Inactivation of Caliciviruses

Abstract

The viruses most commonly associated with food-and waterborne outbreaks of gastroenteritis are the noroviruses. The lack of a culture method for noroviruses warrants the use of cultivable model viruses to gain more insight on their transmission routes and inactivation methods. We studied the inactivation of the reported enteric canine calicivirus no. 48 (CaCV) and the respiratory feline calicivirus F9 (FeCV) and correlated inactivation to reduction in PCR units of FeCV, CaCV, and a norovirus. Inactivation of suspended viruses was temperature and time dependent in the range from 0 to 100°C. UV-B radiation from 0 to 150 mJ/cm 2 caused dose-dependent inactivation, with a 3 D (D ‫؍‬ 1 log 10 ) reduction in infectivity at 34 mJ/cm 2 for both viruses. Inactivation by 70% ethanol was inefficient, with only 3 D reduction after 30 min. Sodium hypochlorite solutions were only effective at >300 ppm. FeCV showed a higher stability at pH <3 and pH >7 than CaCV. For all treatments, detection of viral RNA underestimated the reduction in viral infectivity. Norovirus was never more sensitive than the animal caliciviruses and profoundly more resistant to low and high pH. Overall, both animal viruses showed similar inactivation profiles when exposed to heat or UV-B radiation or when incubated in ethanol or hypochlorite. The low stability of CaCV at low pH suggests that this is not a typical enteric (calici-) virus. The incomplete inactivation by ethanol and the high hypochlorite concentration needed for sufficient virus inactivation point to a concern for decontamination of fomites and surfaces contaminated with noroviruses and virus-safe water.

Evaluation of Human Enteric Viruses in Surface Water and Drinking Water Resources in Southern Ghana

“…However, the detection of viral NA should not be considered detection of noninfectious particles, because, although infectivity cannot be determined, the potential for that microorganism to be infectious before NA extraction cannot be excluded. 47,48 In conjunction with molecular analysis of human enteric viruses, a simple method for the identification of sample inhibition during real-time PCR and RT-PCR assays was also applied. This method uses a commercially available HGV RNA internal standard.…”

Feline calicivirus

“…The virus can also persist in the environment for several days to several weeks on dried surfaces at room temperature, and longer in colder wetter conditions [12,23,24]. Indirect transmission can therefore occur, especially within the close confines of a cattery where secretions may contaminate cages, feeding and cleaning utensils or personnel.…”

Comparative Virucidal Efficacy of Seven Disinfectants Against Murine Norovirus and Feline Calicivirus, Surrogates of Human Norovirus

“…Disinfectants are biocide substances that destroy microorganisms or inhibit their activity on inanimate objects or surfaces (McDonnell and Russell 1999). Previous studies (Doultree et al 1999;Duizer et al 2004a;Radford et al 2007) concluded that ethanol and quaternary ammonium-based products were ineffective disinfectants of FCV and the inactivation of FCV required high concentrations of sodium hypochlorite. MNV is sensitive both to alcohols and to bleach and its resistance to basic and acidic pHs as well as it longterm resistance at room temperature is higher than that of FCV (Cannon et al 2006;Belliot et al 2008;Park and Sobsey 2011).…”