Phylogenetic and recombination analysis of human bocavirus 2

We collected 632 diarrhea and 162 healthy children in Lanzhou, China. Using PCR, Human bocavirus (HBoV), HBoV2, HBoV3 and HBoV4 were screened. The partial genes of NS, NP1 and VP, and two nearly complete sequences of HBoV2 were obtained.Phylogenetic analysis showed the different genes of HBoV2 strain were homogenous with different reference strains. HBoV3 may be a recombinant derived from HBoV and HBoV4. We also observed that the VP1 and VP2 region of HBoV3 is as similar to HBoV2 as to HBoV4.A single genetic lineage of HBoV2 is circulating in children with and without gastroenteritis in Lanzhou, China. Current evidence in this study was not enough to support recombination between HBoV2 strains, and HBoV3 may be a recombinant between HBoV and the common ancestor of HBoV2 and HBoV4.Human bocavirus (HBoV), HBoV2, HBoV3, and HBoV4 have been discovered recently [1-4]. These viruses belong to the genus Bocavirus in the subfamily Parvovirinae of the family Parvoridae, among which the human parvovirus B19 (B19V) is the only known human pathogen [5]. HBoV was detected in respiratory tract samples in 2005[1]. In 2009, Kapoor et al. [2] reported a new bocavirus species, HBoV2, isolated from stool samples in children with nonpolio acute flaccid paralysis, and suggested that recombination between HBoV2 strains may occurs. Almost simultaneously, Arthur et al. [3] reported that HBoV3 was detected in stool samples from children with acute gastroenteritis (AGE). In addition, they proposed that HBoV3 is a hybrid of HBoV and HBoV2. Subsequently these two new viruses were detected in nasopharyngeal aspirates or stool samples in other regions [6-11]. Recently Kapoor et al reported the discovery of HBoV4 and the detection of recombination signals between and within bocavirus species [4]. Among these human bocaviruses, HBoV2 had higher prevalence and genetic diversity in stool samples than the others [3,8], but the precise phylogenetic relationships among these viruses were not clear yet.