Biology subjects

Draper, S. L.

Publications and source records attributed to Draper, S. L..

4 recordsLinked to original sources

bioRxiv2026

Circular RNA vaccine performance is determined by RNA quality and epitranscriptomic tuning rather than innate activation

Circular RNA (circRNA) is an emerging vaccine modality that is proposed to improve stability, reduce reactogenicity and extend antigen expression compared with linear mRNA. However, the relative contributions to vaccine performance of its covalently closed structure, its purity, and of nucleotide modifications remain poorly described. Here, we systematically dissected these parameters in vivo across two antigen systems. We identified RNA quality as a major determinant of circRNA reactogenicity, with differences in innate immune activation tracking with the presence of residual RNA species in less refined preparations. In contrast, highly purified circRNA exhibited markedly reduced reactogenicity compared with linear mRNA, independent of nucleotide modification. Despite these differences, circRNA and mRNA vaccines elicited comparable antibody titres and T cell responses, indicating that reduced innate activation does not enhance adaptive immune magnitude. Notably, incorporating N6-methyladenosine (m6A) did not affect reactogenicity or antigen expression but selectively enhanced antibody quality, increasing binding affinity and neutralisation capacity. CircRNA vaccination also altered the anatomical distribution of germinal centre responses, reducing splenic antigen-specific germinal centre B cells while preserving lymph node responses. Together, these findings show that circRNA vaccine performance is governed by RNA preparation quality and epitranscriptomic tuning rather than innate activation alone.

immunology↗

bioRxiv2026

Optimization of a liver Trm cell-inducing mRNA vaccine by reduction of type I interferon response

CD8+ tissue-resident memory T cells provide rapid frontline protection at pathogen invasion sites, making them attractive targets for vaccine-mediated immunity. We previously developed an NKT cell-adjuvanted mRNA lipoplex vaccine capable of inducing liver Trm cells and sterile protection against malaria in mice. Here, we show that type I interferon (IFN-I) signalling through dendritic cells -- not T cells -- is a key brake on liver Trm induction by this vaccine. Optimising mRNA manufacturing to reduce immunostimulatory contaminants substantially dampened IFN-I production, boosted antigen expression in the lymphoid tissues, and drove significantly greater Trm accumulation. These enhanced responses translated into superior protection against parasite challenge. Our findings identify DC-intrinsic IFN-I signalling as a tractable target, and mRNA manufacturing quality as a critical and underappreciated lever, for maximising Trm-based vaccine efficacy.

immunology↗

bioRxiv2026

Temporal expression of liver-stage malaria antigens shapes vaccine efficacy

Vaccine-induced cytotoxic T cells can prevent malaria by killing parasite-infected hepatocytes during the liver stage. While several antigenic targets have been identified, little consideration has been given to their temporal expression. Here, we identified SERA1 of Plasmodium berghei as a late liver-stage target in rodent malaria and further showed that the classic vaccine antigen thrombospondin-related adhesion protein (TRAP) is only an early target. While vaccination with either antigen alone was modestly protective, combining these antigens enabled killing over the entire liver-stage, greatly improving efficacy. Given the relatively long liver-stage in human malaria, our findings imply TRAP-dependent vaccines likely utilize only a small proportion of the available liver-stage to eradicate parasites. Our findings further indicate that considerations of temporal coverage when selecting vaccine antigens will improve efficacy. One-Sentence SummaryTemporally defining presentation of liver-stage antigens informs rational combinations that maximize malaria vaccine efficacy.

immunology↗

bioRxiv2026

Engineering antigenic breadth against SARS-CoV-2 by pairing divergent RBDs within a single mRNA immunogen

Vaccines capable of eliciting broadly neutralising antibodies (bnAbs) are a major goal for pandemic preparedness. A persistent challenge across vaccine Wields is how to deliberately recruit the rare B cell clones that recognise conserved epitopes shared across diverse viral variants. BnAbs have been known to frequently emerge through extensive somatic hypermutation during afWinity maturation, here we describe an alternative, structure-driven mechanism for bnAb selection. We designed an mRNA vaccine in which two antigenically distinct SARS-CoV-2 variants (Omicron and Delta; O-{Delta}) receptor binding domains (RBDs) are physically fused on a single polypeptide. This design is predicted to favour B cell antigen receptors capable of engaging conserved epitopes on both RBDs with enhanced avidity. A matched non-divergent tandem RBD (Delta-Delta; {Delta}-{Delta}) served as a control. The divergent (O-{Delta}) immunogen was robustly expressed and retained high-afWinity ACE2 binding. In mice, immunisation elicited potent antibody responses and increased the frequency of antigen-speciWic cross-reactive B cells, recognising Delta, Omicron, and the 2002 pandemic strain SARS-CoV RBDs. Using multicolour RBD tetramers and single-cell B cell receptor sequencing, we show that breadth arises via two distinct pathways. The divergent vaccine preferentially enriches clonally distinct cross-reactive B cells (not present within non-cross-reactive B cell pools) with low levels of somatic hypermutation (SHM), consistent with selection of germline-biased precursors. In contrast, the matched control vaccine yields cross-reactivity primarily within existing clonal lineages (clonal overlap between cross-reactive and non-cross-reactive cells) and at higher mutational burdens, consistent with afWinity-maturation-driven acquisition of breadth. Together, these Windings demonstrate that antigen structure can bias B cell selection towards cross-reactive speciWicities without requiring extensive SHM. This work establishes a simple, modular antigen-design principle in which juxtaposing appropriately divergent antigens on a single scaffold promotes the enrichment of bnAb-prone B cells, providing a scalable strategy for vaccine development against rapidly evolving pathogens.

immunology↗