Impact of the Heterogeneity in Free Chlorine, UV254, and Ozone Susceptibilities Among Coxsackievirus B5 on the Prediction of the Overall Inactivation Efficiency

The disinfection susceptibilities of viruses vary even among variants, yet the inactivation efficiency of a certain virus genotype, species, or genus was determined based on the susceptibility of its laboratory strain. The objectives were to evaluate the variability in susceptibilities to free chlorine, UV254, and ozone among 13 variants of coxsackievirus B5 (CVBS) and develop the model allowing for predicting the overall inactivation of heterogeneous CVBS. Our results showed that the susceptibilities differed by up to 3.4-fold, 1.3-fold, and 1.8-fold in free chlorine, UV254, and ozone, respectively. CVBS in genogroup B exhibited significantly lower susceptibility to free chlorine and ozone than genogroup A, where the laboratory strain, Faulkner, belongs. The capsid protein in genogroup B contained a lower number of sulfur-containing amino acids, readily reactive to oxidants. We reformulated the Chick-Watson model by incorporating the probability distributions of inactivation rate constants to capture the heterogeneity. This expanded Chick-Watson model indicated that up to 4.2-fold larger free chlorine CT is required to achieve 6-log inactivation of CVBS than the prediction by the Faulkner strain. Therefore, it is recommended to incorporate the variation in disinfection susceptibilities for predicting the overall inactivation of a certain type of viruses.