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Dengue is one of the most important diseases transmitted by mosquitoes. Dengvaxia®, a vaccine registered in several countries, cannot be administered to non-immune individuals and children younger than 9 years old, due to safety reasons. There are two vaccine candidates in phase 3 efficacy trials, but their registration date is completely unknown at this moment. So, the development of new vaccines or vaccine strategies continues to be a priority for the WHO. This work reviews some complementary prime-boost immunization studies against important human pathogens. Additionally, it reviews the results obtained using this regimen of immunization against dengue virus as a potential alternative approach for finding a safe and efficient vaccine. Finally, the main elements associated with this strategy are also discussed. The generation of new strategies of vaccination against dengue virus, must be directed to reduce the risk of increasing viral load through sub-neutralizing antibodies and it must be also directed to induce a polyfunctional T cell response. Complementary prime-boost immunization strategies could emerge as an interesting approach to induce solid immunity or at least to reduce viral load after natural infection, avoiding severe dengue. Subunit vaccine could be safe and attractive antigens for this strategy, especially proteins including B, and T-cells epitopes for inducing humoral and cellular immune responses, which can play an important role controlling the disease.

Introduction: Dengue fever remains as a health problem worldwide. Although Dengvaxia®, was registered in several countries, the results after the immunization of people suggest an increase of risk in non-immune persons and children younger than 9 years old. No other vaccine is registered so far, thus the development of a safe and effective vaccine continues to be a priority for the WHO and the scientific community., Areas Covered: This work reviews the structural and antigenic properties of the capsid protein of Dengue virus, along with results of studies performed to assess the immunogenicity and protective capacity in animals of vaccine candidates based on this protein., Expert Opinion: The generation of a memory cellular immune response alone, after vaccination against Dengue virus, could be advantageous, as there would not be risk of increasing viral infectivity through sub-neutralizing antibodies. However, it is improbable to achieving sterilizing immunity. In this scenario, an infection could stablished but without the appearance of the severe disease. The cell-mediated immunity should keep the virus at bay. The capsid protein induces a protective immune response in animals without the induction of virus-binding antibodies. Vaccine candidates based on this protein could be an attractive strategy to induce protection against the severe Dengue disease.

Tetra DIIIC is a subunit vaccine candidate based on domain III of the envelope protein and the capsid protein of the four serotypes of dengue virus. This vaccine preparation contains the DIIIC proteins aggregated with a specific immunostimulatory oligodeoxynucleotide (ODN 39M). Tetra DIIIC has already been shown to be immunogenic and protective in mice and monkeys. In this study, we evaluated the immunogenicity in mice of several formulations of Tetra DIIIC containing different amounts of the recombinant proteins. The Tetra DIIIC formulation induced a humoral immune response against the four DENV serotypes, even at the lowest dose assayed. In contrast, the highest level of cell-mediated immunity, measured as frequency of IFNγ-producing cells, was detected in animals immunized with the lowest dose. The protective capacity of the tetravalent formulations was assessed using the mouse model of dengue virus encephalitis. Upon challenge, vaccinated mice showed significantly reduced virus replication in all tested groups. This study provides new information about the functionality of Tetra DIIIC as a vaccine candidate and also supports the crucial role of cell-mediated immunity in protection against dengue virus.

Despite the many efforts made by the scientific community in the development of vaccine candidates against dengue virus (DENV), no vaccine has been licensed up to date. Although the immunopathogenesis associated to the disease is a key factor to take into account by vaccine developers, the lack of animal models that reproduce the clinical signs of the disease has hampered the vaccine progress. Non-human primates support viral replication, but they are very expensive and do not show signs of disease. Immunocompromised mice develop viremia and some signs of the disease; however, they are not valuable for vaccine testing. Nowadays, immunocompetent mice are the most used model to evaluate the immunogenicity of vaccine candidates. These animals are resistant to DENV infection; therefore, the intracranial inoculation with neuroadapted virus, which provokes viral encephalitis, represents an alternative to evaluate the protective capacity of vaccine candidates. Previous results have demonstrated the crucial role of cellular immune response in the protection induced by the virus and vaccine candidates in this mouse encephalitis model. However, in the present work we are proposing that the magnitude of the cell-mediated immunity and the inflammatory response generated by the vaccine can modulate the survival rate after viral challenge. We observed that the intracranial challenge of naïve mice with DENV-2 induces the recruitment of immune cells that contribute to the reduction of viral load, but does not increase the survival rate. On the contrary, animals treated with cyclophosphamide, an immunosuppressive drug that affects proliferating lymphocytes, had a higher viral load but a better survival rate than untreated animals. These results suggest that the immune system is playing an immunopathogenic role in this model and the survival rate may not be a suitable endpoint in the evaluation of vaccine candidates based on antigens that induce a strong cellular immune response., (Copyright © 2016 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.)

Our group developed a subunit vaccine candidate against dengue virus based on two different viral regions: the domain III of the envelope protein and the capsid protein. The novel chimeric protein from dengue-2 virus [domain III-capsid (DIIIC-2)], when presented as aggregated incorporating oligodeoxynucleotides, induced anti-viral and neutralizing antibodies, a cellular immune response and conferred significant protection to mice and monkeys. The remaining constructs were already obtained and properly characterized. Based on this evidence, this work was aimed at assessing the immune response in mice of the chimeric proteins DIIIC of each serotype, as monovalent and tetravalent formulations. Here, we demonstrated the immunogenicity of each protein in terms of humoral and cell-mediated immunity, without antigen competition on the mixture forming the formulation tetra DIIIC. Accordingly, significant protection was afforded as measured by the limited viral load in the mouse encephalitis model. The assessment of the tetravalent formulation in non-human primates was also conducted. In this animal model, it was demonstrated that the formulation induced neutralizing antibodies and memory cell-mediated immune response with IFN-γ-secreting and cytotoxic capacity, regardless the route of immunization used. Taken together, we can assert that the tetravalent formulation of DIIIC proteins constitutes a promising vaccine candidate against dengue virus, and propose it for further efficacy experiments in monkeys or in the dengue human infection model, as it has been recently proposed., (© The Japanese Society for Immunology. 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Dengue disease is a global challenge for healthcare systems particularly during outbreaks, and millions of dollars are spent every year for vector control. An efficient and safe vaccine that is cost-effective could resolve the burden that dengue virus imposes on affected countries. We describe here the immunogenicity of a tetravalent formulation of a recombinant fusion protein consisting of E domain III and the capsid protein of dengue serotypes 1-4 (Tetra DIIIC). E domain III is an epitope for efficient neutralizing antibodies while the capsid protein contains T cell epitopes. Besides combining B and T cell epitopes, Tetra DIIIC is highly immunogenic due to its aggregate form and a two-component adjuvant. Following previous studies assessing the monovalent DIIIC formulations, we addressed here the quality and breadth of the T cell- and antibody response of Tetra DIIIC in mice. Tetra DIIIC induced a Th1-type response against all four DENV serotypes and dengue-specific antibodies were predominantly IgG1 and IgG2a and neutralizing, while the induction of neutralizing antibodies was dependent on IFN signaling. Importantly, the Th1 and IgG1/IgG2a profile of the DIIIC vaccine approach is similar to an efficient natural anti-dengue response., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Recombinant fusion proteins containing domain III of the dengue virus envelope protein fused to the P64k protein from Neisseria meningitidis and domain III of dengue virus type 2 (D2) fused to the capsid protein of this serotype were immunogenic and conferred protection in mice against lethal challenge, as reported previously. Combining the domain III-P64k recombinant proteins of dengue virus types 1, 3 and 4 (D1, D3, and D4) with the domain III-capsid protein from D2, we obtained a novel tetravalent formulation containing different antigens. Here, the IgG and neutralizing antibody response, the cellular immune response, and the protective capacity against lethal challenge in mice immunized with this tetravalent formulation were evaluated. The neutralizing antibody response obtained against D1, D2 and D3, together with the high levels of IFNγ secretion induced after stimulation with the four dengue serotypes, supports the strategy of using a new tetravalent formulation containing domain III of the envelope protein fused to the capsid protein of each dengue virus serotype.

Unlabelled: Dengue virus (DENV) infects an estimated 400 million people every year, causing prolonged morbidity and sometimes mortality. Development of an effective vaccine has been hampered by the lack of appropriate small animal models; mice are naturally not susceptible to DENV and only become infected if highly immunocompromised. Mouse models lacking both type I and type II interferon (IFN) receptors (AG129 mice) or the type I IFN receptor (IFNAR(-/-) mice) are susceptible to infection with mouse-adapted DENV strains but are severely impaired in mounting functional immune responses to the virus and thus are of limited use for study. Here we used conditional deletion of the type I IFN receptor (IFNAR) on individual immune cell subtypes to generate a minimally manipulated mouse model that is susceptible to DENV while retaining global immune competence. Mice lacking IFNAR expression on CD11c(+) dendritic cells and LysM(+) macrophages succumbed completely to DENV infection, while mice deficient in the receptor on either CD11c(+) or LysM(+) cells were susceptible to infection but often resolved viremia and recovered fully from infection. Conditional IFNAR mice responded with a swift and strong CD8(+) T-cell response to viral infection, compared to a weak response in IFNAR(-/-) mice. Furthermore, mice lacking IFNAR on either CD11c(+) or LysM(+) cells were also sufficiently immunocompetent to raise a protective immune response to a candidate subunit vaccine against DENV-2. These data demonstrate that mice with conditional deficiencies in expression of the IFNAR represent improved models for the study of DENV immunology and screening of vaccine candidates., Importance: Dengue virus infects 400 million people every year worldwide, causing 100 million clinically apparent infections, which can be fatal if untreated. Despite many years of research, there are no effective vaccine and no antiviral treatment available for dengue. Development of vaccines has been hampered in particular by the lack of a suitable small animal model. Mouse models used to test dengue vaccine are deficient in interferon (IFN) type I signaling and severely immunocompromised and therefore likely not ideal for the testing of vaccines. In this study, we explored alternative models lacking the IFN receptor only on certain cell types. We show that mice lacking the IFN receptor on either CD11c- or LysM-expressing cells (conditional IFNAR mice) are susceptible to dengue virus infection. Importantly, we demonstrate that conditional IFN receptor knockout mice generate a better immune response to live virus and a candidate dengue vaccine compared to IFNAR mice and are resistant to subsequent challenge., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

Dengue is currently one of the most important arthropod-borne diseases, causing up to 25,000 deaths annually. There is currently no vaccine to prevent dengue virus infection, which needs a tetravalent vaccine approach. In this work, we describe the cloning and expression in Escherichia coli of envelope domain III-capsid chimeric proteins (DIIIC) of the four dengue serotypes as a tetravalent dengue vaccine candidate that is potentially able to generate humoral and cellular immunity. The recombinant proteins were purified to more than 85 % purity and were recognized by anti-dengue mouse and human sera. Mass spectrometry analysis verified the identity of the proteins and the correct formation of the intracatenary disulfide bond in the domain III region. The chimeric DIIIC proteins were also serotype-specific, and in the presence of oligonucleotides, they formed aggregates that were visible by electron microscopy. These results support the future use of DIIIC recombinant chimeric proteins in preclinical studies in mice for assessing their immunogenicity and efficacy.

The role of cellular immune response in dengue virus infection is not yet fully understood. Only few studies in murine models propose that CD8(+) T-cells are associated with protection from infection and disease. At the light of recent reports about the protective role of CD8(+) T-cells in humans and the no correlation between neutralizing antibodies and protection observed in several studies, a vaccine based on cell-mediated immunity constitute an attractive approach. Our group has developed a capsid-based vaccine as nucleocpasid-like particles from dengue-2 virus, which induced a protective CD4(+) and CD8(+) cell-mediated immunity in mice, without the contribution of neutralizing antibodies. Herein we evaluated the immunogenicity and protective efficacy of this molecule in monkeys. Neither IgG antibodies against the whole virus nor neutralizing antibodies were elicited after the antigen inoculation. However, animals developed a cell-mediated immunity, measured by gamma interferon secretion and cytotoxic capacity. Although only one out of three vaccinated animals was fully protected against viral challenge, a viral load reduction was observed in this group compared with the placebo one, suggesting that capsid could be the base on an attractive vaccine against dengue., (Copyright © 2014 Elsevier Inc. All rights reserved.)

In previous studies we reported the cloning, expression and purification of the capsid protein from Dengue-2 virus. Subsequently, we described an in vitro-assembly process for the capsid protein, which resulted in nucleocapsid-like particles (recNLPs) that induced functional cell-mediated immunity and protection in mice. Moreover, our group reported the evaluation in non-human primates of the fusion protein P64k-domain III from Dengue-1 (PD10). This protein proved to be immunogenic and protective when Freund's adjuvant, but not alum, was used. Based on the previously demonstrated capacity of recNLPs to potentiate the immunogenicity of heterologous proteins, in this study we assess the immune response elicited by the formulation PD10-recNLPs-alum and its protective capacity against Dengue-1 and Dengue-2 virus. As expected, the humoral immune response was mainly directed against Dengue-1, while high levels of IFN-γ secretion were detected after stimulation with Dengue-1 and Dengue-2. Consistently, animals immunized with the bivalent formulation were significantly protected against challenge with either Dengue serotype. In conclusion, this report describes a novel formulation based on recombinant proteins and alum, which is protective against Dengue-1 and Dengue-2 in mice., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Recombinant fusion protein containing domain III of the dengue envelope protein fused to capsid protein from dengue 2 virus was immunogenic and conferred protection in mice against lethal challenge in previously report. Here, the antigenic specificity of this recombinant protein using anti-dengue antibodies from mice and humans and the cross-reactive humoral and cellular response induced in immunized mice were evaluated. The homologous anti-dengue antibodies showed a higher reactivity to the recombinant protein compared to the wide cross-reactivity observed for viral antigen as determined by ELISA. The IgG anti-dengue and functional antibodies, induced by the recombinant proteins in mice, were highly serotype specific by ELISA, hemaglutination inhibition and plaque reduction neutralizing tests. Accordingly, the cellular immune response determined by the IFNγ and TNFα secretion, was serotype specific. The specificity of serotype associated to this recombinant protein in addition to its high antigenicity, immunogenicity and protecting capacity suggest its advantage as a possible functional and safe vaccine candidate against dengue in a future tetravalent formulation., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Here we evaluated the suitability of the synthetic adjuvant IC31® to potentiate the protective capacity of PD5 protein (domain III of the envelope protein of dengue 2 virus fused to the carrier protein P64k). Unlike Alum, PD5 mixed with IC31® induced complete protection against virus challenge in mice and increased IFN-γ secretion after in vitro re-stimulation. The induced antibody response was highly specific to the homologous serotype and showed both IgG1 and IgG2a subtypes. IC31® is a promising adjuvant for PD5 recombinant protein based vaccination against dengue. Future work should address the suitability of PD5/IC31® formulations in non-human primate models., (Copyright © 2011. Published by Elsevier Ltd.)

Use of a heterologous prime-boost strategy based on a combination of nonreplicative immunogens and candidate attenuated virus vaccines against dengue virus in the same schedule is an attractive approach. These combinations may result in a condensed immunization regime for humans, thus reducing the number of doses with attenuated virus and the time spacing. The present work deals with the evaluation of the heterologous prime-boost strategy combining a novel chimeric protein (domain III-capsid) of dengue virus serotype 2 (DEN-2) and the infective homologous virus in the same immunization schedule in monkeys. Primed monkeys received one dose of infective DEN-2 and were then vaccinated with the recombinant protein. We found that animals developed a neutralizing antibody response after the infective dose and were notably boosted with a second dose of the chimeric protein 3 months later. The neutralizing antibodies induced were long lasting, and animals also showed the ability to induce a specific cellular response 6 months after the booster dose. As a conclusion, we can state that the domain III region, when it is properly presented as a fusion protein to the immune system, is able to recall the neutralizing antibody response elicited following homologous virus infection in monkeys. Further prime-boost approaches can be performed in a condensed regime combining the chimeric domain III-capsid protein and candidate live attenuated vaccines against DEN-2.

In this study, we evaluate in mice a novel formulation containing nucleocapsid-like particles of dengue-2 virus (recNLP) co-immunized with a chimeric protein composed of the dengue-4 envelope domain III fused twice within the meningococcal P64k protein of Neisseria meningitidis (PD24). The animals receiving the PD24-recNLP mixture showed the highest levels of antiviral antibodies. Similar results were obtained for IFNγ secretion levels, indicating a functional Th1 cellular response. Consistently, the percentage of mice surviving after viral challenge was significantly higher for those immunized with the mixture than for those inoculated with PD24 protein alone. In addition, in vivo depletion experiments demonstrated the decisive role of CD4(+) and CD8(+) cells in the protection conferred by immunization with PD24-recNLP. In conclusion, this report demonstrates for the first time the adjuvant capacity of dengue-2 virus recNLP. Additionally, the evidence presented highlights the potential of these particles for enhancing the immune response against heterologous recombinant proteins.

Objective: The aim of the present work was to test the concept of the heterologous prime-boost strategy combining an infective dengue virus with a recombinant chimeric protein carrying domain III of the envelope protein., Methods: Two studies in monkeys, combining recombinant protein PD5 (domain III of the envelope protein from dengue-2 virus, fused to the protein carrier P64k) and the infective dengue virus in the same immunization schedules were carried out. Humoral and cell-mediated immunity were evaluated., Results: In the first study, monkeys received four doses of the protein PD5 and were subsequently infected with one dose of dengue virus. Antibody response measured after virus inoculation was significantly higher compared to that in non-primed monkeys and comparable to that elicited after two doses of infective virus. In a second study, monkeys were infected with one dose of the virus and subsequently boosted with one dose of the recombinant protein, reaching high levels of neutralizing antibodies, which were still detectable 14 months after the last immunization. In addition, the cellular immune response was also recalled., Conclusions: The results obtained in the present work support the approach of heterologous prime-boosting, in either order prime or boost, combining the chimeric protein PD5 (formulated in alum-CPS-A) and an infective dengue virus. The latter could potentially be replaced by an attenuated vaccine candidate., (Copyright 2009 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

A dengue vaccine should induce long-lasting, simultaneous protection to the four dengue viruses while avoiding the immune enhancement of viral infection. Domain III of the dengue envelope protein has been implicated in receptor binding, and is also the target of specific neutralizing antibodies. Domain III has emerged as a promising region for a subunit vaccine candidate. Here, we review the current state of knowledge on vaccine candidates based on domain III. Due to the results obtained concerning the immune response and protection in mice and monkeys, particular attention is paid to the chimeric protein domain III fused to p64k of Neisseria meningitidis.

In the present work, we evaluated the neutralizing capacity of the antibodies induced by dengue virus type 1 and 2 envelope domain III recombinant proteins in monkeys against strains of different dengue virus type 1 and 2 genotypes. Here we demonstrated that dengue virus type 1 and 2 recombinant proteins induced high titers of neutralizing antibodies against different genotype strains.

Virus-like particles are a highly effective type of subunit vaccine that mimics the overall structure of virus particles without containing infectious genetic material. In this work, a particulate form of the recombinant capsid protein from dengue-2 was evaluated in mice to determine the level of protection against viral challenge and to measure the antigen-induced cell-mediated immunity (CMI). The nucleocapsid-like particles (NLPs) adjuvanted with alum did not induce antiviral antibodies. However, splenocytes from the immunized animals secreted high levels of IFN-gamma upon virus stimulation, and a significant protection rate was achieved after challenge with lethal dengue-2 virus. Finally, both IFN-gamma secretion and protection against viral encephalitis were demonstrated to be dependent on CD4(+) and CD8(+) cells. This study provides new evidences regarding the protective role of the CMI in the mouse model without the induction of neutralizing antibodies. Further studies in non-human primates or humanized mice should be carried out to elucidate the usefulness of the NLPs as a potential vaccine candidate against dengue disease.

A vaccine against dengue virus must be able to induce an effective and equivalent immune response to the four viral serotypes; however, some studies have revealed that DEN4 (dengue-virus serotype 4) induces a weaker immune response than the others in quadrivalent (tetravalent') formulations. We have previously reported the protective capacity, in a viral encephalitis murine model, of fusion protein P64k-envelope domain III of DEN1, DEN2 and DEN3. We also reported that the P64k protein can be used as a carrier in two different positions: the insertion following the first 45 amino acids and the fusion at the C-terminus. Considering the low immunogenicity described for DEN4, in the present study we obtained a novel chimaeric protein by inserting two dengue-4 envelope domains III in both sites of P64k (PD24), and hence increasing the presence of the virus in the final construct. After expression in Escherichia coli and semipurification, the protein exhibited a pattern of high molecular mass and was well recognized by human and murine polyclonal antibodies. The protein was finally evaluated in mice, Al(OH)(3) being employed as the adjuvant. Even though the animals exhibited low levels of antiviral antibodies, the recombinant protein induced significant protection against lethal challenge with dengue-4 virus.

The main problem in the development of successful vaccines against dengue based on recombinant proteins is the necessity to use potent adjuvants to reach a proper functional immune response. Our group reported the expression, characterization and immunological evaluation of the recombinant protein PD5, which contains the domain III of the Envelope protein from dengue 2 virus fused to the carrier protein P64k. This construct completely protected monkeys against viral challenge when the Freund's adjuvant was employed. Therefore, to define suitable formulations for human use, the present work relies on the evaluation of PD5, produced with a high purity and under GMP conditions, when formulated either with outer membrane vesicles (OMV) or the serogroup A capsular polysaccharide (CPS-A) from Neisseria meningitidis, both adsorbed on aluminium hydroxide. The antibody response to the formulation containing the CPS-A was clearly superior to that of the formulation with OMV. The experiment of in vivo protection supported this evidence, since only the group immunized with PD5 and CPS-A was partially protected upon viral challenge. This is the first study in which the polysaccharide A of N. meningitidis is successfully employed as adjuvant for viral antigens.

Recombinant fusion proteins containing the aa 286-426 of the dengue envelope protein fused to P64k protein from Neisseria meningitidis have been previously reported. Particularly, the immunogenicity and protective capacity of the dengue 2 recombinant protein was demonstrated in Macaca fascicularis monkeys. Here we evaluate the recombinant fusion protein containing the domain III of the dengue 1 envelope protein (PD10) in non-human primates (M. fascicularis and rhesus monkeys) and compare the effect of aluminum hydroxide and Freund adjuvant on the immunity induced. The PD10 protein emulsified in Freund adjuvant was highly immunogenic in M. fascicularis and rhesus monkeys. Following dengue 1 virus challenge, animals immunized with PD10 in Freund adjuvant were protected from viremia. However, monkeys receiving PD10 in aluminum hydroxide developed a poor antibody response and were not protected from viral challenge. These preliminary experiments are encouraging. Other formulations or vaccine schedules are being studied in an attempt to find regimens that enhance immunological protection.

The suitability of dengue 2 envelope domain III recombinant fusion proteins [(fusion (PD5) and insertion (PD3) variants)] for inducing functional antibodies and a protective immune response in nonhuman primates has been reported. However, the evaluation of the antibody response after immunization did not correlate with the protection data as measured by viremia detection. Here, we characterized the anamnestic immune response after viral challenge in monkeys immunized with the dengue 2 recombinant proteins in an attempt to define correlates of protection useful for vaccine studies. Monkeys immunized with PD5 (most protected group) exhibited an earlier increase in the anti-DENV-2 IgM response after challenge compared to control animals. Hemagglutination-inhibiting (HAI) antibodies were increased significantly earlier in PD5-immunized animals compared to those immunized with PD3. The fully protected monkeys showed the earliest HAI antibody response. These results underline the usefulness of the anamnestic antibody response for supporting protection data. The induction of an early HAI and IgM antibody response after challenge suggest a protective role against dengue virus (DENV) infection in monkeys, supporting their use as correlates of protection in vaccine studies.

In the present work, we study the immunogenicity and protective capacity of a recombinant capsid protein from Dengue-2 virus. The capsid gene was cloned under the T5 phage promoter and expressed in Escherichia coli. The recombinant protein was obtained mainly associated to the soluble fraction upon cellular disruption and exhibited a pattern of high aggregation, determined by gel filtration chromatography. The semipurified preparation was inoculated in mice and after three doses, no antiviral antibodies were induced. On the other hand, mice intracranially challenged with homologous lethal virus, exhibited statistically significant protection with respect to the control group. These results describe, for the first time, the protective capacity of the capsid protein of Dengue virus indicating the existence of a protector mechanism, which is totally independent of the antibodies. This lack of induction of antiviral antibodies makes the capsid protein an attractive vaccine candidate against dengue since eliminates the potential risk of the induction of antibody dependent enhancement associated to the current vaccines under study.