For example, the CD8+ T cells induced by a rhesus cytomegalovirus (CMV) strain 68-1-vectored SIV vaccine that enable ~55% of vaccinated rhesus macaques to clear infection following challenge with SIVmac239 (11, 12) are restricted by Mamu-E, the Rhesus macaque orthologue of HLA-E, and MHC class II rather than MHC class Ia (13). Here, HLA-E is linked to infection.