Evaluation of murine norovirus, feline calicivirus, poliovirus, and MS2 as surrogates for human norovirus in a model of viral persistence in surface water and groundwater

Human noroviruses (NoVs) are a significant cause of nonbacterial gastroenteritis worldwide, with contam-inated drinking water a potential transmission route. The absence of a cell culture infectivity model for NoV necessitates the use of molecular methods and/or viral surrogate models amenable to cell culture to predict NoV inactivation. The NoV surrogates murine NoV (MNV), feline calicivirus (FCV), poliovirus (PV), and male-specific coliphage MS2, in conjunction with Norwalk virus (NV), were spiked into surface water samples (n 9) and groundwater samples (n 6). Viral persistence was monitored at 25°C and 4°C by periodically analyzing virus infectivity (for all surrogate viruses) and nucleic acid (NA) for all tested viruses. FCV infectivity reduction rates were significantly higher than those of the other surrogate viruses. Infectivity reduction rates were significantly higher than NA reduction rates at 25°C (0.18 and 0.09 log10/day for FCV, 0.13 and 0.10 log10/day for PV, 0.12 and 0.06 log10/day for MS2, and 0.09 and 0.05 log10/day for MNV) but not significant at 4°C. According to a multiple linear regression model, the NV NA reduction rates (0.04 0.01 log10/day) were not significantly different from the NA reduction rates of MS2 (0.05 0.03 log10/day) and MNV (0.04 0.03 log10/day) and were significantly different from those of FCV (0.08 0.03 log10/day) and PV (0.09 0.03 log10/day) at 25°C. In conclusion, MNV shows great promise as a human NoV surrogate due to its genetic similarity and environmental stability. FCV was much less stable and thus questionable as an adequat