Yeast display of MHC-II enables rapid identification of peptide ligands from protein antigens(RIPPA)

摘要

CD4^(+)T cells orchestrate adaptive immune responses via binding of antigens to their receptors through specific peptide/MHC-II complexes.To study these responses,it is essential to identify protein-derived MHC-II peptide ligands that constitute epitopes for T cell recognition.However,generating cells expressing single MHC-II alleles and isolating these proteins for use in peptide elution or binding studies is time consuming.Here,we express human MHC alleles(HLA-DR4 and HLA-DQ6)as native,noncovalentαβdimers on yeast cells for direct flow cytometry-based screening of peptide ligands from selected antigens.We demonstrate rapid,accurate identification of DQ6 ligands from pre-pro-hypocretin,a narcolepsy-related immunogenic target.We also identify 20 DR4-binding SARS-CoV-2 spike peptides homologous to SARS-CoV-1 epitopes,and one spike peptide overlapping with the reported SARS-CoV-2 epitope recognized by CD4^(+)T cells from unexposed individuals carrying DR4 subtypes.Our method is optimized for immediate application upon the emergence of novel pathogens.