A Retrospective Analysis of Porcine Circovirus Type 3 in Samples Collected from 2008 to 2021 in Mexico.

Porcine circovirus type 3 (PCV3) is a nonenveloped virus of the family. This virus has been identified in pigs of different ages and pigs with several clinical manifestations of the disease or even in apparently healthy pigs. While PCV3 was first reported in 2015, several retrospective studies have reported the virus before that year. The earliest report indicates that PCV3 has been circulated in swine farms since 1996. In this study, we evaluated the presence of PCV3 in samples collected in Mexico in 2008, 2015, 2020, and 2021. This study assessed PCV3 DNA by qPCR and antibodies against CAP protein by indirect ELISA. The results showed that PCV3 (DNA and anti-CAP antibodies) was detected in the samples collected from 2008 to 2021. The highest prevalence was in 2008 (100%), and the lowest was in 2015 (negative). Genetic analysis of ORF2 showed that the virus identified belonged to genotype a, as most of the viruses identified thus far. PCV3 was detected in samples from piglets with respiratory signs and growth retardation, sows with reproductive failure, or asymptomatic piglets and sows. Pigs with respiratory signs, growth retardation, or reproductive failure had a higher prevalence of antibodies and qPCR-positive samples. In conclusion, this study showed that PCV3 has been circulating in Mexico since 2008 and that PCV3 DNA and antibodies were more prevalent in samples from pigs with clinical manifestations of diseases.