The retrospective identification and molecular epidemiology of porcine circovirus type 3 ( PCV 3) in swine in Thailand from 2006 to 2017

Porcine circovirus type 3 ( PCV 3) has recently been detected in pigs worldwide, with similar clinical manifestations to porcine circovirus‐associated disease ( PCVAD ) from porcine circovirus type 2 ( PCV 2) infection. Here, we report the identification and molecular epidemiology of PCV 3 in swine in Thailand from clinical samples retrieved from 2006 to 2017. The epidemiological data revealed co‐infection with PCV 2, PRRSV , and PCV 2/ PRRSV was common in our samples. Circulating PCV 3 from this study shared a high similarity of nucleotide and deduced amino acid sequences of the partial capsid gene (96.7%–100% and 96.7%–100% respectively), indicated the genetic stability of PCV 3 in Thailand. Phylogenetic analysis based on the capsid gene revealed scatter clustering with current PCV 3 having no relation to the geographical origin of the virus strains. In this retrospective study, results have demonstrated that PCV 3 has spread extensively within Thai swine from as early as 2006 and may also be involved in PRDC and PCVAD .