Porcine Circovirus Type 2 Genotypes and PCV3 in Swine Clinical Samples From Brazil

Abstract Porcine circovirus type 2 (PCV2), an important pathogen in swine, causes PCV disease (PCVD). Although PCVD is effectively controlled using commercial vaccines, its clinical presentation is changing. Moreover, PCV2 is genetically evolving, with new genotypes emerging in vaccinated or unvaccinated pigs. In this study, we aimed to verify the presence of the PCV2a, PCV2b, and PCV2d genotypes in PCV-positive porcine samples. Furthermore, to identify coinfections between the PCV2 genotypes and/or PCV3, which can also induce disease in pigs, we employed a quick, effective, and low-cost PCR diagnostic test. In this study, 333 PCV2 PCR and clinically positive samples from various production stages and herds across Brazil were analyzed. Among these, 266 samples were genotyped, with PCV2b emerging as the most predominant genotype (56.77% of the positive samples), mainly observed in nursery pigs. PCV2d was also identified in 33.10% of the samples, primarily from finishing pigs and breeding sows. The employed PCR test was compared with a commercial kit, proving effective in PCV2 genotyping. This study demonstrates the significance of PCV2 genotyping, showing PCV2b as the most predominant genotype responsible for disease in pig farms in Brazil. PCV2a, the prevalent genotype used in commercial vaccines, was not detected in any of the analyzed samples. While pigs infected with other PCV2 genotypes may receive some heterologous protection from PCV2a vaccines, adequate diagnosis and vaccine monitoring for updates must be considered. Resumo O Circovírus suíno tipo 2 (PCV2) é um importante patógeno para suínos e causador das doenças associadas a circovirose suína (PCVD). Apesar da PCVD ser controlada pelas vacinas comerciais, a sua apresentação está mudando. Além disso, o PCV2 está evoluindo geneticamente e novos genótipos foram identificados em suínos vacinados e não vacinados. O objetivo deste trabalho foi verificar a presença dos genótipos PCV2a, PCV2b e PCV2d em amostras previamente positivas para PCV2. Além disso, identificar coinfecções entre genótipos de PCV2 e/ou com PCV3, que também podem causar doenças em suínos, utilizando um teste de diagnóstico PCR rápido, eficaz e de baixo custo. Foram analisadas 333 amostras clínicas positivas para PCV2 por qPCR e provenientes de diferentes fases de produção e rebanhos do Brasil. Destas, 266 foram genotipadas, sendo o PCV2b o genótipo mais predominante (56,77% das amostras positivas), principalmente provenientes de ani