Abstract
Under Korean field conditions, coinfection with porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) is most commonly observed in porcine respiratory disease complex (PRDC). Despite the wide use of PCV2 vaccination, PRDC remains a serious respiratory problem. Thus, the objective of this study was to determine and compare the efficacy of 4 one-dose PCV2 vaccines on 3-week-old pigs with an experimental PCV2-PRRSV challenge at 17 weeks postvaccination. Regardless of which commercial PCV2 vaccine was used, the vaccination of piglets at 3 weeks of age was efficacious against cochallenge of PCV2 and PRRSV, on the basis of growth performance and PCV2-associated lesions. However, the inactivated chimeric PCV1-2 and the PCV2 vaccines induced higher PCV2-specific neutralizing antibody (NA) titers and PCV2-specific gamma interferon-secreting cells and lower PCV2 viremia levels than the two PCV2 subunit vaccines. The vaccination of piglets against PCV2 at 3 weeks of age was effective in reducing PCV2 viremia and PCV2-associated lesions during the finishing period, which is an age at which pigs are frequently affected by PRDC caused by coinfection with PCV2 and PRRSV under Korean field conditions.