HLA-DRB1 and infection: For HLA class II genes, we found an association of K at residue 101 of HLA-DRB1 when considering the full-length molecule (or residue 71 in the mature protein) with symptomatic infection susceptibility, mostly related to increased frequencies of DRB1*03:01 and DRB1*04:01 among symptomatic patients (Figure 3).