Biology subjects

Murdiyarso, L.

Publications and source records attributed to Murdiyarso, L..

3 recordsLinked to original sources

bioRxiv2026

Defining influenza-specific B cells in vaccine responders, non-responders and influenza breakthrough infections

Although seasonal influenza vaccination programs are effective at a population level, our data from inactivated influenza vaccine (IIV) cohorts in years 2015-2022 reveal that 50-60% of individuals do not seroconvert following immunization. The underlying mechanisms of vaccine non-responsiveness are far from understood. In this study, we sought to define key determinants of optimal B cell immune responses elicited by seasonal influenza vaccination, and to explore why some individuals fail to elicit humoral immunity following immunization. Immune responses associated with seroconversion and vaccine failure from individuals immunized with IIVs were compared at cellular and molecular levels using single-cell transcriptomics. We analyzed HA-specific B cell immunity across vaccine-responders, breakthrough infections and patients hospitalized with acute influenza. Droplet-based single-cell RNA sequencing and VDJ-sequencing of influenza-specific B cells from stored PBMCs was performed using 10x Genomics. Our results show that atypical B cells are the major subset of B cell responses in vaccine non-responders on day 28 post-vaccination. Conversely, individuals who seroconvert had diverse B cell phenotypes. The use of recombinant influenza-specific HA probes allowed us to dissect expression patterns on influenza HA-specific B cells. We found that HA-specific B cells of vaccine non-responders for A/H1N1 and A/H3N2 components displayed elevated atypical-like markers (CD11c, FcRL-5) at baseline, compared to responders. Analysis of differentially expressed genes (DEGs) between responders and non-responders identified differential expression of HLA-DR, CD74, CD83, and CXCR3 genes. We subsequently demonstrated reduced frequencies of HLA-DR-, CD74- and CD83-expressing B cells in patients hospitalized with influenza, compared to healthy participants. Hospitalized influenza patients also had significantly higher proportions of atypical CD21-CD27- B cells. Overall, our data demonstrate an association between elevated frequencies of atypical-like B cells with both lack of seroconversion following immunization and severe influenza infection. These findings broaden our understanding of humoral immunity in influenza vaccination and infection, providing novel insights for vaccination strategies and design.

immunology↗

bioRxiv2025

Immunodominance is a poor predictor of vaccine-induced T follicular helper cell quality

Rational engineering of vaccine immunogens to focus B cell responses on potently neutralizing epitopes is a promising approach to improve the potency, breadth and durability of viral vaccines. Such strategies, however, can compromise vaccine immunogenicity through the unintended exclusion of CD4+ T cell epitopes, which are critical for the development of T follicular helper (TFH) cells and to support high affinity antibody production. Using a prototypic influenza HA stem immunogen lacking effective CD4+ T cell help in BL6 mice, we interrogated the minimal requirements for T cell help needed to drive serological responses to vaccination. We find that priming of naive CD4 T cells is markedly efficient, however the immunodominance of a given CD4 T cell epitope is not predictive of the propensity to provide high quality help to antigen-specific B cells. In the context of soluble antigens, provision of a single MHC class II epitope is sufficient to drive robust germinal centre responses and serum IgG titres. However not all CD4 epitopes provide equivalent levels of B cell help, despite priming comparable numbers of antigen-specific CD4 T cells. Finally, we show multimerizing and arraying antigens on nanoparticle scaffolds unlocks highly subdominant, near-undetectable CD4 T cell helper responses to support a T-dependent antibody response. Our findings emphasize the importance of CD4+ T cell help for programing robust and durable humoral immunity, and provide crucial insights to guide the rational incorporation of favorable T cell epitopes into vaccines.

immunology↗

bioRxiv2025

A novel chimeric coronavirus spike vaccine combining SARS-CoV-2 RBD and scaffold domains from HKU-1 elicits potent neutralising antibody responses

The receptor binding domain (RBD) of the SARS-CoV-2 spike is the major target for neutralising antibodies elicited by current vaccines. Using small domains such as the RBD as vaccine immunogens, however, may constrain the availability of CD4 T follicular helper (TFH) cells and impact immunogenicity. We engineered a novel chimeric trimeric RBD (CTR) glycoprotein, replacing the RBD of human coronavirus HKU-1 spike with SARS-CoV-2 RBD of either ancestral (WT) or Omicron BA.2 strains. This strategy maintains a native trimeric conformation of the RBD, while providing additional sources of CD4 T cell help via the HKU-1 spike scaffold. In C57BL/6 mice, CTR-BA.2 prime-boost vaccination elicited high anti-BA.2-RBD IgG and neutralising titres, matching responses in animals immunised with native SARS-CoV-2 spike proteins. GC B cells elicited by CTR-BA.2 were predominantly WT+/BA.2+ cross- reactive, and TFH cells predominantly recognised HKU-1 epitopes, demonstrating scaffold-directed T cell help. Macaques prime-boost immunised with CTR-WT similarly elicited high anti-RBD IgG, anti-spike IgG and neutralising responses, comparable to native spike-vaccinated animals. In draining lymph nodes of CTR-WT vaccinated macaques, RBD-specific GC B cells were present at elevated levels. In contrast to the murine studies, lymph node-draining TFH responses in macaques were broadly elicited against RBD, NTD/S2 or HKU-1-derived peptides. Although native SARS- CoV-2 spike was also highly immunogenic in animal models, our findings establish the chimeric glycoprotein design as a strategy to overcome the poor immunogenicity of the SARS-CoV-2 RBD by engaging CD4 TFH cells, while maintaining the ability to elicit protective neutralising responses. One sentence summaryA chimeric glycoprotein design preserves SARS-CoV-2 RBD antigenic conformation enabling elicitation of neutralising responses, while allowing recruitment of HKU-1 scaffold-directed CD4 helper responses to support the humoral response.

immunology↗