Efficacy of Porcine Circovirus Type 2a and 2d Based Vaccines Following PCV2 Challenge

Abstract

This study evaluated the efficacy of PCV2a and PCV2d vaccines against a PCV2 challenge. Three-week-old, cesarean-derived, colostrum-deprived pigs were blocked by litter and randomized to treatment group. Pigs received a single 2 mL intramuscular dose of either placebo (PLAC, n=50), PCV2a vaccine (PCV2aV, n=25), or PCV2d vaccine (PCV2dV, n=25) on D0 and were challenged with a PCV2d isolate on D28. Prior to challenge, a naturally occurring PCV2a infection was identified. Both vaccines similarly prevented lymphoid tissue lesions, mortality and clinical signs of PCVAD while PLAC pigs were severely affected. Viremia was significantly reduced 7, 14, 21, and 28 days post-challenge and average daily weight gain was significantly increased for both vaccine groups. The prevention of mortality and very minimal occurrence of lymphoid tissue lesions in both vaccine groups, provides clear evidence of the benefit of PCV2 vaccination in the face of a virulent mixed PCV2 challenge.