Detection and genetic characteristics of porcine bocavirus in central China

To investigate the epidemic profile and genetic diversity of porcine bocavirus (PBoV), 281 clinical samples, including 236 intestinal tissue samples and 45 fecal samples were collected from diarrheic piglets on 37 different pig farms in central China, and two SYBR Green I-based quantitative PCR assays were developed to detect PBoV1/2 and PBoV3/4/5, respectively. One hundred forty-eight (52.67%) of the 281 clinical samples were positive for PBoV1/2, 117 (41.63%) were positive for PBoV3/4/5, 55 (19.57%) were positive for both PBoV1/2 and PBoV3/4/5, and 86.49% (32/37) of the pig farms were positive for PBoV. Overall, the prevalence of PBoV was 74.73% (210/281) in central China. Subsequently, nearly full-length genomic sequences of two PBoV strains (designated CH/HNZM and PBoV-TY) from two different farms were determined. Phylogenetic analysis demonstrated that the two PBoV strains obtained in this study belonged to the PBoV G2 group and had a close relationship to 10 other PBoV G2 strains but differed genetically from PBoV G1, PBoV G3, and seven other bocaviruses. CH/HNZM and PBoV-TY were closely related to the PBoV strain GD18 (KJ755666), which may be derived from the PBoV strains 0912/2012 (MH558677) and 57AT-HU (KF206160) through recombination. Compared with reference strain ZJD (HM053694)-China, more amino acid variation was found in the NS1 proteins of CH/HNZM and PBoV-TY. These data extend our understanding of the molecular epidemiology and evolution of PBoV.