Chlorine sensitivity of feline calicivirus, a norovirus surrogate

Abstract

The sensitivity to free chlorine of feline calicivirus (FCV), a norovirus surrogate, was examined relative to chlorine demand. When a crude suspension of FCV was treated with a sodium hypochlorite solution containing 10 microg/ml free chlorine, the extent of the decrease of viral infectivity clearly depended on the volume of the reaction mixture. The apparent sensitivity of FCV to free chlorine increased with the reduction of host cell debris, indicating that chlorine demand must be minimized to know the true sensitivity of the virus. We therefore partially purified the viruses from the host cell components and found that the infectivity of FCV was reduced by more than log 4.6 by 5 min of treatment with 300 ng/ml free chlorine.

FIG. 1.

Infectivity of crude FCV after treatment with 10 μg/ml free chlorine in different volumes of reaction mixture. Filled circle, infectivity without treatment. Vertical bars represent 95% confidence limits. *, lower limit is

FIG. 2.

Infectivity of partially purified FCV suspensions containing different concentrations of protein after treatment with various concentrations of free chlorine. Circles, results with 10 ng/ml protein. Triangles, results with 120 ng/ml protein. Vertical bars represent 95% confidence limits.