Figure 4. Combination approach of conventional virus isolation and molecular techniques to detect human metapneumovirus (HMPV) infection. Nasopharyngeal aspirates were examined in this study. This approach can be applied to other respiratory specimens. Prolonged incubation of rhesus monkey kidney (LLC-MK2) cells to 28 days for culture of original specimens may improve sensitivity of detection. Detection based on cytopathic effect is not sensitive for first-round culture from original specimens. All cell cultures should be examined by HMPV–specific reverse transcription-polymerase chain reaction. RT-PCR, reverse transcription-polymerase chain reaction.