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

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 beta 2M, 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.

Automated summary

The virucidal efficacies of disinfectants vary depending on the host cell used in the infectivity assay. Different host cells may have different entry routes for enteroviruses, and the choice of host cell can affect the observed inactivation kinetics of the disinfectant. The inactivation rates of echovirus 11 by UV or heat were independent of the host cell, but the inactivation by free chlorine was faster when enumerated on BGMK cells compared to RD and A549 cells. This host cell-dependent inactivation kinetics were also observed for other enteroviruses.