Viral peptide–Major Histocompatibility Complex (pMHC)

Viral peptide–Major Histocompatibility Complex (pMHC) complexes are molecular assemblies consisting of a viral peptide fragment bound to a host Major Histocompatibility Complex (MHC) molecule, displayed on the surface of infected cells (asm.org, 2025). These complexes serve as the primary recognition signal for the adaptive immune system, specifically for the T-cell receptor (TCR) on CD8+ and CD4+ T-cells (researchgate.net, 2024). In the context of respiratory infections caused by influenza, parainfluenza virus (PIV), respiratory syncytial virus (RSV), and human metapneumovirus (hMPV), these pMHCs are critical targets for virus-specific T-cell (VST) therapies (clinicaltrials.gov, 2021). Therapeutic candidates like ALVR106 utilize allogeneic, off-the-shelf VSTs that are specifically expanded to recognize immunodominant peptides from these four viruses presented on MHC (firstwordpharma.com, 2020). Upon recognition of the pMHC, the therapeutic T-cells induce targeted lysis of the infected host cells and release antiviral cytokines to control viral replication (ashpublications.org, 2023). This approach is particularly valuable for immunocompromised patients, such as hematopoietic stem cell transplant recipients, who are at high risk for severe respiratory disease due to a lack of endogenous T-cell responses (delveinsight.com, 2026).

Other names

Peptide-MHC complexHLA-peptide complexViral antigen-MHC complexpMHC

T-cell mediated cytotoxicity