Virucidal efficacy of food additive grade calcium hydroxide against surrogate of human norovirus

Abstract An alkaline agent, namely, food additive grade calcium hydroxide (FdCa(OH) 2 ) in the solution, powder and suspension forms was evaluated as a virucidal agent, using a murine norovirus (MNV) as the surrogate for human norovirus. The main constituent of FdCa(OH) 2 is Ca(OH) 2 , which has pH 13 in 0.17% solution. The results showed that 0.17% FdCa(OH) 2 solution could inactivate MNV within 30 s even in the presence of organic materials (5% fetal bovine serum (FBS)). In a contaminated surface experiment, MNV with 5% FBS was inoculated on rayon sheets, and the result showed FdCa(OH) 2 solution could markedly reduce virus titer within 1 min. When mouse feces were spiked with MNV and FdCa(OH) 2 powder as 10% and 20% w/w was added to the feces, these concentrations could inactivate the virus within 30 min and 15 min, respectively. Whereas, FdCa(OH) 2 suspension at 2.5% and 5% could inactivate the virus within 30 min and at 1% within 45 min. These and additional results obtained here indicate that FdCa(OH) 2 is an effective virucidal agent against MNV, and can serve as a useful alternative disinfectant for inactivation and prevention of human norovirus in house and hospital.