Conserved amino acids in α1 and β1 domains of HLA-DR modulate H18-mediated entry.

(A) Localization of surface-exposed amino acids in the α1 (gray) and β1 (black) domains of HLA-DR that are present in 75% of all MHC-II homologs and have a conservation score >8. These amino acids were substituted with their HLA-DM counterparts or alanine when conserved. (B) Surface expression of the indicated HLA-DR variants on transfected HEK293T cells. The bar graph depicts the median fluorescent intensity of the β-chain determined from cells that fall into the HLA-DR α-chain and HLA-DR β-chain double positive gate. Values were normalized to wild-type HLA-DR (dashed line). Underlying data: S7 Data. (C) VSV-H18 infection rate of cells expressing the indicated HLA-DR variants depicted in (B). Underlying data: S7 Data. (D) Localization of the highly conserved amino acids substituted with their HLA-DM counterparts or alanine shown in (A) in relation to the predicted H18 binding of model 1 (see also Fig 2H). M61 and D60 are part of the modeled H18 binding surface. For statistical analysis, one-way ANOVA followed by Dunnett test was performed for panels B and C. ns, not significant. HEK293T, human embryonic kidney 293T; HLA-DR, human leukocyte antigen DR; MHC-II, major histocompatibility complex class II. (TIFF)