Cytomegalovirus immediate-early 1 peptide–MHC class I complex (CMV IE-1–MHC I complex)

The Cytomegalovirus immediate-early 1 (IE-1) peptide–MHC class I complex is a primary immunological target presented on the surface of cells infected with human cytomegalovirus (HCMV) (Wills et al., 1996). IE-1 is a regulatory protein expressed immediately upon viral entry, making it an early marker for immune recognition before the virus can complete its replication cycle (Almanzar et al., 2005). The complex is formed when intracellular IE-1 proteins are degraded by the proteasome into short peptides, which are then loaded onto MHC class I molecules in the endoplasmic reticulum and transported to the plasma membrane (Khan et al., 2002). CD8+ cytotoxic T lymphocytes (CTLs) recognize these specific peptide-MHC combinations via their T-cell receptors (TCRs), triggering the release of perforin and granzymes to kill the infected cell. In the context of disease, CMV can cause severe complications in immunocompromised individuals, such as transplant recipients and HIV patients, where the natural T-cell response is insufficient (Schub et al., 2009). Therapeutic strategies targeting this complex include the infusion of donor-derived CMV-specific T cells and the development of TCR-engineered T cells (TCR-T) or TCR-like monoclonal antibodies (Atara Biotherapeutics; Eureka Therapeutics). These therapies aim to bypass viral immune evasion tactics, such as the downregulation of MHC molecules, by providing high-affinity recognition of the IE-1 epitopes. Monitoring the presence of these complexes and the corresponding T-cell frequency is essential for managing CMV reactivation and assessing the efficacy of immunotherapies.

Other names

CMV IE1-HLA complexIE1 peptide-HLA-A*02:01 complexHuman cytomegalovirus IE1 antigen-MHC complexpMHC IE-1UL123 peptide-MHC complex

Targeted cell lysis via T-cell receptor (TCR) recognition of viral peptides presented on MHC class I molecules, leading to the release of cytotoxic granules (perforin/granzymes).