Human leukocyte antigen class II: SARS-CoV-2 peptide complex (HLA-II:SARS-CoV-2 peptide complex)

The Human leukocyte antigen (HLA) class II: SARS-CoV-2 peptide complex is a molecular assembly found on the surface of professional antigen-presenting cells (APCs), such as dendritic cells, B cells, and macrophages. This complex consists of an HLA class II molecule (typically HLA-DR, HLA-DQ, or HLA-DP) bound to a proteolytic fragment derived from SARS-CoV-2 proteins, including the Spike (S), Nucleocapsid (N), and Membrane (M) proteins (PubMed: 32979941). Its primary biological function is to present these viral antigens to the T-cell receptors (TCRs) of CD4+ T helper cells, which is a critical step in orchestrating the adaptive immune response against COVID-19 (NIH: PMC7462629). By activating CD4+ T cells, these complexes facilitate B-cell maturation for antibody production and enhance the activity of CD8+ cytotoxic T cells. In the context of therapeutics, COVID-19 vaccines work by inducing the expression of viral proteins that are subsequently processed and presented as HLA-II complexes to prime the immune system (Nature: 586, 594–599). Furthermore, these complexes serve as essential targets for monitoring vaccine efficacy and developing next-generation immunotherapies, such as epitope-specific vaccines and TCR-based treatments (Science: 370, 89-94).

Other names

MHC class II:SARS-CoV-2 peptide complexHLA-II:SARS-CoV-2 pMHCSARS-CoV-2 peptide-HLA-II complexHLA-DR/DQ/DP:SARS-CoV-2 peptide complexMajor histocompatibility complex class II:SARS-CoV-2 peptide complex

Presentation of viral epitopes to CD4+ T-cell receptors (TCRs) to initiate helper T-cell responses, cytokine secretion, and B-cell maturation.