HIV-1 p17 Gag (77-85), also called SL9, is a short part of the Human Immunodeficiency Virus 1 especially a short peptide of matrix composed of the viral protein p17 ensuring the integrity of the virion particle. HIV-1 p17 Gag (77-85) HLA-A*02:01 -restricted was one of the first cytotoxic T lymphocytes epitope identified for HIV-1.