Date Full Report Received


Date Abstract Report Received



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PRRSV is an important swine pathogen and infections caused by this virus have not been efficiently controlled. This is in part due to the lack of knowledge about the insufficient swine immune responses seen after infection with PRRSV. This proposal sought to pinpoint PRRSV structural proteins that may interfere with one arm of the swine immune system, called type I interferon. Type I interferon plays an extremely important role in early innate antiviral immune responses and the initiation of adaptive immune responses.

Individual PRRSV structural proteins of one viral strain were cloned and an attempt was made to express these clones as proteins. The results of this study aim were disappointing in that no PRRSV protein could be detected. Extensive research ensued in order to identify the experimental conditions needed to express the PRRSV proteins. PRRSV structural and nonstructural proteins have now been successfully expressed in Marc-145 cells, which was a critical step for further study in our laboratory. The initial PRRSV interferon antagonist screening method also did not perform as well as expected, providing inconclusive data. After much study, we concluded that the tools outlined in the proposal would not suffice. We are now collaborating with Dr. Laura Miller of The National Animal Disease Center, who had concurrently established an optimal method to identify type I interferons in infected cells. Screening of individual PRRSV proteins that may serve as Type I interferon antagonists, down-regulating the immune response, is currently underway.
Once the PRRSV protein(s) that act as type I interferon antagonists have been identified, we will pinpoint the actual polypeptides that down-regulate this important arm of the immune response and seek to mutate the protein region in our reverse genetic system to eliminate the antagonism. We will also seek to understand if other PRRSV strains act in a similar manner. This research will ultimately provide new strategies in designing new vaccines and control methods. Kay Suzanne Faaberg, Ph.D. Research Microbiologist USDA-ARS B-14 Virus and Prion Diseases of Livestock National Animal Disease Center 2300 Dayton Avenue Ames, IA 50010 Phone: (515) 663-7259 Fax: (515) 663-7458 Email: kay.faaberg@ars.usda.gov