Human leukocyte antigen class I-HIV peptide complex (HLA-I-HIV peptide complex)

Peptide-loaded Human Leukocyte Antigen (HLA) class I molecules on HIV-infected cells are specialized protein complexes that display fragments of viral proteins on the cell surface for immune surveillance [PMID: 31406037]. These complexes are composed of an HLA heavy chain, beta-2 microglobulin, and a short viral peptide (epitope) typically 8-11 amino acids in length, derived from HIV-1 proteins such as Gag, Pol, or Env [PMID: 28253128]. Their primary biological role is to serve as ligands for the T-cell receptors (TCRs) of CD8+ cytotoxic T lymphocytes, which recognize the foreign peptide and initiate the destruction of the infected cell [PMID: 25762537]. In chronic HIV infection, the virus often evades this mechanism by using the Nef protein to downregulate HLA-I expression, thereby reducing the density of these targets on the cell surface [PMID: 8598909]. Modern therapeutic approaches, such as Immune mobilizing monoclonal TCRs Against Cancer/Infection (ImmTACs), are engineered to bind these complexes with high affinity to redirect T-cell killing toward the HIV reservoir [PMID: 31406037]. However, the high mutational rate of HIV can lead to escape mutations in the peptide sequence, rendering the target invisible to specific TCRs or drugs [PMID: 11752511].

Other names

peptide-HLA complexpHLApMHC class IHIV-specific peptide-MHC complexHIV epitope-HLA-I complexMHC-peptide complex

Drugs targeting this complex, such as bispecific T-cell receptor (TCR) molecules, bind with high affinity to the specific HIV peptide presented within the HLA groove and simultaneously engage the CD3 receptor on T cells to induce directed lysis of the HIV-infected cell.