Prevalence of human metapneumovirus in adults with acute respiratory tract infection in Beijing, China

Abstract

Objective: To evaluate the prevalence and clinical manifestations of human metapneumovirus (hMPV) in immunocompetent Chinese adults with acute respiratory tract infections (ARTIs).

Methods: A reverse transcription PCR (RT-PCR) assay targeting the P gene was developed in this study and used to detect hMPV in nasal and throat swabs collected from 2936 immunocompetent adult patients with ARTIs in Beijing, China between July 2008 and June 2010.

Results: Among the 2936 patients studied, 49 (1.7%) were positive for hMPV, of whom 14 (28.6%) were positive for hMPV_A2b, 19 (38.8%) for hMPV_B1, and 16 (32.6%) for hMPV_B2. hMPV_A1 was not detected. An average detection rate of 6.6% was observed in the peak months of the two epidemic seasons studied. The hMPV prevalence was higher in the sampled elderly (>65 years, 3.2%) than in middle aged adults (25-65 years; 2.0%) and teenagers (14-25 years; 0.9%). During the study period, hMPV infections showed a biennial rhythm of seasonality, peaking from November to March in 2008/09 and from March to June in 2010.

Conclusion: hMPV infection plays an important role in immunocompetent adults in its epidemic season. The demographic and clinical data presented in this study improves our understanding of the pathogenesis and clinical burden of hMPV infection in adults.

Figure 1

Number of samples positive for human metapneumovirus and detection rate in adult respiratory samples. The bar graph indicates the number of hMPV A1, A2, B1, and B2 positive cases, and the line graph indicates the total detection rates of human metapneumovirus in each month. The sampling number and the portion of sampling are indicated for each month below the x-axis.

Figure 2

Phylogenetic analysis of hMPV based on partial sequences of the P gene. Fragments of the P genes of hMPV_A2, hMPV_B1, and hMPV_B2 were amplified by RT-PCR and analyzed with MEGA 4.0 software using the distance method and the neighbor-joining algorithm with Kimura-2 parameters. Each strain from this study is indicated by a specific identification code (PUMCH) followed by the patient number and GenBank accession number. The GenBank accession numbers of the reference sequences of hMPV_A1 are AF371337 and AY530092. Those for hMPV_A2 are AB503857, AY297749, AY530090, AY530091, AY 530093, AY530095, DQ843659, FJ168779, GQ153651, and NC_004148. Those for hMPV_B1 are AY525843, AY530089, and AY530094. Those for hMPV_B2 are AY297748, DQ843658, EF535506, and FJ168778. Scale bar indicates nucleotide substitutions per site.