Date Full Report Received


Date Abstract Report Received



Primary Investigator:

The research here shows that PRRSV grows in cells as a population of viruses with the same shape, the same RNA molecules, and the same protein composition. There was no evidence for multiple forms that varied in infectivity or in other properties. This finding implies that variation in the behavior of PRRSV isolates in the laboratory is primarily determined by the viral genetic material rather than external factors like culture conditions. It also means that instrinsic features of PRRSV, such as protein composition of the virion, are probably shared by all viruses regardless of biological differences in virulence or immune reactivity. One possible exception would be glycosylation patterns, which we are beginning to study. Our data are also the first direct demonstration of the protein composition of the virion. This information is essential to understanding the antigens that are present on the surface of the PRRSV that might contribute to viral neutralization and to cellular infection. This information is needed because the current model of viral neutralization and immune response, i.e. antibodies to GP5 neutralize the virus and are key to control of infection and resistance to challenge, have so far not been helpful in the development of effective strategies for controlling PRRS in swine herds.