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

Rongzeng Liu, Wei Jiang, Elizabeth D Mellins

Cellular & molecular immunology 2021 Aug

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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, noncovalent αβ dimers 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. © 2021. The Author(s), under exclusive licence to CSI and USTC.

Citation

Rongzeng Liu, Wei Jiang, Elizabeth D Mellins. Yeast display of MHC-II enables rapid identification of peptide ligands from protein antigens (RIPPA). Cellular & molecular immunology. 2021 Aug;18(8):1847-1860