title: Impact of a modified-live porcine reproductive and respiratory syndrome virus vaccine intervention on a population of pigs infected with a heterologous isolate.
abstract: 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.
authors: 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.
authors: Jean Paul
authors: JP
authors: Cano
authors: Scott A
authors: SA
authors: Dee
authors: Michael P
authors: MP
authors: Murtaugh
authors: Carlos
authors: C
authors: Pijoan
mesh_terms: 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
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral; D014765:Viral Vaccines