CD4 and infection: Indeed, in the rhesus macaque Simian Immunodeficiency Virus (SIV) infection model, immunization with a modified rhesus cytomegalovirus vector expressing SIV genes induces potent CD8+ cytotoxic T cells that recognize SIV infected CD4+ T cells in the context of MHC-E and eliminates infected cells completely in 50% of macaques [5].