Human cytomegalovirus immediate-early 1 peptide–HLA class I complex (HCMV IE-1–HLA-I complex)

The Human Cytomegalovirus (HCMV) Immediate-Early 1 (IE-1) peptide–HLA class I complex is a critical immunological target found on the surface of cells infected with HCMV (NIH, 2020). IE-1, encoded by the UL123 gene, is one of the first proteins expressed during the viral lytic cycle and serves as a dominant antigen for CD8+ cytotoxic T lymphocytes (CTLs) (IntechOpen, 2018). The complex consists of a specific IE-1-derived peptide, such as the immunodominant VLEETSVML sequence, non-covalently bound within the groove of a Human Leukocyte Antigen (HLA) class I molecule, most commonly HLA-A*02:01 (ResearchGate, 2018). This presentation allows the host's immune system to identify and eliminate infected cells through T-cell receptor (TCR) recognition (MDPI, 2024). In clinical settings, this complex is targeted by adoptive T-cell therapies, such as posoleucel (ALVR105), to treat refractory CMV infections in transplant recipients (Allovir, 2024). Additionally, TCR-like antibodies and fusion proteins like ReTARG are being developed to specifically bind these complexes, offering a highly specific approach to viral clearance or redirecting immune responses against tumors (TandfOnline, 2023). This target is particularly important because CMV often employs immune evasion strategies, such as downregulating HLA molecules, to avoid detection (Gosset.ai, 2026).

Other names

HCMV IE1-pMHCIE1 peptide-HLA complexUL123 peptide-HLA complexVLEETSVML-HLA-A*02:01 complexQIKVRVDMV-HLA-B*08:01 complexIE-1-pMHC complex

Recognition by T-cell receptors (TCRs) or TCR-like antibodies leading to targeted lysis of infected cells via granzyme and perforin release.