Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 20, 1998
Publication Date: N/A
Interpretive Summary: Porcine reproductive and respiratory disease (PRRS) is currently considered to be one of the most costly diseases faced by the swine industries worldwide. Recently what appear to be new strains of the causative virus, namely, PRRS virus (PRRSV), have appeared in the United States. Such strains have been associated with a more severe clinical form of PRRS commonly referred to as "atypical" or "acute" PRRS. In this study we provided experimental evidence that supported the hypothesis that more virulent strains of PRRSV are now present in the United States swine population. The identification of such strains provides a first step in developing more effective vaccines and diagnostic procedures for the control of PRRS.
Technical Abstract: Pregnant gilts were exposed to strains of porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) that had been isolated from field cases of PRRS commonly referred to as "atypical" or "acute" PRRS. The clinical consequences of these experimental infections were especially severe and supported the hypothesis that new more virulent strains of PRRSV had recently appeared in the United States. The fact that many of the naturally occurring cases were in vaccinated gilts indicated that current vaccines are, at best, only partially effective against the new strains. Collectively our observations suggest that there is a need for a new generation of vaccines developed from these more virulent strains.