Rapid and sensitive detection of mumps virus RNA directly from clinical samples by real-time PCR

A rapid, sensitive, and specific assay to detect mumps virus RNA directly from clinical specimens using a real-time PCR assay was developed. The assay was capable of detecting five copies of standard plasmid containing cDNA from the mumps virus F gene. No cross-reactions were observed with other members of Paramyxoviridae, or with viruses or bacteria known to be meningitis pathogens. Seventy-three clinical samples consisting of throat swabs collected from patients with parotitis, and cerebrospinal fluid (CSF) collected from patients with aseptic meningitis, were examined with a real-time PCR assay developed by the authors, reverse-transcription nested-PCR (RT-n-PCR), and virus isolation using cell culture. Like the RT-n-PCR assay, the real-time PCR assay could detect mumps virus RNA in approximately 70% of both throat swabs and CSF samples, while, by tissue culture, mumps virus was isolated from only approximately 20% of CSF and 50% of throat swab samples. In addition, the real-time PCR assay could be developed easily into a quantitative assay for clinical specimens containing more than 1,800 copies of mumps virus RNA/ml by using serial dilutions of the standard plasmid. The results suggest that the real-time PCR assay is useful for identification of mumps virus infections, not only in typical cases, but also in suspected cases, which show only symptoms of meningitis or encephalitis.