Cytomegalovirus immediate-early 1 peptide–MHC complex (CMV IE1-MHC)

The Cytomegalovirus (CMV) immediate-early 1 (IE1) peptide–MHC complex is a molecular assembly presented on the surface of cells infected with human cytomegalovirus. The IE1 protein, encoded by the UL123 gene, is one of the first viral proteins synthesized during the lytic cycle and is essential for initiating viral gene expression and inhibiting host antiviral responses (Taylor and Bresnahan, 2006, PubMed: 16415024). Fragments of the IE1 protein are processed by the proteasome and loaded onto Major Histocompatibility Complex (MHC) Class I molecules for presentation to the immune system. These complexes are primary targets for CD8+ cytotoxic T lymphocytes, which recognize the specific peptide-MHC combination via their T-cell receptors (TCRs) to initiate the destruction of the infected cell (Ameres et al., 2014, PubMed: 24741099). In clinical settings, these complexes are targeted by adoptive T-cell therapies, such as posoleucel, to treat or prevent CMV disease in immunocompromised patients, particularly those undergoing hematopoietic stem cell or solid organ transplantation (Blyth et al., 2013, PubMed: 23407338). Because IE1 is expressed so early, targeting these complexes allows the immune system to intervene before the virus can complete its replication cycle and spread. However, the efficacy of such therapies is strictly limited by the patient's HLA type, as the TCR must match the specific MHC molecule presenting the IE1 peptide.

Other names

CMV IE1-HLA complexUL123 peptide-MHC complexIE1 pMHCCytomegalovirus IE1 antigen

T-cell receptor (TCR) mediated recognition and subsequent lysis of infected cells.