Rapid and simultaneous detection of three major diarrhea-causing viruses by multiplex real-time nucleic acid sequence-based amplification.

Rotaviruses, noroviruses and astroviruses are the major viral pathogens leading to diarrhea worldwide. Epidemiological investigations of outbreaks associated with these viruses have been impeded by the lack of methods for quick diagnosis and detection. In the current study, a multiplex real-time nucleic acid sequence-based amplification (RT-NASBA) system was developed for the simultaneous detection of rotavirus A/norovirus genogroup II/astrovirus. The specificity and sensitivity of the assay were compared with multiplex RT-PCR. The results showed that the multiplex RT-NASBA assay was established successfully, and robust signals could be observed in 10 minutes with high specificity. The limit of detection of the multiplex RT-NASBA assay was 7, 100, and 200 copies per reaction for rotavirus A, norovirus genogroup II, and astrovirus, respectively. The assay was thus 10 to 100 times more sensitive than multiplex RT-PCR. Clinical evaluation indicated that the assay was 100% concordant with multiplex RT-PCR and was reliable for the detection of both single infections and multiple infections in stool samples. To the best of our knowledge, this is the first multiplex RT-NASBA assay established for the detection of three major diarrhea-causing viruses. This assay provides a valuable platform for the rapid, specific, sensitive and simultaneous diagnosis of these pathogens, especially in resource-limited countries where expensive thermocycling equipment is not available.