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

Abstract

Virucidal efficacies of disinfectants are typically assessed by infectivity assay utilizing a single type of host cell. Enteroviruses infect multiple host cells via various entry routes, and each entry route may be impaired differently by a given disinfectant. Yet, it is unknown how the choice of host cells affects the observed inactivation kinetics. Here, we evaluated the inactivation kinetics of echovirus 11 (E11) by free chlorine, ultraviolet (UV) irradiation, and heat, using three different host cells (BGMK, RD, and A549). Inactivation rates were independent of the host cell for treatment of E11 by UV or heat. Conversely, E11 inactivation by free chlorine occurred 2-fold faster when enumerated on BGMK cells compared with RD and A549 cells. Host cell-dependent inactivation kinetics by free chlorine were also observed for echovirus 7, 9, and 13, and coxsackievirus A9. E11 inactivation by free chlorine was partly caused by a loss in host cell attachment, which was most pronounced for BGMK cells. BGMK cells lack the attachment receptor CD55 and a key subunit of the uncoating receptor β2M, which may contribute to the differential inactivation kinetics for this cell type. Consequently, inactivation kinetics of enteroviruses should be assessed using host cells with different receptor profiles.

Persistence and Free Chlorine Disinfection of Human Coronaviruses and Their Surrogates in Water

“…49 Moreover, given that the choice of host cell line is indispensable to virus culture and titration, the observed kinetics of enterovirus inactivation by free chlorine have been noted to be host cell-dependent. 50 Discrepancies in inactivation kinetics of rotavirus during free chlorine disinfection were also observed in experiments using mice model versus cell culture model. 41 These considerations underscore the importance of meticulous experimental design in future virus research to ensure accurate and meaningful results.…”

Influence of Amino Acid Substitutions in Capsid Proteins of Coxsackievirus B5 on Free Chlorine and Thermal Inactivation

“…The passaged viral stock was recovered as described above. Then, 30 mL of the passaged virus stock was purified by sucrose-cushion ultracentrifugation followed by 0.22 μm membrane filtration as described previously . The purified viral stock was stored at 4 °C before use.…”

“…7,15,17 Free chlorine has been found to oxidize the viral capsid, 18,19 which protects the viral genome from chemical and enzymatic damage, 20,21 and has been reported to inhibit the viral attachment function, thereby partially contributing to enter-ovirus inactivation. 13,17,22,23 Sulfur-containing amino acids (cysteine (Cys) and methionine (Met)) react with free chlorine much faster than other amino acid residues. 24,25 Thus, differing abundances and solvent-accessibilities of Cys and Met in capsid proteins have been suggested as a rationale for the varying virus sensitivities to commonly used oxidants.…”

“…Free chlorine has been found to oxidize the viral capsid, , which protects the viral genome from chemical and enzymatic damage, , and has been reported to inhibit the viral attachment function, thereby partially contributing to enterovirus inactivation. ,,, Sulfur-containing amino acids (cysteine (Cys) and methionine (Met)) react with free chlorine much faster than other amino acid residues. , Thus, differing abundances and solvent-accessibilities of Cys and Met in capsid proteins have been suggested as a rationale for the varying virus sensitivities to commonly used oxidants. ,,,− This theory is consistent with the findings on the free chlorine susceptibility of 13 environmental isolates of CVB5, where isolates belonging to genogroup B, which contain fewer Met in the capsid proteins, also exhibited a 1.9-fold lower sensitivity to free chlorine compared to isolates falling within genogroup A …”

Influence of amino acid substitutions in capsid proteins of coxsackievirus B5 on free chlorine and thermal inactivation

“…Free chlorine has been found to oxidize the viral capsid 18,19 , which protects the viral genome from chemical and enzymatic damage 20,21 , and has been reported to inhibit the viral attachment function, thereby partially contributing to enterovirus inactivation 13,17,22,23 . Cysteine (Cys) and methionine (Met) react with free chlorine much faster than other amino acid residues 24,25 .…”