DENV Peptides Delivered as Spherical Nucleic Acid Constructs Enhance Antigen Presentation and Immunogenicity in vitro and in vivo.

Background: The global prevalence of Dengue virus (DENV) infection poses a significant health risk, urging the need for effective vaccinations. Peptide vaccines, known for their capacity to induce comprehensive immunity against multiple virus serotypes, offer promise due to their stability, safety, and design flexibility. Spherical nucleic acid (SNA), particularly those with gold nanoparticle cores, present an attractive avenue for enhancing peptide vaccine efficacy due to their modularity and immunomodulatory properties. Methods: The spherical nucleic acid-TBB (SNA-TBB), a novel nanovaccine construct, was fabricated through the co-functionalization process of SNA with epitope peptide, targeting all four serotypes of the DENV. This innovative approach aims to enhance immunogenicity and provide broad-spectrum protection against DENV infections. The physicochemical properties of SNA-TBB were characterized using dynamic light scattering, zeta potential measurement, and transmission electron microscopy. In vitro assessments included endocytosis studies, cytotoxicity evaluation, bone marrow-dendritic cells (BMDCs) maturation and activation analysis, cytokine detection, RNA sequencing, and transcript level analysis in BMDCs. In vivo immunization studies in mice involved evaluating IgG antibody titers, serum protection against DENV infection and safety assessment of nanovaccines. Results: SNA-TBB demonstrated successful synthesis, enhanced endocytosis, and favorable physicochemical properties. In vitro assessments revealed no cytotoxicity and promoted BMDCs maturation. Cytokine analyses exhibited heightened IL-12p70, TNF-α, and IL-1ß levels. Transcriptomic analysis highlighted genes linked to BMDCs maturation and immune responses. In vivo studies immunization with SNA-TBB resulted in elevated antigen-specific IgG antibody levels and conferred protection against DENV infection in neonatal mice. Evaluation of in vivo safety showed no signs of adverse effects in vital organs. Conclusion: The study demonstrates the successful development of SNA-TBB as a promising nanovaccine platform against DENV infection and highlights the potential of SNA-based peptide vaccines as a strategy for developing safe and effective antiviral immunotherapy.

The greatest Dengue epidemic in Brazil: Surveillance, Prevention, and Control.

In this review, we discuss dengue surveillance, prevention, and control measures in Brazil. Data on dengue epidemics between 2000 and 2024 indicates an increase in the number of dengue cases and deaths. Global climate change is a key driver of this growth. Over the past 25 years, nearly 18 million Brazilians have been infected with the dengue virus, and the highest number of dengue cases in Brazil's history is projected to reach 2024. Dengue mortality in Brazil increased geographically over time. As of June, there were approximately 6 million probable cases and 4,000 confirmed deaths in Brazil, which represents the greatest dengue epidemic to date. Several technologies have been developed to control Aedes aegypti, including the deployment of Wolbachia-infected mosquitoes, indoor residual spraying, sterile insect techniques, and mosquito-disseminated insecticides. The Ministry of Health recommends integrating these technologies into health services. Brazil is the first country to incorporate the Takeda vaccine into its public health system, and the Butantan vaccine is currently undergoing Phase 3 clinical trials. Increasing the vaccination coverage and implementing novel Ae. aegypti control technologies could reduce the number of dengue cases in Brazil in the coming years. Community activities such as home cleaning and elimination of potential mosquito breeding sites, facilitated by social media and health education initiatives, must continue to achieve this reduction. Ultimately, a multisectoral approach encompassing sanitary improvements, mosquito control, vaccination, and community mobilization is crucial in the fight against dengue epidemics.

Role of the dengue vaccine TAK-003 in an outbreak response: Modeling the Sri Lanka experience.

BACKGROUND: Outbreaks of dengue can overburden hospital systems, drastically reducing capacity for other care. The 2017 dengue serotype 2 (DENV-2) outbreak in Sri Lanka coincided with vaccination in an ongoing phase 3 efficacy trial of a tetravalent dengue vaccine, TAK-003 (NCT02747927). Here, we present data on the efficacy of TAK-003 following two doses of the vaccine administered 3 months apart in participants aged 4-16 years in Sri Lanka. In addition, we have used the 2017 outbreak dynamics to model the potential impact of TAK-003 on virologically confirmed dengue (VCD) cases and hospitalizations during an outbreak situation. METHODOLOGY/PRINCIPAL FINDINGS: Modeling was performed using an age-structured, host-vector, spatial and stochastic transmission model, assuming 65% vaccine coverage and 30 days until initiation of vaccination. Efficacy of TAK-003 against VCD and hospitalized VCD cases was based on data against DENV-2 from the first year of the phase 3 trial. Vaccine efficacy and safety findings in Sri Lanka were in line with those of the overall trial population. The efficacy estimates in Sri Lanka up to the first 12 months after the second dose of TAK-003 were 94.7% and 95.7% against VCD and hospitalized VCD cases, respectively. Modeling of the trial data over an extended geographic area showed a substantial reduction in cases and a flattening of outbreak curves from TAK-003 use. The baseline vaccination scenario (initiation at 30 days, 65% target coverage, vaccine effective at 14 days, 70% hospitalization rate, VE of 95% for VCD and 97% for hospitalized VCD, and 47% for asymptomatic) resulted in a 69.1% reduction in VCD cases and 72.7% reduction in VCD hospitalizations compared with no vaccination. An extreme high scenario (vaccination initiated at Day 15, 80% coverage rate, baseline VE) resulted in 80.3% and 82.3% reduction in VCD and VCD hospitalizations, respectively. Vaccine performance, speed of vaccination campaign initiation, and vaccine coverage were key drivers in reducing VCD cases and hospitalizations. CONCLUSIONS/SIGNIFICANCE: Overall, the study and modeling results indicate that TAK-003 has the potential of meaningful utility in dengue outbreaks in endemic areas.

[Observations on the dengue vaccination strategy in Argentina]. / Observaciones sobre la estrategia de vacunación contra el dengue en Argentina.

A new dengue vaccine has recently been licensed in Argentina, with the Argentine government planning to acquire it in order to develop a vaccination strategy. As the disease is gradually following a path to endemicity in some regions of the country, the incorporation of these vaccines will have the potential to tackle the growing incidence of the disease and to reduce the disease burden. However, the establishment of the vaccination programme may also be susceptible of threats related to the epidemiological shift of the disease. Selecting a specific age group for the vaccine may result in a change in the peak incidence to other age groups more susceptible to severe forms of the disease, such as children or the elderly. Furthermore, the perception of protection following vaccine introduction in one jurisdiction may reduce adherence to vector control activities, increasing the risk of virus introduction and transmission in other areas not prioritised by the vaccination strategy, and the risk of other arboviral diseases such as Zika and chikungunya fever. These and other potential limitations to be considered prior to the implementation of vaccination programmes are discussed in this article, with a series of recommendations on how to address these concerns. These recommendations can help decision makers and public health practitioners at this early stage of the vaccination programme development.

Una nueva vacuna contra el dengue ha sido recientemente aprobada en Argentina, y el gobierno argentino se encuentra planificando su adquisición para desarrollar una estrategia de vacunación. Mientras la enfermedad se está dirigiendo gradualmente hacia la endemicidad en algunas regiones del país, la incorporación de estas vacunas tendrá el potencial de atacar la creciente incidencia de la enfermedad y de reducir su carga. Sin embargo, el establecimiento de un programa de vacunación puede también ser susceptible de amenazas relacionadas con el cambio epidemiológico de la enfermedad. La selección de un grupo de edad específico para la vacunación puede resultar en un cambio en el pico de la incidencia hacia otros grupos de edad más vulnerables a las formas graves de la enfermedad, como los niños o los ancianos. Además, la percepción de protección luego de la introducción de la vacuna en una jurisdicción puede reducir la adherencia a las actividades de control del vector, incrementando el riesgo de introducción y transmisión del virus en otras áreas no priorizadas por la estrategia de vacunación, y aumentando el riesgo de otras arbovirosis como las fiebres Zika y chikungunya. Estas y otras potenciales limitaciones para ser consideradas antes de la implementación de los programas de vacunación son discutidas en este artículo, en conjunto con una serie de recomendaciones sobre cómo abordar estas preocupaciones. Estas recomendaciones pueden resultar de utilidad para los tomadores de decisión y actores sanitarios, en esta etapa temprana del desarrollo de un programa de vacunación.

Effectiveness and safety of the tetravalent TAK-003 dengue vaccine: a systematic review.

In Argentina, the dengue virus has experienced an increase in recent years. This study aims to conduct a systematic review to evaluate the effectiveness and safety of the TAK-003 tetravalent dengue vaccine in this context. A systematic review of randomized controlled trials comparing the effectiveness and safety of the vaccine with placebo in the general population was conducted. The search was carried out in Epistemonikos, and two researchers independently assessed the studies. Risk of bias was evaluated using the Cochrane Rob 2 tool. A meta-analysis of the results was performed, and the certainty of evidence was assessed using the GRADE methodology. We concluded, with high certainty of evidence, that the tetravalent dengue vaccine reduces severe infections (RR 0.17, 95% CI 0.12 to 0.24) and infections by the dengue virus (RR 0.40, 95% CI 0.36 to 0.45) in a population ≤17 years. The vaccine may not increase the risk of serious adverse events, although it is important to note the low certainty of evidence (RR 1.04, 95% CI: 0.69-1.55). The use of the tetravalent dengue vaccine decreases the risk of severe and non-severe dengue infections in this population. However, there is low certainty of evidence regarding the vaccine's safety. The decision to vaccinate should consider the magnitude of benefits relative to the risk of infection.

En Argentina, el virus del dengue ha experimentado un aumento en los últimos años. Este estudio se propone realizar una revisión sistemática para evaluar la efectividad y seguridad de la vacuna TAK-003 tetravalente contra el dengue en este contexto. Se llevó a cabo una revisión sistemática de ensayos clínicos controlados aleatorizados que comparaban la efectividad y seguridad de la vacuna con placebo en la población general. La búsqueda se efectuó en Epistemonikos y dos investigadores evaluaron los estudios de manera independiente. El riesgo de sesgo se evaluó con la herramienta Rob 2 de Cochrane. Se realizó un metaanálisis de los resultados y la certeza en la evidencia se evaluó mediante la metodología GRADE. Concluimos, con alta certeza de evidencia, que la vacuna tetravalente contra el dengue reduce las infecciones graves (RR 0.17, IC 95% 0.12 a 0.24) e infecciones por el virus del dengue (RR 0.40, IC 95% 0.36 a 0.45) en una población de ≤17 años. La vacuna podría no incrementar el riesgo de eventos adversos serios, aunque es importante destacar la baja certeza de evidencia (RR 1.04, IC 95%: 0.69-1.55). La aplicación de la vacuna tetravalente contra el dengue disminuye el riesgo de infecciones graves y no graves por el dengue en esta población. No obstante, existe baja certeza en la evidencia en relación a la seguridad de la vacuna. La decisión de la vacunación debe considerar la magnitud de los beneficios en función del riesgo de infección.

Regional molecular epidemiology of dengue and the potential optimization of its control through the use of vaccines. Report of the Arbovirus Committee of the Latin American Society of Pediatric Infectious Diseases, SLIPE.

INTRODUCTION: Dengue disease represents a large and growing global threat to public health, accounting for a significant burden to health systems of endemic countries. The World Health Organization's (WHO) Strategic Advisory Group of Experts (SAGE) and the European Medicines Agency (EMA) currently recommend the use of TAK-003 dengue vaccine in high dengue burden and transmission settings for countries considering vaccination as part of their integrated management strategy for prevention and control of Dengue. AREAS COVERED: This paper describes the main conclusions of a workshop held by the Arbovirus Committee of the Latin American Society of Pediatric Infectious Diseases (SLIPE) in November 2023, to generate consensus recommendations on the introduction of this new vaccine in the region. Considerations were made regarding the molecular epidemiology of dengue infection in the Americas and the need for more precise phylogenetic classification and correlation with clinical outcome and disease severity. EXPERT OPINION: Introduction of dengue vaccine should be considered as an strategy for health entities in the region, with participation of social sectors, scientific societies, and ministries of health that could be able to create a successful vaccination program.

Proceedings of the dengue endgame summit: Imagining a world with dengue control.

The first dengue "endgame" summit was held in Syracuse, NY over August 9 and 10, 2023. Organized and hosted by the Institute for Global Health and Translational Sciences at SUNY Upstate Medical University, the gathering brought together researchers, clinicians, drug and vaccine developers, government officials, and other key stakeholders in the dengue field for a highly collaborative and discussion-oriented event. The objective of the gathering was to discuss the current state of dengue around the world, what dengue "control" might look like, and what a potential roadmap might look like to achieve functional dengue control. Over the course of 7 sessions, speakers with a diverse array of expertise highlighted both current and historic challenges associated with dengue control, the state of dengue countermeasure development and deployment, as well as fundamental virologic, immunologic, and medical barriers to achieving dengue control. While sustained eradication of dengue was considered challenging, attendees were optimistic that significant reduction in the burden of dengue can be achieved by integration of vector control with effective application of therapeutics and vaccines.

[Dengue vaccines, a time for cautious optimism?] / Vaccins contre la dengue, le temps de l'optimisme prudent ?

Vaccine could take a central role in the strategy to reduce the burden of dengue. The development of an effective and safe vaccine must address various immunological challenges. Several vaccines are currently in development. To date, two live-attenuated vaccines have been deployed. Both have an effectiveness that varies depending on the serotypes. The deployment of the Dengvaxia vaccine, which began in 2015, was marked by a major safety alert leading to its use being restricted to previously dengue-seropositive people over 9 years old. The Qdenga vaccine is currently being deployed. There is for now insufficient data to ensure its safety in seronegative people. Some travelers, who have previously been infected with dengue, are a group for whom a vaccination recommendation applies.

Les vaccins pourraient occuper une place centrale dans la stratégie de réduction du fardeau de la dengue. Le développement d'un vaccin efficace et sûr est complexe car il doit relever plusieurs défis immunologiques. Différents vaccins sont en développement. À ce jour, deux vaccins vivants atténués ont été déployés. Tous deux ont une efficacité qui varie selon les sérotypes. Le déploiement du vaccin Dengvaxia, débuté en 2015, a été marqué par une alerte de sécurité majeure conduisant à restreindre son usage aux personnes de plus de 9 ans, préalablement séropositives pour la dengue. Le vaccin Qdenga est en cours de déploiement. Le recul est insuffisant pour assurer son innocuité chez les séronégatifs. Certains voyageurs, ayant déjà été infectés par la dengue, constituent un groupe pour lequel une recommandation vaccinale s'applique.

Dengue: A review of laboratory diagnostics in the vaccine age.

Background. Dengue is an important arboviral infection of considerable public health significance. It occurs in a wide global belt within a variety of tropical regions. The timely laboratory diagnosis of Dengue infection is critical to inform both clinical management and an appropriate public health response. Vaccination against Dengue virus is being introduced in some areas.Discussion. Appropriate diagnostic strategies will vary between laboratories depending on the available resources and skills. Diagnostic methods available include viral culture, the serological detection of Dengue-specific antibodies in using enzyme immunoassays (EIAs), microsphere immunoassays, haemagglutination inhibition or in lateral flow point of care tests. The results of antibody tests may be influenced by prior vaccination and exposure to other flaviviruses. The detection of non-structural protein 1 in serum (NS1) has improved the early diagnosis of Dengue and is available in point-of-care assays in addition to EIAs. Direct detection of viral RNA from blood by PCR is more sensitive than NS1 antigen detection but requires molecular skills and resources. An increasing variety of isothermal nucleic acid detection methods are in development. Timing of specimen collection and choice of test is critical to optimize diagnostic accuracy. Metagenomics and the direct detection by sequencing of viral RNA from blood offers the ability to rapidly type isolates for epidemiologic purposes.Conclusion. The impact of vaccination on immune response must be recognized as it will impact test interpretation and diagnostic algorithms.

Next-generation Dengue Vaccines: Leveraging Peptide-Based Immunogens and Advanced Nanoparticles as Delivery Platforms.

Dengue, caused by the dengue virus (DENV), is a prevalent arthropod-borne disease in humans and poses a significant burden on public health. Severe cases of dengue can be life-threatening. Although a licensed dengue vaccine is available, its efficacy varies across different virus serotypes and may exacerbate the disease in some seronegative recipients. Developing a safe and effective vaccine against all DENV serotypes remains challenging and requires continued research. Conventional approaches in dengue vaccine development, using live or attenuated microorganisms or parts of them often contain unnecessary epitopes, risking allergenic or autoimmune reactions. To address these challenges, innovative strategies such as peptide vaccines have been explored. Peptide vaccines offer a safer alternative by inducing specific immune responses with minimal immunogenic fragments. Chemical modification strategies of peptides have revolutionized their design, allowing for the incorporation of multi-epitope presentation, self-adjuvanting features, and self-assembling properties. These modifications enhance the antigenicity of the peptides, leading to improved vaccine efficacy. This review outlines advancements in peptide-based dengue vaccine development, leveraging nanoparticles as antigen-displaying platforms. Additionally, key immunological considerations for enhancing efficacy and safety against DENV infection have been addressed, providing insight into the next-generation of dengue vaccine development leveraging on peptide-nanoparticle technology.

IgG, IgM, and Nonstructural Protein 1 Response Profiles after Receipt of Tetravalent Dengue Vaccine TAK-003 in a Phase 2 Randomized Controlled Trial.

The profiles of vaccine-induced dengue antibodies may differ from those produced following natural infection and could potentially interfere with the interpretation of diagnostic tests. We assessed anti-dengue IgG and IgM antibodies, and nonstructural protein 1 antigen profiles in the serum of adults who received a single dose of the tetravalent dengue vaccine TAK-003 as either an initially developed high-dose formulation or the standard approved formulation in a phase 2 study in Singapore (#NCT02425098). Immunoglobulin G and IgM profiles during the first 30 days postvaccination varied by baseline serostatus (microneutralization assay). Nonstructural protein 1 antigen was not detected in the serum of any participants. Vaccine-induced IgG and IgM antibodies can affect serological confirmation of subsequent dengue infection in vaccinees. These results highlight the limitations of using serological tests for dengue diagnosis, particularly in a postvaccination setting, and emphasize the need for more sensitive antigen- and molecular-based testing for accurate dengue diagnosis.

Efficacy and immunogenicity following dengue virus-1 human challenge after a tetravalent prime-boost dengue vaccine regimen: an open-label, phase 1 trial.

BACKGROUND: Dengue human infection models (DHIMs) are important tools to down-select dengue vaccine candidates and establish tetravalent efficacy before advanced clinical field trials. We aimed to provide data for the safety and immunogenicity of DHIM and evaluate dengue vaccine efficacy. METHODS: We performed an open-label, phase 1 trial at the University of Maryland (Baltimore, MD, USA). Eligible participants were healthy individuals aged 18-50 years who either previously received a tetravalent dengue purified inactivated vaccine prime followed by a live-attenuated vaccine boost (ie, the vaccinee group), or were unvaccinated flavivirus-naive participants (ie, the control group). Participants in the vaccinee group with detectable pre-challenge dengue virus-1 neutralising antibody titres and flavivirus-naive participants in the control group were inoculated with dengue virus-1 strain 45AZ5 in the deltoid region, 27-65 months following booster dosing. These participants were followed-up from days 4-16 following dengue virus-1 live virus human challenge, with daily real-time quantitative PCR specific to dengue virus-1 RNA detection, and dengue virus-1 solicited local and systemic adverse events were recorded. The primary outcomes were safety (ie, solicited local and systemic adverse events) and vaccine efficacy (ie, dengue virus-1 RNAaemia) following dengue challenge. This study is registered with ClinicalTrials.gov, number NCT04786457. FINDINGS: In January 2021, ten eligible participants were enrolled; of whom, six (60%) were in the vaccinee group and four (40%) were in the control group. Daily quantitative PCR detected dengue virus-1 RNA in nine (90%) of ten participants (five [83%] of six in the vaccinee group and all four [100%] in the control group). The mean onset of RNAaemia occurred on day 5 (SD 1·0) in the vaccinee group versus day 8 (1·5) in the control group (95% CI 1·1-4·9; p=0·007), with a trend towards reduced RNAaemia duration in the vaccinee group compared with the control group (8·2 days vs 10·5 days; 95% CI -0·08 to 4·68; p=0·056). Mild-to-moderate symptoms (nine [90%] of ten), leukopenia (eight [89%] of nine), and elevated aminotransferases (seven [78%] of nine) were commonly observed. Severe adverse events were detected only in the vaccinee group (fever ≥38·9°C in three [50%] of six, headache in one [17%], and transient grade 4 aspartate aminotransferase elevation in one [17%]). No deaths were reported. INTERPRETATION: Participants who had tetravalent dengue purified inactivated vaccine prime and live-attenuated vaccine boost were unprotected against dengue virus-1 infection and further showed increased clinical, immunological, and transcriptomic evidence for inflammation potentially mediated by pre-existing infection-enhancing antibodies. This study highlights the impact of small cohort, human challenge models studying dengue pathogenesis and downstream vaccine development. FUNDING: Military Infectious Disease Research Program and Medical Technology Enterprise Consortium and Advanced Technology International.

A tetravalent dengue virus-like particle vaccine induces high levels of neutralizing antibodies and reduces dengue replication in non-human primates.

Dengue virus (DENV) represents a significant global health burden, with 50% of the world's population at risk of infection, and there is an urgent need for next-generation vaccines. Virus-like particle (VLP)-based vaccines, which mimic the antigenic structure of the virus but lack the viral genome, are an attractive approach. Here, we describe a dengue VLP (DENVLP) vaccine which generates a neutralizing antibody response against all four DENV serotypes in 100% of immunized non-human primates for up to 1 year. Additionally, DENVLP vaccination produced no ADE response against any of four DENV serotypes in vitro. DENVLP vaccination reduces viral replication in a non-human primate challenge model. We also show that transfer of purified IgG from immunized monkeys into immunodeficient mice protects against subsequent lethal DENV challenge, indicating a humoral mechanism of protection. These results indicate that this DENVLP vaccine is immunogenic and can be considered for clinical evaluation. Immunization of non-human primates with a tetravalent DENVLP vaccine induces high levels of neutralizing antibodies and reduces the severity of infection for all four dengue serotypes.IMPORTANCEDengue is a viral disease that infects nearly 400 million people worldwide and causes dengue hemorrhagic fever, which is responsible for 10,000 deaths each year. Currently, there is no therapeutic drug licensed to treat dengue infection, which makes the development of an effective vaccine essential. Virus-like particles (VLPs) are a safe and highly immunogenic platform that can be used in young children, immunocompromised individuals, as well as healthy adults. In this study, we describe the development of a dengue VLP vaccine and demonstrate that it induces a robust immune response against the dengue virus for over 1 year in monkeys. The immunity induced by this vaccine reduced live dengue infection in both murine and non-human primate models. These results indicate that our dengue VLP vaccine is a promising vaccine candidate.

Low-dose dengue virus 3 human challenge model: a phase 1 open-label study.

Dengue human infection models present an opportunity to explore the potential of a vaccine, anti-viral or immuno-compound for clinical benefit in a controlled setting. Here we report the outcome of a phase 1 open-label assessment of a low-dose dengue virus 3 (DENV-3) challenge model (NCT04298138), in which nine participants received a subcutaneous inoculation with 0.5 ml of a 1.4 × 103 plaque-forming unit per ml suspension of the attenuated DENV-3 strain CH53489. The primary and secondary endpoints of the study were to assess the safety of this DENV-3 strain in healthy flavivirus-seronegative individuals. All participants developed RNAaemia within 7 days after inoculation with peak titre ranging from 3.13 × 104 to 7.02 × 108 genome equivalents per ml. Solicited symptoms such as fever and rash, clinical laboratory abnormalities such as lymphopenia and thrombocytopenia, and self-reported symptoms such as myalgia were consistent with mild-to-moderate dengue in all volunteers. DENV-3-specific seroconversion and memory T cell responses were observed within 14 days after inoculation as assessed by enzyme-linked immunosorbent assay and interferon-gamma-based enzyme-linked immunospot. RNA sequencing and serum cytokine analysis revealed anti-viral responses that overlapped with the period of viraemia. The magnitude and frequency of clinical and immunologic endpoints correlated with an individual's peak viral titre.