Detection and genetic characteristic of porcine bocavirus in central China
Lan-Lan Zheng1, Jian-Tao Cui1, Han Qiao2, Xin-Sheng Li1, Xiao-Kang Li3, Hong-Ying Chen1
1Zhengzhou Key Laboratory for Pig Disease Prevention and Control, College of Animal Science and Veterinary Medicine, Henan Agricultural University, Nongye Road 63#, Zhengzhou 450002, Henan Province, People’s Republic of China.
2College of Life Science, South China Agricultural University, Guangzhou 510642, Guangdong Province, People’s Republic of China.
3College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan Province, People’s Republic of China.
Corresponding author : Hong-Ying Chen, E-mail: chhy927@163.com. Mailing address: College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengdong New District Longzi Lake#15, 450046 Zhengzhou, Henan Province, People’s Republic of China. Tel: +86 371 55369208; fax: +86 371 55369208. Xiaokang Li, E-mail: xiaokangli00@163.com. Mailing address: College of Animal Science and Technology, Henan University of Science and Technology, 263 Kaiyuan Avenue, 471000 Luoyang, Henan Province, People’s Republic of China. Tel: +86 379 64563979; fax: +86 379 64563979.
Abstract: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 diarrheal piglets in 37 different pig farms of central China, and two SYBR Green I-based quantitative PCR assays were developed to detect PBoV1/2 and PBoV3/4/5 respectively. The results showed the detection limits of two assays were 1.66 × 101 genome copies/μl of PBoV1/2 and 3.3 × 101 copies/µL of PBoV 3/4/5. 148 (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. Subsequently, complete genomic sequences of two PBoV strains (designated CH/HNZM and PBoV-TY) from two different farms were sequenced. The phylogenetic analysis demonstrated that the two PBoV strains obtained in this study belonged to the PBoV2 group and had a close relationship with other 12 PBoV2 strains, but differed genetically from PBoV1, PBoV3/4/5 and 7 other bocaviruses. CH/HNZM and PBoV-TY were closely related to the PBoV strain GD18 (KJ755666) which may be derived from PBoV strains 0912/2012 (MH558677) and 57AT-HU (KF206160) through the recombination analysis. Compared with reference strain ZJD (HM053694)-China, a higher amino acid variation was found in the NS1 protein of CH/HNZM and PBoV-TY. These results extend our understanding of the molecular epidemiology and evolution of PBoV.
Key words: porcine bocavirus, complete genome sequence, phylogenetic analysis, evolutionary analysis
1 INTRODUCTION
Bocavirus is a novel classified genus in the family ofParvoviridae , subfamily Parvovirinae , which includes human bocavirus (HBoV), porcine bocavirus (PBoV), canine minute virus (CMV), bovine bocavirus (BPV), gorillas bocavirus (GBoV), and California sea lion bocavirus (CslBoV) (Lau et al., 2008; Li et al., 2011). In 2009, porcine boca-like virus (PBo-likeV) was first reported from lymph nodes of pigs with post-weaning multi-systemic wasting syndrome (PMWS) in Sweden (Blomstrom et al., 2009). PBo-likeV was subsequently discovered in China in 2010 and named as porcine bocavirus (PBoV) or PBoV1 (Zhai et al., 2010). Since then, PBoV has been identified in Europe, Asia, North America and Africa (Zhou et al., 2014).
PBoV is a non-enveloped single-stranded DNA virus which consists of three open reading frames (ORFs), ORF1, ORF2, and ORF3 (Arthur et al., 2009). ORF1 encodes a nonstructural protein 1 (NS1), ORF2 encodes viral caspid proteins 1 and 2 (VP1/2), and VP1 consists of the entireVP2 sequence and an additional N-terminal region (Sun et al., 2009), ORF3 encodes nuclear phosphoprotein 1(NP1). Based on theVP 1 and VP 2 sequences, PBoV has been classified into different clades, which includes PBoV1, PBoV2, PBoV3, PBoV4, PBoV5, PBoV3C, PBoV-6V and PBoV-7V. And PBoV was proposed to be classified into three different groups, PBoV G1, PBoV G2, and PBoV G3 (Zhou et al., 2014).
Co-infection of PBoV with other porcine viruses has also been reported, such as porcine epidemic diarrhea virus (PEDV), porcine circovirus type 2 (PCV2), pseudorabies virus (PRV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine torque teno virus (PTTV) and classic swine fever virus (CSFV) (Blomstrom et al., 2010; McMenamy et al., 2013; Zhang et al., 2014; Huang et al., 2014; Zhou et al., 2014; Luo et al., 2015). PBoV was detected from livers of healthy pigs with prevalence of 6% in Brazil, and the co-infection of PBoV with torque teno sus virus 1(TTSuV1), TTSuVk2 and porcine parvovirus (PPV) was also found in these healthy pigs (Silva et al., 2020). In addition, PBoV has a significantly higher infection rate in diseased pigs than in healthy pigs, and the co-infection rate of PEDV and PBoV was higher in samples of diarrheal pigs than that of healthy pigs, suggesting that the PBoV might play an important role in causing diarrhea in piglets (Zhai et al., 2010).
To date, PBoVs have been reported in pigs in 20 provinces or regions in China with the prevalence between 7.3% and 64% (Wang et al., 2014; Zhang et al., 2015; Zhou et al., 2018). However, little is known about the presence of PBoV in central China. Here, we aimed to investigate the occurrence of PBoV and characterized two PBoV strains from diarrheal pigs in central China.