Characterization of human metapneumoviruses isolated in Chongqing, China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Human metapneumovirus (hMPV) has recently been recognized as a notable respiratory pathogen in children. However, no isolation processes and only a limited understanding of hMPV epidemiology present in Chinese children are documented by far.</p><p><b>METHODS</b>Nasopharyngeal aspirates from 86 hospitalized children with acute respiratory tract infections from December 2004 to July 2005 were inoculated onto Vero-E6 cells for hMPV isolation. Total RNA was extracted from infected cells with a cytopathic effect and then subjected to a RT-PCR amplification of the N and F genes of the hMPV. Nucleotide sequences of amplified F gene products were examined using a variation analysis with the MegAlign program and the phylogenetic tree construction using the neighbor-joining algorithm with a Phylip package.</p><p><b>RESULTS</b>Six strains of hMPV were isolated from the samples during winter, spring and summer. The most common symptoms were coughing and cyanosis, and the diagnoses were bronchiolitis, bronchopneumonia, infantile asthma, or upper respiratory tract infection. All isolates were in the A2 genetic sublineage and shared a high percentage of homology with the F gene in the nucleotide (99.8%-100%) and amino acid (99.3%-100%) sequences.</p><p><b>CONCLUSIONS</b>This report indicates that hMPV is an important viral agent for acute respiratory tract infections present in Chongqing, China. Knowledge of phylogeny and genes will benefit the studies on the treatment and prophylaxis of hMPV infection.</p>

Isolation of human metapneumovirus from children with acute respiratory tract infection in Chongqing, China / 中华儿科杂志

<p><b>OBJECTIVE</b>To isolate and characterize the newly discovered human metapneumovirus (hMPV) in Chongqing, China and elucidate the clinical manifestations of hMPV infection.</p><p><b>METHODS</b>Eighty-six patients hospitalized for acute respiratory tract infection in Children's Hospital, Chongqing University of Medical Sciences from December 2004 to July 2005 were enrolled in the present study. Nasopharyngeal aspirates were collected for screening for common respiratory viruses by direct immunofluorescence assay, including respiratory syncytial virus, influenza virus types A and B, parainfluenza virus types 1, 2, 3 and adenovirus, and for inoculating onto Vero-E6 and LLC-MK2 cells for hMPV isolation. Cultures were maintained in the presence of trypsin and observed for development of cytopathic effect (CPE) for 3 weeks. Presence of hMPV was first indicated by positive CPE and subsequently confirmed by reverse transcription polymerase chain reaction targeting N and F genes. Sequence of amplified F fragments were analyzed and submitted to NCBI GenBank. The clinical findings of hMPV infection were collected and analyzed.</p><p><b>RESULTS</b>Of the collected 86 NPAs, six showed CPE characterized by clustering of infected cells, increased granules and eventuall detachment from cell monolayer and obvious syncytium formation. Successful isolation of hMPVs was confirmed with RT-PCR targeting hMPV F and N genes. Of the six hMPV-positive specimens, two were collected in winter (December, January), two in spring (May) and the other two in autumn (June, July). All the six patients were younger than 2 years of age with disease spectrum of bronchiolitis (2/6), bronchopneumonia (2/6), infantile asthma (1/6) and upper respiratory tract infection (1/6). Clinical findings included fever, cough, wheezing, polypnea, cyanosis and rales. Parainfluenza 3 and adenovirus seemed to beviral pathogens of co-infection.</p><p><b>CONCLUSION</b>Six hMPVs were successfully isolated in the mainland of China for the first time. HMPV appears to be one important viral pathogen for acute lower respiratory tract infections in young children with a detection rate of 7% (6/86) by viral isolation. The virus causes respiratory diseases similar to those caused by respiratory syncytial virus. These findings highlight the need for future investigations to define disease burden of hMPV infection and molecular epidemiology among children in China.</p>