Molecular Epidemiology Of Human Metapneumovirus In Wuhan, China

Objectives:Human metapneumovirus (HMPV) is a worldwide distributed pathogen of therespiratory tract. The objectives of this study were to identify HMPV A and Bgenotypes among the influenza-like illness (ILI) patients in Wuhan and to assessHMPV circulation patterns in this city.Methods:Four thousand and nine throat swab samples of ILI outpatients were collected from July,2008to December,2011and were tested for the presence of HMPV RNA by real-timereverse transcription-polymerase chain reaction (real-time RT-PCR). For HMPV RNApositive samples, partial N gene and partial F gene were amplified by RT-PCR andproducts were sequenced to specify genotype of samples. Phylogenic andepidemiological analyses were also conducted.Results:Of the4,009samples,117(2.92%) were positive for HMPV RNA. The prevalence washigher in young children under5years (5.34%) than in older children (6-15years;0.82%) and adults (16-64years;0.31%). Surprisingly, no HMPV positive were foundamong the sampled elderly over65years. During the study period, HMPV infectionsshowed a biennial rhythm of seasonality, peaking from October to March in2008/09 and from March to June in2010. The highest detection rates of peak months were19.44%and24.76%, respectively. A total of102HMPV isolates were subtyped, of whom36(30.8%) were positive for subtype A2,41(35.0%) were subtype B1and25(21.4%)were subtype B2. Subtype A1was not present in the study and all the A2positivesamples detected were belong to sublineage A2b. Two genotypes co-circulated duringeach epidemic season of the3.5years of study, yet an alternating dominance of the twogenotypes was revealed, with genotype A prevailing in epidemic season08/09andgenotype B prevailing during09/10,10/11and the second half year of2011. HMPVstrains circulated in Wuhan were closely related to the previously sequenced prototypes,however, evidences of gene diversity were also observed.Conclusions:In sum, this study reports a large-scale analysis of HMPV prevalence in ILI outpatientsin Wuhan, China. It improves our understanding of the local HMPV circulation patternand provides further evidence about HMPV infection in adults as well as in children.