Detection of human metapneumovirus by direct antigen test and shell vial cultures using immunofluorescent antibody staining

Human metapneumovirus (hMPV) has emerged as an important etiologic agent of upper and lower respiratory tract infections, especially in young children. Although rapid and simple diagnostic methods for hMPV are needed in clinical laboratories, routine diagnostic tests are not readily available. The purpose of this study was to evaluate a commercial anti-hMPV monoclonal antibody for a direct antigen test and a shell vial culture of hMPV. In the pilot study, 15 nasopharyngeal aspirates from 15 children with acute respiratory tract infections positive for hMPV by reverse transcriptase polymerase chain reaction (RT-PCR) were tested. Both direct antigen test and shell vial culture detected hMPV in 14 of 15 (93.3%) nasopharyngeal aspirates at initial diagnosis. In the larger group prospective study, nasopharyngeal aspirates from 92 children with acute respiratory tract infections were tested for hMPV with RT-PCR, direct antigen test, and shell vial culture. Both direct antigen test and shell vial culture showed positivity for 4 out of 5 specimens positive by RT-PCR. These findings indicate that direct antigen test and shell vial culture would be reliable and timely methods for the diagnosis of hMPV infection in clinical laboratories.