Virus-derived peptide–Major Histocompatibility Complex (pMHC)

Virus-derived peptide–Major Histocompatibility Complex (pMHC) complexes are molecular assemblies on the surface of infected host cells that present fragments of viral proteins to the immune system. These complexes are formed when viral proteins are degraded by the proteasome into short peptides, which are then loaded onto MHC Class I (or Class II) molecules in the endoplasmic reticulum and transported to the cell membrane. The primary biological function of pMHC complexes is to serve as ligands for T-cell receptors (TCRs) on CD8+ cytotoxic T cells, triggering an immune response to eliminate the infected cell. In many viral diseases, such as HIV, HBV, and CMV, viruses have evolved mechanisms to downregulate MHC expression to evade detection. Therapeutically, these complexes are targeted by adoptive T-cell therapies (e.g., Tabelecleucel), TCR-engineered T cells (TCR-T), and TCR-like antibodies or bispecific T-cell engagers (BiTEs) to selectively kill infected or virally-transformed cells.

Other names

Viral peptide–MHC complexViral pMHCPeptide-HLA complexMHC-peptide complexViral epitope-MHC complexVirus-derived peptide–MHC complexes on infected host cells

T-cell mediated cytotoxicity, T-cell redirection, and antibody-dependent cellular cytotoxicity (ADCC) through the recognition of viral peptides presented on MHC molecules.