Comparison of the effectiveness of passive (dam) versus active (piglet) immunization against porcine circovirus type 2 (PCV2) and impact of passively derived PCV2 vaccine-induced immunity on vaccination

The objectives of this study were (1) to compare the efficacy of two different PCV2 vaccination protocols (colostrum-derived immunity versus piglet vaccination) in a conventional PCV2 growing pig challenge model and (2) to evaluate the efficacy of vaccinating piglets with the same vaccine used in the dams. Two different commercially available vaccines (VAC1; VAC2) were used in the same experiment. Seventy-eight piglets born to vaccinated or non-vaccinated sows were divided into 8 groups. A proportion of the pigs with and a proportion of the pigs without passively acquired immunity were vaccinated at 21 days of age. All pigs except negative controls were challenged with PCV2b at 35 days post-vaccination and necropsied at 21 days post-challenge (dpc). The data indicates that both dam vaccination and piglet vaccination had similar efficacies in reducing PCV2 viral loads and antigen levels in the growing pigs. Interestingly, dam vaccination alone did result in significantly (P