Cytomegalovirus peptide-Major Histocompatibility Complex class I complex (CMV pMHC-I)

Cytomegalovirus (CMV) peptide-Major Histocompatibility Complex (MHC) class I complexes are molecular assemblies presented on the surface of cells infected with Human Cytomegalovirus (HCMV). These complexes consist of a viral-derived peptide, typically from highly immunogenic proteins like pp65 (UL83) or IE1 (UL123), non-covalently bound to an MHC class I molecule, known as HLA in humans (PubMed: 10508250). Their primary biological function is to signal the presence of intracellular viral infection to the immune system, specifically to CD8+ cytotoxic T lymphocytes (CTLs) (PubMed: 1633861). Recognition of these pMHC complexes by specific T-cell receptors (TCRs) triggers the activation of CTLs, leading to the targeted destruction of the infected host cell through the release of perforins and granzymes (PubMed: 28923938). In clinical settings, these complexes serve as critical therapeutic targets for adoptive T-cell therapies and TCR-engineered cells aimed at managing CMV reactivation in immunocompromised patients, such as hematopoietic stem cell or solid organ transplant recipients (PubMed: 31515463). Therapeutic strategies often involve the infusion of donor-derived or off-the-shelf virus-specific T cells (VSTs), such as Posoleucel, that precisely recognize these complexes to restore cellular immunity (ClinicalTrials.gov: NCT04350177).

Other names

CMV pMHCHCMV peptide-HLA class I complexCMV antigen-MHC complexpp65-HLA complexIE1-HLA complexCMV-specific pMHC

The mechanism of action involves the specific binding of T-cell receptors (TCRs) on the surface of therapeutic T cells to the CMV peptide-MHC class I complex on the target cell. This interaction forms an immunological synapse, leading to the release of cytotoxic granules such as perforin and granzymes, as well as pro-inflammatory cytokines like IFN-gamma and TNF-alpha, which collectively result in the apoptosis of the CMV-infected host cell (PubMed: 1633861, PubMed: 28923938).