Implementation of real-time RT-PCR for detection of human metapneumovirus and its comparison with enzyme immunoassay

Abstract

Human metapneumovirus (hMPV) is responsible for outbreaks of bronchiolitis in winter and early spring in young children. Due to the relatively recent discovery of hMPV, the diagnostic opportunities are limited, while differential diagnosis with respiratory syncytial virus (RSV) remains important. We validated the RT-PCR by comparing various methods of RNA extraction, one-step RT-PCR kits and primer-probe combinations. The optimized RT-PCR was evaluated using 47 nasopharyngeal aspirates (NPAs) collected from children younger than 5 years, with clinically suspected RSV infection. The evaluated RT-PCRs were also compared to a commercially available hMPV enzyme immunoassay (EIA). We found 8.5% hMPV positivity with both RT-PCRs, in agreement with published literature. hMPV EIA showed positive and indeterminate results in 17% and 8.5%, respectively, of the tested NPAs. Positive RT-PCR samples were positive or indeterminate by hMPV EIA. Samples that were positive for RSV and influenza A virus interfered with the hMPV EIA. In conclusion, although RT-PCR is already a valuable tool for diagnosing hMPV infections, further optimization of the RT-PCR method is recommended. The hMPV EIA kit shows poor specificity and therefore needs further improvement.