The Combined Effect of a Novel Vaccine for Herd Immunization on PRRSV and PCV on JinzhongShanxi of China - Abstract
PRRSV and PCV were two of the most significant swine diseases that affect the pig industry. NADC30-like or NADC34-like PRRSV and PCV3 have had a strong in China and could cause clinical disease on pigs. Co-infection of PRRSV and PCV is frequently observed under field conditions and elicits more severe diseases. However, the endemic status of NADC30-like/NADC34-like PRRSV and PCV3/PCV4 in Jinzhong of Shanxi is unclear under the field condition of immune inactivated vaccines or subunit vaccine (Virus-LikeParticles, VLPs). In this study, we examined 120 weaner dead pigs-lung tissue samples collected from a single PRRSV and PCV positive pig farm in Jinzhong-Shanxi from January to November 2021. Six NADC30-like PRRSV and PCV3 strains were discovered in samples, and PRRSV NSP2 and ORF5 genomes & PCV3 Cap genomes of these strains were sequenced. Phylogenetic analysis indicated that these novel PRRSV and PCV strains belong to NADC30-like PRRSV and PCV3, forming one group in Shanxi, Jinzhong. After NADC30-like PRRSV, pregnant sows (African swine fever infection pressure) were immunized with Ch-1a inactivated vaccine for one year, NADC34-like PRRSV was not identified, and NADC30-like PRRSV was still an epidemic strain in the piglet herd. Importantly, PCV2 pregnant sows were immunized with subunit (Cap protein) vaccine for one year, PCV-4 was not detected, and PCV-3 was still an epidemic strain in the piglet herd. Immunization of sows with PRRSV inactivated vaccine and circular VLPs vaccine can reduce viremia and increase the survival rate of piglets, but cannot provide complete virological protection.