Generation of recombinant nucleocapsid protein of human metapneumovirus in baculovirus for detecting antibodies in the Beijing population.

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 6x 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.