Generation And Application Of Human Bocaviruses-like Particles

Following the first indentification of HBoVl in nasopharyngeal secretion of a child with respiratory problems in 2005, HBoV2 and HBoV3 have recently been characterized in fecal samples from children with non-polio acute flaccid paralysis and diarrhea. Human bocaviruses (HBoVs) are small, non-enveloped, single-stranded DNA viruses, which have been provisionally classified in the family Parvoviridae, subfamily Parvovirinae, genus Bocavirus.Since no in vitro cell culture systems and animal models are available, whatever role HBoVs plays in respiratory infections and gastrointestinal illness remains uncertain. However, many of these problems will likely be solved within the nearestly years by production of recombinant antigens enabling serology.In this study, the major capsid protein HBoVs-VP2 genes, expressed in insect cells by baculovirus expression vector system, produced virus-like particles (VLPs), which were served to develop an ELISA. The VLPs-based ELISA was used to screen for HBoVs-IgG&IgM in 376 serum specimens from Xi'an and Beijing in China and 373 serum specimens from Fukuoka in Japan.SDS-PAGE and Electron microscopy results revealed a molecular weight of 60.5kD was generated and effectively released to culture supernatant, the 60.5kDa protein self-assembled into VLPs with a buoyant density of 1.31 g/cm3 and a diameter of 22nm. By the VLPs-based ELISA, 20%, 14% and 13.5% of serum specimens from infants, respectively, were found to be HBoVl, HBoV2 and HBoV3 IgG-positive; in contrast, the percentage of HBoVl, HBoV2 and HBoV3 IgG-positive increased to75.6%, 44.3% and 42% for adults; but the percentage of HBoVl IgG-positive is more than 80.0% in Fukuoka. Be different from IgG-seroprevalence, the percentage of HBoVs IgM-positive is higher in infants.The baculovirus expression vector system is well established for production of HBoVs capsid protein which could be self-assembled into VLPs. Preliminary seroepidemiologic data suggest that HBoVs are widely circulating in human populations and HBoVs infection is common during childhood.