Identification and characterization of porcine parvovirus in Hunan province, China

Porcine parvovirus (PPV) is considered one of the most important infectious agents of reproductive failure in sows. Little information, however, is available on its prevalence in healthy fattening pigs. Therefore, in the present study, 197 fecal swabs, 197 nasal swabs, 389 serum samples, and 310 lung samples were collected from pigs aged 10-25 weeks across Hunan, China, and tested for the presence of PPV. PPV DNA was amplified by polymerase chain reaction, demonstrating an overall positivity rate of 7.69%, with a particularly high infection rate of 22.90% in the lungs. A total of five PPV strains (PPV-HuN1-5) were isolated on the basis of cytopathic effects in swine testicular cells, and the near-complete genomes were sequenced and subjected to phylogenetic analysis with reference to reported PPV sequences in GenBank. The five Hunan isolates showed a close relationship with each other and predominantly with reported European PPV strains. Moreover, seven amino acid substitutions were detected within the coding region of the VP2 of PPV-HuNs when compared with that of the Chinese vaccine strain PPV-NJ. The relatively high prevalence of PPV discovered in healthy fattening pigs despite a long-term vaccination program in China, highlights the need for improved prevention, monitoring, and control of related diseases in herds.