Biology subjects

Jayathilaka, D.

Publications and source records attributed to Jayathilaka, D..

3 recordsLinked to original sources

bioRxiv2026

Mode of T cell priming durably shapes the TCR repertoire, effector function and α4β1 integrin expression of human virus-specific CD4+ T cells

The generation of an effective T cell response against an antigen depends on the recognition of the antigen by the T cell receptor (TCR), followed by T cell priming, initiating coordinated biophysical, biochemical and proliferative changes that drive differentiation into effector and memory clones. The immunological environments in which priming occurs, such as natural infection or vaccination, influences the quality and persistence of memory T cells, but the long-term impacts remain incompletely understood. Here, we investigate how the mode of priming shapes durable antigen-specific CD4+ T cell memory, utilising two cohorts 3-4 years after initial antigen encounter: individuals recovered from SARS-CoV-2 infection and infection-naive individuals who received a SARS-CoV-2 vaccination. Using ex vivo single-cell RNA sequencing, paired TCR sequencing and in vitro functional analyses, we characterise the transcriptional, clonal and functional profile of Spike-specific CD4+ T cells. Across both cohorts, CD4+ T cell responses against spike epitopes S166-180, S751-765 and S866-880, were immunodominant, with shared public TCR clonotypes indicating conserved antigen-recognition regardless of mode of priming. Despite this shared specificity, infection-primed individuals exhibited greater TCR repertoire diversity and lower CDR3{beta} sequence convergence. Transcriptionally, infection-primed cells exhibited a more cytotoxic and effector phenotype, while vaccine-primed cells preferentially adopted T follicular helper (Tfh)- and Th1-associated phenotypes. Infection-primed individuals also displayed enrichment of cell adhesion and integrin signalling pathways, with a greater proportion of spike-specific CD4+ T cells expressing 4{beta}1 integrin subunits, consistent with enhanced migratory and effector potential. Collectively, our findings demonstrate that the mode of antigen priming may influence the long-term CD4+ T cell memory states, influencing TCR repertoire diversity, functional differentiation and tissue-homing potential, years after the initial immune response.

immunology↗

bioRxiv2019

Phenotype and functionality of follicular helper T cells in patients with acute dengue infection

BackgroundThe association of functionality and phenotype of follicular helper T cells (Tfh) with dengue virus (DENV) specific antibody responses and clinical disease severity is has not been well studied.\n\nMethodology/Principal findingsWe investigated the phenotype and functionality of Tfhs in adult patients (DF = 18, DHF = 22) with acute dengue of varying severity using multiparametric flowcytometry. We determined if the properties of Tfhs were correlated with viraemia, disease severity, plasmablast responses and DENV-specific serum antibody responses. We further evaluated the changes in neutralizing antibodies (Neut50) with viraemia and clinical disease severity in a different cohort of patients with acute secondary DENV1 (DF=12, DHF=10) and DENV2 infection (DF=8, DHF=9).\n\nTfhs (especially those producing IL-21 and co-expressing PD-1 and ICOS) were found to be significantly expanded (p<0.0001) and highly activated in patients with DHF compared to those with DF. The frequency of Tfh cells significantly correlated with DENV-specific IgG, NS1-specific antibodies and Neut50 antibody titres, which were also significantly higher in patients with DHF. Although the Neut50 titres increased during the course of acute secondary DENV infection, they showed differences based on serotype. For instance, the Neut50 titres were significantly higher during the latter part of illness in patients with DF compared DHF in DENV1 infection, while in DENV2, patients with DHF had significantly higher titres. The viral loads during early illness did not correlate with the subsequent rise in the Neut50 antibody titres during time point of illness.\n\nConclusions/SignificanceThe expansion of Tfhs is associated with DHF and DENV-specific IgG, NS1-specific and neutralising antibodies. Neut50 titres did not associate with disease severity or viraemia at the point of first presentation during the febrile phase, but later titres do show differential association with severity in patients with DENV1 compared to DENV2.\n\nAuthor summaryFollicular helper T cells (Tfh cells) are a subset of T cells which are important in activation of germinal centre T cells and induction of long-lasting virus specific antibodies. The association of the functional status and phenotype of Tfh cells in relation to dengue virus (DENV) specific antibodies, clinical disease severity and the degree of viraemia in patients with acute dengue has not been extensively studied. Here we show that the Tfh cells are significantly expanded in patients with severe clinical disease and associate with levels of serum DENV envelop specific IgG, NS1-specific antibodies and neutralising antibodies (Neu50). Although DENV Neu50 antibody titres are thought to associate with protection, the Neut50 antibody titres were similar in patients who proceeded to develop mild or severe clinical disease and also the increase in their titres showed significant variation based on infecting DENV serotype and clinical disease severity. Therefore, although Tfh cells are expanded in patients with more severe forms of disease, and associate with DENV-specific antibody responses, they do not appear to have a protective role.

immunology↗

bioRxiv2018

Role of NS1 antibodies in the pathogenesis of acute dengue infection

The role of NS1-specific antibodies in the pathogenesis of dengue virus infection is of particular interest to the dengue field, yet remains poorly understood. We therefore investigated the immunoglobulin responses of patients with dengue fever (DF) and dengue hemorrhagic fever (DHF) to NS1. Antibody responses to recombinant-NS1 were assessed in serum samples obtained throughout illness of patients with acute secondary DENV1 and DENV2 infection by ELISA. NS1 antibody titres were significantly higher in patients with DHF compared to those with DF for both serotypes, during the critical phase of illness. Antibody responses were further assessed to NS1 peptides and showed that in both acute secondary DENV1 and DENV2 infection, the antibody repertoire of DF and DHF patients is directed towards distinct regions of the NS1 protein. Further experiments in healthy individuals, with either past severe dengue or past asymptomatic dengue infection revealed that individuals with past inapparent disease mounted antibody responses directed to the same NS1 epitope regions as those with mild acute infection (DF). Our results suggest that the specific epitope target of NS1-antibodies generated by patients could predict disease severity and be of potential therapeutic benefit in aiding vaccine and treatment design.

immunology↗