Human metapneumovirus infectkn in children with lower respiratory tract infectians in Shanghai
Objective To investigate the role of the human metapneumovirus(hMPV) in children with lower respiratory infection in Shanghai. Methods Four hundred and seventy-nine respiratory specimens were collected from the hospitalized children aged 10 days to 13 years from Aug 2004 to Jan 2005 for virus detection. Of 479 samples, 259 were tested for hMPV M gene by RT-PCR, which were negative for respiratory syncytial virus, influenza A and B, parainfluenza viruses 1-3 and adenovirus by the direct immunofluorescent antibody. Twenty-three hMPV M gene positive PCR products were randomly chosen for sequencing. Sequences were compared with hMPV M gene sequences in the GenBank. Nucleotide sequences alignment and phylogenetic analysis were performed with DNAStar software. Results Overall, 59 (22.8%) of 259 individuals tested were positive for hMPV, which was the common virus during the observation period. The 52 (88.1 % ) hMPV-positive specimen were obtained in the winter, 7(11.9%) obtained in the fall. hMPV was significantly more prevalent in the winter than in the fall (31.3% vs 7.5%, P 0.01). 89.8% (53 cases) aged≤5 years. Twenty-three hMPV M gene fragments of sequences were closely related to hMPV in the GenBank. Similarity of hMPV partial M gene with hMPV M gene published at nucleotide levels varied from 82.8% to 100% . The amino acid indentity of hMPV partial M gene with other published hMPV was 93.0%-100%. Phylogenetic tree analysis of nucleotide sequences revealed 2 different genotypes circulating during the period. Fourteen isolates clustered in the Bj1816 group, the remain 9 in the BJ1887 group. Conclusion hMPV plays an important role in causing acute lower respiratory infection in children in Shanghai and is prevalent in the winter season of 2004. Further surveillance for the hMPV epidemiology is warranted.