Human leukocyte antigen class II–Cytomegalovirus phosphoprotein 65 peptide complex (HLA-II–CMV pp65) (HLA-II–CMV pp65)

Human leukocyte antigen class II–Cytomegalovirus phosphoprotein 65 peptide complex is a molecular assembly consisting of a Human Leukocyte Antigen (HLA) class II molecule bound to a specific peptide fragment derived from the Cytomegalovirus (CMV) phosphoprotein 65 (pp65). These complexes are primarily expressed on the surface of professional antigen-presenting cells and are critical for the activation of CD4+ T helper cells, which coordinate the immune response against CMV (Source: PubMed: 15141007). The pp65 protein, encoded by the UL83 gene, is the most abundant internal matrix protein of CMV and serves as a dominant target for the cellular immune system (Source: UniProt: P06725). In clinical settings, these complexes are the primary targets for adoptive T-cell therapies designed to treat or prevent CMV reactivation in immunocompromised patients, such as those undergoing hematopoietic stem cell transplantation (Source: PubMed: 23982173). Therapeutic agents like virus-specific T cells (VSTs) recognize these complexes via their T-cell receptors (TCRs), triggering the release of antiviral cytokines and the orchestration of a broader immune response (Source: AlloVir). The specificity of this interaction is determined by the particular HLA allele presenting the peptide, making HLA typing a crucial component of therapy (Source: IEDB). Challenges in targeting these complexes include the risk of graft-versus-host disease in allogeneic settings and the need for broad HLA coverage in off-the-shelf products.

Other names

MHC class II–CMV pp65 complexHLA-DR–pp65 peptide complexCMV UL83–HLA class II complexHLA-II–pp65HLA class II–pp65 complex

T-cell receptor (TCR) mediated recognition of the peptide-MHC complex leading to T-cell activation and antiviral effector functions.