Project Number: 3635-32000-015-00
Project Type: Appropriated

Start Date: Apr 04, 2007
End Date: Feb 28, 2012

Objective:
Identify genetic predictors of Marek's disease virus (MDV) virulence. Identify host-viral genetic determinants that control avian tumor virus pathgenicity and shedding. Elucidate the genetic determinants that modulate MDV interactions within the avian immune system. Elucidate host-viral interactions that drive the evolution of new virulent strains of avian tumor viruses. Discover safe and highly effective vaccine platforms that convey protection against emerging MDV strains.

Approach:
Avian tumor viruses of economic importance include: 1) Marek¿s disease virus (MDV), a herpesvirus that induces a lymphoproliferative disease of chickens that, in the absence of effective control measures, is capable of causing devastating losses in commercial layer and broiler flocks; and 2) avian retroviruses, namely avian leukosis virus (ALV) and reticuloendotheliosis virus (REV), both are associated with neoplastic diseases and other production problems in poultry. Also, both ALV and REV are potential contaminants of live-virus vaccines of poultry. Critical needs are: 1) better MDV vaccines to protect against the current and next generation of virulent field strains of MDV; and 2) a long-term strategy designed to reduce the ongoing emergence of new virulent MDV, and creation of recombinant ALVs through multiple barriers or reduction in viral load and shedding. The primary emphasis will be on molecular approaches to better understand which viral genes are important for immunopathogenesis and shedding of MDV. Parallel studies will monitor the virulence of field strains of MDV and ALV. Studies are also aimed at characterization of new virus isolates and on improving assays for their detection; additional efforts will be devoted to better understand MDV immunity. The project also emphasizes studies on: 1) elucidating factors involved in creation of recombinant ALVs; and 2) determining whether REV genome insertion into MDV and fowlpox virus influences transmission and epidemiology of REV. The end product will be a better understanding of viral gene function, virus-host interactions and the development of materials and improved methodology for control of avian tumor viruses. BSL-2; recertified 8/31/06 valid through 8/30/09.