Human immunodeficiency virus type 1 Gag peptide presented by HLA-A*02:01 (HIV Gag-HLA-A*02:01 complex (no universally standardized abbreviation; sometimes referred to as HIV Gag/HLA-A2, HIV Gag/HLA-A*02:01, or SL9/HLA-A*02:01, with SL9 referring to the SLYNTVATL epitope))

The HIV Gag peptide presented by HLA-A*02:01 refers to a specific protein-peptide complex where fragments (epitopes) of the HIV-1 Gag polyprotein—most notably the SLYNTVATL sequence (SL9)—are loaded into the binding groove of the human leukocyte antigen class I molecule HLA-A*02:01. This complex is displayed on the surface of infected cells, allowing cytotoxic CD8+ T cells to recognize and eliminate HIV-infected targets. It is a central focus for vaccine research and immunotherapy approaches against HIV-1, due to its ability to elicit focused, antiviral T-cell responses. Its immunogenicity, however, varies, as viral escape mutations and poor acute reactivity complicate clinical application. The HLA-A*02:01 molecule can present peptides of canonical length (8-11 amino acids), but also longer 'bulged' peptides, and its peptide presentation dynamics influence vaccine and T cell therapy strategies. The ability of these peptide-HLA complexes to direct CD8+ T-cell responses remains a key mechanism for immune control of viral infections and a therapeutic target in the search for an HIV cure and functional vaccines.

Other names

HIV-1 Gag epitope/HLA-A*02:01 complexHLA-A*02:01/S9 (for the SLYNTVATL epitope, also called SL9)HLA-A2-restricted HIV Gag peptideHIV Gag SLYNTVATL/HLA-A*02:01pHLA-A*02:01 (peptide-HLA complex)

Stimulation of CD8+ cytotoxic T lymphocytes to recognize and kill HIV-infected cells; Induction of antiviral immune response via TCR recognition of peptide-MHC complex; Vaccine-induced immune response: peptides formulated for delivery and presentation by HLA-A*02:01 to elicit anti-HIV T-cells