SARS-CoV-2 Spike peptide-MHC Class II complex (Spike-MHCII complex)

The SARS-CoV-2 Spike peptide-MHC Class II complex is a molecular assembly consisting of a proteolytic fragment of the SARS-CoV-2 Spike protein bound within the peptide-binding groove of a Major Histocompatibility Complex Class II (MHC II) molecule [Grifoni et al., 2020, Cell]. This complex is presented on the surface of professional antigen-presenting cells (APCs), such as dendritic cells and B cells, where it serves as the primary ligand for the T cell receptor (TCR) of CD4+ T helper cells [Mateus et al., 2020, Science]. Recognition of this complex is a critical step in the adaptive immune response, as it triggers the activation and proliferation of T cells that coordinate antibody production and cellular immunity [Sette and Crotty, 2021, Cell]. The specific peptides presented are determined by the individual's Human Leukocyte Antigen (HLA) genotype, which significantly influences the breadth and magnitude of the immune response to the virus or vaccines [NIH, 2021]. Therapeutic strategies, particularly mRNA and protein-subunit vaccines, are designed to induce the formation of these complexes to prime the immune system against the Spike protein [PubMed, 2021]. Understanding the structural and functional dynamics of this complex is vital for assessing long-term immunity and the impact of emerging viral variants on vaccine efficacy.

Other names

SARS-CoV-2 Spike-HLA-II complexSpike-MHC-II complexSpike peptide-HLA-DR complexSpike-peptide-HLA-DQ complexSpike-peptide-HLA-DP complex

The complex acts as a ligand for the T cell receptor (TCR) on CD4+ T cells, triggering signal transduction that leads to T cell differentiation, cytokine release, and B cell help for antibody production [Sette and Crotty, 2021, Cell].