Influenza A virus nucleoprotein peptide-MHC complex (IAV NP pMHC)

The Influenza A virus nucleoprotein (NP) peptide-MHC complex is a molecular assembly formed when the highly conserved internal NP protein is degraded into short peptides and presented on the surface of infected cells by Major Histocompatibility Complex (MHC) molecules. These complexes are the primary targets for CD8+ cytotoxic T lymphocytes (CTLs), which recognize the specific peptide-MHC (pMHC) combination via their T cell receptors (TCRs). Because the nucleoprotein is significantly more conserved across different influenza strains than surface proteins like hemagglutinin, these pMHC complexes are critical for heterosubtypic (cross-protective) immunity. In therapeutic development, they are targeted by universal influenza vaccines designed to elicit broad T cell responses and by engineered TCR-T cell therapies that provide direct viral clearance. The stability and prevalence of these complexes on the cell surface are key determinants of the efficacy of cellular immune responses against seasonal and pandemic influenza A viruses.

Other names

Influenza A nucleoprotein-derived peptide–MHC complexIAV NP-MHC complexNucleoprotein epitope-MHC complexNP-HLA complexpMHC complex (Influenza A NP)

The peptide-MHC complex serves as the primary ligand for the T cell receptor (TCR) on CD8+ or CD4+ T cells. Recognition of the specific viral peptide (e.g., NP380-388) presented by the MHC molecule triggers TCR signaling, leading to T cell activation, the secretion of pro-inflammatory cytokines like IFN-gamma, and the targeted destruction of the infected cell through the release of perforin and granzymes.