Rapid and sensitive method using multiplex real-time PCR for diagnosis of infections by influenza a and influenza B viruses, respiratory syncytial virus, and parainfluenza viruses 1, 2, 3, and 4.

Laboratory diagnosis of viral respiratory infections is generally performed by virus isolation in cell culture and immunofluorescent assays. Reverse transcriptase PCR is now recognized as a sensitive and specific alternative for detection of respiratory RNA viruses. A rapid real-time multiplex PCR assay was developed for the detection of influenza A and influenza B viruses, human respiratory syncytial virus (RSV), parainfluenza virus 1 (PIV1), PIV2, PIV3, and PIV4 in a two-tube multiplex reaction which used molecular beacons to discriminate the pathogens. A total of 358 respiratory samples taken over a 1-year period were analyzed by the multiplex assay. The incidence of respiratory viruses detected in these samples was 67 of 358 (19%) and 87 of 358 (24%) by culture and real-time PCR, respectively. Culture detected 3 influenza A virus, 2 influenza B virus, 57 RSV, 2 PIV1, and 2 PIV3 infections. All of these culture-positive samples and an additional 5 influenza A virus, 6 RSV, 2 PIV1, 1 PIV2, 1 PIV3, and 3 PIV4 infections were detected by the multiplex real-time PCR. The application of real-time PCR to clinical samples increases the sensitivity for respiratory viral diagnosis. In addition, results can be obtained within 6 h, which increases clinical relevance. Therefore, use of this real-time PCR assay would improve patient management and infection control.