Epidemiological Investigation and Bioinformatics Analysis of PRRSV, PCV2, and PCV3 in Guangdong Province, China

Abstract

• Background: Reproductive disorders and multiple organ damage in pigs can be caused by various pathogens. Among them, Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and Porcine Circovirus Type 2 (PCV2) and Type 3 (PCV3) have coexisted in Chinese pig farms for over 20 years. Recently, the emergence of new outbreaks of these three viruses indicates possible changes in their genetic characteristics. • Results: We conducted detection and isolation of suspected PRRSV and Porcine Circovirus(PCV) infections from multiple pig farms in Guangdong Province between 2020 and 2022. The sample positivity rates for PRRSV, PCV2, and PCV3 reached 33.2% (75/226), 37.6% (85/226), and 7.5% (17/226), respectively. Bioinformatics analysis of the isolated variant strains revealed their alignment with the current dominant epidemic trends. PRRSV strains were mainly composed of HP-PRRSV and NADC30-like, and notably, all isolated strains were wild-type, including three recombinant strains and seven highly virulent strains. PCV2 exhibited high genetic variability, primarily in the form of subtypes 2b and 2d, while PCV3, in comparison, demonstrated more stability and was concentrated in PCV3a-IM. • Conclusions: In conclusion, this study provides the latest investigative and analytical data on the epidemiological characteristics and genetic evolution of PRRSV, PCV2, and PCV3 in Guangdong Province, emphasizing their significant practical implications for disease prevention and control.