The efficacy and performance impact of Fostera PRRS in a Vietnamese commercial pig farm naturally challenged by a highly pathogenic PRRS virus.

ABSTRACT

Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) is characterized by high fever, respiratory distress, and high mortality in pigs of all ages and has severely affected the Vietnam pork industry in recent years. The study was conducted to compare the efficacy, safety, and overall performance of a modified live PRRSV-2 vaccine (Fostera PRRS) to an existing PRRSV modified live vaccine on a farm with a recent history of HP-PRRSV-associated respiratory diseases. A total of 351 pigs were randomly allocated to three treatment groups (i) vaccinated with Fostera PRRS at 1 day of age (n = 118), (ii) vaccinated with Fostera PRRS (n = 118) at 21 days of age, and (iii) vaccinated with Amervac PRRS (n = 115) at 21 days of age. The Fostera PRRS vaccinated pigs had milder clinical symptoms, lower levels of HP-PRRSV viremia, fewer pathological changes in the lung, and higher body weight gain at the end of the study compared with the Amervac PRRS group. Vaccination of pigs with Fostera PRRS at 1 day of age also significantly reduced viral loads in their blood (P < 0.05) and induced higher anti-PRRSV antibody titers (P < 0.01) compared with pigs vaccinated with Amervac PRRS at 21 days of age. Fostera PRRS vaccination at 1 day of age can be useful in protecting young piglets from early HP-PRRSV infection because the immunized pigs were marketed 20 days earlier than their peers immunized at 21-day old as they reached the target market weight earlier in this study.