Strain-specific interaction of a GII.10 Norovirus with HBGAs

•Vietnam 026 of GII.10 genotype binds saliva samples of all ABO types.•Vietnam 026 binds oligosaccharides representing H1, H3, Ley, and Lea antigens.•Single mutations at the core of the HBGA-binding site destroy the binding function.•Mutations around HBGA-binding site may change the binding specificity of the mutants.

Noroviruses (NoVs), an important cause of gastroenteritis in humans, recognize human histo-blood group antigens (HBGAs) as receptors. The crystal structures of the protruding (P) domain of a GII.10 NoV (Vietnam 026) in complex with various HBGA oligosaccharides were elucidated. However, the HBGA binding profile of this virus remains unknown. In this study, we determined the saliva and oligosaccharide binding profiles of this virus and the roles of amino acids that are involved in HBGA binding. Our data showed that Vietnam 026 bound to all ABO secretor and non-secretor saliva with clear signals detected by monoclonal antibodies against H3, H1, Ley, Lea and sialyl Lea. Mutagenesis study confirmed the binding site determined by the crystallography study, in which single mutations wiped out the binding function. We also identified amino acids surrounding the central binding pocket that may participate in the binding by affecting the HBGA binding specificity of the GII.10 NoV.