Detection and genetic characteristics of human bocavirus in children in Tianjin

ObjectiveTo investigate the infection status of human bocavirus (HBoV) in infants and young children with acute respiratory tract infection in Tianjin and identify molecular characteristics of the virus.

MethodsRespiratory samples were taken from 248 hospitalized pediatric patients in Tianjin from May 2018 to April 2019. The pathogens were detected by using multiplex real-time PCR kit for respiratory viruses. VP1/VP2 genes of the HBoV strainsisolated from the HBoV positive samples and the HBoVstrains stored in our laboratory from 2015 to 2018 were amplified and sequenced.The sequences were analyzed,phylogenetic tree was constructed using software DNAstar and Mega.

ResultsOf all 248 pediatric patients, 15 (6.05%) were positive for HBoV. The HBoV-positive children were aged 6 months-4 years old and all had pneumonia or asthmatic bronchitis. The detection rate of HBoV peaked during October - November in Tianjin. The VP1/VP2 genes of 17 HBoVstrains were successfully sequenced, and phylogenetic analyses showed that they all belonged to HBoV-1, and Ⅰb cluster was predominant. The nucleic acid identity was 97.9%–100.0% compared with standard strains ST2 and ST1. There were 6 key amino acid mutations within antigenic domains.

ConclusionThe incidence of HBoV peaked during October-November in Tianjin, most HBoV strains in Tianjin belonged to Ⅰb cluster. The genetic characteristics of HBoVwere stable without obvious variation, but some key amino acid mutations were observed.