Conventional fluorescent-antibody (FA) methods were compared to real-time PCR assays for detection of respiratory syncytial virus (RSV), influenza virus type A (FluA), parainfluenza virus types 1, 2, and 3 (PIV1, PIV2, and PIV3), human metapneumovirus (MPV), and adenovirus (AdV) in 1,138 specimens from children with respiratory illnesses collected over a 1-year period. At least one virus was detected in 436 (38.3%) specimens by FA and in 608 (53.4%) specimens by PCR (P < 0.001). Specimen quality was inadequate for FA in 52 (4.6%) specimens; 13 of these (25%) were positive by PCR. In contrast, 18 (1.6%) specimens could not be analyzed by PCR; 1 of these was positive by FA. The number of specimens positive only by PCR among specimens positive by PCR and/or FA was 18 (7.0%) of 257 for RSV, 18 (13.4%) of 134 for FluA, 25 (64.1%) of 39 for PIV1, 8 (88.9%) of 9 for PIV2, 17 (30.1%) of 55 for PIV3, and 101 (76.5%) of 132 for AdV. MPV was detected in 6.6% of all specimens and in 9.5% of the 702 specimens negative by FA. The mean number of virus copies per milliliter in specimens positive by both PCR and FA was significantly higher, at 6.7 ؋ 10 7 , than that in specimens positive only by PCR, at 4.1 ؋ 10 4 (P < 0.001). The PCR assays were significantly more sensitive than FA assays for detecting respiratory viruses, especially parainfluenza virus and adenovirus. Use of real-time PCR to identify viral respiratory pathogens in children will lead to improved diagnosis of respiratory illness.Accurate detection of respiratory viruses is important to guide antiviral therapy, prevent nosocomial spread, provide surveillance, and in some cases, decrease hospital costs and lengths of stay (1, 2, 11, 21). By using standard laboratory methods, such as staining with fluorescent antibodies (FA) and isolation by culture, viruses have been detected in 13 to 45% of children with symptoms of respiratory illness (3,8,12,22,28). Disadvantages of FA include requiring multiple reagents which may vary in sensitivity, potential variability in technical reading, and the need for an adequate number of cells to examine each specimen. Several studies have shown that PCR methods appear to be more sensitive than FA and culture for the diagnosis of acute respiratory virus infections (8,22,23,24,26,28). PCR is less affected by specimen quality and transport and provides an objective interpretation of results. Real-time PCR technology, which combines nucleic acid amplification with amplicon detection, provides results more quickly than conventional PCR, has in some cases shown improved sensitivity compared to conventional PCR, and provides a uniform platform for quantifying both single and multiple pathogens in a single sample (4,7,18).In this study, separate quantitative real-time reverse transcription (RT)-PCR assays were used to detect six RNA viruses, including respiratory syncytial virus (RSV), influenza virus type A (FluA), parainfluenza virus types 1, 2, and 3 (PIV1, PIV2, and PIV3), and human metapneumovirus (MPV). A quantitative real-time PCR a...

Although 4 subtypes of coronavirus were detected, the recently discovered coronavirus subtypes NL63 and HKU1 accounted for the majority of coronaviruses detected in our cohort of mostly hospitalized children with respiratory symptoms. New subtypes likely represent a substantial portion of previously unexplained respiratory illnesses.

These real-time RT-PCR assays provide a rapid, specific, and highly sensitive alternative for detecting, quantifying, and subtyping RSV in clinical specimens.

The rapid real-time RT-PCR assay described here is a sensitive test for clarifying the epidemiology of and diseases associated with h MPV.

Routine testing for these viruses in immunocompromised patients is not recommended.