The Lancet Infectious Diseases

Typhoid fever remains a significant public health challenge in low- and middle-income countries. In 2018, The World Health Organization recommended a single dose typhoid conjugate vaccine (TCV) for routine immunization in endemic settings; however, evidence guiding booster doses remains limited. Homologous TCV booster doses have demonstrated immune boosting. This study assessed the immunogenicity and safety of a heterologous booster using a Vi capsular polysaccharide-CRM197 TCV (Vi-CRM) administered 5-6 years after primary vaccination with a Vi capsular polysaccharide tetanus toxoid TCV (Vi-TT) in children. Children previously enrolled in a Phase 2 trial were recruited. Participants who had received TCV at 9-11 or 15-23 months were given a Vi-CRM booster at 6-7 years of age (Booster-TCV group), and controls received their first TCV dose at the same age (1st-TCV group). Serum anti-Vi IgG concentrations were measured at baseline and 28 days post-vaccination. Solicited and unsolicited adverse events (AEs) and serious adverse events (SAEs) were recorded. Among 147 children enrolled, 87 received a second and 60 received a first TCV dose. Baseline anti-Vi IgG geometric mean titers (GMT) were higher in the Booster-TCV group (21.5 EU/mL; 95% CI: 17.2-26.8) than in the 1st-TCV group (5.5 EU/mL; 95% CI: 4.5-6.7). At day 28, GMTs rose markedly in both groups: 5140.0 EU/mL (95% CI: 4302.0-6141.3) in the Booster-TCV group and 2084.8 EU/mL (95% CI: 1724.4-2520.5) in the 1st-TCV group. Local reactions and systemic AEs were mild. No SAEs were observed. Vi-TT-induced immunity persisted for at least 5-6 years, and a heterologous booster triggered a strong immune response with universal seroconversion. These findings support heterologous prime-boost strategies to maintain protection in school-age children and inform optimization of TCV schedules in endemic regions.

We evaluated 2024/25 KP.2 vaccine effectiveness (VE) against COVID-19 hospitalization among adults >60 years old eligible for publicly-funded vaccination during fall and/or spring campaigns in the province of Quebec, Canada. We included Quebec residents tested for COVID-19-compatible symptoms in an acute-care hospital between October 13, 2024 (epi-week 2024-42) and August 23, 2025 (2025-34), linking vaccine, hospital, chronic diseases and laboratory administrative records to assess VE through test-negative design. We compared the odds of being COVID-19 test-positive versus test-negative among vaccinated versus non-vaccinated participants, adjusting for sex, age, comorbidities, place of residence, and epidemiological week. Overall, 49,949 (43%) participants were vaccinated. Over an analysis period spanning up to ten months, including median time since vaccination of 16 weeks (interquartile range 9-24 weeks), VE was 34% overall, declining from 43% <8 weeks to negligible by the 32nd week post-vaccination. Findings confirm meaningful but short-lived COVID-19 vaccine protection against hospitalization in older adults.

Influenza viruses present a significant public health risk, causing substantial illness and death in humans each year. Seasonal flu vaccines must be updated regularly, and their effectiveness often decreases due to mismatches with circulating strains. Furthermore, inactivated vaccines do not provide protection against shifted influenza viruses that have the potential to cause a pandemic. The highly pathogenic avian influenza H5N1 clade 2.3.4.4b is prevalent among wild birds worldwide and is causing a multi-state outbreak affecting poultry and dairy cows in the United States (US) since March 2024. In this study, we have generated a NS1 deficient mutant of a low pathogenic version of the cattle-origin human influenza A/Texas/37/2024 H5N1, namely LPhTXdNS1, and validated its safety, immunogenicity, and protection efficacy in a prime vaccination regimen against wild-type (WT) A/Texas/37/2024 H5N1. The attenuation of LPhTXdNS1 in vitro was confirmed by its reduced replication in cultured cells and inability to control IFN{beta} promoter activation. In C57BL/6J mice, LPhTXdNS1 has reduced viral replication and pathogenicity compared to WT A/Texas/37/2024 H5N1. Notably, LPhTXdNS1 vaccinated mice exhibited high immunogenicity that reach its peak at weeks 3 and 4 post-immunization, leading to robust protection against subsequent lethal challenge with WT A/Texas/37/2024 H5N1. Altogether, we demonstrate that a single dose vaccination with LPhTXdNS1 is safe and able to induce protective immune responses against H5N1. Both safety profile and protection immunity suggest that LPhTXdNS1 holds promise as a potential solution to address the urgent need for an effective vaccine in the event of a pandemic for the treatment of infected animals and humans.

An efficacious blood-stage malaria vaccine would serve as a highly useful public health tool alongside licensed vaccines targeting the pre-erythrocytic life cycle stage of the Plasmodium falciparum parasite. RH5 is the leading blood-stage malaria vaccine candidate antigen due to its highly-conserved sequence and non-redundant role in merozoite invasion of red blood cells. Following encouraging immunogenicity data in UK and Tanzanian Phase Ia/b vaccine trials, RH5-based vaccines have progressed to Phase IIb evaluation in Burkina Faso in recent years. Here, we report a Phase Ia clinical trial in malaria-naive UK adults to assess the safety and immunogenicity of the malaria vaccine candidate RH5.1 soluble protein with Matrix-M adjuvant using two different booster dosing regimens: 10-10-10 micrograms versus 50-50-10 micrograms RH5.1, both delivered in a 0-1-6-month schedule with 50 micrograms Matrix-M adjuvant per dose (ClinicalTrials.gov NCT06141057). A total of n=24 participants were recruited to this study, with n=23 completing all follow-up visits through to 1 year following final vaccination. The RH5.1/Matrix-M formulation was well-tolerated in this population, with injection site pain, myalgia and fatigue being the most commonly reported symptoms up to 7 days post-vaccination. There were no serious adverse events, adverse events of special interest, or suspected unexpected serious adverse reactions reported over the course of the trial. Both vaccination regimens were similarly immunogenic; no differences were observed in peak anti-RH5.1 serum IgG concentrations, in vitro functional anti-parasitic activity, avidity, or durability. Our findings build on other observations from clinical trials of adjuvanted RH5.1 indicating that humoral immunogenicity can be enhanced by delaying the final booster vaccination, but that there is limited impact of fractionation of the final dose. These insights can help to guide the next steps of multi-antigen, multi-stage malaria vaccine development in malaria-endemic settings.

Dementia affects tens of millions of people worldwide, yet disease-modifying treatments remain strikingly limited. Although the recombinant zoster vaccine Shingrix has been associated with reduced dementia incidence, its potential influence on individuals already living with dementia is unknown. Here, we followed a propensity-score matched cohort of 68,960 US dementia patients using a nationwide electronic health record network, comparing Shingrix recipients within two years of diagnosis to recipients of any other vaccine. Shingrix was associated with substantially reduced all-cause mortality across the first three years of follow-up (hazard ratios 0.74, 0.88, and 0.89; P[&le;]0.006), robust across multiple sensitivity analyses. Furthermore, within-individual subgroup analyses of repeated Mini-Mental State Examinations conducted 3-6 years apart revealed significantly divergent cognitive decline rates across groups (time-by-group interaction P=0.002). Interval vaccination was associated with more stable cognition, contrasting with steeper declines in unvaccinated individuals. These findings support prospective evaluation of recombinant zoster vaccination as a potential strategy to improve outcomes in patients with established dementia.

The recent MPXV epidemic across Africa revealed extensive viral diversity and complex transmission dynamics, prompting a continent-wide genomic investigation. We analysed 3,450 high-quality MPXV virus whole genomes from 24 African Union Member States, revealing the complex and concurrent circulation of Subclades Ia, Ib, IIa, and IIb. Subclade Ia showed high levels of virus diversity in reservoir hosts in Central Africa, detected through zoonotic transmission and some sustained human outbreak lastly detected. In contrast, Clade Ib exhibited signatures of sustained human to human transmission across Eastern and Southern Africa. Clade IIa remains largely zoonotic in West Africa. Like Ia, IIb shows continued zoonotic transmission, and sustained human outbreak linked to lineage G1 and G2 circulation. Phylogeographic analyses revealed frequent cross border transmission and interconnectedness, which was aligned with both human mobility corridors and international boundaries. For instance, the Democratic Republic of the Congo or Sierra Leone seems to emerge as a source of regional exportation, while the Cameroon and Nigeria, CAR and Cameroon or CAR and DRC interfaces reflected ongoing cross border zoonotic spillovers. These findings underscore the need for harmonised genomic surveillance, APOBEC3-aware triage, and integrated One Health strategies to prevent local outbreaks from escalating into regional epidemics and to inform vaccine deployment and public health preparedness.

Background Use of oral cholera vaccine (OCV) is globally recommended as a public health response to cholera outbreaks, alongside water, sanitation and hygiene (WASH) interventions. Estimating vaccine effectiveness during emergencies in low-and middle-income countries is challenging because vaccination campaigns are often implemented over short time frames, while individual-level data are frequently incomplete due to constraints in infrastructure, resources and data systems. There is a need for pragmatic approaches that can generate timely, policy-relevant evidence using routinely collected data. Methods We analysed routine surveillance data from a large 2022-2023 cholera outbreak in Blantyre District, Malawi. The EpiEstim framework was used to generate estimates of the time-varying reproduction number (Rt) from line-listed case data. We modelled changes in Rt as a function of cumulative OCV coverage using a log-linear framework and propagated uncertainty through posterior sampling. Lagged WASH exposure variables were incorporated in the model to generate adjusted vaccine effectiveness estimates and to explore potential interaction effects. Sensitivity analyses assessed robustness to alternative lag structures. Findings The Blantyre outbreak was characterised by an initial period of low-level transmission followed by a sharp increase in cases from late November 2022, after which transmission declined steadily through April 2023. This decline coincided with the implementation of a reactive OCV campaign. The majority of the cases were among middle-aged men living in urban Blantyre. The unadjusted vaccine-associated reduction in transmission was estimated at 53.52% (95% credible interval (CrI):42.5-64.1%). After adjusting for a 7-day rolling average WASH activity, total vaccine effectiveness increased to 62.1% (95% CrI: 49.3-74.9%). Sensitivity analyses using alternative lag structures for WASH exposure produced comparable adjusted estimates. Interpretation Implementation of OCV contributed to a substantial reduction in cholera transmission during the outbreak. This study demonstrates a feasible approach for estimating vaccine-attributable impact whilst accounting for public health and social measures, such as WASH interventions. The methods described will be useful in outbreaks where classical observational designs are not possible, providing actionable evidence to policy makers for outbreak response in resource-limited settings.

BackgroundWidespread immunity from vaccination and infection has reduced COVID-19 morbidity and mortality, but this immunity varies across the population. Understanding how repeated antigenic exposures influence antibody responses helps to inform future vaccination strategies. MethodsSerum samples collected one and six months after XBB.1.5 vaccination from 25 generally healthy healthcare workers with varying exposure histories were assessed for neutralizing activity against a range of variants, from pre-Omicron variants to latest Omicron JN.1 sublineage variants and divergent BA.3.2 variants, using lentiviral pseudoviruses. Participants were stratified by vaccination and infection history. ResultsXBB.1.5 vaccination elicited broad neutralizing responses, with strong boosting against previously encountered antigens relative to vaccine-matched XBB.1.5 and newer variants. Geometric mean neutralization titers were generally comparable across exposure groups, indicating limited influence of prior Omicron infection or bivalent vaccination, though intra-group heterogeneity was observed. At six months, overall titers declined by 36-62%. Titers remained highest against the pre-Omicron and lowest against JN.1 sublineage variants. N-terminal glycosylation (DelS31, T22N) modestly affected neutralization. ConclusionsXBB.1.5 vaccination elicited broad neutralizing antibody responses against previously encountered and vaccine-matched antigens regardless of exposure history, but titers waned after six months. This waning, compounded by continued emergence of immune-evasive variants and heterogenous population immunity, underscores the need for continually monitoring neutralizing antibody durability and breadth to guide evidence-based COVID-19 vaccine formulation updates.

Drug resistance hampers malaria treatment and control. Resistance to nearly all clinically used antimalarials has emerged and spread globally. With multi-drug-resistant parasites now on the rise, understanding resistance mechanisms, and their ability to spread, is crucial for optimal treatment and control strategies. Clindamycin is an apicoplast-targeting antimalarial used as a partner compound in second-line treatment combinations, but mechanisms of clindamycin resistance remain largely unexplored, and it is unclear whether resistant parasites could spread readily. We selected in vitro for clindamycin resistance in African and Southeast Asian strains of Plasmodium falciparum. All resistant lines carried mutations in the apicoplast-encoded large ribosomal subunit RNA (23S rRNA), reminiscent of clindamycin resistance mechanisms found in bacteria. We recovered three different mutations, all located in the peptidyl transferase region of apicoplast 23S rRNA. Each 23S rRNA mutation was associated with >20-fold resistance, although some mutants grew extremely poorly in vitro and therefore may lack clinical relevance in vivo. We assessed how well our most vigorously growing 23S rRNA mutant could infect Anopheles mosquitoes and found a modest reduction in vector infectivity, indicating that high-level clindamycin resistance is likely to be transmissible in the field. This is in contrast to atovaquone resistance, which exhibits a total block to transmission (and hence spread), and azithromycin resistance, which does not significantly impact P. falciparum development in the mosquito.

Background: The 2025/2026 COVID-19 vaccine season introduced updated formulations targeting the LP.8.1 lineage. This study assessed the absolute vaccine effectiveness (aVE) of mRNA-1283 and BNT162b2 on COVID-19 outcomes in adults aged [&ge;]65 years. Methods: Background: The 2025/2026 COVID-19 vaccine season introduced updated formulations targeting the LP.8.1 lineage. This study assessed the absolute vaccine effectiveness (aVE) of mRNA-1283 and BNT162b2 on COVID-19 outcomes in adults aged [&ge;]65 years. Methods: This retrospective study used linked electronic health record and administrative claims data through Jan 31, 2026. Adults [&ge;]65 years who received the mRNA-1283 or BNT162b2 2025/2026 COVID-19 vaccine were matched to unvaccinated individuals. Inverse probability of treatment weighting was applied to matched cohorts of each vaccine to balance covariates. Each vaccine was evaluated independently against its own unvaccinated comparator group. aVE against COVID-19 related hospitalization and medically-attended COVID-19 was estimated using Cox proportional hazards models; aVE = 100 x (1 - hazard ratio [HR]). Results: We identified 233,072 mRNA-1283 recipients and 422,610 BNT162b2 recipients [&ge;]65 years. The aVE (95% confidence interval) of mRNA-1283 against COVID-19 related hospitalization and medically-attended COVID-19 was 59.3% (39.0%, 72.9%) and 42.0% (35.0%, 48.3%) among adults [&ge;]65 years and 66.9% (45.9%, 79.8%) and 50.2% (42.1%, 57.2%) in [&ge;]75 years, respectively. The aVE of BNT162b2 against COVID-19 related hospitalization and medically-attended COVID-19 was 48.3% (32.4%, 60.5%) and 41.2% (36.2%, 45.8%) in [&ge;]65 years and 45.9% (26.0%, 60.4%) and 44.0% (37.8%, 49.6%) in [&ge;]75 years, respectively. Conclusions: This is the first real-world evidence showing that mRNA-1283 prevents COVID-19-related hospitalizations and medically attended events in vulnerable older adults at highest risk of severe disease. These findings support mRNA-1283 as an important public health tool for reducing the ongoing burden of COVID-19.Results: We identified 233,072 mRNA-1283 recipients and 422,610 BNT162b2 recipients [&ge;]65 years. The aVE (95% confidence interval) of mRNA-1283 against COVID-19 related hospitalization and medically-attended COVID-19 was 59.3% (39.0%, 72.9%) and 42.0% (35.0%, 48.3%) among adults [&ge;]65 years and 66.9% (45.9 %, 79.8%) and 50.2% (42.1%, 57.2%) in [&ge;]75 years, respectively. The aVE of BNT162b2 against COVID-19 related hospitalization and medically-attended COVID-19 was 48.3% (32.4%, 60.5%) and 41.2% (36.2%, 45.8%) in [&ge;]65 years and 45.9% (26.0%, 60.4%) and 44.0% (37.8%, 49.6%) in [&ge;]75 years, respectively. Conclusions: This is the first real-world evidence showing that mRNA-1283 prevents COVID-19-related hospitalizations and medically attended events in vulnerable older adults at highest risk of severe disease. These findings support mRNA-1283 as an important public health tool for reducing the ongoing burden of COVID-19.

Antimicrobial resistance is one of the most serious challenges to global health, yet the development of new molecules with novel mechanisms of action to combat resistance is lacking. Here, we report the discovery of molecular glue-like compounds that recruit TEM-family {beta}-lactamases to the bacterial protease DegP for degradation. {beta}-lactamase inhibitor tazobactam was found to accelerate degradation of TEM {beta}-lactamases by DegP, which was further enhanced by linkerless incorporation of dipeptide motifs enriched among DegP substrates. The resulting molecular glue-like degraders showed improved synergy with {beta}-lactam piperacillin against resistant E. coli compared to tazobactam, as well as good pharmacokinetic properties for oral dosing. Collectively, this work establishes periplasmic targeted protein degradation as a promising new mechanism for combating {beta}-lactamase resistance.

Accurate prediction of protein-ligand interactions is central to computational drug discovery. Recent foundation models such as Boltz-2 have achieved remarkable accuracy in binding affinity prediction, yet their prohibitive computational cost remains a major barrier to large-scale virtual screening. Here we introduce FlashBind, a lightweight structure-based model that achieves a 50x speedup over Boltz-2 at inference time by replacing expensive structure prediction with a fast docking model and substituting costly PairFormer modules with a streamlined EGNN architecture. FlashBind matches Boltz-2 on standard virtual screening benchmarks and demonstrates superior generalization to enzyme-substrate specificity prediction. To evaluate real-world applicability, we apply FlashBind to target-based antibiotic screening against the essential bacterial proteins in E. coli and show that FlashBind substantially outperforms Boltz-2 and other virtual screening baselines. Notably, several top-ranked candidates exhibit potent inhibition of DnaG and effective bacterial growth inhibition against E. coli in wet-lab validation. Together, these results demonstrate that FlashBind bridges the gap between accuracy and efficiency, enabling ultra-fast, high-fidelity screening of massive chemical libraries for drug discovery.

West Nile virus (WNV) is a mosquito-borne pathogen of global concern that can cause fatal neuroinvasive disease. No specific prophylaxis or treatment exists for WNV or related orthoflavivirus infections, and the determinants of human disease severity remain poorly understood. Here, we report that neutralizing autoantibodies against type I interferons do not impair antiviral antibody development. Among the fully human monoclonal antibodies with potent neutralizing activity against WNV that were discovered, W010 targets a unique epitope within the envelope protein domain III (EDIII) and confers both pre- and post-exposure protection in a murine WNV model, even when interferon signaling is impaired. A second protective antibody, W014, exhibits broad cross-neutralization of other pathogenic orthoflavivirus members, including Japanese encephalitis virus, Murray Valley encephalitis virus, Saint Louis encephalitis virus, and Usutu virus. These findings identify key neutralizing epitopes on WNV EDIII and provide candidates for the development of antibody-based interventions against encephalitic orthoflavivirus infections.

West Nile virus (WNV) is the causative agent of fatal West Nile encephalitis. To date, no human vaccine against WNV has been approved. Adjuvants are important for developing effective and affordable vaccines that enhance the immunogenicity and decrease the required antigen doses. In this study, we assessed the efficacy of AddaS03, a synthetic adjuvant analogous to AS03, in a WNV subunit vaccine composed of soluble recombinant envelope protein (sEnv). Using a passive immunization mouse model, we defined the neutralizing antibody titer threshold required for protection against lethal WNV infections and applied this threshold as a surrogate marker to evaluate adjuvant efficacy. AddaS03-adjuvanted formulations elicited markedly higher neutralizing antibody titers compared to Alhydrogel adjuvant 2% (Alhydrogel), even at suboptimal antigen doses, and consistently exceeded the defined protective threshold titer. Moreover, in a sequential challenge mouse model, AddaS03-adjuvanted vaccines completely protected mice from symptomatic WNV infections, whereas Alhydrogel-adjuvanted vaccines failed to confer full protection. Collectively, these findings demonstrate that AddaS03 is a promising adjuvant for WNV subunit vaccine development and highlights the utility of a passive immunization model for defining protective antibody thresholds as a surrogate marker for vaccine evaluation.

The emergence of new SARS-CoV-2 variants and breakthrough infections underscores the need for next-generation vaccines capable of protecting from natural infection and/or preventing virus transmission to others. Intranasal vaccination offers a promising approach by eliciting local immune responses in the nasal mucosa, the primary site of infection and reservoir for transmissible virus. We evaluated two live-attenuated, respiratory syncytial virus vectored vaccines in which the RSV F and G surface glycoproteins were replaced with a chimeric SARS-CoV-2 Spike protein from either the ancestral USA/WA-1/2020 strain (MV-014-212) or the Delta variant (MV-014-212-delta). A single intranasal dose of either vaccine elicited systemic and mucosal immunity in K18-hACE2 mice, including serum neutralizing antibodies, Spike-specific memory B cells and plasmablasts, and Spike-specific CD8 lung-resident memory T cells. Although MV-014-212-delta vaccination provided the best protection against Delta variant virus challenge, both vaccines decreased viral loads in nasal discharge, lung and brain, and reduced weight loss and mortality. In naturally acquired infection studies, vaccinated hamsters exposed to infected cagemates exhibited minimal weight loss, limited viral replication within the nasal mucosa, and attenuated lung pathology. Therefore, intranasal RSV-vectored vaccines can elicit broad protective respiratory immunity, suggesting that this platform could be leveraged for other respiratory pathogens.

BackgroundCoronavirus outbreaks remain a persistent threat to global health, and vaccines based primarily on spike-specific immune responses are susceptible to antigenic variation. T-cell immunity directed against conserved internal viral proteins may provide a complementary and more variant-tolerant strategy for next-generation coronavirus vaccines. MethodsWe combined machine learning-guided antigen prioritization with ex vivo functional immunological validation to identify conserved non-spike T-cell targets across betacoronaviruses. Candidate sequences were screened for immunogenicity using primary human peripheral blood mononuclear cells from healthy donors using intracellular cytokine staining and activation-induced marker assays. Top-ranked conserved regions were incorporated into multiepitope mRNA constructs, and their intracellular expression and HLA class I presentation were confirmed by immunopeptidomics. Immunogenicity was further evaluated ex vivo and in vivo using mRNA immunization of mice and T-cell FluoroSpot assays. FindingsAcross a panel of 97 peptides derived from 19 viral proteins, evolutionary conservation across distinct betacoronavirus taxa was strongly associated with functional T-cell immunogenicity in human donors. Highly conserved peptides elicited significantly stronger and more frequent CD4 and CD8 T-cell responses than taxon-restricted peptides. Multiepitope mRNA constructs encoding conserved regions were efficiently expressed and presented on HLA class I molecules and induced T-cell responses in human PBMCs. In mice, mRNA immunization with conserved multiepitope constructs generated robust interferon-{gamma}- and interleukin-2-producing T-cell responses that exceeded those induced by unconserved control constructs. InterpretationThese results link evolutionary conservation to functional cellular immunogenicity and demonstrate the feasibility of multiepitope mRNA delivery for inducing conserved coronavirus-directed T-cell responses. Although protective efficacy remains to be established, conservation-guided antigen selection represents a scalable strategy for developing T-cell-focused vaccines with broad lineage coverage, supporting pandemic preparedness beyond spike-centered immunity. FundingThe research was supported by CEPI, NEC, University of Oslo and Oslo university hospital. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSPrior coronavirus vaccine development has focused predominantly on spike protein-directed neutralizing antibodies. While highly effective against matched strains, spike-centered immunity is vulnerable to antigenic drift and lineage-specific escape. Multiple observational and experimental studies have shown that T-cell responses, particularly against internal viral proteins, are more conserved and correlate with reduced disease severity and cross-variant recognition. Epitope prediction algorithms and immunoinformatics approaches have been widely used to nominate candidate T-cell targets; however, systematic functional validation of conserved non-spike antigens across betacoronaviruses in primary human immune systems, combined with antigen presentation data and in vivo vaccine testing, has remained limited. Searches of PubMed and bioRxiv up to December 2025 using terms including "coronavirus T-cell vaccine," "conserved coronavirus epitopes," "betacoronavirus cross-reactive T cells," and "mRNA T-cell vaccine" identified studies demonstrating cross-reactive T-cell immunity and computational epitope selection, but few integrated machine-learning-guided antigen prioritization with ex vivo human functional screening, immunopeptidomics, and in vivo mRNA immunization in a unified workflow. Added value of this studyThis study provides an integrated experimental and computational framework for identifying and validating conserved non-spike T-cell antigens across betacoronaviruses. We functionally screened a panel of candidate peptides derived from multiple viral proteins and demonstrated that evolutionary conservation across species is strongly associated with T-cell immunogenicity. We further demonstrate that multiepitope mRNA constructs encoding these top-ranked conserved regions can be intracellularly expressed, presented on HLA class I molecules to induce polyfunctional T-cell responses in primary human PBMCs. Finally, in vivo mRNA immunization in mice induces robust interferon-{gamma} and interleukin-2 T-cell responses exceeding those induced by unconserved control constructs. Together, these findings link evolutionary conservation to functional cellular immunogenicity and extend beyond in silico prediction by demonstrating antigen processing, presentation, and immunogenicity across human and murine systems. Implications of all the available evidenceCollectively, the available evidence indicates that T-cell immunity directed toward conserved internal coronavirus proteins represents a complementary and potentially more variant-tolerant axis of vaccine design than spike-only strategies. Our findings suggest that evolutionary conservation can serve as a practical selection principle for prioritizing T-cell antigens with broad lineage coverage and that multiepitope mRNA delivery is a feasible platform for inducing such responses. While direct protection and heterologous challenge studies will be required to establish clinical efficacy, the integration of computational prioritization with functional validation supports a scalable approach to pandemic preparedness that may be applicable to other rapidly evolving viral families.

Chronic hepatitis B persists due to the stability of nuclear covalently closed circular DNA (cccDNA), which maintains viral transcription despite prolonged antiviral therapy, highlighting the need for strategies that suppress cccDNA via host-targeted mechanisms. Here, we identify Spiperone, a clinically approved compound, as a repurposed anti-HBV candidate with strong translational potential. Spiperone robustly reduced HBsAg, HBeAg, viral DNA, and pgRNA across HepG2.2.15, HBV-infected HepG2-NTCP-C4 and HepaRG cells, and multiple in vivo models, including HBV transgenic, hydrodynamic injection, and AAV- HBV1.04x models. Notably, intrahepatic cccDNA was significantly diminished. In combination, Spiperone potentiated tenofovir activity, exhibiting synergistic effects, while both intraperitoneal and oral administration reduced antigenemia and viremia. Mechanistically, Spiperone activated the PERK-eIF2-ATF4 arm of the ER stress response, coupled with mitochondrial perturbation and cytosolic release of oxidized mitochondrial DNA, leading to activation of IFI16-STING-IRF3 signaling. This cascade induced type I interferon (IFN-I) and interferon-stimulated genes. ChIP-qPCR further demonstrated reduced enrichment of activating histone marks on cccDNA, consistent with transcriptional repression. Collectively, these findings position Spiperone as a host-directed antiviral that converges ER stress-linked innate immunity and epigenetic repression to suppress cccDNA, supporting its advancement in combination strategies toward a functional cure for chronic HBV infection.

For millions of immunocompromised individuals, vaccines may not elicit adequate protection from infections, so alternative strategies for pre-exposure prophylaxis are essential. There is only one non-vaccine product authorized in the U.S. as pre-exposure prophylaxis against COVID-19: the monoclonal antibody pemivibart. We previously showed that pemivibart had lower neutralizing activity in vitro against many recent dominant SARS-CoV-2 variants, such as KP.3.1.1, NB.1.8.1, and LP.8.1.1, than it had against JN.1, which was dominant when the antibody was first authorized. The manufacturer of pemivibart (Invivyd) recently initated clinical testing of a new monoclonal antibody derived from pemivibart, VYD2311, but there are no available studies of the activity of VYD2311 against dominant and emerging SARS-CoV-2 variants. Here, using pseudovirus neutralization assays, we measured the neutralizing activity of laboratory-synthesized VYD2311 and pemivibart against dominant and emerging SARS-CoV-2 variants, including XFG, NB.1.8.1, and the genetically distant BA.3.2.2. We found that VYD2311 potently neutralized all tested variants in vitro, dramatically more so than pemivibart. Combined with interpretation of earlier clinical trials of a parental antibody product, we conclude that VYD2311 is a promising candidate for passive immunoprophylaxis against COVID-19, particularly for those who do not respond well to vaccination.

New tuberculosis (TB) vaccines for adults and adolescents could transform TB prevention programs, but their impact depends on successful implementation. We investigated willingness to be vaccinated with a new TB vaccine in a high HIV and TB burden setting in southern Mozambique in 2024 using a mixed methods approach involving a cross-sectional survey and concurrent in-depth interviews. In 151 surveys and 23 interviews, we found that willingness to receive a new TB vaccine among adults and adolescents was 77% (148/192) overall. In multivariable analysis, adolescents were more willing to receive a new TB vaccine than adults even when adjusting for other factors which may influence vaccination decisions (adjusted OR: 5.6, 95% CI: 1.7-17.7). Personal experience with TB and greater knowledge of the disease was also linked with willingness to be vaccinated. Qualitative findings reinforced quantitative findings, further clarifying that even among those who expressed hesitancy, a safe and effective TB vaccine endorsed by healthcare workers, government agencies, and community leaders would likely have high uptake. Our findings are specific to southern Mozambique and can shape vaccine introduction efforts after a TB vaccine is licensed and approved for use in this age group.

Severe fever with thrombocytopenia syndrome virus (SFTSV) and Heartland virus (HRTV) are emerging tick-borne bandaviruses. They have high case fatality rates (10%), and no FDA-approved vaccines exist for disease prevention. SFTSV and HRTV are therefore identified as priority pathogens. A recombinant vesicular stomatitis virus (rVSV) vaccine, which replaces the original VSV glycoprotein with the SFTSV glycoproteins, shows early promise for SFTSV as it induces strong immune responses that are protective against lethal challenge. However, rVSV-SFTSV is highly attenuated in cell culture, which may be due to incompatibility between the assembly sites of SFTSV (the Golgi and ERGIC) and that of VSV (the plasma membrane). In this study, we identify a noncanonical COPI binding motif found in the cytoplasmic tail of SFTSV glycoproteins and demonstrate that an amino acid substitution in this motif (K1071A) inhibits binding to COPI. This mutation results in increased surface expression of SFTSV glycoproteins, improved incorporation onto VSV virions, and enhanced replication of rVSV-SFSTV in vitro. A mutation in a homologous site (K1074A) of HRTV has similar results, and rVSV-HRTV K1074A exhibits increased replication in vitro and in vivo. We show that vaccination with rVSV-HRTV K1074A results in improved induction of neutralizing antibody responses in immunocompetent C57BL/6 mice, and neutralizing antibodies elicited by vaccination are protective when administered to severely immunocompromised mice via passive transfer. Overall, our study identifies a mutation that improves the efficacy of the rVSV-SFTSV vaccine candidate and introduces the first vaccine candidate directly addressing HRTV infections. ImportanceSevere fever with thrombocytopenia syndrome virus (SFTSV) and Heartland bandavirus (HRTV) are emerging tick-borne viruses with high fatality rates. FDA-approved vaccines and antiviral drugs are unavailable but critically needed. We identify an important mutation in the SFTSV glycoprotein that disrupts a previously unreported COPI binding site. The mutation improves the efficacy of the previously described recombinant vesicular stomatitis virus vaccine candidate for SFTSV (rVSV-SFTSV). We also develop an rVSV-HRTV vaccine and show potent induction of neutralizing antibodies and protection from lethal challenge. This is the first study directly addressing the lack of vaccines specifically targeting HRTV.