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

The sensitivity of enteroviruses to disinfectants varies among genetically similar variants and coincides with amino acid changes in capsid proteins, though the effect of individual substitutions remains unknown. Here, we employed reverse genetics to investigate how amino acid substitutions in coxsackievirus B5 (CVB5) capsid proteins affect its sensitivity to free chlorine and heat treatment. Of ten amino acid changes hypothesized to coincide with free chlorine resistance, none significantly reduced the chlorine-sensitivity, indicating a minor role of the capsid composition in chlorine sensitivity of CVB5. Conversely, we observed reduced heat sensitivity in mutants with substitutions at the C-terminal region of the viral protein 1. Cryo-electron microscopy revealed that these changes affect the assembly of intermediate viral states (particle A and E), suggesting that the mechanism for reduced heat sensitivity could be related to improved molecular packing of CVB5, resulting in greater stability and/or altered dynamics of virus uncoating during infection.