Efficacy comparison of commercial porcine circovirus type 2 (PCV2) and monovalent and bivalent vaccines against a dual challenge.

The objective of this study was to compare the efficacy of commercially available porcine circovirus type 2 (PCV2) and vaccines. A total of 80 pigs was randomly divided into 6 treatment groups; 4 of the groups each received a different vaccine as well as a dual challenge. The remaining 2 groups were used as controls, 1 of which also received a dual challenge. Two of the 4 groups of pigs were administered 2 monovalent vaccines (designated as either monovalent vaccine A or B) of PCV2 at 7 days old and of at 21 days old. The remaining 2 vaccinated groups of pigs received a bivalent vaccine (designated as either bivalent vaccine A or B) of PCV2 and at 21 days old. All 4 vaccinated groups were challenged with at 42 days old [-14 d post-challenge (dpc)], followed by a PCV2d challenge at 56 days old (0 dpc). All 4 vaccinated/challenged groups displayed a reduction in clinical signs, PCV2d viremia, nasal shedding of , and lung lesions compared with pigs in the unvaccinated and challenged groups. Vaccination and challenge improved growth performance and increased the immunologic responses (- and PCV2-specific antibodies and interferon-γ-secreting cells) when compared to pigs in the unvaccinated/challenged groups. Pigs in groups vaccinated with either a monovalent or bivalent vaccine A treatment and challenge produced a larger amount of - and PCV2d-specific interferon-γ-secreting cells within the pigs and simultaneously reduced the nasal shedding of and PCV2d viremia compared with groups vaccinated with either a monovalent or bivalent vaccine B treatment and challenge. Both the bivalent vaccines and the respective monovalent vaccines were efficacious against a dual challenge of and PCV2d.