The C-terminal T234 residue of VP3 is required for KREMEN1 receptor-dependent infectivity and pathogenesis of coxsackieviruses A10 and A8.

Coxsackievirus A10 (CVA10) is a major causative agent of hand, foot and mouth disease and utilizes KREMEN1 (KRM1) as its cellular receptor. While our previous work identifies VP2 residue K140 as a universal anchor for KRM1 binding among KRM1-utilizing enteroviruses, the functional significance of other receptor-interface residues remains poorly characterized. Here, through structure-guided mutagenesis, we demonstrate that VP3-T234, a completely conserved residue at the C-terminus of VP3, is essential for CVA10 infectivity. The T234A mutation does not affect virion assembly but abolishes both KRM1 binding and cellular attachment. Interestingly, this requirement shows remarkable virus specificity: the homologous residue is critical for CVA8, but is not required for other KRM1-utilizing enteroviruses including CVA2-CVA6 and CVA12. The T234A mutation significantly attenuates the pathogenesis of both CVA10 and CVA8 in neonatal mice. Moreover, the CVA8-T234A mutant provides complete protection as an attenuated vaccine against lethal CVA8 challenge. Our findings establish a model wherein KRM1 engagement relies on the conserved VP2-K140 anchor complemented by virus-specific secondary residues, with VP3-T234 representing a key determinant for CVA10 and CVA8. These insights advance our understanding of enterovirus-receptor interactions and provide new directions for vaccine development.