Quantitative study of persistence of human norovirus genome in water using TaqMan real-time RT-PCR

AIMS: To evaluate the persistence of human norovirus (NoV) in different types of water at various temperatures using conventional and TaqMan real-time reverse transcription-PCR (RT-PCR). METHODS AND RESULTS: Water from different sources was spiked with NoV and incubated at different temperatures over a 3-month period. NoV viral RNA was amplified by one-step TaqMan real-time RT-PCR and by conventional two-step RT-PCR. NoV persisted in mineral and tap water for over 2 months at all tested temperatures but disappeared after 100 days. At 4 and -20 degrees C, viral degradation was slower than that at 25 degrees C. In river water and effluent from primary sewage treatment, a slight reduction in viral load was observed after 1 month at 4 degrees C. This is the first demonstration of medium-to-long-term survival of human NoVs in different types of water using TaqMan real-time detection. CONCLUSIONS: NoV genome may persist for long periods of time in different types of water. Quantitative TaqMan real-time RT-PCR is a sensitive system that allows accurate evaluation of the persistence of human NoVs in different water samples. SIGNIFICANCE AND IMPACT OF THE STUDY: Our study is one of the few to demonstrate the ability of NoV to survive for a long time in water.