Int’l - PRRSV vaccine did not affect virus shedding in PRRSV-infected pigs

A killed porcine reproductive and respiratory syndrome virus (PRRSV) vaccine did not affect virus shedding in previously PRRSV-infected pigs. According to a study from the United States, "Two experiments were conducted to investigate if virus shedding could be reduced following a killed porcine reproductive and respiratory syndrome virus (PRRSV) vaccination (KV) of PRRSV infected pigs. In experiment 1, PRRSV infected pigs were vaccinated with KV on days 14 and 28 following infection. Viremia and serum neutralizing (SN) antibody were compared to infected pigs with no KV. The second experiment was conducted in an identical manner. In addition to viremia and SN antibody, virus in oropharyngeal scrapings and interferon gamma (IFN-gamma) producing cells were monitored." "Magnitude and duration of viremia were not different between KV vaccinated and non-vaccinated groups," reported Dachrit Nilubol and colleagues at Iowa State University. "No virus was detected in oropharyngeal scraping from any pig, nor was there a difference in the detection of viral RNA. In both experiments, however, increases in SN titer and number of IFN-gamma producing cells were observed. The SN titer was significantly higher in KV vaccinated groups than in non-vaccinated group on days 42 and 42-56 following infection in experiments 1 and 2, respectively." The researchers reported, "The number of IFN-gamma producing cells was slightly higher in KV vaccinated groups than in non-vaccinated group on days 42 and 63. These observations suggest that KV had no effect on virus shedding. However, previously infected pigs responded immunologically to KV, as demonstrated by increases in SN antibody titers and IFN-gamma producing cells." Nilubol and associates published the results of their research in Veterinary Microbiology (The effect of a killed porcine reproductive and respiratory syndrome virus (PRRSV) vaccine treatment on virus shedding in previously PRRSV infected pigs. Vet Microbiol, 2004;102(1-2):11-18). For additional information, contact D. L. Harris, Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University of Science and Technology, Ames, IA 50011, USA. E-mail: hharris@iastate.edu. The publisher of the journal Veterinary Microbiology can be contacted at: Elsevier Science BV, PO Box 211, 1000 AE Amsterdam, The Netherlands.