Immune control of Burkholderia pseudomallei––common, high-frequency T-cell responses to a broad repertoire of immunoprevalent epitopes
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Supporting information
Supporting information
Author(s)
Type
Journal Article
Abstract
Burkholderia pseudomallei (Bp) is an environmental bacterial pathogen that causes potentially lethal sepsis in susceptible individuals and is considered a Category B, Tier-1 biothreat agent. As such, it is crucial to gain an improved understanding of protective immunity and potential vaccine candidates. The nature of immune correlates dictating why most exposed individuals in endemic regions undergo asymptomatic seroconversion while others succumb to life-threatening sepsis is largely uncharted. Bp seroreactive, immunogenic proteins have previously been identified by antigen microarray. We here set out to conduct an analysis of T-cell recognition of the Bp immunome using serodominant antigens represented in the original antigen microarray, examining immune correlates of disease in healthy seropositive individuals and those with acute disease or in convalescence. By screening a library of 739 overlapping peptides representing the sequences of 20 different Bp antigens, we aimed to define immune correlates of protection at the level of immunoprevalent T-cell epitopes. Responses to a large number of epitopes were common in healthy seropositive individuals: we found remarkably broad responsiveness to Bp epitopes, with 235 of 739 peptides recognized by ≥80% of all tested donors. The cumulative response to Bp epitopes in healthy, seropositive, donors from this endemic region were of the order of thousands of spot forming cells per million cells, making Bp recognition a significant component of the T-cell repertoire. Noteworthy among our findings, analysis revealed 10 highly immunoprevalent T-cell epitopes, able to induce Bp-specific IFNγ responses that were high in responding T-cell frequency within the repertoire, and also common across individuals with different human leukocyte antigen types. Acute melioidosis patients showed poor T-cell responses to the immunoprevalent epitopes, but acquired responsiveness following recovery from infection. Our findings suggest that a large repertoire of CD4 T cells, high in frequency and with broad coverage of antigens and epitopes, is important in controlling Bp infection. This offers an attractive potential strategy for subunit or epitope-based vaccines.
Date Issued
2018-03-20
Date Acceptance
2018-02-23
Citation
Frontiers in Immunology, 2018, 9
ISSN
1664-3224
Publisher
Frontiers Media
Journal / Book Title
Frontiers in Immunology
Volume
9
Copyright Statement
© 2018 Nithichanon, Rinchai, Buddhisa, Saenmuang, Kewcharoenwong, Kessler, Khaenam, Chetchotisakdi, Maillere, Robinson, Reynolds, Boyton, Altmann and Lertmemongkolchai. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Sponsor
Welton Foundation
National Institutes of Health
Imperial College Healthcare NHS Trust- BRC Funding
Grant Number
N/A
HHSN272200900046C
RDF01 79560
Publication Status
Published
Article Number
484