Cytomegalovirus immediate-early protein 1-derived peptide–Major Histocompatibility Complex (CMV IE1 pMHC)

Cytomegalovirus immediate-early protein 1 (IE1)-derived peptide–Major Histocompatibility Complex (MHC) complexes are molecular assemblies presented on the surface of cells infected with Human Cytomegalovirus (HCMV). IE1 is a critical regulatory protein (encoded by the UL123 gene) that is expressed within minutes of viral entry or reactivation, playing a vital role in initiating the lytic cycle and evading host intrinsic immunity (UniProt P13202). These complexes, which typically involve IE1 peptides bound to MHC Class I molecules, serve as primary recognition signals for the host's CD8+ cytotoxic T lymphocytes (PMID: 15919923). Because IE1 is expressed so early in the viral life cycle, these pMHC complexes are highly attractive targets for immunotherapies aimed at preventing CMV disease in immunocompromised individuals, such as hematopoietic stem cell transplant recipients. Therapeutic strategies include the infusion of ex vivo expanded CMV-specific T cells (VSTs) or the use of TCR-engineered T cells that specifically bind to immunodominant IE1 epitopes like VLEETSVML (PMID: 12134020). Monitoring the presence and frequency of T cells specific to these complexes is a key biomarker for assessing a patient's functional immunity against CMV (PMID: 25653437).

Other names

HCMV IE1 peptide-HLA complexIE1-MHC complexCMV IE1-derived epitope-MHC complexUL123-derived peptide-MHCCMV IE1 pMHC

Recognition of the peptide-MHC complex by specific T-cell receptors (TCRs) on CD8+ T cells triggers the release of perforin and granzymes, leading to the apoptosis of the CMV-infected cell, while also stimulating the production of antiviral cytokines like IFN-gamma.