#03-046

Complete

Date Full Report Received

10/07/2004

Date Abstract Report Received

07/26/2006

Investigation

Institution:
Primary Investigator:

PRRSV-positive sow herds can produce PRRSV-negative pigs. This phenomenon is important in herd stabilization against PRRSV-induced disease. One possible explanation of this phenomenon would be that MDAs provides protection against clinical disease and reduce virus levels in the pigs. However, the half-life of MDA against PRRSV is relatively short compared to MDAs against other swine pathogens. In addition, individual immunity of pigs in the breeding herd varies and as a result, some pigs have high levels of antibodies, while other pigs have lower levels. This creates a problem as pigs with a low level of immunity may be more vulnerable to infection. Furthermore, it changes the status of the total herd immunity due to the presence of subpopulations of susceptible pigs. This study determined that the use of KV in previously infected sows prior to farrowing boosters the existing immunity of sows. The sows used in this study were from a stable, PRRSV-positive sow herd with minimal clinical disease. Vaccination with KV resulted in an increased duration and magnitude of PRRSV specific MDA and relatively increased protection in the pigs against disease.