Prevalence and molecular characterization of human metapneumovirus in influenza a negative sample in Thailand.

BACKGROUND: Human metapneumovirus (hMPV) causes respiratory tract infection in influenza-like illness. The role of hMPV infections in all age groups in Thailand has not yet been investigated. Thus, the objective of this study was to determine prevalence of hMPV infection in all age groups in Thailand during 2011. METHODS: A total of 1,184 nasopharyngeal washes were collected from hospitalized patients and sent to the Department of Microbiology, Siriraj Hospital, for influenza A virus detection. Real-time polymerase chain reaction (PCR) was used to detect hMPV infection. Partially, F gene from hMPV positive samples were sequenced and used for genotyping by phylogenetic tree analysis. RESULTS: The prevalence of hMPV for all age groups was 6.3%. The highest prevalence of hMPV infection was in children aged <2 years. Of 71 hMPV-positive patients, three (4.2%) were coinfected with respiratory syncytial virus (RSV), two with rhinovirus (2.8%), one with coronavirus (1.4%), and one with RSV and adenovirus (1.4%). Phylogenetic analysis of F gene revealed that 96.8% of hMPV detected was subgenotype B1, 1.6% was sublineage A2a, and 1.6% was A2b. Genetic variation of F gene was much conserved. CONCLUSION: We demonstrated the prevalence of hMPV subgenotype B1 circulating in Thailand during 2011.