SARS-CoV-2 JN.1 spike protein-derived peptide-MHC complex (JN.1 S-pMHC complex)

The SARS-CoV-2 JN.1 spike protein-derived peptide-MHC complex is a critical immunological target formed when fragments of the JN.1 variant's spike protein are presented on the surface of host cells. These complexes consist of short viral peptides (epitopes) non-covalently bound to Major Histocompatibility Complex (MHC) Class I or Class II molecules [1][2]. MHC Class I complexes are typically recognized by CD8+ T cells, which mediate the direct killing of infected cells, while MHC Class II complexes are recognized by CD4+ T cells to facilitate B-cell activation and cytokine production [3]. The JN.1 variant, characterized by the L455S mutation, represents a significant evolutionary step in the Omicron lineage, potentially altering the landscape of presented epitopes [4]. While neutralizing antibodies often fail against new variants, T-cell recognition of these pMHC complexes remains a cornerstone of long-term protection against severe disease [5]. Modern vaccines, such as the updated 2024-2025 mRNA and protein-subunit formulations, are designed to elicit an immune response specifically against these JN.1-derived targets to maintain efficacy against circulating strains [6].

Other names

JN.1 spike-derived T-cell epitopesSARS-CoV-2 JN.1 HLA-peptide complexJN.1 spike epitopesSARS-CoV-2 JN.1 MHC-I/II presented peptides

Vaccines deliver the genetic sequence or protein of the JN.1 spike, which is processed by antigen-presenting cells into peptides and loaded onto MHC molecules to prime and activate T-cell responses.