Impact of a modified-live porcine reproductive and respiratory syndrome virus vaccine intervention on a population of pigs infected with a heterologous isolate.
The objectives of this study were to evaluate the effects of a therapeutic vaccine intervention with a modified-live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine on the dynamics of a heterologous viral infection in a population of pigs, and to determine the clinical and virological response of previously exposed and vaccinated pigs against a second virulent heterologous challenge. A population of 320 pigs were infected with a field isolate, PRRSV MN-30100, alone or followed by Ingelvac PRRS MLV vaccine administered one to three times at 30 days intervals beginning 1 week after infection. Vaccine intervention reduced the duration of viral shedding, but did not reduce the viral load in tissues or the proportion of persistently infected pigs. A different and highly virulent field isolate, MN-184, was then given as a heterologous viral challenge at 97 days after first exposure. Previously infected and vaccinated pigs showed a significant reduction in clinical signs and enhanced weight gain after the highly virulent challenge with PRRSV MN-184, but infection with and shedding of the challenge isolate were not prevented.
Cano
Jean Paul
JP
Swine Disease Eradication Center, University of Minnesota, College of Veterinary Medicine, 385C Animal Science Veterinary Medicine Building, 1988 Fitch Avenue, St. Paul, MN 55108, USA.
Dee
Scott A
SA
Murtaugh
Michael P
MP
Pijoan
Carlos
C
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology / Q000503:physiopathology / Q000517:prevention & control* / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000145:classification* / Q000276:immunology / Q000302:isolation & purification / Q000472:pathogenicity*; D012367:RNA, Viral / Q000097:blood; D013552:Swine; D014611:Vaccination / Q000662:veterinary*; D019562:Viral Load; D014765:Viral Vaccines / Q000008:administration & dosage* / Q000235:genetics / Q000276:immunology; D014766:Viremia / Q000276:immunology / Q000517:prevention & control / Q000821:virology; D014774:Virulence
D000914:Antibodies, Viral; D012367:RNA, Viral; D014765:Viral Vaccines