U.S. patent application number 13/588217 was filed with the patent office on 2012-12-27 for modified vaccinia ankara virus variant.
This patent application is currently assigned to BAVARIAN NORDIC A/S. Invention is credited to PAUL CHAPLIN, PAUL HOWLEY, CHRISTINE MEISINGER-HENSCHEL.
Application Number | 20120328650 13/588217 |
Document ID | / |
Family ID | 8159864 |
Filed Date | 2012-12-27 |
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United States Patent
Application |
20120328650 |
Kind Code |
A1 |
CHAPLIN; PAUL ; et
al. |
December 27, 2012 |
MODIFIED VACCINIA ANKARA VIRUS VARIANT
Abstract
The present invention provides an attenuated virus, which is
derived from Modified Vaccinia Ankara virus, wherein the MVA-BN
virus, or a derivative thereof, induces at least substantially the
same level of immunity in vaccinia virus prime/vaccina virus boost
regimes when compared to DNA prime/vaccinia virus boost regimes. It
further describes recombinant viruses derived from this virus and
the use of the virus, or its recombinants, as a medicament or
vaccine. A method is provided for inducing an immune response in
individuals who may be immune-compromised, receiving antiviral
therapy, or have a pre-existing immunity to the vaccine virus.
Inventors: |
CHAPLIN; PAUL; (GRAFELFING,
DE) ; HOWLEY; PAUL; (BERWICK, AU) ;
MEISINGER-HENSCHEL; CHRISTINE; (NEURIED, DE) |
Assignee: |
BAVARIAN NORDIC A/S
KVISTGAARD
DK
|
Family ID: |
8159864 |
Appl. No.: |
13/588217 |
Filed: |
August 17, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13053361 |
Mar 22, 2011 |
8268325 |
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13588217 |
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12471144 |
May 22, 2009 |
7939086 |
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13053361 |
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11977808 |
Oct 26, 2007 |
7923017 |
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12471144 |
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11198557 |
Aug 5, 2005 |
7384644 |
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11977808 |
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10440073 |
May 16, 2003 |
7189536 |
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11198557 |
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PCT/EP01/13628 |
Nov 22, 2001 |
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10440073 |
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Current U.S.
Class: |
424/199.1 ;
424/232.1 |
Current CPC
Class: |
A61P 43/00 20180101;
A61K 2039/53 20130101; C12N 2710/24121 20130101; C12N 2710/24143
20130101; A61P 33/02 20180101; C07K 14/005 20130101; C12N 7/00
20130101; A61P 31/12 20180101; A61P 31/14 20180101; A61P 31/16
20180101; A61P 31/18 20180101; A61P 37/04 20180101; A61K 48/00
20130101; A61P 35/00 20180101; C12N 2740/16322 20130101; C12N 15/86
20130101; A61P 31/20 20180101; A61K 2039/545 20130101; A61K 39/285
20130101; A61P 31/00 20180101; A61P 31/04 20180101; A61K 2039/5254
20130101; A61K 2039/5256 20130101; A61K 39/12 20130101 |
Class at
Publication: |
424/199.1 ;
424/232.1 |
International
Class: |
A61K 39/275 20060101
A61K039/275; A61P 31/12 20060101 A61P031/12; A61K 39/295 20060101
A61K039/295 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 23, 2000 |
DK |
PA 200001764 |
Claims
1-25. (canceled)
26. A method for generating a modified vaccinia Ankara (MVA) virus
comprising: a) culturing an MVA virus; b) isolating an MVA virus
that reproductively replicates in chicken embryo fibroblast cells;
and c) selecting for an MVA virus that is unable to reproductively
replicate in the human keratinocyte cell line HaCaT, in the human
bone osteosarcoma cell line 143B, in the human cervix
adenocarcinoma cell line HeLa, and in the human embryo kidney cell
line 293.
27. The method of claim 26, wherein the selected MVA virus is
capable of a replication amplification ratio of greater than 500 in
chicken embryo fibroblast cells.
28. The method of claim 26, wherein the MVA virus cultured in step
a) is MVA 572.
29. The method of claim 26, wherein the MVA virus cultured in step
a) is MVA 575.
30. The method of claim 26, further comprising converting the
selected MVA virus to a physiologically acceptable form.
31. The method of claim 27, further comprising converting the
selected MVA virus to a physiologically acceptable form.
32. The method of claim 28, further comprising converting the
selected MVA virus to a physiologically acceptable form.
33. The method of claim 29, further comprising converting the
selected MVA virus to a physiologically acceptable form.
34. A modified vaccinia Ankara (MVA) virus prepared by: a)
culturing an MVA virus; b) isolating an MVA virus that
reproductively replicates in chicken embryo fibroblast cells; and
c) selecting for an MVA virus that is unable to reproductively
replicate in the human keratinocyte cell line HaCaT, in the human
bone osteosarcoma cell line 143B, in the human cervix
adenocarcinoma cell line HeLa, and in the human embryo kidney cell
line 293.
35. The MVA virus of claim 34, wherein the selected MVA virus is
capable of a replication amplification ratio of greater than 500 in
chicken embryo fibroblast cells.
36. The MVA virus of claim 34, wherein the MVA virus cultured in
step a) is MVA 572.
37. The MVA virus of claim 34, wherein the MVA virus cultured in
step a) is MVA 575.
38. The MVA virus of claim 34, in a physiologically acceptable
form.
39. The MVA virus of claim 35, in a physiologically acceptable
form.
40. The MVA virus of claim 36, in a physiologically acceptable
form.
41. The MVA virus of claim 37, in a physiologically acceptable
form.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 13/053,361, filed Mar. 22, 2011, which is a continuation of
U.S. application Ser. No. 12/471,144, filed May 22, 2009 (now U.S.
Pat. No. 7,939,086), which is a continuation of U.S. application
Ser. No. 11/977,808, filed Oct. 26, 2007 (now U.S. Pat. No.
7,923,017), which is a divisional of U.S. application Ser. No.
11/198,557, filed Aug. 5, 2005 (now U.S. Pat. No. 7,384,644), which
is a continuation of U.S. application Ser. No. 10/440,073, filed
May 16, 2003 (now U.S. Pat. No. 7,189,536), which is a continuation
of International Application PCT/EP01/013628, filed Nov. 22, 2001,
which claims the benefit of PA 2000 01764, filed Nov. 23, 2000. All
of these applications are incorporated by reference herein.
[0002] The present invention provides an attenuated virus which is
derived from Modified Vaccinia Ankara virus and which is
characterized by the loss of its capability to reproductively
replicate in human cell lines. It further describes recombinant
viruses derived from this virus and the use of the virus or its
recombinants as a medicament or vaccine. Additionally, a method is
provided for inducing an immune response even in immune-compromised
patients, patients with pre-existing immunity to the vaccine virus,
or patients undergoing antiviral therapy.
BACKGROUND OF THE INVENTION
[0003] Modified Vaccinia Ankara (MVA) virus is related to vaccinia
virus, a member of the genera Orthopoxvirus in the family of
Poxyiridae. MVA was generated by 516 serial passages on chicken
embryo fibroblasts of the Ankara strain of vaccinia virus (CVA)
(for review see Mayr, A., et al. Infection 3, 6-14 [1975]). As a
consequence of these long-term passages, the resulting MVA virus
deleted about 31 kilobases of its genomic sequence and, therefore,
was described as highly host cell restricted to avian cells (Meyer,
H. et al., J. Gen. Virol. 72, 1031-1038 [1991]). It was shown in a
variety of animal models that the resulting MVA was significantly
avirulent (Mayr, A. & Danner, K. [1978] Dev. Biol. Stand. 41:
225-34). Additionally, this MVA strain has been tested in clinical
trials as a vaccine to immunize against the human smallpox disease
(Mayr et al., Zbl. Bakt. Hyg. I, Abt. Org. B 167, 375-390 [1987],
Stickl et al., Dtsch. med. Wschr. 99, 2386-2392 [1974]). These
studies involved over 120,000 humans, including high-risk patients,
and proved that compared to vaccinia based vaccines, MVA had
diminished virulence or infectiousness while it induced a good
specific immune response.
[0004] In the following decades, MVA was engineered for use as a
viral vector for recombinant gene expression or as a recombinant
vaccine (Sutter, G. et al. [1994], Vaccine 12: 1032-40).
[0005] In this respect, it is most astonishing that even though
Mayr et al. demonstrated during the 1970s that MVA is highly
attenuated and avirulent in humans and mammals, some recently
reported observations (Blanchard et al., 1998, J Gen Virol 79,
1159-1167; Carroll & Moss, 1997, Virology 238, 198-211;
Altenberger, U.S. Pat. No. 5,185,146; Ambrosini et al., 1999, J
Neurosci Res 55(5), 569) have shown that MVA is not fully
attenuated in mammalian and human cell lines since residual
replication might occur in these cells. It is assumed that the
results reported in these publications have been obtained with
various known strains of MVA since the viruses used essentially
differ in their properties, particularly in their growth behavior
in various cell lines.
[0006] Growth behavior is recognized as an indicator for virus
attenuation. Generally, a virus strain is regarded as attenuated if
it has lost its capacity or only has reduced capacity to
reproductively replicate in host cells. The above-mentioned
observation, that MVA is not completely replication incompetent in
human and mammalian cells, brings into question the absolute safety
of known MVA as a human vaccine or a vector for recombinant
vaccines.
[0007] Particularly for a vaccine, as well as for a recombinant
vaccine, the balance between the efficacy and the safety of the
vaccine vector virus is extremely important.
OBJECT OF THE INVENTION
[0008] Thus, an object of the invention is to provide novel virus
strains having enhanced safety for the development of safer
products, such as vaccines or pharmaceuticals. Moreover, a further
object is to provide a means for improving an existing vaccination
regimen.
SUMMARY OF THE INVENTION
[0009] The invention inter alia comprises the following, alone or
in combination:
[0010] A method for inducing an immune response for treating a
human patient comprising:
[0011] (a) administering to the patient a priming inoculation of an
effective amount of a MVA virus, wherein the MVA virus is
characterized by reproductive replication in vitro in chicken
embryo fibroblasts and by being non-replicative in vitro in human
cell lines selected from the human keratinocyte cell line HaCaT,
the human embryo kidney cell line 293, the human bone osteosarcoma
cell line 143B, and the human cervix adenocarcinoma cell line HeLa;
and
[0012] (b) administering to the patient a boosting inoculation of
an effective amount of a MVA virus, such a
[0013] method wherein the MVA is MVA-BN as deposited at the
European Collection of Cell Cultures (ECACC), Salisbury (UK) under
number V00083008 or a derivative thereof, such a
[0014] method wherein the MVA virus comprises a heterologous
nucleic acid sequence, such a
[0015] method wherein the heterologous nucleic acid sequence is
selected from a sequence encoding at least one antigen, antigenic
epitope, and/or a therapeutic compound, such a
[0016] method wherein the antigen or antigenic epitope is derived
from a virus selected from the family of Influenza virus,
Flavivirus, Paramyxovirus, Hepatitis virus, Cytomegalovirus, Human
immunodeficiency virus or from viruses causing hemorrhagic fever,
such a
[0017] method wherein the antigen or antigenic epitope comprises
nef, such a
[0018] method wherein an immune response is directed against HIV,
such a
[0019] method wherein the MVA virus is administered as a vaccine,
such a
[0020] method wherein the immune response is directed against an
orthopox virus, selected from smallpox, such a
[0021] method wherein the patient is immune compromised, such a
[0022] method wherein the patient exhibits preexisting immunity to
MVA, such a
[0023] method wherein the MVA is administered by intravenous,
intramuscular, and/or subcutaneous injection, such a
[0024] method wherein the MVA prime/MVA boost inoculation regime
induces at least the same level of immune response when compared to
a DNA-prime/vaccinia virus boost inoculation regime, such a
[0025] method wherein the MVA is administered at a dose of at least
about 1.times.10.sup.8 TCID.sub.50, such a
[0026] method wherein the priming inoculation MVA is administered
about 4 weeks prior to the boosting inoculation MVA, such a
[0027] method for inducing an immune response for treating a mammal
comprising:
[0028] (a) administering to the mammal a priming inoculation of an
effective amount of a MVA virus, wherein the MVA virus is
characterized by reproductive replication in vitro in chicken
embryo fibroblasts and by being non-replicative in vitro in human
cell lines selected from the human keratinocyte cell line HaCaT,
the human embryo kidney cell line 293, the human bone osteosarcoma
cell line 143B, and the human cervix adenocarcinoma cell line HeLa;
and
[0029] (b) administering to the mammal a boosting inoculation of an
effective amount of a MVA virus.
[0030] A kit for treating a human patient comprising:
[0031] (a) a MVA characterized by reproductive replication in vitro
in chicken embryo fibroblasts and by being non-replicative in vitro
in human cell lines selected from the human keratinocyte cell line
HaCaT, the human embryo kidney cell line 293, the human bone
osteosarcoma cell line 143B, and the human cervix adenocarcinoma
cell line HeLa; and
[0032] (b) instructions to administer the MVA in a priming
inoculation and in a boosting inoculation, such a
[0033] kit wherein the MVA is MVA-BN as deposited at the European
Collection of Cell Cultures (ECACC), Salisbury (UK) under number
V00083008 or a derivative thereof, such a
[0034] kit wherein the MVA virus comprises a heterologous nucleic
acid sequence, such a
[0035] kit wherein the heterologous nucleic acid sequence is
selected from a sequence encoding at least one antigen, antigenic
epitope, and/or a therapeutic compound, such a
[0036] kit wherein the antigen or antigenic epitope is derived from
a virus selected from the family of Influenza virus, Flavivirus,
Paramyxovirus, Hepatitis virus, Cytomegalovirus, Human
immunodeficiency virus or from viruses causing hemorrhagic fever,
such a
[0037] kit wherein the MVA virus is administered as a vaccine, such
a
[0038] kit wherein the treatment is directed against an orthopox
virus, selected from smallpox, such a
[0039] kit wherein the treatment is directed to a patient who is
immune compromised, such a
[0040] kit wherein the MVA is administered by intravenous,
intramuscular, and/or subcutaneous injection.
DETAILED DESCRIPTION OF THE INVENTION
[0041] To achieve the foregoing objectives, according to a
preferred embodiment of the present invention, new vaccinia viruses
are provided which are capable of reproductive replication in
non-human cells and cell lines, especially in chicken embryo
fibroblasts (CEF), but not capable of reproductive replication in a
human cell line known to permit replication with known vaccinia
strains.
[0042] Known vaccinia strains reproductively replicate in at least
some human cell lines, in particular the human keratinocyte cell
line HaCaT (Boukamp et al. 1988, J Cell Biol 106(3): 761-71).
Replication in the HaCaT cell line is predictive for replication in
vivo, in particular for in vivo replication in humans. It is
demonstrated in the example section that all known vaccinia strains
tested that show a residual reproductive replication in HaCaT also
replicate in vivo. Thus, the invention preferably relates to
vaccinia viruses that do not reproductively replicate in the human
cell line HaCaT. Most preferably, the invention concerns vaccinia
virus strains that are not capable of reproductive replication in
any of the following human cell lines: human cervix adenocarcinoma
cell line HeLa (ATCC No. CCL-2), human embryo kidney cell line 293
(ECACC No. 85120602), human bone osteosarcoma cell line 143B (ECACC
No. 91112502) and the HaCaT cell line.
[0043] The growth behaviour or amplification/replication of a virus
is normally expressed by the ratio of virus produced from an
infected cell (Output) to the amount originally used to infect the
cell in the first place (Input) ("amplification ratio). A ratio of
"1" between Output and Input defines an amplification status
wherein the amount of virus produced from the infected cells is the
same as the amount initially used to infect the cells. This ratio
is understood to mean that the infected cells are permissive for
virus infection and virus reproduction.
[0044] An amplification ratio of less than 1, i.e., a decrease of
the amplification below input level, indicates a lack of
reproductive replication and thus, attenuation of the virus.
Therefore, it was of particular interest for the inventors to
identify and isolate a strain that exhibits an amplification ratio
of less than 1 in several human cell lines, in particular all of
the human cell lines 143B, HeLa, 293, and HaCaT.
[0045] Thus, the term "not capable of reproductive replication"
means that the virus of the present invention exhibits an
amplification ratio of less than 1 in human cell lines, such as 293
(ECACC No. 85120602), 143B (ECACC No. 91112502), HeLa (ATCC No.
CCL-2) and HaCaT (Boukamp et al. 1988, J Cell Biol 106(3): 761-71)
under the conditions outlined in Example 1 of the present
specification. Preferably, the amplification ratio of the virus of
the invention is 0.8 or less in each of the above human cell lines,
i.e., HeLa, HaCaT, and 143B.
[0046] Viruses of the invention are demonstrated in Example 1 and
Table 1 not to reproductively replicate in cell lines 143B, HeLa
and HaCaT. The particular strain of the invention that has been
used in the examples was deposited on Aug. 30, 2000 at the European
Collection of Cell Cultures (ECACC) under number V00083008. This
strain is referred to as "MVA-BN" throughout the Specification. It
has already been noted that the known MVA strains show residual
replication in at least one of the human cell lines tested (FIG. 1,
Example 1). All known vaccinia strains show at least some
replication in the cell line HaCaT, whereas the MVA strains of the
invention, in particular MVA-BN, do not reproductively replicate in
HaCaT cells. In particular, MVA-BN exhibits an amplification ratio
of 0.05 to 0.2 in the human embryo kidney cell line 293 (ECACC No.
85120602). In the human bone osteosarcoma cell line 143B (ECACC No.
91112502), the ratio is in the range of 0.0 to 0.6. For the human
cervix adenocarcinoma cell line HeLa (ATCC No. CCL-2) and the human
keratinocyte cell line HaCaT (Boukamp et al. 1988, J Cell Biol
106(3): 761-71), the amplification ratio is in the range of 0.04 to
0.8 and of 0.02 to 0.8, respectively. MVA-BN has an amplification
ratio of 0.01 to 0.06 in African green monkey kidney cells (CV1:
ATCC No. CCL-70). Thus, MVA-BN, which is a representative strain of
the invention, does not reproductively replicate in any of the
human cell lines tested.
[0047] The amplification ratio of MVA-BN is clearly above 1 in
chicken embryo fibroblasts (CEF: primary cultures). As outlined
above, a ratio of more than "1" indicates reproductive replication
since the amount of virus produced from the infected cells is
increased compared to the amount of virus that was used to infect
the cells. Therefore, the virus can be easily propagated and
amplified in CEF primary cultures with a ratio above 500.
[0048] In a particular embodiment of the present invention, the
invention concerns derivatives of the virus as deposited under
ECACC V0083008. "Derivatives" of the viruses as deposited under
ECACC V00083008 refer to viruses exhibiting essentially the same
replication characteristics as the deposited strain but exhibiting
differences in one or more parts of its genome. Viruses having the
same "replication characteristics" as the deposited virus are
viruses that replicate with similar amplification ratios as the
deposited strain in CEF cells and the cell lines HeLa, HaCaT and
143B; and that show a similar replication in vivo, as determined in
the AGR129 transgenic mouse model (see below).
[0049] In a further preferred embodiment, the vaccinia virus
strains of the invention, in particular MVA-BN and its derivatives,
are characterized by a failure to replicate in vivo. In the context
of the present invention, "failure to replicate in vivo" refers to
viruses that do not replicate in humans and in the mouse model
described below. The "failure to replicate in vivo" can be
preferably determined in mice that are incapable of producing
mature B and T cells. An example of such mice is the transgenic
mouse model AGR129 (obtained from Mark Sutter, Institute of
Virology, University of Zurich, Zurich, Switzerland). This mouse
strain has targeted gene disruptions in the IFN receptor type I
(IFN-.alpha./.beta.) and type II (IFN-.gamma.) genes, and in RAG.
Due to these disruptions, the mice have no IFN system and are
incapable of producing mature B and T cells, and as such, are
severely immune-compromised and highly susceptible to a replicating
virus. In addition to the AGR129 mice, any other mouse strain can
be used that is incapable of producing mature B and T cells, and as
such, is severely immune-compromised and highly susceptible to a
replicating virus. In particular, the viruses of the present
invention do not kill AGR129 mice within a time period of at least
45 days, more preferably within at least 60 days, and most
preferably within 90 days post infection of the mice with 10.sup.7
pfu virus administered via intra-peritoneal injection. Preferably,
the viruses that exhibit "failure to replicate in vivo" are further
characterized in that no virus can be recovered from organs or
tissues of the AGR129 mice 45 days, preferably 60 days, and most
preferably 90 days after infection of the mice with 10.sup.7 pfu
virus administered via intra-peritoneal injection. Detailed
information regarding the infection assays using AGR129 mice and
the assays used to determine whether virus can be recovered from
organs and tissues of infected mice can be found in the example
section.
[0050] In a further preferred embodiment, the vaccinia virus
strains of the invention, in particular MVA-BN and its derivatives,
are characterized as inducing a higher specific immune response
compared to the strain MVA-575, as determined in a lethal challenge
mouse model. Details of this experiment are outlined in Example 2,
shown below. Briefly, in such a model unvaccinated mice die after
infection with replication competent vaccinia strains such as the
Western Reserve strain L929 TK+ or IHD-J. Infection with
replication competent vaccinia viruses is referred to as
"challenge" in the context of description of the lethal challenge
model. Four days after the challenge, the mice are usually killed
and the viral titre in the ovaries is determined by standard plaque
assays using VERO cells (for more details see example section). The
viral titre is determined for unvaccinated mice and for mice
vaccinated with vaccina viruses of the present invention. More
specifically, the viruses of the present invention are
characterized in that, in this test after the vaccination with
10.sup.2 TCID.sub.50/ml of virus of the present invention, the
ovarian virus titres are reduced by at least 70%, preferably by at
least 80%, and more preferably by at least 90%, compared to
unvaccinated mice.
[0051] In a further preferred embodiment, the vaccinia viruses of
the present invention, in particular MVA-BN and its derivatives,
are useful for immunization with prime/boost administration of the
vaccine. There have been numerous reports suggesting that
prime/boost regimes using a known MVA as a delivery vector induce
poor immune responses and are inferior to DNA-prime/MVA-boost
regimes (Schneider et al., 1998, Nat. Med. 4; 397-402). In all of
those studies the MVA strains that have been used are different
from the vaccinia viruses of the present invention. To explain the
poor immune response if MVA was used for prime and boost
administration it has been hypothesized that antibodies generated
to MVA during the prime-administration neutralize the MVA
administered in the second immunization, thereby preventing an
effective boost of the immune response. In contrast,
DNA-prime/MVA-boost regimes are reported to be superior at
generating high avidity responses because this regime combines the
ability of DNA to effectively prime the immune response with the
properties of MVA to boost the response in the absence of a
pre-existing immunity to MVA. Clearly, if a pre-existing immunity
to MVA and/or vaccinia prevents boosting of the immune response,
then the use of MVA as a vaccine or therapeutic would have limited
efficacy, particularly in the individuals that have been previously
vaccinated against smallpox. However, according to a further
embodiment, the vaccinia virus of the present invention, in
particular MVA-BN and its derivatives, as well as corresponding
recombinant viruses harboring heterologous sequences, can be used
to efficiently first prime and then boost immune responses in naive
animals, as well as animals with a pre-existing immunity to
poxviruses. Thus, the vaccinia virus of the present invention
induces at least substantially the same level of immunity in
vaccinia virus prime/vaccinia virus boost regimes compared to
DNA-prime/vaccinia virus boost regimes. The term "animal" as used
in the present description is intended to also include human
beings. Thus, the virus of the present invention is also useful for
prime/boost regimes in human beings. If the virus is a
non-recombinant virus such as MVA-BN or a derivative thereof, the
virus may be used as a smallpox vaccine in humans, wherein the same
virus can be used in both the priming and boosting vaccination. If
the virus is a recombinant virus such as MVA-BN or a derivative
thereof that encodes a heterologous antigen, the virus may be used
in humans as a vaccine against the agent from which the
heterologous antigen is derived, wherein the same virus can be used
in both the priming and boosting vaccination.
[0052] A vaccinia virus is regarded as inducing at least
substantially the same level of immunity in vaccinia virus
prime/vaccinia virus boost regimes if, when compared to
DNA-prime/vaccinia virus boost regimes, the CTL response, as
measured in one of the following two assays ("assay 1" and "assay
2"), preferably in both assays, is at least substantially the same
in vaccinia virus prime/vaccinia virus boost regimes when compared
to DNA-prime/vaccinia virus boost regimes. More preferably, the CTL
response after vaccinia virus prime/vaccinia virus boost
administration is higher in at least one of the assays, when
compared to DNA-prime/vaccinia virus boost regimes. Most
preferably, the CTL response is higher in both of the following
assays.
[0053] Assay 1:
[0054] For vaccinia virus prime/vaccinia virus boost
administrations, 6-8 week old BALB/c (H-2d) mice are
prime-immunized by intravenous administration with 10.sup.7
TCID.sub.50 vaccinia virus of the invention expressing the murine
polytope as described in Thomson et al., 1998, J. Immunol. 160,
1717 and then boost-immunized with the same amount of the same
virus, administered in the same manner three weeks later. To this
end, it is necessary to construct a recombinant vaccinia virus
expressing the polytope. Methods to construct such recombinant
viruses are known to a person skilled in the art and are described
in more detail below. In DNA prime/vaccinia virus boost regimes the
prime vaccination is done by intra muscular injection of the mice
with 50 .mu.g DNA expressing the same antigen as the vaccinia
virus. The boost administration with the vaccinia virus is done in
exactly the same way as for the vaccinia virus prime/vaccinia virus
boost administration. The DNA plasmid expressing the polytope is
also described in the publication referenced above, i.e., Thomson,
et al. In both regimes, the development of a CTL response against
the epitopes SYI, RPQ and/or YPH is determined two weeks after the
boost administration. The determination of the CTL response is
preferably done using the ELISPOT analysis as described by
Schneider, et al., 1998, Nat. Med. 4, 397-402, and as outlined in
the examples section below for a specific virus of the invention.
The virus of the invention is characterized in this experiment in
that the CTL immune response against the epitopes mentioned above,
which is induced by the vaccinia virus prime/vaccinia virus boost
administration, is substantially the same, preferably at least the
same, as that induced by DNA prime/vaccinia virus boost
administration, as assessed by the number of IFN-.gamma. producing
cells/10.sup.6 spleen cells (see also experimental section).
[0055] Assay 2:
[0056] This assay basically corresponds to assay 1. However,
instead of using 10.sup.7 TCID.sub.50 vaccinia virus administered
i.v., as in Assay 1; in Assay 2, 10.sup.8 TCID.sub.50 vaccinia
virus of the present invention is administered by subcutaneous
injection for both prime and boost immunization. The virus of the
present invention is characterized in this experiment in that the
CTL immune response against the epitopes mentioned above, which is
induced by the vaccinia virus prime/vaccinia virus boost
administration, is substantially the same, preferably at least the
same, as that induced by DNA prime/vaccinia virus boost
administration, as assessed by the number of IFN-.gamma. producing
cells/10.sup.6 spleen cells (see also experimental section).
[0057] The strength of a CTL response as measured in one of the
assays shown above corresponds to the level of protection.
[0058] Thus, the viruses of the present invention are particularly
suitable for vaccination purposes.
[0059] In summary, a representative vaccinia virus of the present
invention is characterized by having at least one of the following
properties: [0060] (i) capability of reproductive replication in
chicken embryo fibroblasts (CEF), but no capability of reproductive
replication in a human cell line known to permit replication with
known vaccinia strains, [0061] (ii) failure to replicate in vivo in
those animals, including humans, in which the virus is used as a
vaccine or active ingredient of a pharmaceutical composition,
[0062] (iii) induction of a higher specific immune response
compared to a known vaccinia strain and/or [0063] (iv) induction of
at least substantially the same level of a specific immune response
in vaccinia virus prime/vaccinia virus boost regimes when compared
to DNA-prime/vaccinia virus boost regimes.
[0064] Preferably, the vaccinia virus of the present invention has
at least two of the above properties, and more preferably at least
three of the above properties. Most preferred are vaccinia viruses
having all of the above properties.
[0065] Representative vaccinia virus strains are MVA-575 deposited
on Dec. 7, 2000 at the European Collection of Animal Cell Cultures
(ECACC) with the deposition number V00120707; and MVA-BN, deposited
on Aug. 30, 2000, at ECACC with the deposition number V000083008,
and derivatives thereof, in particular if it is intended to
vaccinate/treat humans. MVA-BN and its derivatives are most
preferred for humans.
[0066] In a further embodiment, the invention concerns a kit for
vaccination comprising a virus of the present invention for the
first vaccination ("priming") in a first vial/container and for a
second vaccination ("boosting") in a second vial/container. The
virus may be a non-recombinant vaccinia virus, i.e., a vaccinia
virus that does not contain heterologous nucleotide sequences. An
example of such a vaccinia virus is MVA-BN and its derivatives.
Alternatively, the virus may be a recombinant vaccinia virus that
contains additional nucleotide sequences that are heterologous to
the vaccinia virus. As outlined in other sections of the
description, the heterologous sequences may code for epitopes that
induce a response by the immune system. Thus, it is possible to use
the recombinant vaccinia virus to vaccinate against the proteins or
agents comprising the epitope. The viruses may be formulated as
shown below in more detail. The amount of virus that may be used
for each vaccination has been defined above.
[0067] A process to obtain a virus of the instant invention may
comprise the following steps: [0068] (i) introducing a vaccinia
virus strain, for example MVA-574 or MVA-575 (ECACC V00120707) into
non-human cells in which the virus is able to reproductively
replicate, wherein the non-human cells are preferably selected from
CEF cells, [0069] (ii) isolating/enriching virus particles from
these cells and [0070] (iii) analyzing whether the obtained virus
has at least one of the desired biological properties as previously
defined above, wherein the above steps can optionally be repeated
until a virus with the desired replication characteristics is
obtained. The invention further relates to the viruses obtained by
the method of the instant invention. Methods for determining the
expression of the desired biological properties are explained in
other parts of this description.
[0071] In applying this method, a strain of the present invention
may be identified and isolated which corresponds to the strain with
the accession number ECACC V0083008, mentioned above.
[0072] The growth behavior of the vaccinia viruses of the present
invention, in particular the growth behavior of MVA-BN, indicates
that the strains of the present invention are far superior to any
other characterized MVA isolates in terms of attenuation in human
cell lines and failure to replicate in vivo. The strains of the
present invention are therefore ideal candidates for the
development of safer products such as vaccines or pharmaceuticals,
as described below.
[0073] In one further embodiment, the virus of the present
invention, in particular MVA-BN and its derivatives, is used as a
vaccine against human poxvirus diseases, such as smallpox.
[0074] In a further embodiment, the virus of the present invention
may be recombinant, i.e., may express heterologous genes as, e.g.,
antigens or epitopes heterologous to the virus, and may thus be
useful as a vaccine to induce an immune response against
heterologous antigens or epitopes.
[0075] The term "immune response" means the reaction of the immune
system when a foreign substance or microorganism enters the
organism. By definition, the immune response is divided into a
specific and an unspecific reaction although both are closely
related. The unspecific immune response is the immediate defence
against a wide variety of foreign substances and infectious agents.
The specific immune response is the defence raised after a lag
phase, when the organism is challenged with a substance for the
first time. The specific immune response is highly efficient and is
responsible for the fact that an individual who recovers from a
specific infection is protected against this specific infection.
Thus, a second infection with the same or a very similar infectious
agent causes much milder symptoms or no symptoms at all, since
there is already a "pre-existing immunity" to this agent. Such
immunity and immunological memory persist for a long time, in some
cases even lifelong. Accordingly, the induction of an immunological
memory can be used for vaccination.
[0076] The "immune system" means a complex organ involved in the
defence of the organism against foreign substances and
microorganisms. The immune system comprises a cellular component,
comprising several cell types, such as, e.g., lymphocytes and other
cells derived from white blood cells, and a humoral component,
comprising small peptides and complement factors.
[0077] "Vaccination" means that an organism is challenged with an
infectious agent, e.g., an attenuated or inactivated form of the
infectious agent, to induce a specific immunity. The term
vaccination also covers the challenge of an organism with
recombinant vaccinia viruses of the present invention, in
particular recombinant MVA-BN and its derivatives, expressing
antigens or epitopes that are heterologous to the virus. Examples
of such epitopes are provided elsewhere in the description and
include e.g., epitopes from proteins derived from other viruses,
such as the Dengue virus, Hepatitis C virus, HIV, or epitopes
derived from proteins that are associated with the development of
tumors and cancer. Following administration of the recombinant
vaccinia virus, the epitopes are expressed and presented to the
immune system. A specific immune response against these epitopes
may be induced. The organism, thus, is immunized against the
agent/protein containing the epitope that is encoded by the
recombinant vaccinia virus.
[0078] "Immunity" means partial or complete protection of an
organism against diseases caused by an infectious agent due to a
successful elimination of a preceding infection with the infectious
agent or a characteristic part thereof. Immunity is based on the
existence, induction, and activation of specialized cells of the
immune system.
[0079] As indicated above, in one embodiment of the invention the
recombinant viruses of the present invention, in particular
recombinant MVA-BN and its derivatives, contain at least one
heterologous nucleic acid sequence. The term "heterologous" is used
hereinafter for any combination of nucleic acid sequences that is
not normally found intimately associated with the virus in nature;
such virus is also called a "recombinant virus".
[0080] According to a further embodiment of the present invention,
the heterologous sequences are preferably antigenic epitopes that
are selected from any non-vaccinia source. Most preferably, the
recombinant virus expresses one or more antigenic epitopes from:
Plasmodium falciparum, mycobacteria, influenza virus, viruses of
the family of flaviviruses, paramyxoviruses, hepatitis viruses,
human immunodeficiency viruses, or from viruses causing hemorrhagic
fever, such as hantaviruses or filoviruses, i.e., ebola or marburg
virus.
[0081] According to still a further embodiment, but also in
addition to the above-mentioned selection of antigenic epitopes,
the heterologous sequences can be selected from another poxyiral or
a vaccinia source. These viral sequences can be used to modify the
host spectrum or the immunogenicity of the virus.
[0082] In a further embodiment the virus of the present invention
may code for a heterologous gene/nucleic acid expressing a
therapeutic compound. A "therapeutic compound" encoded by the
heterologous nucleic acid in the virus can be, e.g., a therapeutic
nucleic acid, such as an antisense nucleic acid or a peptide or
protein with desired biological activity.
[0083] According to a further preferred embodiment, the expression
of a heterologous nucleic acid sequence is preferably, but not
exclusively, under the transcriptional control of a poxvirus
promoter, more preferably of a vaccinia virus promoter.
[0084] According to still a further embodiment, the heterologous
nucleic acid sequence is preferably inserted into a non-essential
region of the virus genome. In another preferred embodiment of the
invention, the heterologous nucleic acid sequence is inserted at a
naturally occurring deletion site of the MVA genome as disclosed in
PCT/EP96/02926. Methods for inserting heterologous sequences into
the poxyiral genome are known to a person skilled in the art.
[0085] According to yet another preferred embodiment, the invention
also includes the genome of the virus, its recombinants, or
functional parts thereof. Such viral sequences can be used to
identify or isolate the virus or its recombinants, e.g., by using
PCR, hybridization technologies, or by establishing ELISA assays.
Furthermore, such viral sequences can be expressed from an
expression vector to produce the encoded protein or peptide that
then may supplement deletion mutants of a virus that lacks the
viral sequence contained in the expression vector.
[0086] "Functional part" of the viral genome means a part of the
complete genomic sequence that encodes a physical entity, such as a
protein, protein domain, or an epitope of a protein. Functional
part of the viral genome also describes parts of the complete
genomic sequence that code for regulatory elements or parts of such
elements with individualized activity, such as promoter, enhancer,
cis- or trans-acting elements.
[0087] The recombinant virus of the present invention may be used
for the introduction of a heterologous nucleic acid sequence into a
target cell, the sequence being either homologous or heterologous
to the target cell. The introduction of a heterologous nucleic acid
sequence into a target cell may be used to produce in vitro
heterologous peptides or polypeptides, and/or complete viruses
encoded by the sequence. This method comprises the infection of a
host cell with the recombinant MVA; cultivation of the infected
host cell under suitable conditions; and isolation and/or
enrichment of the peptide, protein and/or virus produced by the
host cell.
[0088] Furthermore, the method for introduction of a homologous or
heterologous sequence into cells may be applied for in vitro and
preferably in vivo therapy. For in vitro therapy, isolated cells
that have been previously (ex vivo) infected with the virus are
administered to a living animal body for inducing an immune
response. For in vivo therapy, the virus or its recombinants are
directly administered to a living animal body to induce an immune
response. In this case, the cells surrounding the site of
inoculation are directly infected in vivo by the virus, or its
recombinants, of the present invention.
[0089] Since the virus of the invention is highly growth restricted
in human and monkey cells and thus, highly attenuated, it is ideal
to treat a wide range of mammals, including humans. Hence, the
present invention also provides a pharmaceutical composition and a
vaccine, e.g., for inducing an immune response in a living animal
body, including a human. The virus of the invention is also safe in
any other gene therapy protocol.
[0090] The pharmaceutical composition may generally include one or
more pharmaceutical acceptable and/or approved carriers, additives,
antibiotics, preservatives, adjuvants, diluents and/or stabilizers.
Such auxiliary substances can be water, saline, glycerol, ethanol,
wetting or emulsifying agents, pH buffering substances, or the
like. Suitable carriers are typically large, slowly metabolized
molecules such as proteins, polysaccharides, polylactic acids,
polyglycolic acids, polymeric amino acids, amino acid copolymers,
lipid aggregates, or the like.
[0091] For the preparation of vaccines, the virus or a recombinant
of the present invention, is converted into a physiologically
acceptable form. This can be done based on experience in the
preparation of poxvirus vaccines used for vaccination against
smallpox (as described by Stickl, H. et al. [1974] Dtsch. med.
Wschr. 99, 2386-2392). For example, the purified virus is stored at
-80.degree. C. with a titre of 5.times.10.sup.8 TCID.sub.50/ml
formulated in about 10 mM Tris, 140 mM NaCl, pH 7.4. For the
preparation of vaccine shots, e.g., 10.sup.2-10.sup.8 particles of
the virus are lyophilized in 100 ml of phosphate-buffered saline
(PBS) in the presence of 2% peptone and 1% human albumin in an
ampoule, preferably a glass ampoule. Alternatively, the vaccine
shots can be produced by stepwise, freeze-drying of the virus in a
formulation. This formulation can contain additional additives such
as mannitol, dextran, sugar, glycine, lactose,
polyvinylpyrrolidone, or other additives, such as antioxidants or
inert gas, stabilizers or recombinant proteins (e.g. human serum
albumin) suitable for in vivo administration. The glass ampoule is
then sealed and can be stored between 4.degree. C. and room
temperature for several months. However, as long as no need exists
the ampoule is stored preferably at temperatures below -20.degree.
C.
[0092] For vaccination or therapy, the lyophilisate can be
dissolved in 0.1 to 0.5 ml of an aqueous solution, preferably
physiological saline or Tris buffer, and administered either
systemically or locally, i.e., by parenteral, intramuscular, or any
other path of administration know to a skilled practitioner. The
mode of administration, dose, and number of administrations can be
optimized by those skilled in the art in a known manner.
[0093] Additionally according to a further embodiment, the virus of
the present invention is particularly useful to induce immune
responses in immune-compromised animals, e.g., monkeys
(CD4<400/.mu.l of blood) infected with SIV, or
immune-compromised humans. The term "immune-compromised" describes
the status of the immune system of an individual that exhibits only
incomplete immune responses or has a reduced efficiency in the
defence against infectious agents. Even more interesting and
according to still a further embodiment, the virus of the present
invention can boost immune responses in immune-compromised animals
or humans even in the presence of a pre-existing immunity to
poxvirus in these animals or humans. Of particular interest, the
virus of the present invention can also boost immune responses in
animals or humans receiving an antiviral, e.g., antiretroviral
therapy. "Antiviral therapy" includes therapeutic concepts in order
to eliminate or suppress viral infection including, e.g., (i) the
administration of nucleotide analogs, (ii) the administration of
inhibitors for viral enzymatic activity or viral assembling, or
(iii) the administration of cytokines to influence immune responses
of the host.
[0094] According to still a further embodiment, the vaccine is
especially, but not exclusively, applicable in the veterinary
field, e.g., immunization against animal pox infection. In small
animals, the immunizing inoculation is preferably administered by
nasal or parenteral administration, whereas in larger animals or
humans, a subcutaneous, oral, or intramuscular inoculation is
preferred.
[0095] The inventors have found that a vaccine shot containing an
effective dose of only 10.sup.2 TCID.sub.50 (tissue culture
infectious dose) of the virus of the present invention is
sufficient to induce complete immunity against a wild type vaccinia
virus challenge in mice. This is particularly surprising since such
a high degree of attenuation of the virus of the present invention
would be expected to negatively influence and thereby, reduce its
immunogenicity. Such expectation is based on the understanding that
for induction of an immune response, the antigenic epitopes must be
presented to the immune system in sufficient quantity. A virus that
is highly attenuated and thus, not replicating, can only present a
very small amount of antigenic epitopes, i.e., as much as the virus
itself incorporates. The amount of antigen carried by viral
particles is not considered to be sufficient for induction of a
potent immune response. However, the virus of the invention
stimulates, even with a very low effective dose of only 10.sup.2
TCID.sub.50, a potent and protective immune response in a
mouse/vaccinia challenge model. Thus, the virus of the present
invention exhibits an unexpected and increased induction of
specific immunity compared to other characterized MVA strains. This
makes the virus of the present invention and any vaccine derived
thereof, especially useful for application in immune-compromised
animals or humans.
[0096] According to still another embodiment of the invention, the
virus is used as an adjuvant. An "adjuvant" in the context of the
present description refers to an enhancer of the specific immune
response in vaccines. "Using the virus as adjuvant" means including
the virus in a pre-existing vaccine to additionally stimulate the
immune system of the patient who receives the vaccine. The
immunizing effect of an antigenic epitope in most vaccines is often
enhanced by the addition of a so-called adjuvant. An adjuvant
co-stimulates the immune system by causing a stronger specific
immune reaction against an antigenic epitope of a vaccine. This
stimulation can be regulated by factors of the unspecific immune
system, such as interferon and interleukin. Hence, in a further
embodiment of the invention, the virus is used in mammals,
including humans, to activate, support, or suppress the immune
system, and preferably to activate the immune response against any
antigenic determinant. The virus may also be used to support the
immune system in a situation of increased susceptibility to
infection, such as in the case of stress.
[0097] The virus used as an adjuvant may be a non-recombinant
virus, i.e., a virus that does not contain heterologous DNA in its
genome. An example of this type of virus is MVA-BN. Alternatively,
the virus used as an adjuvant is a recombinant virus containing in
its genome heterologous DNA sequences that are not naturally
present in the viral genome. For use as an adjuvant, the
recombinant viral DNA preferably contains and expresses genes that
code for immune stimulatory peptides or proteins such as
interleukins.
[0098] According to a further embodiment, it is preferred that the
virus is inactivated when used as an adjuvant or added to another
vaccine. The inactivation of the virus may be performed by e.g.,
heat or chemicals, as known in the art. Preferably, the virus is
inactivated by .beta.-propriolacton. According to this embodiment
of the invention, the inactivated virus may be added to vaccines
against numerous infectious or proliferative diseases to increase
the immune response of the patient to this disease.
BRIEF DESCRIPTION OF THE FIGURES
[0099] FIG. 1: Growth kinetics of different strains of MVA in
different cell lines. In 1A, the results are grouped according to
the MVA strains tested; whereas in 1B, the results are grouped
according to the cell lines tested. In 1B, the amount of virus
recovered from a cell line after four days (D4) of culture was
determined by plaque assay and expressed as the ratio of virus
recovered after 4 days to the initial inoculum on day 1 (D1).
[0100] FIG. 2: Protection provided against a lethal challenge of
vaccinia following vaccinations with either MVA-BN or MVA-575. The
protection is measured by the reduction in ovarian titres
determined 4 days post challenge by standard plaque assay.
[0101] FIG. 3: Induction of CTL and protection provided against an
influenza challenge using different prime/boost regimes.
[0102] 3A: Induction of CTL responses to 4 different H-2d
restricted epitopes following vaccination with different
combinations of DNA or MVA-BN vaccines encoding a murine polytope.
BALB/c mice (5 per group) were vaccinated with either DNA
(intramuscular) or MVA-BN (subcutaneous) and received booster
immunizations three weeks later. CTL responses to 4 different
epitopes encoded by the vaccines (TYQ, infuenza; SYI, P. berghei;
YPH, cytomegalovirus; RPQ, LCV) were determined using an ELISPOT
assay 2 weeks post booster immunizations.
[0103] 3B: Induction of CTL responses to 4 different epitopes
following vaccination with different combinations of DNA or MVA-BN
vaccines encoding a murine polytope. BALB/c mice (5 per group) were
vaccinated with either DNA (intramuscular) or MVA-BN (intraveneous)
and received booster immunizations three weeks later. CTL responses
to 4 different epitopes encoded by the vaccines (TYQ, influenza;
SYI, P. berghei; YPH, cytomegalovirus; RPQ, LCV) were determined
using an ELISPOT assay 2 weeks post booster immunizations.
[0104] 3C: Frequency of peptide and MVA specific T cells following
homologous prime/boost using an optimal dose (1.times.10.sup.8
TCID.sub.50) of recombinant MVA-BN, administered subcutaneous.
Groups of 8 mice were vaccinated with two shots of the combinations
as indicated in the figure. Two weeks after the final vaccination,
peptide-specific splenocytes were enumerated using an IFN-gamma
ELISPOT assay. The bars represent the mean number of specific spots
plus/minus the standard deviation from the mean.
[0105] FIG. 4: Induction of antibodies to MVA following vaccination
of mice with different smallpox vaccines. The levels of antibodies
generated to MVA following vaccination with MVA-BN (week 0 and 4),
was compared to conventional vaccinia strains, Elstree and Wyeth,
given via tail scarification (week 0), MVA-572 (week 0 and 4), and
MVA-BN and MVA-572 given as a pre-Elstree vaccine. MVA-572 has been
deposited at the European Collection of Animal Cell Cultures as
ECACC V94012707. The titres were determined using a capture ELISA
and calculated by linear regression using the linear part of the
graph and defined as the dilution that resulted in an optical
density of 0.3. *MVA-BN:MVA-BN is significantly (p>0.05)
different to MVA-572:MVA-572.
EXAMPLES
[0106] The following examples further illustrate the present
invention. It should be understood by a person skilled in the art
that the examples may not be interpreted in any way to limit the
applicability of the technology provided by the present invention
to specific application in these examples.
Example 1
Growth Kinetics of a New Strain of MVA in Selected Cell Lines and
Replication In Vivo
(1.1) Growth Kinetics in Cell Lines:
[0107] To characterize a newly isolated strain of the present
invention (further referred to as MVA-BN) the growth kinetics of
the new strain were compared to those of known MVA strains that
have already been characterized.
[0108] The experiment compared the growth kinetics of the following
viruses in the subsequently listed primary cells and cell lines:
[0109] MVA-BN (Virus stock #23, 18. 02. 99 crude, titered at
2.0.times.10.sup.7 TCID.sub.50/ml); [0110] MVA as characterized by
Altenburger (U.S. Pat. No. 5,185,146) and further referred to as
MVA-HLR; [0111] MVA (passage 575) as characterized by Anton Mayr
(Mayr, A., et al. [1975]Infection 3; 6-14) and further referred to
as MVA-575 (ECACC V00120707); and [0112] MVA-Vero as characterized
in the International Patent Application PCT/EP01/02703 (WO
01/68820); Virus stock, passage 49, #20, 22.03.99 crude, titered at
4.2.times.10.sup.7 TCID.sub.50/ml.
[0113] The primary cells and cell lines used were: [0114] CEF
Chicken embryo fibroblasts (freshly prepared from SPF eggs); [0115]
HeLa Human cervix adenocarcinoma (epithelial), ATCC No. CCL-2;
[0116] 143B Human bone osteosarcoma TK-, ECACC No. 91112502; [0117]
HaCaT Human keratinocyte cell line, Boukamp et al. 1988, J Cell
Biol 106(3): 761-771; [0118] BHK Baby hamster kidney, ECACC
85011433; [0119] Vero African green monkey kidney fibroblasts,
ECACC 85020299; [0120] CV1 African green monkey kidney fibroblasts,
ECACC 87032605.
[0121] For infection the cells were seeded onto 6-well-plates at a
concentration of 5.times.10.sup.5 cells/well and incubated
overnight at 37.degree. C., 5% CO.sub.2 in DMEM (Gibco, Cat. No.
61965-026) with 2% FCS. The cell culture medium was removed and
cells were infected at approximately moi 0.05 for one hour at
37.degree. C., 5% CO.sub.2 (for infection it is assumed that cell
numbers doubled over night). The amount of virus used for each
infection was 5.times.10.sup.4 TCID.sub.50 and is referred to as
Input. The cells were then washed 3 times with DMEM and finally 1
ml DMEM, 2% FCS was added and the plates were left to incubate for
96 hours (4 days) at 37.degree. C., 5% CO.sub.2. The infections
were stopped by freezing the plates at -80.degree. C.; followed by
titration analysis.
Titration Analysis (Immunostaining with a Vaccinia Virus Specific
Antibody)
[0122] For titration of amount of virus test cells (CEF) were
seeded on 96-well-plates in RPMI (Gibco, Cat. No. 61870-010), 7%
FCS, 1% Antibiotic/Antimycotic (Gibco, Cat. No. 15240-062) at a
concentration of 1.times.10.sup.4 cells/well and incubated over
night at 37.degree. C., 5% CO.sub.2. The 6-well-plates containing
the infection experiments were frozen/thawed 3 times and dilutions
of 10.sup.-1 to 10.sup.-12 were prepared using RPMI growth medium.
Virus dilutions were distributed onto test cells and incubated for
five days at 37.degree. C., 5% CO.sub.2 to allow CPE (cytopathic
effect) development. Test cells were fixed (Acetone/Methanol 1:1)
for 10 min, washed with PBS and incubated with polyclonal vaccinia
virus specific antibody (Quartett Berlin, Cat. No. 9503-2057) at a
1:1000 dilution in incubation buffer for one hour at RT. After
washing twice with PBS (Gibco, Cat. No. 20012-019) the HRP-coupled
anti-rabbit antibody (Promega Mannheim, Cat. No. W4011) was added
at a 1:1000 dilution in incubation buffer (PBS containing 3% FCS)
for one hour at RT. Cells were again washed twice with PBS and
incubated with staining solution (10 ml PBS+200 .mu.l saturated
solution of o-dianisidine in 100% ethanol+15 .mu.l H.sub.2O.sub.2
freshly prepared) until brown spots were visible (two hours).
Staining solution was removed and PBS was added to stop the
staining reaction. Every well exhibiting a brown spot was marked as
positive for CPE and the titre was calculated using the formula of
Kaerber (TCID.sub.50 based assay) (Kaerber, G. 1931. Arch. Exp.
Pathol. Pharmakol. 162, 480).
[0123] The viruses were used to infect duplicate sets of cells that
were expected to be permissive for MVA (i.e., CEF and BHK) and
cells expected to be non-permissive for MVA (i.e., CV-1, Vero,
HeLa, 143B and HaCaT). The cells were infected at a low
multiplicity of infection, i.e., 0.05 infectious units per cell
(5.times.10.sup.4 TCID.sub.50). The virus inoculum was removed and
the cells were washed three times to remove any remaining
unabsorbed viruses. Infections were left for a total of 4 days when
viral extracts were prepared and then titered on CEF cells. Table 1
and FIG. 1 show the results of the titration assays where values
are given as total amount of virus produced after 4 days
infection.
[0124] It was demonstrated that all viruses amplified well in CEF
cells as expected, since this is a permissive cell line for all
MVAs. Additionally, it was demonstrated that all viruses amplified
well in BHK (Hamster kidney cell line). MVA-Vero performed the
best, since BHK is a permissive cell line for this strain.
[0125] Concerning replication in Vero cells (Monkey kidney cell
line), MVA-Vero amplified well, as expected, i.e., 1000 fold above
Input. MVA-HLR and also MVA-575 amplified well with a 33-fold and
10-fold increase above Input, respectively. Only MVA-BN was found
to not amplify as well in these cells when compared to the other
strains, i.e., only a 2-fold increase above Input.
[0126] Also concerning replication in CV1 cells (Monkey kidney cell
line), it was found that MVA-BN is highly attenuated in this cell
line. It exhibited a
200-fold decrease below Input. MVA-575 did not amplify above the
Input level and also exhibited a slight negative amplification,
i.e., 16-fold decrease below Input. MVA-HLR amplified the best with
a 30-fold increase above Input, followed by MVA-Vero with 5-fold
increase above Input.
[0127] It is most interesting to compare the growth kinetics of the
various viruses in human cell lines. Regarding reproductive
replication in 143B cells (human bone cancer cell line) it was
demonstrated that MVA-Vero was the only strain to show
amplification above Input (3-fold increase). All other viruses did
not amplify above Input, however there was a big difference between
the MVA-HLR and both MVA-BN and MVA-575. MVA-HLR was "borderline"
(1-fold decrease below Input), whereas MVA-BN exhibited the
greatest attenuation (300-fold decrease below Input), followed by
MVA-575 (59-fold decrease below Input). To summarize, MVA-BN is
superior with respect to attenuation in human 143B cells.
[0128] Furthermore, concerning replication in HeLa cells (human
cervix cancer cells) it was demonstrated that MVA-HLR amplified
well in this cell line, and even better than it did in the
permissive BHK cells (HeLa=125-fold increase above Input;
BHK=88-fold increase above Input) MVA-Vero also amplified in this
cell line (27-fold increase above Input). However, MVA-BN, and also
to a lesser extent MVA-575, were attenuated in these cell lines
(MVA-BN=29-fold decrease below Input and MVA-575=6-fold decrease
below Input).
[0129] Concerning the replication in HaCaT cells (human
keratinocyte cell line), it was demonstrated that MVA-HLR amplified
well in this cell line (55-fold increase above Input). Both
MVA-Vero adapted and MVA-575 exhibited amplification in this cell
line (1.2 and 1.1-fold increase above Input, respectively).
However, MVA-BN was the only one to demonstrate attenuation (5-fold
decrease below Input).
[0130] From this experimental analysis, we may conclude that MVA-BN
is the most attenuated strain in this group of viruses. MVA-BN
demonstrates extreme attenuation in human cell lines by exhibiting
an amplification ratio of 0.05 to 0.2 in human embryo kidney cells
(293: ECACC No. 85120602) (data not incorporated in Table 1).
Furthermore, it exhibits an amplification ratio of about 0.0 in
143B cells; an amplification ratio of about 0.04 in HeLa cells; and
an amplification ratio of about 0.22 in HaCaT cells. Additionally,
MVA-BN exhibits an amplification ratio of about 0.0 in CV1 cells.
Amplification in Vero cells can be observed (ratio of 2.33),
however, not to the same extent as in permissive cell lines such as
BHK and CEF (compare to Table 1). Thus, MVA-BN is the only MVA
strain exhibiting an amplification ratio of less than 1 in each
human cell line examined, i.e., 143B, Hela, HaCaT, and 293.
[0131] MVA-575 exhibits a profile similar to that of MVA-BN,
however it is not as attenuated as MVA-BN.
[0132] MVA-HLR amplified well in all (human or otherwise) cell
lines tested, except for 143B cells. Thus, it can be regarded as
replication competent in all cell lines tested, with the exception
of 143B cells. In one case, it even amplified better in a human
cell line (HeLa) than in a permissive cell line (BHK).
[0133] MVA-Vero does exhibit amplification in all cell lines, but
to a lesser extent than demonstrated by MVA-HLR (ignoring the 143B
result). Nevertheless, it cannot be considered as being in the same
"class" with regards to attenuation, as MVA-BN or MVA-575.
1.2 Replication In Vivo
[0134] Given that some MVA strains clearly replicate in vitro,
different MVA strains were examined with regard to their ability to
replicate in vivo using a transgenic mouse model AGR129. This mouse
strain has targeted gene disruptions in the IFN receptor type I
(IFN-.alpha./.beta.) and type II (IFN-.gamma.) genes, and in RAG.
Due to these disruptions, the mice have no IFN system and are
incapable of producing mature B and T cells and, as such, are
severely immune-compromised and highly susceptible to a replicating
virus. Groups of six mice were immunized (i.p) with 10.sup.7 pfu of
either MVA-BN, MVA-HLR or MVA-572 (used in 120,000 people in
Germany) and monitored daily for clinical signs. All mice
vaccinated with MVA-HLR or MVA-572 died within 28 and 60 days,
respectively. At necropsy, there were general signs of severe viral
infection in the majority of organs. A standard plaque assay
measured the recovery of MVA (10.sup.8 pfu) from the ovaries. In
contrast, mice vaccinated with the same dose of MVA-BN
(corresponding to the deposited strain ECACC V00083008) survived
for more than 90 days and no MVA could be recovered from organs or
tissues.
[0135] When taken together, data from the in vitro and in vivo
studies clearly demonstrate that MVA-BN is more highly attenuated
than the parental and commercial MVA-HLR strain, and may be safe
for administration to immune-compromised subjects.
Example 2
Immunological and In Vivo Data in Animal Model Systems
[0136] These experiments were designed to compare different dose
and vaccination regimens of MVA-BN compared to other MVAs in animal
model systems.
2.1. Different Strains of MVA Differ in their Ability to Stimulate
the Immune Response.
[0137] Replication competent strains of vaccinia induce potent
immune responses in mice and at high doses are lethal. Although MVA
are highly attenuated and have a reduced ability to replicate on
mammalian cells, there are differences in the attenuation between
different strains of MVA. Indeed, MVA-BN appears to be more
attenuated than other MVA strains, even the parental strain
MVA-575. To determine whether this difference in attenuation
affects the efficacy of MVA to induce protective immune responses,
different doses of MVA-BN and MVA-575 were compared in a lethal
vaccinia challenge model. The levels of protection were measured by
a reduction in ovarian vaccinia titres determined 4 days post
challenge, as this allowed a quantitative assessment of different
doses and strains of MVA.
Lethal Challenge Model
[0138] Specific pathogen-free 6-8-week-old female BALB/c (H-2d mice
(n=5) were immunized (i.p.) with different doses (10.sup.2,
10.sup.4 or 10.sup.6 TCID.sub.50/ml) of either MVA-BN or MVA-575.
MVA-BN and MVA-575 had been propagated on CEF cells, and had been
sucrose purified and formulated in Tris pH 7.4. Three weeks later
the mice received a boost of the same dose and strain of MVA, which
was followed two weeks later by a lethal challenge (i.p.) with a
replication competent strain of vaccinia. As replication competent
vaccinia virus (abbreviated as "rVV") either the strain WR-L929 TK+
or the strain IHD-J were used. Control mice received a placebo
vaccine. The protection was measured by the reduction in ovarian
titres determined 4 days post challenge by standard plaque assay.
For this, the mice were sacrificed on day 4 post the challenge and
the ovaries were removed, homogenized in PBS (1 ml) and viral
titres determined by standard plaque assay using VERO cells
(Thomson, et al., 1998, J. Immunol. 160: 1717).
[0139] Mice vaccinated with two immunizations of either 10.sup.4 or
10.sup.6 TCID.sub.50/ml of MVA-BN or MVA-575 were completely
protected as judged by a 100% reduction in ovarian rVV titres 4
days post challenge (FIG. 2). The challenge virus was cleared.
However, differences in the levels of protection afforded by MVA-BN
or MVA-575 were observed at lower doses. Mice that received two
immunizations of 10.sup.2 TCID.sub.50/ml of MVA-575 failed to be
protected, as judged by high ovarian rVV titres (mean
3.7.times.10.sup.7 pfu+/-2.11.times.10.sup.7). In contrast, mice
vaccinated with the same dose of MVA-BN exhibited a significant
reduction (96%) in ovarian rVV titres (mean 0.21.times.10.sup.7
pfu+/-0.287.times.10.sup.7). The control mice that received a
placebo vaccine had a mean viral titre of 5.11.times.10.sup.7 pfu
(+/-3.59.times.10.sup.7) (FIG. 2).
[0140] Both strains of MVA induce protective immune responses in
mice against a lethal rVV challenge. Although both strains of MVA
are equally efficient at higher doses, differences in their
efficacy are clearly evident at sub-optimal doses. MVA-BN is more
potent than its parent strain MVA-575 at inducing a protective
immune response against a lethal rVV challenge, which may be
related to the increased attenuation of MVA-BN compared to
MVA-575.
2.2. MVA-BN in Prime/Boost Vaccination Regimes
[0141] 2.2.1.: Induction of Antibodies to MVA Following Vaccination
of Mice with Different Smallpox Vaccines
[0142] The efficacy of MVA-BN was compared to other MVA and
vaccinia strains previously used in the eradication of smallpox.
These included single immunizations using the Elstree and Wyeth
vaccinia strains produced in CEF cells and given via tail
scarification, and immunizations using MVA-572 that was previously
used in the smallpox eradication program in Germany. In addition,
both MVA-BN and MVA-572 were compared as a pre-vaccine followed by
Elstree via scarification. For each group eight BALB/c mice were
used and all MVA vaccinations (1.times.10.sup.7 TCID.sub.50) were
given subcutaneous at week 0 and week 3. Two weeks following the
boost immunization the mice were challenged with vaccinia (IHD-J)
and the titres in the ovaries were determined 4 days post
challenge. All vaccines and regimes induced 100% protection.
[0143] The immune responses induced using these different vaccines
or regimes were measured in animals prior to challenge. Assays to
measure levels of neutralizing antibodies, T cell proliferation,
cytokine production (IFN-.gamma. vs IL-4) and IFN-.gamma.
production by T cells were used. The level of the T cell responses
induced by MVA-BN, as measured by ELISPOT, was generally equivalent
to other MVA and vaccinia viruses demonstrating bio-equivalence. A
weekly analysis of the antibody titres to MVA following the
different vaccination regimes revealed that vaccinations with
MVA-BN significantly enhanced the speed and magnitude of the
antibody response compared to the other vaccination regimes (FIG.
4). Indeed, the antibody titres to MVA were significantly higher
(p>0.05) at weeks 2, 4 and 5 (1 week post boost at week 4) when
vaccinated with MVA-BN compared to mice vaccinated with MVA-572.
Following the boost vaccination at week 4, the antibody titres were
also significantly higher in the MVA-BN group compared to the mice
receiving a single vaccination of either the vaccinia strains
Elstree or Wyeth. These results clearly demonstrate that 2
vaccinations with MVA-BN induced a superior antibody response
compared to the classical single vaccination with traditional
vaccinia strains (Elstree and Wyeth) and confirm the findings from
section 1.5 that MVA-BN induces a higher specific immunity than
other MVA strains.
2.2.2.: MVA-Prime and Boost Regimes Generate the Same Level of
Protection as DNA-Prime/MVA-Boost Regimes in an Influenza Challenge
Model.
[0144] The efficacy of MVA prime/boost regimes to generate high
avidity CTL responses was assessed and compared to DNA prime/MVA
boost regimes that have been reported to be superior. The different
regimes were assessed using a murine polytope construct encoded by
either a DNA vector or MVA-BN and the levels of CTL induction were
compared by ELISPOT; whereas the avidity of the response was
measured as the degree of protection afforded following a challenge
with influenza.
Constructs
[0145] The DNA plasmid encoding the murine polytope (10 CTL
epitopes including influenza, ovalbumin) was described previously
(Thomson, et al., 1998, J. Immunol. 160: 1717). This murine
polytope was inserted into deletion site II of MVA-BN, propagated
on CEF cells, sucrose purified and formulated in Tris pH 7.4.
Vaccination Protocols
[0146] In the current study, specific pathogen free 6-8 week old
female BALB/c (H-2d) mice were used. Groups of 5 mice were used for
ELISPOT analysis, whereas 6 mice per group were used for the
influenza challenge experiments. Mice were vaccinated with
different prime/boost regimes using MVA or DNA encoding the murine
polytope, as detailed in the results. For immunizations with DNA,
mice were given a single injection of 50 .mu.g of endotoxin-free
plasmid DNA (in 50 .mu.l of PBS) in the quadricep muscle. Primary
immunizations using MVA were done either by intravenous
administration of 10.sup.7 pfu MVA-BN per mouse, or by subcutaneous
administration of 10.sup.7 pfu or 10.sup.8 pfu MVA-BN per mouse.
Boost immunizations were given three weeks post primary
immunization. Boosting with plasmid DNA was done in the same way as
the primary immunization with DNA (see above). In order to
establish CTL responses, standard ELISPOT assays (Schneider et al.,
1998, Nat. Med. 4; 397-402) were performed on splenocytes 2 weeks
after the last booster immunization using the influenza CTL epitope
peptide (TYQ), the P. berghei epitope peptide (SYI), the
Cytomegalovirus peptide epitope (YPH) and/or the LCV peptide
epitope (RPQ).
[0147] For the challenge experiments, mice were infected i.n. with
a sub-lethal dose of influenza virus, Mem71 (4.5.times.10.sup.5 pfu
in 50 ml PBS). At day 5 post-infection, the lungs were removed and
viral titres were determined in duplicate on Madin-Darby canine
kidney cell line using a standard influenza plaque assay.
Results:
[0148] Using the DNA vaccine alone, the induction of CTL to the 4
H-2d epitopes encoded by the murine polytope was poor and only weak
responses could be detected to two of the epitopes for P. Berghei
(SYI) and lymphocytic choriomeningitis virus (RPQ). In contrast,
using a DNA prime/MVA boost regime (10.sup.7 pfu MVA-BN given
subcutaneous) there were significantly more CTL induced to SLY
(8-fold increase) and RPQ (3-fold increase) and responses were also
observed to a third epitope for murine cytomegalovirus (YPH) (FIG.
3A). However, 10.sup.7 pfu MVA-BN given subcutaneous in a
homologous prime/boost regime induced the same level of response as
DNA followed by MVA-BN (FIG. 3A). Surprisingly, there was no
significant difference in the numbers of CTLs induced to the three
epitopes when one immunization of MVA-BN (10.sup.7 TCID.sub.50) was
used, indicating that a secondary immunization with MVA-BN did not
significantly boost CTL responses.
[0149] The subcutaneous administration of 10.sup.7 pfu MVA has
previously been shown to be the most inefficient route and virus
concentration for vaccination using other strains of MVA;
particularly when compared to intravenous immunizations (Schneider,
et al. 1998). In order to define optimal immunization regimes, the
above protocol was repeated using various amounts of virus and
modes of administration. In one experiment, 10.sup.7 pfu MVA-BN was
given intravenously (FIG. 3B). In another experiment, 10.sup.8 pfu
MVA-BN was administered subcutaneous (FIG. 3C). In both of these
experiments, MVA-BN prime/boost immunizations induced higher mean
CTL numbers to all three CTL epitopes when compared to DNA
prime/MVA boost regimes. Also unlike 10.sup.7 pfu MVA-BN
administered subcutaneous, immunization with 10.sup.7 pfu MVA-BN
given intravenously and immunization with 10.sup.8 pfu given
subcutaneous significantly boosted the CTL response. This clearly
indicates that MVA-BN can be used to boost CTL responses in the
presence of a pre-existing immunity to the vector.
[0150] The present invention is not to be limited in scope by the
specific embodiments described herein. Indeed, various
modifications of the invention in addition to those described
herein will become apparent to those skilled in the art from the
foregoing description.
[0151] All patents, applications, publications, test methods,
literature, and other materials cited herein are hereby
incorporated by reference.
TABLE-US-00001 TABLE 1 CEF HeLa HaCaT 143B BHK Vero CV-1 MVA-
579.73 0.04 0.22 0.00 65.88 2.33 0.00 BN MVA- 796.53 0.15 1.17 0.02
131.22 10.66 0.06 575 MVA- 86.68 124.97 59.09 0.83 87.86 34.97
29.70 HLR MVA- 251.89 27.41 1.28 2.91 702.77 1416.46 4.48 Vero
Virus amplification above the input level after 4 days
infection
Amplification ratio=output TCID.sub.50-input TCID.sub.50.
Values are in TCID.sub.50.
* * * * *