A simple method for isolation of enteric viruses (noroviruses and enteroviruses) in water

A simple and improved protocol for the isolation and detection of noroviruses ('Norwalk-like viruses', NLVs) and enteroviruses in ground- and drinking water is described. An improved procedure was developed for concentration of enteric viruses from water, whereby viruses are directly lysed after filtration on a negatively charged membrane. As the method is free from possible recovery losses during usual rinsing, elution, flocculation or concentration steps prior to RNA extraction, a high sensitivity and reliability is achieved. Detection was carried out by using a modified reverse-transcription polymerase chain reaction described previously and agarose gel electrophoresis. The overall detection sensitivity of our method by spiking 1 l of water was 0.1 PFU for polioviruses (Sabine 1). For Norwalk-like viruses ggII (Lordsdale), the detection limit is clearly lower compared to older protocols with elution and concentration steps (concentration of viral particles in positive stool samples were not known). Another simple protocol was used to isolate NLVs from contaminated stool samples.