U.S. patent application number 13/841684 was filed with the patent office on 2013-09-26 for modified mareks disease virus, and vaccines made therefrom.
This patent application is currently assigned to MERIAL LIMITED. The applicant listed for this patent is MERIAL LIMITED. Invention is credited to Michel Bublot, Teshome Mebatsion, Joyce Pritchard.
Application Number | 20130251737 13/841684 |
Document ID | / |
Family ID | 48045766 |
Filed Date | 2013-09-26 |
United States Patent
Application |
20130251737 |
Kind Code |
A1 |
Pritchard; Joyce ; et
al. |
September 26, 2013 |
Modified Mareks Disease Virus, and Vaccines Made Therefrom
Abstract
The present invention provides an effective vaccine for Marek's
disease, which may be prepared using a recombinant Marek's Disease
Virus (MDV), strain CVI988, having been transformed with a foreign
DNA construct that includes a long terminal repeat sequence of a
reticuloendotheliosis virus. This safe viral agent elicits a highly
protective immune response in a chicken against virulent MDV
challenge without causing a significant degree of pathogenicity.
Suitable formulations of the vaccine for use in chickens include an
effective immunization dosage of this novel viral agent, along with
a pharmaceutically acceptable carrier or diluent.
Inventors: |
Pritchard; Joyce;
(Gainesville, GA) ; Mebatsion; Teshome;
(Watkinsville, GA) ; Bublot; Michel; (Chaponost,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MERIAL LIMITED |
Duluth |
GA |
US |
|
|
Assignee: |
MERIAL LIMITED
Duluth
GA
|
Family ID: |
48045766 |
Appl. No.: |
13/841684 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61614142 |
Mar 22, 2012 |
|
|
|
Current U.S.
Class: |
424/186.1 ;
435/235.1; 435/349 |
Current CPC
Class: |
A61P 31/22 20180101;
A61K 2039/5254 20130101; A61K 39/255 20130101; A61P 31/20 20180101;
A61K 2039/552 20130101; A61P 31/12 20180101; C12N 2710/16334
20130101; C12N 2740/13022 20130101; A61K 39/12 20130101; C12N
2830/60 20130101; A61P 37/00 20180101 |
Class at
Publication: |
424/186.1 ;
435/235.1; 435/349 |
International
Class: |
A61K 39/255 20060101
A61K039/255 |
Claims
1. A method of eliciting in an avian animal a safe and protective
immune response against Marek's Disease virus (MDV) comprising
administering to said animal a therapeutically effective amount of
a composition comprising a viral agent comprising a recombinant
Marek's disease virus stably transformed with a foreign DNA
construct, comprising a long terminal repeat (LTR) sequence of a
reticuloendotheliosis virus, thereby eliciting the protective
immune response.
2. The method of claim 1 wherein the composition further comprises
a veterinarily or pharmaceutically acceptable carrier or
diluent.
3. The method of claim 1 or 2 wherein the MDV is a CVI988/X
MDV.
4. The method of claim 3 wherein the CVI988/X MDV is CVI988.
5. The method of claim 1 or 2 wherein the avian animal is a
chicken.
6. The method of claim 1 or 2 wherein the LTR is as set forth in
SEQ ID NO:2.
7. The method of claim 1 or 2 wherein the LTR sequence comprises a
Pac I excised-DNA segment from an MDV having all of the identifying
characteristics of the strain deposited at ATCC under the accession
number PTA-4945.
8. The method of claim 1 or 2 wherein the LTR sequence is inserted
5' of the ICP4 gene of said MDV.
9. The method of claim 1 or 2 wherein the viral agent is effective
to elicit an immune response in an avian against MDV without
causing a significant degree of pathogenicity in said avian.
10. The method of claim 1 or 2 wherein the viral agent is
cell-associated.
11. A method of making a viral agent effective for protecting an
avian against Marek's disease comprising transforming an MDV strain
CVI988 with a foreign DNA construct which comprises a LTR sequence
of a reticuloendotheliosis virus.
12. A Marek's disease virus (MDV) stably transformed with a foreign
DNA construct, comprising a long terminal repeat (LTR) sequence of
a reticuloendotheliosis virus.
13. The MDV of claim 12 comprising a nucleotide having at least 90%
homology as the sequence as set forth in SEQ ID NO:2.
14. The MDV of claim 13 wherein the nucleotide has the sequence as
set forth in SEQ ID NO:2.
15. An immunological composition comprising the MDV of any one of
claims 12-14.
16. The composition of claim 15 wherein the MDV is a clonal virus,
and not a mixed population of parental and recombinant virus.
17. The composition of claim 16 which is a vaccine composition.
18. The composition of claim 17 which provides a protection rate of
at least 85%.
19. The composition of claim 18 which provides a protection rate of
at least 90%.
20. The composition of claim 19 which provides a protection rate of
at least 95%.
21. An isolated cell stably transformed with the MDV of claim 13 or
14.
22. The isolated cell of claim 15, wherein the cell is either a
chicken or duck embryo fibroblast (CEF, DEF) cell.
Description
INCORPORATION BY REFERENCE
[0001] This application claims priority to U.S. provisional patent
application No. 61/614,142, which was filed on Mar. 22, 2012, and
is herein incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to viral vaccines
and methods of using the same. More particularly, the present
invention relates to novel vaccines for protecting chickens against
infection with Marek's disease virus, and having improved safety
and efficacy over existing vaccines.
BACKGROUND
[0003] Marek's disease (MD), a highly prevalent and important
lymphoproliferative disease of chickens, is controlled in
commercial chickens by live virus vaccines consisting of attenuated
or naturally avirulent MD-related herpesviruses. Although
vaccination programs have been considered effective overall, the
poultry industry continues to experience losses due to MD. Given
the tendency of MD virus to become more virulent with time (e.g. by
reversion to more virulent form) coupled with the economic
pressures confronting the poultry industry, there remains a strong
incentive to develop safer and more efficacious products that will
protect better in the face of early challenge with very virulent
field strains without causing adverse side effects (e.g. thymic
dystrophy).
[0004] There are three distinct serotypes of MD virus found in
chickens: (1) serotype 1, the oncogenic form responsible for the
disease, including high- and low-virulence MD virus and their
attenuated variants; (2) serotype 2, a non-oncogenic MD virus; and
(3) serotype 3, herpesvirus of turkeys (HVT). An early MD vaccine
consists of the serotype 3 virus originally isolated from turkeys
as reported in Witter et al. [Am. J. vet. Res. 31:525-538 (1970)]
and Okazaki et al. [U.S. Pat. No. 3,642,574]. Its lack of
oncogenicity, self-limiting infection, good replication in vivo and
in vitro, availability as cell-free and cell-associated
preparations, and high protective efficacy have established HVT as
a standard for WID vaccines throughout the world. A commonly used
strain of HVT is FC126.
[0005] Vaccines produced from the naturally avirulent SB-1 strain
[Schat et al., J. Natl. Cancer inst. 60:1075-1082 (1978) and U.S.
Pat. No. 4,160,0241, an isolate of a serotype 2 MD virus] have been
licensed in the united States since 1984. The SB-1 strain is poorly
protective against the highly virulent MDV strains. It is usually
used in combination with HVT as a bivalent vaccine since the two
viruses together produce greater protection than does either one
alone [Schat et a/., Avian Pathol. 11:593-606 (1982); Witter, Avian
Pathol. 11:49-62 (1982), the contents of which are incorporated by
reference herein]. This phenomenon has been termed "protective
synergism." The SB-1+HVT bivalent vaccine represents greater than
50% of the United States market for MD vaccines at present and is
considered to be among the most efficacious of the various MD
products available. However, sporadic losses occur despite its
use.
[0006] Another MD vaccine produced from strain CVI988 clone C
(CVI988/C) has been licensed for commercial use in the United
States. This vaccine was derived from a mildly virulent serotype 1
MD virus attenuated by serial passage in tissue culture and has
been reported by De Boer et al. [Avian Dis. 30:276-283 (1986)]. A
further passaged derivative of CVI988/C, identified as CVI988/C/R6,
has also been described by De Boer et al. [Advances in Marek's
Disease Research, pp. 405-4 3 (1988)]. More recently, the original
low-passage strain, designated CVI988/Rispens, which has been in
commercial use in other countries for a number of years, was found
to be highly effective against challenge with several very virulent
MD virus strains by Witter et al. [4th Intl. Symp. Marek's Disease,
pp. 315-319 (1992)].
[0007] An experimental vaccine derived from Md11, a very virulent
serotype 1 MD field isolate, was reported by Witter, supra. Md11
was attenuated by serially passaging 75 times in cell culture, and
the resultant vaccine was designated Md11/75C. This vaccine has
been shown to provide good protection against challenge with Md5
and most other highly virulent MD viruses tested; but it was less
efficacious against challenge with the JM/102W strain, a prototype
MD virus effectively protected against by HVT and SB-1 vaccines.
Furthermore, its efficacy was consistently lower in chicks with HVT
antibody.
[0008] U.S. Pat. No. 4,895,717, Witter disclosed a revertant
derivative of Mdn/75C which was referred to as Md11/75C/R2.
Md11/75C/R2 was shown to be superior to several other monovalent
vaccines and was the equal of a bivalent (HVT+SB-1) vaccine
[Witter, Avian Dis. 31:752-765 (1987)]. However, the inherent
pathogenicity of serotype 1 viruses and the potential of attenuated
strains to revert to greater pathogenicity [Witter et al., Avian
Pathol. 13:75-92 (1984)] are factors to be considered in the
licensing of such products. A clone derived from further passages
of the Mdn/75C/R2 strain, designated Md11/75C/R2/23 (or R2/23), was
found by Witter et al. [Avian Dis., 35:877-891 (1991)] to possess
the highly protective nature of the parent strain without its
residual pathogenicity.
[0009] Witter also described another MD vaccine derived from 301
B/1, a nonpathogenic serotype 2 field isolate, in U.S. Pat. No.
4,895,718, the contents of which are incorporated by reference
herein, strain 301 B/1 possessed superior replicative ability to
SB-1, as well as greater protectivity against challenge to
viruses.
[0010] A recombinant Marek's disease virus, referred to as RM1,
having the long terminal repeats of reticuloendotheliosis virus
stably integrated into the repeat short (RS) regions of its genome
was also described. This strain was generated at the USDA-ARS-ADOL
from a pathogenic serotype 1 Marek's disease virus strain JM
[Witter et al., 1997, Avian Dis., 41:407-421, and Jones et al.,
1996, J. Virology, 70(4):2460-2467i. However, while the RM1 strain
has been shown to provide a level of protection similar or superior
to that of CVI988, it has also been associated with residual
pathogenicity, causing thymic atrophy in treated birds.
[0011] Thus, although existing HVT, SB-1, CVI988, CVI988/C,
Md11/75C, Md11/75C/R2 and 301 B/1 all elicit immune responses
against certain MD viruses, none of these vaccines protect
optimally against all MD challenge viruses in all chickens.
Moreover, these vaccines have exhibited reduced efficacy against
some of the more recently isolated very virulent strains of MD
virus. To avert any large-scale outbreaks of MD in the future, the
need exists to develop safer vaccines having improved efficacy
against highly virulent strains of MD virus.
SUMMARY OF THE INVENTION
[0012] The present invention is based, in part, upon the production
and use of vaccines comprising Marek's Disease Viruses (MDV)
originally disclosed in application number U.S. Ser. No. 10/623,891
(published as US2005/0019348A1, to Reddy et al.), the contents of
which, as well as the application's entire prosecution history, are
both herein incorporated by reference in their entirety.
Specifically, the present invention stems from the surprising and
unexpected finding that the CVRM2 "virus" (MDV strain "CVI988"
transformed with a foreign DNA construct; disclosed, for example,
in Table 1 of Reddy et al.) was not in fact a clonally distinct,
single recombinant attenuated Marek's Disease Virus (MDV). Instead,
Applicants determined the CVRM2 was a heterogeneous population of
recombinant and parental MDV, and when they isolated and
subsequently administered to avians a pure clonal line of CVRM2
(hereinafter referred to as "RN1250"), they obtained safety and
efficacy results far exceeding those a skilled person would have
expected on reading Reddy et al.
[0013] In accordance with this discovery, it is an object of the
invention to provide a novel, highly protective vaccine against MD
in avians, including chickens. It is also an object of the
invention to provide a vaccine which provides greater protection
against highly virulent strains of Marek's disease virus than those
vaccines presently in commercial use.
[0014] It is another object of the invention to improve the
viability and productivity of chickens, particularly broilers and
layers, and to reduce economic losses in the poultry industry
caused by Marek's disease.
[0015] These and other embodiments are disclosed or are obvious
from, and encompassed by, the following Detailed Description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 shows a schematic organization of MDV genome, which
contains a unique long (UL) region flanked by inverted repeat
(IRS), terminal repeat long (TRL), internal repeat long (IRL), and
a unique short region (US), and is flanked by two inverted repeats,
internal repeat short (IRS) and terminal repeat short (TRS). Also
shown is a schematic representation of the overlapping cosmid
clones generated to rescue an infectious virus from a highly
virulent strain of MDV;
[0017] FIG. 2 depicts generation of the B40-Pac cosmid used to
generate the CVRM vaccine;
[0018] FIG. 3 illustrates PCR-based diagnostic of recombinant MDV;
presented are the PCR primers, expected product sizes, and agarose
gel image, which indicates the CVRM2 was not clonal, but in fact a
dual population of recombinant and parental MDV. Lanes: 1) ladder;
2) negative; 3) Rispens; 4) GA 22; 5) Rismavac; 6) RB1B; 7) RN1250;
8) positive (original mixed population);
[0019] FIG. 4 presents PCR confirmation of RN1250 MSV, RN1250 x+5,
and BP5. Lanes: no template (1), RN1250 MSV (2), RN1250 x+5 (3),
RN1250 BP5 (4). PCR reactions with all primer pairs resulted in the
expected PCR product and banding pattern, thus there was no
evidence for presence of the parental Rispens virus among RN1250
MSV, RN1250 x+5, and BP5 isolates.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
[0020] An "immunological response" to a composition or vaccine is
the development in the host of a cellular and/or antibody-mediated
immune response to a composition or vaccine of interest. Usually,
an "immunological response" includes but is not limited to one or
more of the following effects: the production of antibodies, B
cells, helper T cells, and/or cytotoxic T cells, directed
specifically to an antigen or antigens included in the composition
or vaccine of interest. Preferably, the host will display either a
therapeutic or protective immunological response such that
resistance to new infection will be enhanced and/or the clinical
severity of the disease reduced. Such protection will be
demonstrated by either a reduction or lack of symptoms normally
displayed by an infected host, a quicker recovery time and/or a
lowered viral titer in the infected host.
[0021] By "animal" is intended mammals, birds, and the like. Animal
or host as used herein includes mammals and human. The animal may
be selected from the group consisting of equine (e.g., horse),
canine (e.g., dogs, wolves, foxes, coyotes, jackals), feline (e.g.,
lions, tigers, domestic cats, wild cats, other big cats, and other
felines including cheetahs and lynx), ovine (e.g., sheep), bovine
(e.g., cattle), porcine (e.g., pig), avian (e.g., chicken, duck,
goose, turkey, quail, pheasant, parrot, finches, hawk, crow,
ostrich, emu and cassowary), primate (e.g., prosimian, tarsier,
monkey, gibbon, ape), ferrets, seals, and fish. The term "animal"
also includes an individual animal in all stages of development,
including embryonic and fetal stages.
[0022] Unless otherwise explained, all technical and scientific
terms used herein have the same meaning as commonly understood by
one of ordinary skill in the art to which this disclosure belongs.
The singular terms "a", "an", and "the" include plural referents
unless context clearly indicates otherwise. Similarly, the word
"or" is intended to include "and" unless the context clearly
indicate otherwise.
[0023] It is noted that in this disclosure and particularly in the
claims and/or paragraphs, terms such as "comprises", "comprised",
"comprising" and the like can have the meaning attributed to it in
U.S. Patent law; e.g., they can mean "includes", "included",
"including", and the like; and that terms such as "consisting
essentially of" and "consists essentially of" have the meaning
ascribed to them in U.S. Patent law, e.g., they allow for elements
not explicitly recited, but exclude elements that are found in the
prior art or that affect a basic or novel characteristic of the
invention.
[0024] Cloning. The selection and propagation of (a) genetic
material from a single individual, (b) a vector containing one gene
or gene fragment, or (c) a single organism containing one such gene
or gene fragment.
[0025] Cloning vector. A plasmid, virus, retrovirus, bacteriophage,
cosmid, artificial chromosome (bacterial or yeast), or nucleic acid
sequence which is able to replicate in a host cell, characterized
by one or a small number of restriction endonuclease recognition
sites at which the sequence may be cut in a predetermined fashion,
and which may contain an optional marker suitable for use in the
identification. of transformed cells, e.g., tetracycline resistance
or ampicillin resistance. A cloning vector may or may not possess
the features necessary for it to operate as an expression
vector.
[0026] Expression. The process undergone by a structural gene to
produce a polypeptide. Expression requires transcription of DNA,
post-transcriptional modification of the initial RNA transcript,
and translation of RNA.
[0027] Expression Cassette. A nucleic acid sequence within a vector
which is to be transcribed, and a promoter to direct the
transcription. The expression cassette may contain one or more
unrelated DNA sequences encoding one or more peptides of
interest.
[0028] Expression Control Sequence. Expression control sequences
are DNA sequences involved in any way in the control of
transcription or translation and must include a promoter. Suitable
expression control sequences and methods of making and using them
are well known in the art.
[0029] Expression vector. A replicon such as a plasmid, virus,
retrovirus, bacteriophage, cosmid, artificial chromosome (bacterial
or yeast), or nucleic acid sequence which is able to replicate in a
host cell, characterized by a restriction endonuclease recognition
site at which the sequence may be cut in a predetermined fashion
for the insertion of a heterologous DNA sequence. An expression
vector has a promoter positioned upstream of the site at which the
sequence is cut for the insertion of the heterologous DNA sequence,
the recognition site being selected so that the promoter will be
operatively associated with the heterologous D{umlaut over ()} A
sequence. A heterologous DNA sequence is "operatively associated"
with the promoter in a cell when RNA polymerase which binds the
promoter sequence transcribes the coding sequence into mRNA which
is then in turn translated into the protein encoded by the coding
sequence.
[0030] The term "nucleic acid" and "polynucleotide" refers to RNA
or DNA that is linear or branched, single or double stranded, or a
hybrid thereof. The term also encompasses RNA/DNA hybrids. The
following are non-limiting examples of polynucleotides: a gene or
gene fragment, exons, introns, mRNA, tRNA, rRNA, ribozymes, cDNA,
recombinant polynucleotides, branched polynucleotides, plasmids,
vectors, isolated DNA of any sequence, isolated RNA of any
sequence, nucleic acid probes and primers. A polynucleotide may
comprise modified nucleotides, such as methylated nucleotides and
nucleotide analogs, uracyl, other sugars and linking groups such as
fluororibose and thiolate, and nucleotide branches. The sequence of
nucleotides may be further modified after polymerization, such as
by conjugation, with a labeling component. Other types of
modifications included in this definition are caps, substitution of
one or more of the naturally occurring nucleotides with an analog,
and introduction of means for attaching the polynucleotide to
proteins, metal ions, labeling components, other polynucleotides or
solid support. The polynucleotides can be obtained by chemical
synthesis or derived from a microorganism.
[0031] The term "gene" is used broadly to refer to any segment of
polynucleotide associated with a biological function. Thus, genes
include introns and exons as in genomic sequence, or just the
coding sequences as in cDNAs and/or the regulatory sequences
required for their expression. For example, gene also refers to a
nucleic acid fragment that expresses mRNA or functional RNA, or
encodes a specific protein, and which includes regulatory
sequences.
[0032] An "isolated" biological component (such as a nucleic acid
or protein or organelle) refers to a component that has been
substantially separated or purified away from other biological
components in the cell of the organism in which the component
naturally occurs, for instance, other chromosomal and
extra-chromosomal DNA and RNA, proteins, and organelles. Nucleic
acids and proteins that have been "isolated" include nucleic acids
and proteins purified by standard purification methods. The term
also embraces nucleic acids and proteins prepared by recombinant
technology as well as chemical synthesis.
[0033] The term "purified" as used herein does not require absolute
purity; rather, it is intended as a relative term. Thus, for
example, a partially purified polypeptide preparation is one in
which the polypeptide is more enriched than the polypeptide is in
its natural environment. That is the polypeptide is separated from
cellular components. By "substantially purified" is intended that
such that at least 60%, at least 70%, at least 80%, at least 90%,
at least 95%, or at least 98%, or more of the cellular components
or materials have been removed. Likewise, a polypeptide may be
partially purified. By "partially purified" is intended that less
than 60% of the cellular components or material is removed. The
same applies to polynucleotides. The polypeptides disclosed herein
can be purified by any of the means known in the art.
[0034] Variants include allelic variants. The term "allelic
variant" refers to a polynucleotide or a polypeptide containing
polymorphisms that lead to changes in the amino acid sequences of a
protein and that exist within a natural population (e.g., a virus
species or variety). Such natural allelic variations can typically
result in 1-5% variance in a polynucleotide or a polypeptide.
Allelic variants can be identified by sequencing the nucleic acid
sequence of interest in a number of different species, which can be
readily carried out by using hybridization probes to identify the
same gene genetic locus in those species. Any and all such nucleic
acid variations and resulting amino acid polymorphisms or
variations that are the result of natural allelic variation and
that do not alter the functional activity of gene of interest, are
intended to be within the scope of the invention.
[0035] As used herein, the term "derivative" or "variant" refers to
a polypeptide, or a nucleic acid encoding a polypeptide, that has
one or more conservative amino acid variations or other minor
modifications such that (1) the corresponding polypeptide has
substantially equivalent function when compared to the wild type
polypeptide or (2) an antibody raised against the polypeptide is
immunoreactive with the wild-type polypeptide. Such modifications
may be deliberate, as by site-directed mutagenesis, or may be
spontaneous. The term "variant" further contemplates deletions,
additions and substitutions to the sequence, so long as the
polypeptide functions to produce an immunological response as
defined herein.
[0036] The term "conservative variation" denotes the replacement of
an amino acid residue by another biologically similar residue, or
the replacement of a nucleotide in a nucleic acid sequence such
that the encoded amino acid residue does not change or is another
biologically similar residue. In this regard, particularly
preferred substitutions will generally be conservative in nature,
as described above.
[0037] A "vector" refers to a recombinant DNA or RNA plasmid or
virus that comprises a heterologous polynucleotide to be delivered
to a target cell, either in vitro or in vivo. The heterologous
polynucleotide may comprise a sequence of interest for purposes of
prevention or therapy, and may optionally be in the form of an
expression cassette. As used herein, a vector needs not be capable
of replication in the ultimate target cell or subject. The term
includes cloning vectors and viral vectors.
[0038] The term "recombinant" means a polynucleotide with
semisynthetic, or synthetic origin which either does not occur in
nature or is linked to another polynucleotide in an arrangement not
found in nature.
[0039] "Heterologous" means derived from a genetically distinct
entity from the rest of the entity to which it is being compared.
For example, a polynucleotide may be placed by genetic engineering
techniques into a plasmid or vector derived from a different
source, and is a heterologous polynucleotide. A promoter removed
from its native coding sequence and operatively linked to a coding
sequence other than the native sequence is a heterologous
promoter.
[0040] The polynucleotides of the invention may comprise additional
sequences, such as additional encoding sequences within the same
transcription unit, controlling elements such as promoters,
ribosome binding sites, 5'UTR, 3'UTR, transcription terminators,
polyadenylation sites, additional transcription units under control
of the same or a different promoter, sequences that permit cloning,
expression, homologous recombination, and transformation of a host
cell, and any such construct as may be desirable to provide
embodiments of this invention.
[0041] Operably Encodes or Associated. Operably encodes or operably
associated each refer to the functional linkage between a promoter
and nucleic acid sequence, wherein the promoter initiates
transcription of RNA corresponding to the DNA sequence. A
heterologous DNA sequence is "operatively associated" with the
promoter in a cell when RNA polymerase which binds the promoter
sequence transcribes the coding sequence into mRNA which is then in
turn translated into the protein encoded by the coding
sequence.
[0042] Promoter. A DNA sequence within a larger DNA sequence
defining a site to which RNA polymerase may bind and initiate
transcription. A promoter may include optional distal enhancer or
repressor elements. The promoter may be either homologous, i.e.,
occurring naturally to direct the expression of the desired nucleic
acid, or heterologous, I.e., occurring naturally to direct the
expression of a nucleic acid derived from a gene other than the
desired nucleic acid. A promoter may be constitutive or
inducible.
[0043] Vaccine. A vaccine is defined herein in its broad sense to
refer to any type of biological agent in an administrable form
capable of stimulating a protective immune response in an animal
inoculated with the vaccine.
Embodiments
[0044] The present invention provides Recombinant Marek's disease
virus (MDV), into which has been inserted via homologous
recombination, a long terminal repeat (LTR) derived from a
reticuloendotheliosis virus (REV). These recombinants are effective
to elicit an immune response in an avian to Marek's disease virus
without causing a significant degree of pathogenicity in the avian.
As used herein, "without causing a significant degree of
pathogenicity" is defined as no gross MD-specific lesions being
observable with the naked eye in the inoculated/challenged avian,
even in highly susceptible avians. In particular embodiments, the
avians are chickens.
[0045] CVRM-2 was produced by authors of Reddy et al., as described
therein, and as summarized in FIGS. 1 and 2 of this disclosure.
Upon receipt of the CVRM2 sample, instant Applicants performed
careful PCR-based analysis to confirm the identity/integrity of the
virus isolate (FIG. 3 presents the agarose gel resolution of the
amplified products). Applicants found to their surprise the sample
was not a clonal isolate, but was in fact a combined population of
recombinant CVRM2 and the parental MDV strain. Applicants then
performed the necessary plaque purification to obtain a pure
isolate consisting only of CVRM2 (and not the parental MDV Rispens
strain). For clarity, the new, clonal isolate is referred to as
"RN1250" throughout this disclosure.
[0046] The recombinant MDV of this invention may be produced by
modification of MDV serotype 1 strain CVI988, or any of its clones
or serially passaged strains, which are collectively referred to
herein as strains "CVI988/X". Thus, as used herein CVI988/X
includes, but is not limited to, the previously described original
low-passage strain, CVI988/Rispens (Rispens et al., 1972, Avian
Dis., 16:106-125 and 126-138), strain CVI988 clone C (CVI988/C) (De
Boer, U.S. Pat. No. 4,673,572, and De Boer et al., 1986, Avian Dis.
30:276-283), and CVI988/C/R6 (De Boer et al., 1988, Advances in
Marek's Disease Research, pp. 405-413). The contents of each of the
above-mentioned publications/patents are incorporated by reference
herein.
[0047] In an embodiment, the invention provides for a novel,
recombinant, attenuated MDV strain, which is produced replacing a
portion of the native CVI988/X sequence with exogenous DNA, which
comprises a long terminal repeat (LTR) sequence from a
reticuloendotheliosis virus (REV).
[0048] In an embodiment, recombination of strain CVI988 was
effected using MDV serotype 1 strain RM1 as a source of the
exogenous LTRs (RM1 is a recombinant MDV into which REV LTRs had
been integrated). As shown in FIG. 2, the REV LTR was excised from
the purified RM1 viral DNA by Pac 1 digestion and inserted into a
shuttle vector, B40, prepared from a very virulent strain of
Marek's disease virus, Md5. The resultant recombinant vector,
B40-Pac, was used for insertion of the LTRs into the Marek's
disease virus strain CVI988. To generate recombinant MDV with the
LTRs, the purified viral DNA of MDV strain CVI988 was
co-transfected into chicken or duck embryonic fibroblast (CEF or
DEF) cells with Not I-digested recombinant vector. Recombinant
viruses having the RM1 LTRs integrated into their genome replicated
more quickly than the parental CVI988 strain. Without being bound
by theory, it is believed that this increased rate of replication
is the result of the insertion of the reticuloendotheliosis virus
LTR into the genome of the MDV upstream of the ICP4 gene.
[0049] In another embodiment, the MDV CVI988/X may be modified via
the addition of isolated reticuloendotheliosis virus LTRs from
sources other than the RM1 strain. For instance, the insertion site
of the LTR in the RM1 strain of MDV has been shown to be between
IRL and IRS of the genome (Jones et al., 1996, Retroviral
insertional activation in a herpesvirus: transcriptional activation
of US genes by an integrated long terminal repeat in a MDV clone,
J. Virology, 70(4):2460-2467). This corresponds approximately to
position 152,745 of the Md5 strains of Marek's disease virus. This
region is located within a 1,704 base pair long EcoR1 fragment
(nucleotides 152, 198-153, 902) of serotype 1 Md5 (Tulman et al.,
2000, The genome of a very virulent Marek's disease virus, J.
Virology, 74d7):7980-7988). This 1,704 bp EcoR1 fragment can be
cloned into a plasmid vector lacking Drain restriction endonuclease
site and used as a transfer vector for introduction of any LTR in
to the MDV genome. This EcoRX fragment has a unique DraIII
restriction site located 10 bp upstream of the LTR location in RM1.
The LTRs can be inserted into the DraIII site of the 1,704 base
pair EcoR1 fragment to generate the LTR transfer vector, in order
to generate recombinant MDV with LTR insertions, the transfer
vector should be linearized with EcoR1, extracted with phenol and
chloroform and precipitated with ethanol. Co-transfection of the
linearized transfer vector along with DNA from any serotype 1 MDV
strain into permissible cells in culture will result in the
introduction of LTR sequences into the MDV genome by homologous
recombination.
[0050] Reddy et al., supra, indicated the resulting recombinant
virus (i.e. MDV with a reticuloendotheliosis LTR) should "grow more
rapidly than its corresponding parental MDV strain, and thus there
is no need for plaque purification". However, in view of
Applicants' unexpected finding that the CVRM-2 sample was in fact a
combination of recombinant MDV plus its corresponding parental MDV,
the skilled person is advised strongly to plaque purify all
recombinant MDV envisioned by the instant disclosure. This is
particularly important because a skilled person could be mistakenly
encouraged to discard a potentially useful recombinant MDV after
obtaining results indicating immunization with the virus fails to
provide sufficient protection against a subsequent virulent MDV
challenge (please see Table 1 of Reddy et al., where CVRM-2 appears
to provide less than 80% protection).
[0051] In another embodiment, recombinant MDV having the RETV LTRs
may be prepared from any MDV, including other CVI988/X strains,
using the deposited CVRM-2, provided the CVRM-2 is plaque purified
to ensure the virus is RN1250, and not a combination of RN1250 and
the parental MDV strain.
[0052] A variety of REV LTRs are suitable for use herein. Numerous
suitable reticuloendotheliosis viral LTRs have been isolated and
described, and include but are not limited to those described by
Kost et al. (1993, Retrovirus insertion into herpesvirus:
characterization of a Marek's disease virus harboring a solo LTR,
Virology, 192:161-169), Ridgway (1992, REV LTR elements are
efficient promoters in cells of various species and tissue origin,
including human lymphoid cells, Gene, 121:213-218), Boerkoel and
Kung [1992, Transcriptional interaction between retroviral long
terminal repeats (LTRs): mechanism of 5' LTR suppression and 3' LTR
promoter activation of c-myc in avian B-cell lymphomas, J. Virol.,
66:4814-4823], Hippenmeyer and Krivi (1991, Gene expression from
heterologous promoters in a replication-defective avian retrovirus
vector in quail cells, Poult. Sci., 70:982-92), Ridgway et al.
(1989, Transient expression analysis of the reticuloendotheliosis
virus long terminal repeat element, Nucleic Acids Res.,
17:3199-3215), Embretson and Temin (1987, Transcription from a
spleen necrosis virus 5' long terminal repeat is suppressed in
mouse cells, J. Virol., 61:3454-3462), Notani and Sauerbier (1987,
Sequence instability in the long terminal repeats of avian spleen
necrosis virus and reticuloendotheliosis virus, J. Mol. Evol.,
25:241-247), Robinson and Gagnon (1986, Patterns of proviral
insertion and deletion in avian leukosis virus-induced lymphomas,
J. Virol., 57:28-36), and Ridgway et al., (1985, In vitro
transcription analysis of the viral promoter involved in c-myc
activation in chicken B lymphomas: detection and mapping of two RNA
initiation sites within the reticuloendotheliosis virus long
terminal repeat, J. Virol., 54:161-170). The contents of each of
the publications referred to above are incorporated by reference
herein, in addition, numerous LTR sequences are available in
GenBank and other genomic databases and can be synthesized by PCR
using LTR specific primers. The PCR amplified sequences can then be
inserted in any of the two transfer vectors described as indicated
above.
[0053] The REV LTR nucleic acid sequences disclosed herein, or
their biologically functional equivalents, can be used in
accordance with the present invention. The phrase "biologically
functional equivalents" as used herein, denotes nucleic acid
sequences exhibiting the same or similar biological
activity/immunoprotective activity as the above-mentioned
reticuloendotheliosis viral LTR nucleic acid sequences (i.e., when
introduced into the CVI988 MDV host in a functionally operable
manner they elicit a protective immune response without causing a
significant degree of pathogenicity in the chicken).
[0054] For example, the nucleic acid sequences described herein can
be altered by base substitutions, insertions, additions, or
deletions to produce biologically functionally equivalent nucleic
acids that retain promoter or enhancer activity.
[0055] The variants of the genomic DNAs or cDNAs (if obtained by
RT-PCR from RNA), contemplated herein should possess more than 75%
homology, preferably more than 85% homology, and most preferably
more than 95% homology, to the naturally occurring REV LTRs
discussed herein.
[0056] The vaccine of the recombinant Marek's disease virus of the
invention may be prepared as a cell-free preparation, or in the
preferred embodiment, as a cell-associated preparation. A
cell-associated vaccine can be prepared directly from In vitro
culture of the live viral agents in a suitable growth medium, such
as chicken embryo fibroblasts as described by Witter (U.S. Pat. No.
4,895,718, the contents of which are incorporated by reference
herein). Alternatively, to prepare cell-free virus inocula, cells
from infected host tissue or cell culture are sonicated or
otherwise disrupted as previously described. The cellular debris is
removed by centrifugation and the centrifugate recovered as the
inoculum. Moreover, while the preferred vaccine is a viable virus,
it is also envisioned that the vaccine may be prepared from the
killed virus or from immunogenic components separated from the
virus, although such processing would incur significantly greater
costs. For example, a subunit vaccine can be prepared by separating
from the killed virus one or more purified viral proteins
identified as having immunogenic properties.
[0057] The viral agent is prepared for administration by
formulation in an effective immunization dosage with a
pharmaceutically acceptable carrier or diluent, such as
physiological saline or tissue culture medium. The expression
"effective immunization dosage" is defined as being that amount
which will induce immunity in a chicken against challenge by a
virulent strain of Marek's disease virus, immunity is considered as
having been induced in a population of chickens when the level of
protection for the population is significantly higher than that of
an unvaccinated control group (measured at a confidence level of at
least 80%, preferably measured at a confidence level of 95%). One
measure of the level of protection is the protective index (Pi),
which is calculated as the incidence of MD in unvaccinated, MDV
challenged controls minus the incidence of MD in vaccinated, MDV
challenged groups, and the difference divided by the percent of
Marek's disease in unvaccinated, MDV challenged controls, with the
result multiplied by 100.
[0058] Typically, the vaccine will contain at least about 200 PFU
(plaque-forming units) of the virus, and preferably between about
2000 and 5000 PFU. The vaccine can be effectively administered any
time after the chicken attains immunocompetence, which is at about
the 18th day of incubation (3 days prehatch); but it is normally
administered by inoculation within 24-48 hours after hatching.
Alternatively, the recombinant viral DNA may be administered as a
DNA vaccine as described by Tischer et al. (2002, J. Gen. Virology,
83:2367-2376, the contents of which are incorporated by reference
herein).
[0059] Appropriate adjuvants as known in the art may also be
included in the vaccine formulation. In many cases, the vaccinal
efficacy can be enhanced by combining the recombinant Marek's
disease viruses of the invention with other viral agents into
bivalent or polyvalent vaccines.
[0060] In another embodiment, the pharmaceutically or veterinarily
acceptable carrier, excipient, or vehicle may be a water-in-oil
emulsion. In yet another embodiment, the water-in-oil emulsion may
be a water/oil/water (W/O/W) triple emulsion. In yet another
embodiment, the pharmaceutically or veterinarily acceptable
carrier, excipient, or vehicle may be an oil-in-water emulsion.
Methods of Use and Article of Manufacture
[0061] The present invention includes the following method
embodiments. In an embodiment, a method of vaccinating an avian
comprising administering a composition comprising a Marek's Disease
virus (MDV).
[0062] In one embodiment of the invention, a prime-boost regimen
can be employed, which is comprised of at least one primary
administration and at least one booster administration using at
least one common polypeptide, antigen, epitope or immunogen.
Typically the immunological composition or vaccine used in primary
administration is different in nature from those used as a booster.
However, it is noted that the same composition can be used as the
primary administration and the booster administration. This
administration protocol is called "prime-boost".
[0063] A prime-boost regimen comprises at least one
prime-administration and at least one boost administration using at
least one common polypeptide and/or variants or fragments thereof.
The vaccine used in prime-administration may be different in nature
from those used as a later booster vaccine. The
prime-administration may comprise one or more administrations.
Similarly, the boost administration may comprise one or more
administrations.
[0064] The dose volume of compositions is generally between about
0.1 to about 2.0 ml, between about 0.1 to about 1.0 ml, and between
about 0.5 ml to about 1.0 ml.
[0065] It should be understood by one of skill in the art that the
disclosure herein is provided by way of example and the present
invention is not limited thereto. From the disclosure herein and
the knowledge in the art, the skilled artisan can determine the
number of administrations, the administration route, and the doses
to be used for each injection protocol, without any undue
experimentation.
[0066] The present invention contemplates at least one
administration to an animal of an efficient amount of the
therapeutic composition made according to the invention. The animal
may be male, female, pregnant female and newborn. This
administration may be via various routes including, but not limited
to, intramuscular (IM), intradermal (ID) or subcutaneous (SC)
injection or via intranasal or oral administration. The therapeutic
composition according to the invention can also be administered by
a needleless apparatus (as, for example with a Pigjet, Dermojet,
Biojector, Avijet (Merial, GA, USA), Vetjet or Vitajet apparatus
(Bioject, Oreg., USA)). Another approach to administering plasmid
compositions is to use electroporation (see, e.g. Tollefsen et al.,
2002; Tollefsen et al., 2003; Babiuk et al., 2002; PCT Application
No. WO99/01158). In another embodiment, the therapeutic composition
is delivered to the animal by gene gun or gold particle
bombardment. In an advantageous embodiment, the animal is a dog,
ferret or seal.
[0067] Another embodiment of the invention is a kit for performing
a method of eliciting or inducing an immunological or protective
response against MDV in an animal comprising a recombinant MDV
immunological composition or vaccine and instructions for
performing the method of delivery in an effective amount for
eliciting an immune response in the animal.
[0068] In an embodiment, the subject matter disclosed herein is
directed to a kit for performing a method of eliciting or inducing
an immune response which may comprise any one of the recombinant
MDV compositions or vaccines and instructions for performing the
method.
[0069] Other cytokines that may be used in the present invention
include, but are not limited to, granulocyte colony stimulating
factor (G-CSF), granulocyte/macrophage colony stimulating factor
(GM-CSF), interferon .alpha. (IFN.gamma.), interferon .beta.
(IFN.beta.), interferon .gamma., (IFN.gamma.), interleukin-1.alpha.
(IL-1.alpha.), interleukin-1.beta. (IL-1.beta.), interleukin-2
(IL-2), interleukin-3 (IL-3), interleukin-4 (IL-4), interleukin-5
(IL-5), interleukin-6 (IL-6), interleukin-7 (IL-7), interleukin-8
(IL-8), interleukin-9 (IL-9), interleukin-10 (IL-10),
interleukin-11 (IL-11), interleukin-12 (IL-12), tumor necrosis
factor .alpha. (TNF.alpha.), tumor necrosis factor .beta.
(TNF.beta.), and transforming growth factor .beta. (TGF.beta.). It
is understood that cytokines can be co-administered and/or
sequentially administered with the immunological or vaccine
composition of the present invention. Thus, for instance, the
vaccine of the instant invention can also contain an exogenous
nucleic acid molecule that expresses in vivo a suitable cytokine,
e.g., a cytokine matched to this host to be vaccinated or in which
an immunological response is to be elicited (for instance, an avian
cytokine for preparations to be administered to avians).
[0070] The invention will now be further described by way of the
following non-limiting examples.
Example 1
Efficacy of Marek's Disease Virus (MDV), SR-1 Strains, CVRM-2
RN1250 and RMI CN32399, and Rispens CN32553
[0071] A critical aspect of the instant invention is that after
having completed the study outlined in this Example, inventors
later determined the CVRM-2 MDV was not a clonal recombinant MDV,
but in fact was a mixed population of RN1250 recombinant MDV and
parental Rispens MDV. Thus, now that inventors have produced a
stable, clonal RN1250 MDV, which virus' strong efficacy as a
vaccine is demonstrated in later Examples, a skilled person will
not be surprised by the broad (and unacceptable) range of
protection (37-86%) apparently provided by the CVRM-2 MDV in this
preliminary study.
[0072] Objective.
[0073] To evaluate and compare the efficacy of three experimental
MDV SR-1 and Rispens strains to a commercial vaccine product
(Rismavac.RTM.-Intervet, Inc.) in SPF Chickens using an early
challenge with MDV T. King.
[0074] Materials/Methods.
[0075] One hundred fifty one-day-old SPF chicks (SPAFAS flock W-42)
were randomly assigned to five different groups of thirty birds
each (Groups 1-5). Each treatment group was then randomly assigned
to isolation units. The chicks in Group 1 used as the
non-vaccinated, challenged controls were placed into negative
pressure isolation units first, fifteen birds per unit. Each
remaining group (Groups 2-5) were then subcutaneously (SQ)
vaccinated with 0.2 ml per bird with either Intervet Rispens
Rismavac.RTM.; MDV SR-1 RMI CN32399 P.sub.4; MDV SR-1 CVRM-2 RN1250
P.sub.4; or MDV Rispens CN32553 P.sub.4. The SQ vaccinated birds in
Groups 2-5 were also placed in negative pressure isolation units,
15 birds per unit. Four days later on Study Day 4, the birds in
Groups 1-5 were challenged individually with MDV T. King, diluted
1:500 (protocol 02-085 02 January 3). Birds were challenged
intraperitoneally (IP), with 0.2 ml per bird. Birds were observed
for 49 days post-challenge. Any bird that died prior to Study Day
53 was necropsied and examined for MDV lesions. On Day 53, all
remaining birds were terminated, necropsied and examined for MDV
lesions.
[0076] Results.
[0077] The experimental MDV SR-1 and Rispens strains provided
protection rates of 37-86% against the early MDV T. King challenge.
Intervet's Rismavac.RTM. provided 83% protection. The challenge was
validated with the non-vaccinated, challenged control birds showing
MD incidence of 97%.
Example 2
Efficacy of MDV, SR-1, RN1250 Vaccine in Commercial Broilers Using
a Shedder Challenge Model
[0078] Materials & Methods:
[0079] Seventy-six (76) one-day-old commercial broilers obtained
from Harrison poultry flock 1-1 were randomized into three
different colony houses and four different groups as follows: Group
1: 13 birds; Group 2: 13 birds; Group 3: 25 birds; and Group 4: 25
birds (one house was split into two sides in order to create pen
one and pen two). After randomizing, the birds were banded in the
nape of the neck for identification and then were inoculated with
0.2 ml per bird intraperitoneally (IP) with vvMDV T. King
challenge, diluted 1:500. After challenging, the birds were placed
into their respective colony house with 25-26 birds per house.
These birds remained in the colony houses for 14 days prior to the
placement of MDV vaccinated and non-vaccinated, contact control
birds. Fourteen days after placement of the shedder birds, 304
one-day-old commercial broilers were randomized as follows: two
groups with 75 birds each (Groups 3 and 4) and two groups with 38
and 40 birds each (Groups 1 and 2), to serve as vaccinates; in
addition, two groups of 25 birds and two with 13 birds were used to
serve as non-vaccinated, contact control birds for Groups 1-4
(Group 1: 13 birds; Group 2: 13 birds; Group 3: 25 birds; and Group
4: 25 birds). These contact control birds were banded in the nape
of the neck for identification and placed in the colony houses. The
vaccinates were inoculated by the subcutaneous route (SQ) route
(0.2 ml per bird) as follows: Group 1 was vaccinated with RN1250
pre MSV, P6 (isolate I); Group 2 was vaccinated with RN1250 pre
MSV, P7 (isolate U); Group 3 was vaccinated with RN1250 pre MSV, P7
(isolate F); and Group 4 was vaccinated with Rismavac.RTM. serial
02760010, exp. 15 Apr. 2012. After the inoculations, the vaccinates
were placed in the same colony houses where the non-vaccinated,
contact control birds and shedders were placed previously. An
additional fifty (50) non-inoculated one-day-old commercial
broilers were housed in isolation units, and were kept for 49 days
in order to serve as a second group of contact controls at a later
day. All the vaccinated birds were banded in the nape of the neck
eight days later with color coded, numbered bands. The shedders
remained in the colony houses for fifty days, and then all the
survivors were terminated and necropsied.
[0080] Clinical disease and mortality were monitored daily for 49
days post-vaccination. The spleens from any contact control bird
that died were collected for virus isolation. On study day 53, the
forty non-inoculated commercial broilers that were housed in
isolation units, in order to serve as the second group of contact
controls, were placed in the colony houses, Groups 1-4, according
to a randomization schedule, 10 birds per group. These birds were
banded with numbered bands before placement for identification. The
spleens from these birds were also collected for virus isolation in
the event that mortality occurred. The remaining vaccinates and the
initial non-vaccinated, contact control birds were terminated and
necropsied at the of the 49 day observation period on study day 63.
Spleens and at least two feather follicles per bird were collected
from 10 contact controls for virus isolation. The sampled birds
were determined by a randomization schedule. On study day 83, the
remaining contact control birds that were added to the groups on
study day 53 (second group), were terminated. Spleens and at least
two feather follicles per bird were collected from these contact
control birds for virus isolation.
TABLE-US-00001 TABLE 1 Number of birds surviving to five day of age
# survivors to 5 days of age/ Regime Group Name total # birds
Vaccinated 1 RN1250 pre MSV (I) 38/38 Vaccinated 2 RN1250 pre MSV
(U) 40/40 Vaccinated 3 RN1250 pre MSV (F) 73/75 Vaccinated 4
Rismavac .RTM. 73/75 Contact control 1 RN1250 pre MSV (I) 12/13
Contact control 2 RN1250 pre MSV (U) 13/13 Contact control 3 RN1250
pre MSV (F) 22/25 Contact control 4 Rismavac .RTM. 23/25
TABLE-US-00002 TABLE 2 Protective indexes against the wMDV T. King
challenge # infected/ total # Percent Protective Regime Gp Name
birds Infected Index.sup.5 Vaccinated 1 RN1250 pre MSV (I).sup.1
2/38 5.26% 87.4 (81.2).sup.6 Vaccinated 2 RN1250 pre MSV (U).sup.2
6/40 15.0% 2.6 (46.4).sup.6 Vaccinated 3 RN1250 pre MSV (F).sup.3
6/73 8.22% 84.9 Vaccinated 4 Rismavac .RTM..sup.4 15/73 20.5% 63.7
Shedders 1 RN1250 pre MSV (I) 9/12 75.0% N/A Shedders 2 RN1250 pre
MSV (U) 11/12 91.7% N/A Shedders 3 RN1250 pre MSV (F) 20/25 80.0%
N/A Shedders 4 Rismavac .RTM. 22/24 91.7% N/A Contact control 1
RN1250 pre MSV (I) 5/12 41.7% N/A Contact control 2 RN1250 pre MSV
(U) 2/13 15.4% N/A Contact control 3 RN1250 pre MSV (F) 12/22 54.5%
N/A Contact control 4 Rismavac .RTM. 13/23 56.5% N/A 2.sup.nd
controls 1 RN1250 pre MSV (I) 9/10 90.0% N/A 2.sup.nd controls 2
RN1250 pre MSV (U) 8/10 80.0% N/A 2.sup.nd controls 3 RN1250 pre
MSV (F) 9/10 90.0% N/A 2.sup.nd controls 4 Rismavac .RTM. 8/10
80.0% N/A .sup.1RN1250 (I) vaccine titer: 3600 pfu/0.2 ml.
.sup.2RN1250 (U) vaccine titer: 3144 pfu/0.2 ml. .sup.3RN1250 (F)
vaccine titer: 3710 pfu/0.2 ml. .sup.4Rismavac .RTM. vaccine titer:
2328 pfu/0.2 ml. .sup.5Protective index: Percentage of
non-vaccinated contacts with MD lesions (challenge controls) -
Percentage of vaccinated chickens with MD lesions/Percentage of
non-vaccinated contacts with MD lesions (challenge controls).
.sup.6Protective index considering the percentage of non-vaccinated
contact controls with MD lesions in Colony House 10, Groups 1 and
2, as only one group (28% or 7/25).
[0081] Conclusion. The Marek's Disease Vaccine, Serotype 1, RN 1250
Vaccine, pre MSV (I) and (F), were more efficacious than Intervet's
Rismavac.RTM. in commercial broilers using MDV T. King in a shedder
challenge model
Example 3
Safety MDV RN1250 (X+5) in SPF One-Day-Old Chicks
[0082] Two hundred-fifty, one-day-old, SPF chickens were randomly
assigned to five treatment groups, 50 chicks per group, as well as,
randomly assigned to the negative pressure isolation units used for
housing. One hundred chicks were designated as vaccinates and were
identified as Groups 1 and 2. One hundred chicks were designated as
the sham-vaccinated, contact controls of Groups 1 and 2 (Groups 4
and 5, respectively); the remaining sham-vaccinated chicks (50)
were identified as Group 3 to serve as the negative controls. After
randomizing, the sham-vaccinated, contact controls and
sham-vaccinated, negative controls were wing-banded with numbered
bands for identification and were placed into their respective
units (7-10 birds per unit). The sham-vaccinated birds were
inoculated with Marek's Disease diluent, 0.2 ml per bird. The
chicks designated as vaccinates were subcutaneously (SQ) inoculated
with either: RN1250 (X+5) (Group 1) or Rismavac.RTM. (Group 2), 0.2
ml per bird (.about.5000-6500 plaque-forming units (pfu) per dose).
After the inoculations, the vaccinates were placed into their
assigned units (7-10 birds per unit) with their sham-vaccinated,
contact controls which had been previously housed, for a total of
15 to 20 chicks per unit.
TABLE-US-00003 TABLE 3 Study Design VACCINATION* NUMBER of GROUP
VACCINE ROUTE BIRDS 1 MDVSR-1 SQ 50 RN1250 2 MDVSR-1 SQ 50 Rismavac
.RTM. 3 Sham-vaccinated SQ 50 (Negative Controls) 4 Sham-vaccinated
Contact SQ 50 Controls for MDV SR-1 RN1250 vaccinated birds 5
Sham-vaccinated Contact SQ 50 Controls for MDV SR-1 Rismavac .RTM.
vaccinated birds
[0083] On Study Day 7, organ samples (bursa, thymus and spleen)
from five birds belonging to each group, Groups 1-5, were chosen
for harvesting and fixed in 10% buffered formalin for
histopathology. The birds, 2-3 birds per unit, were selected
according to a randomization schedule. On Study Day 14, body
weights and organ weights (bursa, thymus and spleen) of 15 birds
from each group, Groups 1-5, were collected. Organ samples (bursa,
thymus and spleen) from five birds in each group (Groups 1-5) were
harvested and fixed in 10% buffered formalin. Two to three birds
per unit were used for the weighing and organ harvest. The birds
were selected according to a randomization schedule. The procedure
described on Study Day 14, was repeated on Day 28, and on Day 49
with the remaining birds.
[0084] Results.
[0085] Organs Atrophy RN1250. The bursa ratios of birds vaccinated
with MDV SR-1 RN1250 vaccine and the ratios of the sham-vaccinated,
contacts controls were not significantly different from that of the
sham-vaccinated, negative control birds, except that on Day 28, the
bursa ratio of the contact controls for MDVSR-1 RN1250 was
significantly higher than that of the negative controls
(p.gtoreq.0.0111). The thymus ratios of birds vaccinated with
MDVSR-1 RN1250 vaccine and the ratios of the sham-vaccinated,
contacts controls were not significantly different from that of the
sham-vaccinated, negative control birds (p.gtoreq.0.7265). Finally,
the spleen ratios of birds vaccinated with MDVSR-1 RN1250 vaccine
and the ratios of the sham-vaccinated, contacts controls were not
significantly different from that of the sham-vaccinated, negative
control birds (p.gtoreq.0.5286).
Organs Atrophy Rismavac.RTM.
[0086] The bursa ratios of birds vaccinated with MDVSR-1
Rismavac.RTM.-vaccine and the ratios of the sham-vaccinated,
contacts controls were not significantly different from that of the
sham-vaccinated, negative control birds (p.gtoreq.0.0581). The
thymus ratios of birds vaccinated with MDVSR-1
Rismavac.RTM.-vaccine and the ratios of the sham-vaccinated,
contacts controls were not significantly different from that of the
sham-vaccinated, negative control birds (p.gtoreq.0.4004). The
spleen ratio of birds vaccinated with MDVSR-1 Rismavac.RTM.-vaccine
was significantly greater than the spleen ratio of the
sham-vaccinated, negative controls on Day 14 with p-value=0.0141;
and the spleen ratios of birds of sham-vaccinated contract controls
was significantly greater than that of the sham-vaccinated,
negative controls on Day 28 with p-value <0.0001. The ratios
were not significantly different on any other days
(p.gtoreq.0.5558) Histological Examination Results from the
histological examination did not shown evidence of atrophy in the
bursa, thymus or spleen of the birds inoculated with the Marek's
Disease SR-1 RN1250 or Rismavac.RTM..
[0087] Conclusion.
[0088] Under the conditions of this trial the MDV SR-1, RN1250,
X+5, was safe when administered SQ, as evaluated by thymic, bursa
and/or spleen atrophy.
Example 4
Dissemination of MDV, SR-1, RN1250 in SPF One-Day-Old Chicks
[0089] Objective.
[0090] To evaluate the dissemination of the MDV, SR-1, RN1250
experimental vaccine (X+5) in one-day-old specific-pathogen-free
(SPF) chickens when administered SQ and whether it would shed and
spread to non-vaccinated contacts.
[0091] Materials & Methods.
[0092] One hundred twenty (120) one-day-old SPF chickens were
randomized into three different treatment groups and six units with
each unit containing 15 vaccinates and five contacts. The birds
randomized as contacts were banded in the nape of the neck with
colored numbered bands per the randomization schedule and then
placed into their respective units. The birds randomized as
vaccinates were vaccinated with either MDV RN1250 X+5 or Rispens.
The experimental and commercial vaccines were diluted in Marek's
diluent to yield approximately 100,000 pfu per dose (approximately
17.times. the expected field dose) administered by the SQ route.
After vaccination, the birds were placed into their respective
units along with the contacts that were previously placed. The
vaccinated birds were banded at eight days of age in the nape of
the neck with colored numbered bands according to a randomization
schedule. Personnel involved with clinical assessments during the
study were not present for the banding of the contacts or
vaccinates nor did they perform any clinical observations during
this time period in order to maintain blinding.
TABLE-US-00004 TABLE 4 Study Groups NUMBER of BIRDS* VACCINATION
Non- ROUTE/ vaccinated GP VACCINE VOLUME Vaccinated contacts 1 MDV
SR-1 SQ/0.2 ml 30 10 RN1250 per bird 2 MDV SR-1 SQ/0.2 ml 30 10
Rispens vaccine per bird 3 Sham-vaccinated SQ/0.2 ml 30 10 Negative
Controls per bird
[0093] At two weeks post-vaccination, tracheal and cloacal swabs
were taken for virus recovery from all vaccinated birds. The swabs
were pooled by group, with five tracheal or cloacal swabs per swab
tube containing 5 ml of SPGA stabilizer. Primary feather follicles
were collected for virus recovery from two vaccinated birds in each
group, collecting two to three feather samples per bird. The two
birds per group for feather follicle sampling were selected
according to a randomization schedule and were kept alive after
sampling. All samples were taken to Merial Select's analytical
department for processing. The same sampling procedure was repeated
two times at seven day intervals.
[0094] On study day 21, in addition to tracheal and cloacal swab
sampling and feather follicle sampling, five vaccinated and
non-vaccinated contacts per group (selected according to a
randomization schedule) were terminated and necropsied, with
spleens were individually harvested. Virus isolation was attempted
only on the spleens harvested from the non-vaccinated contacts
(vaccinated birds were harvested to maintain blinding). On the last
day of the study (Day 49), all the remaining birds were euthanized
and necropsied and the study was terminated. Spleens from the
remaining five vaccinated and non-vaccinated contacts per group
were individually harvested. Virus isolation was only attempted on
the spleens harvested from the non-vaccinated contacts (vaccinated
birds were harvested to maintain blinding).
[0095] Results.
[0096] Group one MDV SR-1 RN1250 X+5 arithmetic mean titer (AMT)
was 94,160 pfu/0.2 ml dose. Group two MDV SR-1 Rispens was 51,800
pfu/0.2 ml dose. All tracheal and cloacal swabs were negative for
virus recovery.
[0097] Group 1 MDV SR-1 RN1250: All of the samples tested for this
group were negative for virus recovery from feather follicles.
[0098] Group 2 MDV SR-1 Rispens: On day 21, feather follicles from
both of the birds sampled were positive for Marek's disease
cytopathic effect (MD CPE). On days 14 and 28 feather follicles
from all birds sampled were negative.
[0099] Group 3 Sham-vaccinated negative controls: All of the
feather follicle samples tested were negative for virus recovery
from feather.
[0100] There was no virus recovered from any of the spleens
harvested from the contacts birds at Days 21 and 49. The samples
from day 49 were initially contaminated but were tested again using
PCR and were all negative. Frozen buffy coat material from these
same samples was also re-plated and all of these samples were
confirmed negative.
[0101] Conclusion.
[0102] Under the conditions of this study, birds vaccinated SQ with
the MDV, SR-1, RN1250 experimental vaccine showed similar
dissemination patterns to birds vaccinated SQ with the commercially
available MDV, SR-1 Rispens vaccine. There was no recovery of virus
or evidence of clinical disease in non-vaccinated birds that were
in contact with birds vaccinated with the MDV RN1250 experimental
vaccine.
Example 5
Evaluation of the Efficacy of MDV, S1, RN1250 Vaccine (X+5)
Administered to Day-Old Chicks Against vvMDV, RB1B Virus
[0103] Materials & Methods.
[0104] Two hundred eighty (280) one-day-old SPF chicks were
randomized into eight different groups and 24 different isolation
units according to a randomization schedule (11-12 birds per unit;
35 birds per treatment). After the randomization, the birds in
Groups 6 and 7, the sham-vaccinated, challenged and
sham-vaccinated/sham challenged negative controls, were sham
vaccinated with Marek's vaccine diluent and were placed into their
designated units according to the randomization schedule. The
remaining birds were then vaccinated with MDV SR-1 RN1250, at
either 287, 578, 736, 1085, or 1392 plaque forming units (pfu's)
per bird dose, or with MDV SR-3 HVT, 1728 pfu's per bird dose. The
birds were vaccinated subcutaneously (SQ) with 0.2 ml per chick.
After the vaccinations, each vaccinated group was placed into its
designated unit according to the randomization schedule. On study
day 4, the birds in Group 7 were sham challenged with Marek's
vaccine diluent and Groups 1-6 and 8 were challenged with vvMDV
RB1B, by the intraperitoneal (IP) route, 0.2 ml per bird. The birds
were observed daily for 45 days post-challenge for any unfavorable
reactions to the challenge, particularly death or depression. On
study day 49, the birds were terminated and necropsied to examine
for gross lesions associated with Marek's disease.
[0105] Results.
[0106] The prevented fraction rates against the vvMDV RB1B
challenge in Groups 1-5 had a range of 0.84 to 0.94. The prevented
fraction in Group 8, the HVT vaccinated group, was 0.73. The
incidence of MDV in the sham vaccinated, challenge control Group 6
was 91.2%. The birds in Group 7, the sham vaccinated, sham
challenged negative controls, remained free of MDV lesions
throughout the study.
[0107] Conclusion.
[0108] The MDV vaccine, Serotype-1, Live Virus, RN1250 Experimental
Vaccine (X+5) administered subcutaneously (SQ) to day-old SPF
chickens was efficacious at 287 plaque forming units per dose using
the RB1B virus as the challenge.
TABLE-US-00005 TABLE 5 Dose Response Efficacy Summary #
infected/total % % Gp Gp Group Name Actual dose # of birds
Protected infect. 1 B MDV RN1250 (X + 5) vaccine 250 pfu 287.2
pfu/0.2 ml 5/34 85.3% 14.7% (AMT) 2 H MDV RN1250 (X + 5) vaccine
500 pfu 578.4 pfu/0.2 ml 4/34 88.2% 11.8% (AMT) 3 C MDV RN1250 (X +
5) vaccine 750 pfu 736 pfu/0.2 ml 2/34 94.1% 5.9% (AMT) 4 A MDV
RN1250 (X + 5) vaccine 1000 pfu 1084.8 3/35 91.4% 8.6% pfu/0.2 ml
(AMT) 5 D MDV RN1250 (X + 5) vaccine 1500 pfu 1392 pfu/0.2 ml 4/34
88.2% 11.8% (AMT) 6 E Sham vaccinated/Challenge Controls 31/34 N/A
91.2% (8.8%*) 7 G Sham vaccinated/Sham Challenge 0/35 N/A 0.0%
Negative Controls 8 F MDV HVT Release titer 1725 pfu/0.2 ml 8/33
75.8% 24.2% (AMT)
[0109] Having thus described in detail preferred embodiments of the
present invention, it is to be understood that the invention
defined by the above paragraphs is not to be limited to particular
details set forth in the above description as many apparent
variations thereof are possible without departing from the spirit
or scope of the present invention.
Sequence CWU 1
1
21585DNAArtificial SequenceGenbak S82226.1 Recombinant MDV Strain
RM1 intervening rpt 1ttaacctctc tataggcggg ggtgtgggag ggagctccgg
gggaatgtgg gagggagctc 60cggggggaat agcgctggct cgctaactgc catattagct
tctgtaatca tgcttgcttg 120ccttagccgc cattgtactt gatatatttc
gctgatatca tttctcggaa tcggcatcaa 180gagcaggctc ataaaccata
aaaggaaatg tttgttgaag gcaagcatca gaccacttgc 240accatccaat
cacgaacaaa cacgagatcg aactatcata ctgagccaat ggttgtaaag
300ggcagatgct atcctccaat gagggaaaat gtcatgcaac atcctgtaag
cggctatata 360agccaggtgc atctcttgct cggggtcgcc gtcctacaca
ttgttgtgac gtgcggccca 420gattcgaatc tgtaataaaa gctttttctt
ctatatcctc agattggcag tgagaggaga 480ttttgttcgt ggtgttggct
ggcctactgg gtggggtagg gatccggact gaatccgtag 540tatttcggta
caacaggggg gaagtccctc ttatattggc gagtg 5852533DNAArtificial
SequenceLong Terminal Repeat from Reticuloendothelial Virus
2tgtgggaggg agctccgggg gaatgtggga gggagctccg gggggaatag cgctggctcg
60ctaactgcca tattagcttc tgtaatcatg cttgcttgcc ttagccgcca ttgtacttga
120tatatttcgc tgatatcatt tctcggaatc ggcatcaaga gcaggctcat
aaaccataaa 180aggaaatgtt tgttgaaggc aagcatcaga ccacttgcac
catccaatca cgaacaaaca 240cgagatcgaa ctatcatact gagccaatgg
ttgtaaaggg cagatgctat cctccaatga 300gggaaaatgt catgcaacat
cctgtaagcg gctatataag ccaggtgcat ctcttgctcg 360gggtcgccgt
cctacacatt gttgtgacgt gcggcccaga ttcgaatctg taataaaagc
420tttttcttct atatcctcag attggcagtg agaggagatt ttgttcgtgg
tgttggctgg 480cctactgggt ggggtaggga tccggactga atccgtagta
tttcggtaca aca 533
* * * * *