Submitted to: Pig Veterinary Society International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 1, 2000
Publication Date: N/A
Technical Abstract: Porcine reproductive and respiratory syndrome (PRRS) is the number one infectious disease problem for the United States swine industry and is one of the most significant diseases affecting swine around the world. The focus of this paper is on recent PRRS developments reported since the last International Pig Veterinary Society meeting about how PRRSV functions in vivo and why it causes disease. Most work in the area of pathogenesis is shifting from macroscopic to microscopic studies that have reported apoptosis of PRRSV-infected cells and perhaps adjacent cells. In addition, PRRSV has been detected in testicular tissue suggesting PRRSV may establish a persistent infection in boars similar to an Equine Arteritis virus infection in stallions (both viruses are members of the same virus family, Arteriviridae). The knowledge base about PRRSV immunology is rapidly expanding with studies investigating cell mediated immunity that have found immune responses to specific viral proteins. These studies are leading towards identification of protective epitopes and perhaps the design of new vaccines. Recent developments in epidemiology have demonstrated that congenitally infected pigs can shed virus for extended periods of time and molecular studies indicate that there is a clear distinction between European and North American isolates. Whether or not these two genotypes have a distant relative or they evolved independently on different continents is not known. Great strides have been made in understanding the molecular biology of the virus with current work investigating the function of viral genes and the significance of genetic mutations. Collectively, this body of work will aid in the improvement of PRRS control and prevention programs.