggta tccggtaagc ggcagggtcg
gaacaggaga gcgcacgagg gagcttccag 4197ggggaaacgc ctggtatctt
tatagtcctg tcgggtttcg ccacctctga cttgagcgtc 4257gatttttgtg
atgctcgtca ggggggcgga gcctatggaa aaacgccagc aacgcggcct
4317ttttacggtt cctggccttt tgctggcctt ttgctcacat gttctttcct
gcgttatccc 4377ctgattctgt ggataaccgt attaccgcca tgcat
44124239PRTArtificialSynthetic 4Met Val Ser Lys Gly Glu Glu Leu Phe
Thr Gly Val Val Pro Ile Leu1 5 10 15Val Glu Leu Asp Gly Asp Val Asn
Gly His Lys Phe Ser Val Ser Gly 20 25 30Glu Gly Glu Gly Asp Ala Thr
Tyr Gly Lys Leu Thr Leu Lys Phe Ile 35 40 45Cys Thr Thr Gly Lys Leu
Pro Val Pro Trp Pro Thr Leu Val Thr Thr 50 55 60Leu Thr Tyr Gly Val
Gln Cys Phe Ser Arg Tyr Pro Asp His Met Lys65 70 75 80Gln His Asp
Phe Phe Lys Ser Ala Met Pro Glu Gly Tyr Val Gln Glu 85 90 95Arg Thr
Ile Phe Phe Lys Asp Asp Gly Asn Tyr Lys Thr Arg Ala Glu 100 105
110Val Lys Phe Glu Gly Asp Thr Leu Val Asn Arg Ile Glu Leu Lys Gly
115 120 125Ile Asp Phe Lys Glu Asp Gly Asn Ile Leu Gly His Lys Leu
Glu Tyr 130 135 140Asn Tyr Asn Ser His Asn Val Tyr Ile Met Ala Asp
Lys Gln Lys Asn145 150 155 160Gly Ile Lys Val Asn Phe Lys Ile Arg
His Asn Ile Glu Asp Gly Ser 165 170 175Val Gln Leu Ala Asp His Tyr
Gln Gln Asn Thr Pro Ile Gly Asp Gly 180 185 190Pro Val Leu Leu Pro
Asp Asn His Tyr Leu Ser Thr Gln Ser Ala Leu 195 200 205Ser Lys Asp
Pro Asn Glu Lys Arg Asp His Met Val Leu Leu Glu Phe 210 215 220Val
Thr Ala Ala Gly Ile Thr Leu Gly Met Asp Glu Leu Tyr Lys225 230
235560DNAArtificialSynthetic 5ctcgggaaag ggaaaccgaa actgaagccc
ctcgggaaag ggaaaccgaa actgaagccc 60615DNAArtificialSynthetic
6ggraaagwga aactg 15721DNAArtificialSynthetic 7nnnsanttcc
gggaantgns n 21
* * * * *