HLA-B and HIV-1 infection: In HIV-1 infection, HLA-B alleles containing a Bw4 motif are associated with protection from AIDS (69) and all HLA-Bw4 alleles (with the exception of HLA-B*38:01) encode for the −21T polymorphism (42), whereas HLA-Bw6 alleles encode for either −21T or −21M.