Viral antigen presented on MHC class I molecule

A viral antigen presented on an MHC class I molecule refers to a short peptide fragment derived from viral proteins that is bound in the peptide-binding groove of a host cell’s major histocompatibility complex class I (MHC-I) molecule and displayed on the cell surface. This complex serves as a molecular signature alerting cytotoxic CD8+ T lymphocytes to the presence of intracellular viral infection. The viral peptide, usually 8–11 amino acids long, is generated by proteasomal degradation of viral proteins in the cytoplasm, transported into the endoplasmic reticulum by TAP transporters, and loaded onto newly assembled MHC-I molecules. Once at the cell surface, the peptide–MHC-I complex is recognized by CD8+ T cells, triggering targeted cytolysis of infected cells. Many viruses have evolved mechanisms to evade immune detection by disrupting various steps of this antigen presentation pathway, including inhibition of proteasomal processing, TAP transport, and MHC-I surface expression[1][4][5][7]. The efficiency and specificity of viral antigen–MHC class I presentation are central both to the host’s antiviral defense and to the design of T cell–based vaccines and immunotherapies.

Other names

Viral antigen–MHC class I complexViral peptide–HLA class I complexViral epitope–MHC I complex

- Induce CD8+ T cell–mediated cytotoxicity against virally infected cells - Vaccine-induced enhancement of cytotoxic T cell response