design: Viral DNA was extracted according to the manufacturers instructions of Viral Nucleic Acid Extraction Kit  (Geneaid, Taiwan), and identification was carried out with PPV VP2 gene specific primers (Table 1). Five pairs of primers were designed were designed based on conserved regions of the full-length sequences of a PPV HN2011 strain (GenBank number: JX992846.1) (Table 1) to amplified amplify five DNA frargments. The PCR pruducts products were gel purified and cloned into the pEASY-blunt vector (TransGen Biotech, Beijing China). Three or four clones from each PCR product were sequenced by Sangon Biotech (Shanghai, China). Finally, the data was assembled and annotated by Lasergene version 7.0 with default parameters.