The expression of the MHC Class I allele Mamu-A*01 has previously been associated with a better immunologic control of the parental SIVmac239 virus, and antiviral CD8+ CTL responses directed against Mamu-A*01-restricted epitopes (including in Gag and Tat) were found to be dominant during SIVmac239 infection [40,41]. This evidence concerns the gene CD8A and infection.