Characterisation of novel influenza-derived HLA-B*18:01-restricted epitopes

Samuel Liwei Leong; Lawton Murdolo; Janesha C Maddumage; Marios Koutsakos; Katherine Kedzierska; Anthony W Purcell; Stephanie Gras; Emma J Grant

doi:10.1002/cti2.1509

Characterisation of novel influenza-derived HLA-B*18:01-restricted epitopes

Clin Transl Immunology. 2024 May 10;13(5):e1509. doi: 10.1002/cti2.1509. eCollection 2024.

Authors

Samuel Liwei Leong^{1

2}, Lawton Murdolo^{1

2}, Janesha C Maddumage^{1

2}, Marios Koutsakos³, Katherine Kedzierska³, Anthony W Purcell⁴, Stephanie Gras^{1

2

4}, Emma J Grant^{1

2

4}

Affiliations

¹ Infection and Immunity Program, La Trobe Institute for Molecular Science (LIMS) La Trobe University Bundoora VIC Australia.
² Department of Biochemistry and Chemistry, School of Agriculture, Biomedicine and Environment (SABE) La Trobe University Bundoora VIC Australia.
³ Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity University of Melbourne Melbourne VIC Australia.
⁴ Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute Monash University Clayton VIC Australia.

Abstract

Objectives: Seasonal influenza viruses cause roughly 650 000 deaths annually despite available vaccines. CD8⁺ T cells typically recognise influenza-derived peptides from internal structural and non-structural influenza proteins and are an attractive avenue for future vaccine design as they could reduce the severity of disease following infection with diverse influenza strains. CD8⁺ T cells recognise peptides presented by the highly polymorphic Human Leukocyte Antigens class I molecules (HLA-I). Each HLA-I variant has distinct peptide binding preferences, representing a significant obstacle for designing vaccines that elicit CD8⁺ T cell responses across broad populations. Consequently, the rational design of a CD8⁺ T cell-mediated vaccine would require the identification of highly immunogenic peptides restricted to a range of different HLA molecules.

Methods: Here, we assessed the immunogenicity of six recently published novel influenza-derived peptides identified by mass-spectrometry and predicted to bind to the prevalent HLA-B*18:01 molecule.

Results: Using CD8⁺ T cell activation assays and protein biochemistry, we showed that 3/6 of the novel peptides were immunogenic in several HLA-B*18:01⁺ individuals and confirmed their HLA-B*18:01 restriction. We subsequently compared CD8⁺ T cell responses towards the previously identified highly immunogenic HLA-B*18:01-restricted NP₂₁₉ peptide. Using X-ray crystallography, we solved the first crystal structures of HLA-B*18:01 presenting immunogenic influenza-derived peptides. Finally, we dissected the first TCR repertoires specific for HLA-B*18:01 restricted pathogen-derived peptides, identifying private and restricted repertoires against each of the four peptides.

Conclusion: Overall the characterisation of these novel immunogenic peptides provides additional HLA-B*18:01-restricted vaccine targets derived from the Matrix protein 1 and potentially the non-structural protein and the RNA polymerase catalytic subunit of influenza viruses.

Keywords: CD8+ T cells; HLA‐B*18:01; immunodominance hierarchy; immunogenic; influenza.