Summary of the mutagenesis study of the amino acid residues in and around the predicted HBGA-binding interface of Norwalk virus.

1The P particle formation of the wild type (WT) and all mutants were confirmed by gel filtration. The italicized mutants in indicate the mutated residues of another P monomer. 2The number of “+” indicated the relative binding affinity of the wild type and mutant P particles at 3.33 ng/µl to HBGAs: “++++” indicates an OD450 >3.0; “+++” between 2.0 and 3.0; “++” between 1.0 and 2.0; “+” between 0.3 and 1.0; while “−” indicates an OD450 <0.3, suggesting a complete loss of binding. Type O and A saliva were from secretors containing H and A antigen, respectively. 3Predictions were made by two independent crystallographic studies (ref13 and 15).