Resistance of Echovirus 11 to ClO₂ Is Associated with Enhanced Host Receptor Use, Altered Entry Routes, and High Fitness

Waterborne viruses can exhibit resistance to common water disinfectants, yet the mechanisms that allow them to tolerate disinfection are poorly understood. Here, we generated echovirus 11 (E11) with resistance to chlorine dioxide (ClO₂) by experimental evolution, and we assessed the associated genotypic and phenotypic traits. ClO₂ resistance emerged after E11 populations were repeatedly reduced (either by ClO₂-exposure or by dilution) and then regrown in cell culture. The resistance was linked to an improved capacity of E11 to bind to its host cells, which was further attributed to two potential causes: first, the resistant E11 populations possessed mutations that caused amino acid substitutions from ClO₂-labile to ClO₂-stable residues in the viral proteins, which likely increased the chemical stability of the capsid toward ClO₂. Second, resistant E11 mutants exhibited the capacity to utilize alternative cell receptors for host binding. Interestingly, the emergence of ClO₂ resistance resulted in an enhanced replicative fitness compared to the less resistant starting population. Overall this study contributes to a better understanding of the mechanism underlying disinfection resistance in waterborne viruses, and processes that drive resistance development.