First identification of porcine parvovirus 7 in China

Porcine parvovirus (PPV) are small, non-enveloped and single-stranded DNA viruses, taxonomically classifiable within the family Parvoviridae. Seven PPV genotypes (PPV1 to PPV7) have been identified to date. PPV7, the most recently discovered PPV genotype, was first reported in US pigs in 2016. To explore PPV7 status in Chinese pig populations a total of 64 serum samples collected from two commercial farms in Guangdong province in 2014 were analyzed. PPV7 DNA was detected in 32.8% (21/64) of tested samples. On the porcine circovirus type 2 (PCV2) positive farm, the prevalence rate of PPV7 was 65.5% (19/29) which was significantly higher than that on the PCV2 negative farm (2/35, 5.7%), indicating a possible association between PCV2 and PPV7 infections. The sequences of three PPV7 strains were determined. Phylogenetic analysis revealed that the identified PPV7 strains circulating in China shared 98.7%-99.7% nucleotide homology with the US strain. Further sequence comparison analysis indicated that GD-2014-2 and GD-2014-3 possess a consecutive 9-nt deletion in the VP gene. This is the first report of the existence of PPV7 in China and this finding will strengthen understanding of the epidemiology of porcine parvovirus in Chinese pigs.