Control of Viral Contamination of Food and Environment

Cliver, Dean O.

Virus in casually disposed feces or in the untreated wastewater is subject to slow inactivation by physical, chemical, and biological effects. Virus may be shed in association with coproantibody, as well as with fecal solids (Cliver and Kostenbader 1979) . Virions may associate with soil particles; some viruses have more than one isoelectric point (Mandel 1971) . The rate of virus inactivation at or below 30°depends on the pH and the ionic composition of the aqueous environment (Salo and Cliver 1976) . The changes that result in loss of infectivity under these conditions have not been well documented. An early study suggested that the target of low-temperature inactivation was principally the RNA (Dimmock 1967 ), but it has been shown more recently that some virus inactivated at lowtemperature loses its ability to attach to host cell receptors, which implies a subtle denaturation of the coat protein (Nuanualsuwan and Cliver 2003) . It would be especially useful to know how noroviruses are inactivated under these conditions, in that present methods of norovirus detection typically do not distinguish infectious from inactivated virus (Hewitt and Greening 2006; Nuanualsuwan and Cliver 2002) .