Detection of GI and GII Noroviruses in Ground Water Using Ultrafiltration and TaqMan Real-time RT-PCR

Noroviruses (NoVs) are a leading cause of epidemic and sporadic acute gastrointestinal illness globally. These viruses can potentially contaminate rural private wells and non-community drinking water systems, and cause waterborne disease outbreaks related to consumption of contaminated ground water. Detection of NoVs in water samples can be challenging because they are genetically and antigenically diverse, and noncultivable. In the present study, the detection limits of a novel broadly reactive GI assay and an existing GII NoV real-time TaqMan reverse transcriptase-polymerase chain reaction (RT-qPCR) assay in ground water concentrates was determined. Ground water samples (50 l) from two sources (Lawrenceville, GA and Gainesville, FL, USA) were seeded with electron microscopy-enumerated and RT-qPCR quantified NoV and concentrated using hollow-fiber ultrafiltration (UF) followed by either polyethylene glycol (PEG) precipitation or microconcentrators. Detection limits for GI NoV ranged from 1 x 10(4) (GA source) to 2 x 10(5) (FL source) virus particles in 50 l water samples (corresponding to 200-3,000 particles/l) and 5 x 10(4) (GA source) to 5 x 10(5) (FL source) virus particles (corresponding to 1,000-10,000 particles/l) for GII NoV. The reported UF method, sample processing procedures, and RT-qPCR assays should be effective tools for sensitive detection of NoVs in large-volume water samples.