Porcine circovirus type 3 (PCV3) infection in grower pigs from a Thai farm suffering from porcine respiratory disease complex (PRDC)

Porcine circovirus type 3 (PCV3) is a newly emerging virus with unknown pathogenesis. The major objective of this study was to investigate the presence of PCV3 in pigs from a farm in Thailand suffering from porcine respiratory disease complex (PRDC). Initially, a Thai PCV3 strain (PCV3/Thailand/PB01/17) was identified from a pig originated from a farm with PRDC problem during grower period and whole genome analysis showed that the Thai PCV3 shared highest nucleotide identity of 99.60% with the South Korean strain PCV3/KU-1602. The presence of PCV3 infection in PRDC-affected pigs was then investigated in this farm. Serum samples from clinically healthy pigs and pigs showing PRDC-related clinical signs during 5-18 weeks were used in PCV3 detection by PCR. The results showed that the PRDC-affected pigs exhibited higher prevalence of PCV3 infection and higher PCV3 titers comparing with the clinically healthy pigs. These results confirmed the presence of PCV3 in a Thai farm with PRDC problem. The pathogenesis of PCV3 on PRDC should be clarified in further studies.