Paul Ogongo

CD4 T cells are essential for immunity to M tuberculosis ( Mtb ), and emerging evidence indicates that IL-17–producing Th17 cells contribute to immunity to Mtb . While identifying protective T cell effector functions is important for TB vaccine design, T cell antigen specificity is also likely to be important. To identify antigens that induce protective immunity, we reasoned that, as in other pathogens, effective immune recognition drives sequence diversity in individual Mtb antigens. We previously identified Mtb genes under evolutionary diversifying selection pressure whose products we term Rare Variable Mtb Antigens (RVMA). Here, in 2 distinct human cohorts with recent exposure to TB, we found that RVMA preferentially induce CD4 T cells that express RoRγt and produce IL-17, in contrast to “classical” Mtb antigens that induce T cells that produce IFN-γ. Together with emerging evidence showing human Th17 responses are associated with prevention of progression to TB disease, our results suggest that RVMA can be valuable antigens in vaccines for those already infected with Mtb to amplify existing antigen-specific Th17 responses to prevent TB disease.

T cells contribute to immune protection and pathogenesis in tuberculosis, but measurements of polyclonal responses have failed to resolve correlates of outcome. We report the temporal evaluation of the human in vivo clonal repertoire of Mycobacterium tuberculosis ( Mtb )-reactive T cell responses, by T cell receptor (TCR) sequencing at the site of the tuberculin skin test, as a model for a standardised antigenic challenge. Initial non-selective recruitment of T cells is followed by enrichment of Mtb -reactive clones arising from oligoclonal T cell proliferation. We introduce a modular computational pipeline, Metaclonotypist, to sensitively cluster distinct TCRs with shared epitope specificity, which we apply here to establish a catalogue of public Mtb -reactive HLA-restricted T cell metaclones. Although most in vivo Mtb -reactive T cells are private, 10 metaclones were sufficient to identify Mtb -T cell reactivity across our study population (N≥128), indicating striking population level immunodominance of specific TCR-peptide interactions that may inform patient stratification and vaccine development.

No currently licensed vaccine reliably prevents pulmonary tuberculosis (TB), a leading cause of infectious disease mortality. Developing effective new vaccines requires identifying which Mycobacterium tuberculosis ( Mtb ) proteins are presented on major histocompatibility complex class II (MHC-II) by infected human phagocytes (target cells) and defining their capacity for recognition by CD4 ⁺ T cells. Vaccine designs must elicit T cell responses recognizing the same peptide-MHC complexes presented by infected cells. Although many human CD4 ⁺ T cell Mtb epitopes have been described, presentation on MHC-II by infected cells in most cases has not been directly evaluated. Using mass spectrometry (MS), we demonstrated that Mtb type VII secretion system (T7SS) substrates are enriched in the MHC-II repertoire of Mtb -infected human monocyte-derived phagocytes and that many of these antigens are immunogenic in people with prior evidence of Mtb infection. We next used MS to guide TB messenger RNA (mRNA) vaccine design, increasing the presentation of target MHC-II epitopes by orders of magnitude by incorporating design features that mirror aspects of antigen presentation dynamics in infected phagocytes. Our results provide a strategy for TB vaccine design that is guided by bottom-up unbiased discovery. Our approach combines targeted evaluation of antigen presentation in human cells paired with rapid iterative testing of mRNA vaccine designs to optimize antigen presentation before animal studies or human clinical trials.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to evolve, with mutations leading to the emergence of new variants. JN.1, a subvariant of omicron BA.2.86, has demonstrated marked immune escape and is now included in updated vaccine formulations. While reduced sensitivity has been reported for antibody assays using ancestral spike protein subunits to detect omicron-induced responses, the performance of full-length spike-based assays against omicron sublineages remains unclear. We aimed to compare the sensitivity of ELISA and Luminex assays using full-length spike proteins from the ancestral Wuhan strain and the JN.1 variant. Methods: Wuhan and JN.1 full-length spike protein constructs were designed and expressed in Expi293F mammalian cells. In-house ELISAs based on previously validated protocols were used to measure anti-spike IgG levels. Additionally, a Luminex-based assay for anti-spike antibody detection was developed and validated. Both assays were applied to the following sample groups: pre-pandemic samples (designated “gold standard negatives”); PCR confirmed 2020 positives (“gold standard wildtype positives”); PCR confirmed 2024 positives (“gold standard omicron positives”); 2022 vaccinated individuals with verbal confirmed infection (“gold standard hybrid positives”); and 2024 household samples (“unknowns”). Results: Wuhan spike protein showed a sensitivity of 100% (95% CI: 0.88–1.0) in detecting omicron-specific antibodies using gold standard omicron positives with JN.1 spike protein as a reference assay. Overall, across all samples, in ELISA, the Wuhan antigen had a sensitivity of 0.93 (95% CI: 0.89–0.95) and a specificity of 0.98 (95% CI: 0.94–0.99). The JN.1 antigen showed a sensitivity of 0.91 (95% CI: 0.87–0.94) and a specificity of 0.97 (95% CI: 0.93–0.99). In Luminex, sensitivity was 0.95 (95% CI: 0.91–0.97) for Wuhan and 0.94 (95% CI: 0.91–0.96) for JN.1. Specificity for both antigens in Luminex was 0.98 (95% CI: 0.94–0.99). Conclusions: Both ELISA and Luminex assays showed comparable sensitivity and specificity for both Wuhan and JN.1 antigens, indicating that mutations in the JN.1 variant do not significantly impact assay performance. This suggests preserved antigenic recognition across variants.

T cells contribute to immune protection and pathogenesis in tuberculosis, but measurements of polyclonal responses have failed to resolve correlates of outcome. We report the first temporal evaluation of the human in vivo clonal repertoire of Mtb-reactive T cell responses, by T cell receptor (TCR) sequencing at the site of a standardised antigenic challenge. Initial recruitment of non-Mtb reactive T cells is followed by enrichment of Mtb-reactive clones arising from oligoclonal T cell proliferation. We introduce a modular computational pipeline, Metaclonotypist, to sensitively cluster distinct TCRs with shared epitope specificity, which we apply here to establish a catalogue of public Mtb-reactive HLA-restricted T cell metaclones. Although most in vivo Mtb-reactive T cells are private, 10 metaclones were sufficient to identify Mtb-T cell reactivity across our study population (N≥128), indicating striking population level immunodominance of specific TCR-peptide interactions that may offer novel approaches to patient stratification and vaccine development.

No currently licensed vaccine reliably prevents pulmonary tuberculosis (TB), a leading cause of infectious disease mortality. Developing effective new vaccines will require identifying which of the roughly 4000 proteins in the Mycobacterium tuberculosis ( Mtb ) proteome are presented on MHC class II (MHC-II) by infected human phagocytes and can be recognized by CD4+ T cells to mediate protective immunity. Vaccines must also elicit T cell responses recognizing the same peptide-MHC complexes presented by infected cells, and successful presentation of target human MHC-II peptides is currently challenging to evaluate and optimize. Here, we define antigenic targets for TB vaccine development by using mass spectrometry (MS) for proteome-wide discovery of Mtb epitopes presented on MHC-II by infected human cells. We next iteratively design and evaluate candidate mRNA vaccine immunogens, revealing design principles that enhance presentation of target MHC-II peptides. Our results will inform the development of new TB vaccine candidates.

B cells are important in tuberculosis (TB) immunity, but their role in the human lung is understudied. Here, we characterize B cells from lung tissue and matched blood of patients with TB and found they are decreased in the blood and increased in the lungs, consistent with recruitment to infected tissue, where they are located in granuloma associated lymphoid tissue. Flow cytometry and transcriptomics identify multiple B cell populations in the lung, including those associated with tissue resident memory, germinal centers, antibody secretion, proinflammatory atypical B cells, and regulatory B cells, some of which are expanded in TB disease. Additionally, TB lungs contain high levels of Mtb-reactive antibodies, specifically IgM, which promotes Mtb phagocytosis. Overall, these data reveal the presence of functionally diverse B cell subsets in the lungs of patients with TB and suggest several potential localized roles that may represent a target for interventions to promote immunity or mitigate immunopathology.

Background: Interleukin 17 producing CD4 T cells contribute to the control of Mycobacterium tuberculosis (Mtb) infection in humans; whether infection with Human Immunodeficiency Virus (HIV) disproportionately affects distinct Th17 cell subsets that respond to Mtb is incompletely defined. Methods: We performed high-definition characterization of circulating Mtb -specific Th17 cells by spectral flow cytometry in people with latent TB and treated HIV (HIV-ART). We also measured kynurenine pathway activity by LC/MS on plasma and tested the hypothesis that tryptophan catabolism influences Th17 cell frequencies in this context. Results: We identified two subsets of Th17 cells: subset 1 defined as CD4 ⁺ Vα7.2 ^- CD161 ⁺ CD26 ⁺ and subset 2 defined as CD4 ⁺ Vα7.2 ^- CCR6 ⁺ CXCR3 ^- cells of which subset 1 was significantly reduced in LTBI with HIV-ART, yet Mtb -responsive IL17-producing CD4 T cells were preserved; we found that IL17-producing CD4 T cells dominate the response to Mtb antigen but not CMV antigen or staphylococcal enterotoxin B (SEB); and tryptophan catabolism negatively correlates with both subset 1 and subset 2 Th17 cell frequencies. Conclusions: We found differential effects of ART-suppressed HIV on distinct subsets of Th17 cells, that IL17-producing CD4 T cells dominate responses to Mtb but not CMV antigen or SEB, and that kynurenine pathway activity is associated with decreases of circulating Th17 cells that may contribute to tuberculosis immunity.

Malaria drives the adaptive differentiation of the human γδ T cell repertoire.