Two Commercial Type 1 Porcine Reproductive and Respiratory Syndrome Virus (PRRSV)‐Modified Live Vaccines Reduce Seminal Shedding of Type 1 PRRSV but not Type 2 PRRSV in Infected Boars. Issue 1 (16th April 2015)

• Record Type: Journal Article
• Authors: Park, C.; Kim, T.; Choi, K.; Jeong, J.; Kang, I.; Park, S.‐J.; Chae, C.
• Is Part Of: Transboundary and emerging diseases. Volume 64:Issue 1(2017)
• Page Start: 194
• Page End: 203
• Publication Date: 2015-04-16
• Subjects: boar -- cross‐protection -- porcine reproductive and respiratory syndrome virus -- semen -- vaccine; Veterinary medicine -- Periodicals; 636.089
• DOI: 10.1111/tbed.12361
• Languages: English
• ISSNs: 1865-1674

Abstract

Summary: The objective of this study was to compare the effects of two commercial type 1 porcine reproductive and respiratory syndrome virus (PRRSV)‐modified live vaccines on type 1 and type 2 PRRSV shedding in the semen of experimentally infected boars. Upon challenge with PRRSV, unvaccinated boars exhibited an increase in daily rectal temperature (39.4–39.7°C). Vaccination of boars with type 1 PRRSV significantly reduced the amount of type 1 PRRSV load in blood and semen after challenge with type 1 PRRSV, but barely reduced the amount of type 2 PRRSV load in blood and semen after the type 2 PRRSV challenge. There were no significant differences in the reduction of viremia and seminal shedding of type 1 and type 2 PRRSV between the two commercial vaccines. The seminal shedding of PRRSV is independent of viremia. The reduction of type 1 PRRSV seminal shedding coincided with the appearance of type 1 PRRSV‐specific interferon‐γ secreting cells (IFN‐γ‐SC) in vaccinated type 1 PRRSV‐challenged boars. The frequencies of type 1 PRRSV‐specific IFN‐γ‐SC induced by type 1 PRRSV vaccine are relatively high compared to type 2 PRRSV‐specific IFN‐γ‐SC induced by the same vaccine which may explain why type 1 PRRSV vaccine is more effective in reducing seminal shedding of type 1 PRRSV when compared to type 2 PRRSV in vaccinated challenged boars. These results provide clinical information on how to reduce seminal shedding of type 1 PRRSV in boars using type 1 PRRSV‐modified live vaccine.