HLA-DMA and infection: Irrespective of cell surface expression levels, only chimera 7, comprising the α1, α2, and β1 domains of HLA-DR in assembly with the β2 of HLA-DM, allowed infection with VSV-H18 (Figs 1F and S3A, S1 Data), suggesting that the β2 domain of HLA-DR is dispensable for virus entry.