OBJECTIVETo detect human bocavirus (HBoV) and investigate its genetic and evolutionary characteristics in children with acute respiratory infection in Tianjin, China.

METHODSA total of 1,259 samples of nasopharyngeal aspirates were collected from children with a confirmed diagnosis of acute respiratory infection between January and December, 2012. Viral nucleic acid was extracted, HBoV was detected by real-time quantitative PCR, and the gene segments of nucleocapsid protein of HBoV in positive samples were amplified by PCR. Several products were randomly selected and sequenced.The sequence obtained was compared with the known sequence of HBoV, and a phylogenetic analysis was performed. All the samples were examined to detect for other common respiratory tract viruses.

RESULTSAmong the 1,259 samples, the positive rate of HBoV was 4.53% (57/1,259), and among the 57 samples with positive HBoV, 75% (43/57) were positive in children with an age of 6-36 months. The positive rate of HBoV in children peaked in summer (from June to August), and there was a mixed infection with other viruses. Sequence analysis was performed for the PCR products from 36 positive samples, and the presence of HBoV was confirmed, with a higher homology to the known sequence of HBoV.

CONCLUSIONSIn Tianjin, acute respiratory infection in some children may be associated with HBoV infection, which is commonly seen in infants with an age of 6-36 months. The peak of HBoV infection occurs in summer. The phylogenetic analysis shows a high homology to the known sequence of HBoV, with few gene sequence variations.