HLA-DMA and infection: Yet, only chimeras 6e to 6g supported viral entry, with infection rates of 40% to 70% relative to HLA-DR (Fig 2F, S2 Data), suggesting that loop 5, β-sheet 6, and loop 6 are either not essential for the interaction with H18 or contain critical residues that are also conserved in the corresponding HLA-DM sequences.