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

Abstract

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 (CVB5) and develop the model allowing for predicting the overall inactivation of heterogeneous CVB5. 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. CVB5 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 CVB5 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.

Predictive Environmental Microbiology for Safe Use of Sanitation Products in Agriculture: Challenges and Perspectives

“…The Chick−Watson model, one of the conventional inactivation kinetics models, was reformulated by assuming a probability density function of inactivation rate constants to describe the heterogeneity among variants of coxsackievirus B5. 56 Bayesian statistics have been used to embody the uncertainty of viral susceptibility and the properties of the matrices into a model. For example, Bayesian inference allowed for the reduction of uncertainty in the inactivation rate constant among and within enterovirus serotypes.…”

“…Tolerances and the relevant genetic traits (e.g., genetic diversity and nonsynonymous mutations) of isolates from environmental samples, including wastewater, fecal sludge, feces, and urine, need to be evaluated to embed the expected diversity of viral susceptibility into an inactivation kinetic model. The Chick–Watson model, one of the conventional inactivation kinetics models, was reformulated by assuming a probability density function of inactivation rate constants to describe the heterogeneity among variants of coxsackievirus B5 . Bayesian statistics have been used to embody the uncertainty of viral susceptibility and the properties of the matrices into a model.…”

Experimental Adaptation of Murine Norovirus to Calcium Hydroxide

“…Meanwhile, previous studies have reported the heterogeneous susceptibilities of reference viruses and indicators for waterborne enteric viruses within and among genetically relative strains. For example, disinfection studies of the Enterovirus genus have demonstrated that the tolerance to free chlorine, ClO 2 , UV 254 , and ozone varied among serotypes and among strains in the serotype coxsackievirus B5 ( Meister et al, 2018 ; Torii et al, 2021 ). These studies also established that environmental strains are less sensitive to disinfection compared to laboratory strains ( Meister et al, 2018 ; Torii et al, 2021 ).…”

“…For example, disinfection studies of the Enterovirus genus have demonstrated that the tolerance to free chlorine, ClO 2 , UV 254 , and ozone varied among serotypes and among strains in the serotype coxsackievirus B5 ( Meister et al, 2018 ; Torii et al, 2021 ). These studies also established that environmental strains are less sensitive to disinfection compared to laboratory strains ( Meister et al, 2018 ; Torii et al, 2021 ). Similarly, the tolerance to free chlorine varied among environmental strains of F-RNA phage genotype I (GI) and laboratory strains of GI phage ( Torii and Katayama, 2020 ).…”

Observed Kinetics of Enterovirus Inactivation by Free Chlorine Is Host Cell-Dependent

“…To evaluate the virucidal efficacy of various disinfectants, methods relying on the infection of a host cell are utilized (e.g., plaque assay and endpoint dilution assay). Buffalo green monkey kidney (BGMK) cells 11 are most commonly used for enterovirus titration to assess the efficacy of disinfection in water treatment 4,7,8,12–17 . This is assumingly because BGMK cells are the most efficient for enterovirus isolation 18 and are employed to perform EPA method 1615 19,20 which quantifies “total culturable virus” in water samples.…”