Modified Mareks Disease Virus, and Vaccines Made Therefrom

a vaccine and virus technology, applied in the field of virus vaccines, can solve the problems of sporadic losses, sb-1 strain is poorly protective against highly virulent mdv strains, and the poultry industry continues to experience losses due to md, so as to reduce economic losses and improve the viability and productivity of chickens

Inactive Publication Date: 2013-09-26
BOEHRINGER INGELHEIM ANIMAL HEALTH USA INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[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.

Problems solved by technology

Although vaccination programs have been considered effective overall, the poultry industry continues to experience losses due to MD.
The SB-1 strain is poorly protective against the highly virulent MDV strains.
However, sporadic losses occur despite its use.
Furthermore, its efficacy was consistently lower in chicks with HVT antibody.
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.
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.

Method used

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  • Modified Mareks Disease Virus, and Vaccines Made Therefrom
  • Modified Mareks Disease Virus, and Vaccines Made Therefrom
  • Modified Mareks Disease Virus, and Vaccines Made Therefrom

Examples

Experimental program
Comparison scheme
Effect test

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 prod...

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®-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 (SPAFA...

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 rando...

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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.

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...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): A61K39/255
CPCA61K39/255A61K39/12A61K2039/552C12N2830/60A61K2039/5254C12N2740/13022C12N2710/16334A61P31/12A61P31/20A61P31/22A61P37/00C12N2710/16634
Inventor PRITCHARD, JOYCEMEBATSION, TESHOMEBUBLOT, MICHEL
Owner BOEHRINGER INGELHEIM ANIMAL HEALTH USA INC
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