Prediction and validation of immunogenic domains of pneumococcal proteins recognized by human CD4+ T-cells

by van de Garde MDB, van Westen E, Poelen MCM, Rots NY, van Els CACM

Published in Infection and Immunity, 25 March 2019. 

 

 

CD4+ T-cell mechanisms are implied in protection against pneumococcal colonization; however, their target antigens and function are not well defined. In contrast to high-throughput protein arrays for serology, basic antigen tools for CD4+ T-cell studies are lacking. Here researchers evaluate the potential of a bioinformatics tool in silico prediction of immunogenicity as a method to reveal domains of pneumococcal proteins targeted by human CD4+ T-cells.

 

For hundred pneumococcal proteins CD4+ T-cell immunogenicity was predicted based on HLA-DRB1 binding motifs. Then, for twenty potentially CD4+ T-cell-immunogenic proteins epitope regions were verified by testing synthetic peptides in T-cell assays using PBMCs from healthy adults. Peptide pools of 19 out of 20 proteins evoked T-cell responses. Most frequent responses (detectable in ≥20% of donors tested) were found to SP_0117 (PspA), SP_0468 (putative sortase), SP_0546 (BlpZ), SP_1650 (PsaA), SP_1923 (Ply), SP_2048 (Conserved Hypothetical Protein), SP_2216 (PscB), and SPR_0907 (PhtD). Responding donors had diverging recognition patterns and profiles of signature cytokines (IFNγ, TNFα, IL-13 and/or IL-17A) against single epitope regions. Natural HLA-DR restricted presentation and recognition of a predicted SP_1923-derived epitope was validated through the isolation of a CD4+ T-cell clone producing IFNγ, TNFα and IL-17A in response to the synthetic peptide, whole protein, and heat-inactivated pneumococcus.

 

This proof of principle for a bioinformatics tool to identify pneumococcal protein-epitopes targeted by human CD4+ T-cells, provides a peptide-based strategy to study cell-mediated immune mechanisms to the pneumococcal proteome, advancing the development of immunomonitoring assays and targeted vaccine approaches.

 

 

Article access can be found here

 

Comments

No comments made yet. Be the first to submit a comment
Already Registered? Login Here
Guest
Monday, 15 July 2019