Peptide–HLA complex presenting viral epitope

A peptide–HLA complex presenting a viral epitope consists of a short viral peptide (typically 8–10 amino acids, but can range from 4–13 residues) bound in the peptide-binding groove of a human leukocyte antigen (HLA) class I molecule[1][2][3][4][5][6]. This complex is displayed on the surface of nearly all nucleated cells, enabling cytotoxic T lymphocytes (CD8+ T cells) to detect and eliminate cells harboring viral infections or displaying abnormal peptides, such as tumor antigens. The peptide is anchored in the HLA groove by specific side chains at conserved 'anchor' positions, with the peptide termini deeply inserted into the HLA pockets B and F, determining specificity and stability of the complex[1][3][6]. The exposed, central region of the peptide forms a bulge or loop, representing the core structure recognized by T cell receptors[3][6]. This mechanism is essential for cellular immunity, monitoring for pathogen-derived or mutated self-peptides, and forms the molecular basis of most T cell-based immunotherapies and vaccine responses. Alterations in either the peptide or the HLA molecule (due to polymorphism or mutation) can critically impact immune surveillance, making these complexes central to infection control, cancer immunotherapy, and autoimmunity research[1][2][3][4][5][6].

Other names

Peptide–MHC class I complexpHLA viral epitope complexPeptide–HLA complexViral peptide–HLA

Allows cytotoxic T lymphocytes to recognize virally infected or abnormal cells by presenting viral peptide fragments on HLA class I molecules[1][2][3][4][5][6] - Target of engineered T cell receptors and adoptive immunotherapies designed to recognize specific peptide–HLA complexes exposed by infected or tumor cells - Some drugs inhibit downstream signaling post-pHLA recognition (immune checkpoint blockers), rather than directly interacting with the complex