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A novel polyomavirus (WU virus) has been identified in pediatric patients with acute respiratory tract infections (ARI), but its role as a respiratory pathogen has not yet been demonstrated. To investigate if WU virus is related to acute respiratory infections in infants and children in Beijing, specimens collected from 674 pediatric patients with ARI from April 2007 to May 2008 and from 202 children without ARI were used for this investigation. Common respiratory viruses were tested by virus isolation and/or antigen detection by indirect immunofluorescent assay followed by RT-PCR or PCR for other viruses associated with respiratory infections in specimens collected from patients with ARI before WU virus DNA was detected. WU virus DNA was detected by initial screening and secondary confirmation PCR for all specimens. The region encoding the VP2 gene of the virus was amplified from 17 WU-virus-positive clinical specimens, and sequence analysis was performed. Thirty-eight of 674 (5.6%) specimens from patients with ARI and 3 of 202 (1.5%) specimens from children without ARI yielded PCR products with the predicted molecular weight, using either screening or confirmation primer sets, indicating that these specimens were WU virus positive. However, more than 60% of the 38 WU-virus-positive specimens from patients with ARI were also positive for one or more respiratory viruses. The nucleotide and deduced amino acid sequences of the region encoding the VP2 gene from 17 Beijing WU viruses shared high homology (>98.5%) with sequences from GenBank and among themselves. The data indicated that WU virus in Beijing occurred 3.7 times more frequently in pediatric patients with ARI than in those without ARI ( p < 0.05). [ABSTRACT FROM AUTHOR]

Human metapneumovirus (hMPV) is associated with respiratory infections in both adults and children. Recombinant nucleocapsid (N) proteins of hMPV from two major groups of hMPV in Beijing with a 6× His-tag at the C terminus were constructed in a baculovirus and expressed in transfected Sf21 insect cells. The antigenicity and specificity of the expressed recombinant proteins were examined by immunofluorescence assay and western blotting. Preliminary use of the expressed proteins for antibody detection in 187 serum specimens collected from different age groups in Beijing, China, indicated that the purified recombinant N-His proteins were of good antigenicity and specificity and could be a potential antigen for further seroprevalence study of hMPV, especially in the Chinese population. The positive rate for antibody detection suggested that hMPV from two clusters was co-circulating in Beijing and that most of the people in Beijing have been exposed to the virus by age 60. [ABSTRACT FROM AUTHOR]