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2.
Recurso na Internet em Português | LIS - Localizador de Informação em Saúde | ID: lis-49560

RESUMO

O Ministério da Saúde iniciou, nesta quinta-feira (8), a distribuição das vacinas contra dengue para os municípios que atendem aos critérios definidos pela Pasta em conjunto com o Conselho Nacional de Secretários de Saúde (Conass) e Conselho Nacional de Secretarias Municipais de Saúde (Conasems). A operação logística do Ministério da Saúde irá trabalhar ininterruptamente nos próximos dias para garantir a entrega o mais breve possível.


Assuntos
Vacinas contra Dengue/imunologia ,
4.
Cell Rep ; 38(6): 110341, 2022 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-35139383

RESUMO

The tetravalent dengue vaccine candidate, TAK-003, induces a functional antibody response, but the titers of antibodies against the four serotypes of the dengue virus (DENV) can vary. Here, through a transcriptomic analysis on whole blood collected from recipients of a two-dose schedule of TAK-003, we examine gene expression, splicing, and transcript isoform-level changes for both protein-coding and noncoding genes to broaden our understanding of the immune response. Our analysis reveals a dynamic pattern of vaccine-associated regulation of long noncoding RNAs (lncRNAs), differential splicing of interferon-stimulated gene exons, and gene expression changes related to multiple signaling pathways that detect viral infection. Co-expression networks isolate immune cell-type-related and interferon-response modules that represent specific biological processes that correlate with more robust antibody responses. These data provide insights into the early determinants of the variable immune response to the vaccine, highlighting the significance of splicing and isoform-level gene regulatory mechanisms in defining vaccine immunogenicity.


Assuntos
Anticorpos Antivirais/imunologia , Vacinas contra Dengue/imunologia , Vírus da Dengue/patogenicidade , RNA Longo não Codificante/genética , Transcriptoma/genética , Anticorpos Neutralizantes/imunologia , Dengue/virologia , Vírus da Dengue/genética , Humanos , Imunogenicidade da Vacina/imunologia , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/imunologia , Vacinas Virais/imunologia , Vacinas Virais/farmacologia
5.
PLoS Pathog ; 18(1): e1009903, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-35061851

RESUMO

It has been estimated that more than 390 million people are infected with Dengue virus every year; around 96 millions of these infections result in clinical pathologies. To date, there is only one licensed viral vector-based Dengue virus vaccine CYD-TDV approved for use in dengue endemic areas. While initially approved for administration independent of serostatus, the current guidance only recommends the use of this vaccine for seropositive individuals. Therefore, there is a critical need for investigating the influence of Dengue virus serostatus and immunological mechanisms that influence vaccine outcome. Here, we provide comprehensive evaluation of sero-status and host immune factors that correlate with robust immune responses to a Dengue virus vector based tetravalent vaccine (TV003) in a Phase II clinical cohort of human participants. We observed that sero-positive individuals demonstrate a much stronger immune response to the TV003 vaccine. Our multi-layered immune profiling revealed that sero-positive subjects have increased baseline/pre-vaccination frequencies of circulating T follicular helper (cTfh) cells and the Tfh related chemokine CXCL13/BLC. Importantly, this baseline/pre-vaccination cTfh profile correlated with the vaccinees' ability to launch neutralizing antibody response against all four sero-types of Dengue virus, an important endpoint for Dengue vaccine clinical trials. Overall, we provide novel insights into the favorable cTfh related immune status that persists in Dengue virus sero-positive individuals that correlate with their ability to mount robust vaccine specific immune responses. Such detailed interrogation of cTfh cell biology in the context of clinical vaccinology will help uncover mechanisms and targets for favorable immuno-modulatory agents.


Assuntos
Anticorpos Antivirais/imunologia , Vacinas contra Dengue/imunologia , Imunogenicidade da Vacina/imunologia , Células T Auxiliares Foliculares/imunologia , Anticorpos Neutralizantes/imunologia , Dengue/prevenção & controle , Feminino , Humanos , Masculino , Vacinas Combinadas/imunologia
6.
Cell Host Microbe ; 29(11): 1634-1648.e5, 2021 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-34610295

RESUMO

Although divergent dengue viruses (DENVs) have been isolated in insects, nonhuman primates, and humans, their relationships to the four canonical serotypes (DENV 1-4) are poorly understood. One virus isolated from a dengue patient, DKE-121, falls between genotype and serotype levels of sequence divergence to DENV-4. To examine its antigenic relationship to DENV-4, we assessed serum neutralizing and protective activity. Whereas DENV-4-immune mouse sera neutralize DKE-121 infection, DKE-121-immune sera inhibit DENV-4 less efficiently. Passive transfer of DENV-4 or DKE-121-immune sera protects mice against homologous, but not heterologous, DENV-4 or DKE-121 challenge. Antigenic cartography suggests that DENV-4 and DKE-121 are related but antigenically distinct. However, DENV-4 vaccination confers protection against DKE-121 in nonhuman primates, and serum from humans immunized with a tetravalent vaccine neutralize DENV-4 and DKE-121 infection equivalently. As divergent DENV strains, such as DKE-121, may meet criteria for serotype distinction, monitoring their capacity to impact dengue disease and vaccine efficacy appears warranted.


Assuntos
Anticorpos Amplamente Neutralizantes/imunologia , Proteção Cruzada , Vacinas contra Dengue/imunologia , Vírus da Dengue/genética , Vírus da Dengue/imunologia , Dengue/imunologia , Animais , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Antígenos Virais/imunologia , Anticorpos Amplamente Neutralizantes/sangue , Reações Cruzadas , Dengue/prevenção & controle , Dengue/virologia , Feminino , Genótipo , Humanos , Imunização Passiva , Imunogenicidade da Vacina , Macaca mulatta , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Sorogrupo , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/imunologia
7.
Sci Rep ; 11(1): 19707, 2021 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-34611250

RESUMO

Dengue poses a global health threat, which will persist without therapeutic intervention. Immunity induced by exposure to one serotype does not confer long-term protection against secondary infection with other serotypes and is potentially capable of enhancing this infection. Although vaccination is believed to induce durable and protective responses against all the dengue virus (DENV) serotypes in order to reduce the burden posed by this virus, the development of a safe and efficacious vaccine remains a challenge. Immunoinformatics and computational vaccinology have been utilized in studies of infectious diseases to provide insight into the host-pathogen interactions thus justifying their use in vaccine development. Since vaccination is the best bet to reduce the burden posed by DENV, this study is aimed at developing a multi-epitope based vaccines for dengue control. Combined approaches of reverse vaccinology and immunoinformatics were utilized to design multi-epitope based vaccine from the sequence of DENV. Specifically, BCPreds and IEDB servers were used to predict the B-cell and T-cell epitopes, respectively. Molecular docking was carried out using Schrödinger, PATCHDOCK and FIREDOCK. Codon optimization and in silico cloning were done using JCAT and SnapGene respectively. Finally, the efficiency and stability of the designed vaccines were assessed by an in silico immune simulation and molecular dynamic simulation, respectively. The predicted epitopes were prioritized using in-house criteria. Four candidate vaccines (DV-1-4) were designed using suitable adjuvant and linkers in addition to the shortlisted epitopes. The binding interactions of these vaccines against the receptors TLR-2, TLR-4, MHC-1 and MHC-2 show that these candidate vaccines perfectly fit into the binding domains of the receptors. In addition, DV-1 has a better binding energies of - 60.07, - 63.40, - 69.89 kcal/mol against MHC-1, TLR-2, and TLR-4, with respect to the other vaccines. All the designed vaccines were highly antigenic, soluble, non-allergenic, non-toxic, flexible, and topologically assessable. The immune simulation analysis showed that DV-1 may elicit specific immune response against dengue virus. Moreover, codon optimization and in silico cloning validated the expressions of all the designed vaccines in E. coli. Finally, the molecular dynamic study shows that DV-1 is stable with minimum RMSF against TLR4. Immunoinformatics tools are now applied to screen genomes of interest for possible vaccine target. The designed vaccine candidates may be further experimentally investigated as potential vaccines capable of providing definitive preventive measure against dengue virus infection.


Assuntos
Biologia Computacional/métodos , Vacinas contra Dengue/imunologia , Vírus da Dengue/imunologia , Epitopos/química , Epitopos/imunologia , Modelos Moleculares , Vacinologia/métodos , Sequência de Aminoácidos , Antígenos Virais , Fenômenos Químicos , Epitopos de Linfócito B/química , Epitopos de Linfócito B/imunologia , Epitopos de Linfócito T/química , Epitopos de Linfócito T/imunologia , Engenharia Genética , Humanos , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Relação Estrutura-Atividade , Desenvolvimento de Vacinas
8.
Biomed Pharmacother ; 144: 112304, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34634560

RESUMO

Dengue virus (DENV) is a global health threat causing about half of the worldwide population to be at risk of infection, especially the people living in tropical and subtropical area. Although the dengue disease caused by dengue virus (DENV) is asymptomatic and self-limiting in most people with first infection, increased severe dengue symptoms may be observed in people with heterotypic secondary DENV infection. Since there is a lack of specific antiviral medication, the development of dengue vaccines is critical in the prevention and control this disease. Several targets and strategies in the development of dengue vaccine have been demonstrated. Currently, Dengvaxia, a live-attenuated chimeric yellow-fever/tetravalent dengue vaccine (CYD-TDV) developed by Sanofi Pasteur, has been licensed and approved for clinical use in some countries. However, this vaccine has demonstrated low efficacy in children and dengue-naïve individuals and also increases the risk of severe dengue in young vaccinated recipients. Accordingly, many novel strategies for the dengue vaccine are under investigation and development. Here, we conducted a systemic literature review according to PRISMA guidelines to give a concise overview of various aspects of the vaccine development process against DENVs, mainly targeting five potential strategies including live attenuated vaccine, inactivated virus vaccine, recombinant subunit vaccine, viral-vector vaccine, and DNA vaccine. This study offers the comprehensive view of updated information and current progression of immunogen selection as well as strategies of vaccine development against DENVs.


Assuntos
Vacinas contra Dengue/uso terapêutico , Vírus da Dengue/imunologia , Dengue/prevenção & controle , Desenvolvimento de Vacinas , Proteínas do Envelope Viral/imunologia , Proteínas não Estruturais Virais/imunologia , Animais , Dengue/imunologia , Dengue/virologia , Vacinas contra Dengue/efeitos adversos , Vacinas contra Dengue/imunologia , Vírus da Dengue/genética , Vírus da Dengue/patogenicidade , Humanos , Resultado do Tratamento , Eficácia de Vacinas , Vacinas Atenuadas/imunologia , Vacinas Atenuadas/uso terapêutico , Vacinas de DNA/imunologia , Vacinas de DNA/uso terapêutico , Vacinas de Produtos Inativados/imunologia , Vacinas de Produtos Inativados/uso terapêutico , Vacinas Sintéticas/imunologia , Vacinas Sintéticas/uso terapêutico , Proteínas do Envelope Viral/genética , Proteínas não Estruturais Virais/genética
9.
PLoS One ; 16(9): e0257182, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34507347

RESUMO

BACKGROUND: The dengue vaccine (Dengvaxia) is only recommended for individuals with prior dengue infection (PDI). This study aimed to perform a serosurvey to inform decision-making for vaccine introduction and identify appropriate target populations. We also evaluated the performance of the serological tests using plaque reduction neutralization test (PRNT) as a reference test in identifying PDI to determine suitability for pre-vaccination screening. METHODS: We enrolled 115 healthy individuals between 10 and 22 years of age living in the Ratchaburi province of Thailand. The serum samples were tested by PRNT to measure the prevalence and concentration of serotype-specific neutralizing antibodies. The performance of the IgG rapid diagnostic test (RDT, SD Bioline, Korea) and IgG enzyme-linked immunosorbent assay (ELISA, EUROIMMUN, Germany) in identifying PDI were evaluated by using PRNT as a reference method. RESULTS: Ninety-four (81.7%) individuals neutralized one or more dengue serotypes at a titer threshold greater than or equal to 10. Multitypic profiles were observed in 70.4% of the samples which increased to 91.9% in subjects aged 19-22. Among monotypic samples, the highest proportion was reactive against DENV-1 followed by DENV-2, DENV-3, and DENV-4. The highest anti-dengue antibody titers were recorded against DENV-1 and increased with age to a geometric mean NT50 titer (GMT) of 188.6 in the 19-22 age group. While both RDT and ELISA exhibited 100% specificity, RDT demonstrated low sensitivity (35%) with ELISA displaying much greater sensitivity (87%). CONCLUSIONS: Almost 80% of adolescents and youth in Ratchaburi province had already been exposed to one or more of the dengue virus serotypes. The dengue IgG RDT displayed low sensitivity and is likely not be suitable for dengue pre-vaccination screening. These results support the use of IgG ELISA test for dengue vaccination in endemic areas.


Assuntos
Vacinas contra Dengue/imunologia , Dengue/epidemiologia , Dengue/imunologia , Doenças Endêmicas , Programas de Rastreamento , Vacinação , Adolescente , Fatores Etários , Animais , Anticorpos Neutralizantes/sangue , Linhagem Celular , Criança , Dengue/sangue , Vacinas contra Dengue/sangue , Feminino , Humanos , Imunoglobulina G/sangue , Macaca mulatta , Masculino , Testes de Neutralização , Estudos Soroepidemiológicos , Adulto Jovem
10.
Viruses ; 13(9)2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34578424

RESUMO

The use of dengue virus (DENV) vaccines has been hindered by the complexities of antibody dependent enhancement (ADE). Current late-stage vaccine candidates utilize attenuated and chimeric DENVs that produce particles of varying maturities. Antibodies that are elicited by preferentially exposed epitopes on immature virions have been linked to increased ADE. We aimed to further understand the humoral immunity promoted by DENV particles of varying maturities in an AG129 mouse model using a chimeric insect specific vaccine candidate, bDENV-2. We immunized mice with mature, partially mature, and immature bDENV-2 and found that immunization with partially mature bDENV-2 produced more robust and cross-neutralizing immune responses than immunization with immature or mature bDENV-2. Upon challenge with mouse adapted DENV-2 (D220), we observed 80% protection for mature bDENV-2 vaccinated mice and 100% for immature and partially mature vaccinated mice, suggesting that protection to homotypic challenge is not dependent on maturation. Finally, we found reduced in vitro ADE at subneutralising serum concentrations for mice immunized with mature bDENV-2. These results suggest that both immature and mature DENV particles play a role in homotypic protection; however, the increased risk of in vitro ADE from immature particles indicates potential safety benefits from mature DENV-based vaccines.


Assuntos
Vacinas contra Dengue/imunologia , Vírus da Dengue/crescimento & desenvolvimento , Vírus da Dengue/imunologia , Dengue/prevenção & controle , Imunidade Humoral , Animais , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Anticorpos Facilitadores , Anticorpos Amplamente Neutralizantes/sangue , Anticorpos Amplamente Neutralizantes/imunologia , Dengue/imunologia , Camundongos , Eficácia de Vacinas
11.
Front Immunol ; 12: 715136, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34489965

RESUMO

The four serotypes of Dengue virus (DENV1-4) are arboviruses (arthropod-borne viruses) that belong to the Flavivirus genus, Flaviviridae family. They are the causative agents of an infectious disease called dengue, an important global public health problem with significant social-economic impact. Thus, the development of safe and effective dengue vaccines is a priority according to the World Health Organization. Only one anti-dengue vaccine has already been licensed in endemic countries and two formulations are under phase III clinical trials. In this study, we aimed to compare the main anti-dengue virus vaccines, DENGVAXIA®, LAV-TDV, and TAK-003, regarding their antigens and potential to protect. We studied the conservation of both, B and T cell epitopes involved in immunological control of DENV infection along with vaccine viruses and viral isolates. In addition, we assessed the population coverage of epitope sets contained in each vaccine formulation with regard to different human populations. As main results, we found that all three vaccines contain the main B cell epitopes involved in viral neutralization. Similarly, LAV-TDV and TAK-003 contain most of T cell epitopes involved in immunological protection, a finding not observed in DENGVAXIA®, which explains main limitations of the only licensed dengue vaccine. In summary, the levels of presence and absence of epitopes that are target for protective immune response in the three main anti-dengue virus vaccines are shown in this study. Our results suggest that investing in vaccines that contain the majority of epitopes involved in protective immunity (cellular and humoral arms) is an important issue to be considered.


Assuntos
Vacinas contra Dengue/imunologia , Vírus da Dengue/imunologia , Dengue/prevenção & controle , Epitopos de Linfócito B/imunologia , Epitopos de Linfócito T/imunologia , Sequência de Aminoácidos , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Sequência Conservada , Vacinas contra Dengue/genética , Epitopos de Linfócito B/química , Epitopos de Linfócito B/genética , Epitopos de Linfócito T/química , Epitopos de Linfócito T/genética , Humanos , Programas de Imunização , Modelos Moleculares , Relação Estrutura-Atividade , Vacinação , Vacinas Sintéticas
12.
J Virol ; 95(23): e0095621, 2021 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-34549976

RESUMO

Dengue virus cocirculates globally as four serotypes (DENV1 to -4) that vary up to 40% at the amino acid level. Viral strains within a serotype further cluster into multiple genotypes. Eliciting a protective tetravalent neutralizing antibody response is a major goal of vaccine design, and efforts to characterize epitopes targeted by polyclonal mixtures of antibodies are ongoing. Previously, we identified two E protein residues (126 and 157) that defined the serotype-specific antibody response to DENV1 genotype 4 strain West Pac-74. DENV1 and DENV2 human vaccine sera neutralized DENV1 viruses incorporating these substitutions equivalently. In this study, we explored the contribution of these residues to the neutralization of DENV1 strains representing distinct genotypes. While neutralization of the genotype 1 strain TVP2130 was similarly impacted by mutation at E residues 126 and 157, mutation of these residues in the genotype 2 strain 16007 did not markedly change neutralization sensitivity, indicating the existence of additional DENV1 type-specific antibody targets. The accessibility of antibody epitopes can be strongly influenced by the conformational dynamics of virions and modified allosterically by amino acid variation. We found that changes at E domain II residue 204, shown previously to impact access to a poorly accessible E domain III epitope, impacted sensitivity of DENV1 16007 to neutralization by vaccine immune sera. Our data identify a role for minor sequence variation in changes to the antigenic structure that impacts antibody recognition by polyclonal immune sera. Understanding how the many structures sampled by flaviviruses influence antibody recognition will inform the design and evaluation of DENV immunogens. IMPORTANCE Dengue virus (DENV) is an important human pathogen that cocirculates globally as four serotypes. Because sequential infection by different DENV serotypes is associated with more severe disease, eliciting a protective neutralizing antibody response against all four serotypes is a major goal of vaccine efforts. Here, we report that neutralization of DENV serotype 1 by polyclonal antibody is impacted by minor sequence variation among virus strains. Our data suggest that mechanisms that control neutralization sensitivity extend beyond variation within antibody epitopes but also include the influence of single amino acids on the ensemble of structural states sampled by structurally dynamic virions. A more detailed understanding of the antibody targets of DENV-specific polyclonal sera and factors that govern their access to antibody has important implications for flavivirus antigen design and evaluation.


Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Vírus da Dengue , Conformação Molecular , Sorogrupo , Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/química , Anticorpos Antivirais/sangue , Formação de Anticorpos , Dengue , Vacinas contra Dengue/química , Vacinas contra Dengue/imunologia , Epitopos/química , Epitopos/imunologia , Flavivirus , Humanos , Mutação , Taiwan , Proteínas do Envelope Viral , Vírion/metabolismo
13.
Crit Rev Eukaryot Gene Expr ; 31(5): 7-19, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34591385

RESUMO

Dengue is a vector-borne highly systemic infectious disease of the tropical and subtropical countries and is devastating millions of lives worldwide. It may be self-eliminated like a mild fever or may cause life-threatening fatal complications as dengue hemorrhagic fever and dengue shock syndrome. The lack of specific and effective antiviral drugs and vaccines amplify its transmission rate across the world. The development of the dengue vaccine has been an ambitious task due to the presence of four different dengue serotypes capable of carrying antibody enhancement complex mechanisms. In this review, we have summarized the ongoing challenges in the construction of a dengue vaccine and the current status of the vaccine development. Limited knowledge of immune responses against dengue infection, lack of human or animal model of disease, and suboptimal assay strategies to detect immune responses after infection or vaccination, are some barriers to vaccine and drug development. A tetravalent vaccine with low cost, high efficiency, and capable of eliciting immune responses against all four serotypes is needed to minimize the epidemics. Currently, only one live attenuated chimeric dengue vaccine, the CYD Dengue Vaccine, has completed its third phase and has been licensed. DENVax and TetraVax-DV-TV003 (TV003) are in the third phase while others are still in the first trial phase.


Assuntos
Vacinas contra Dengue/imunologia , Vírus da Dengue/imunologia , Dengue/imunologia , Dengue/virologia , Imunidade , Desenvolvimento de Vacinas , Aedes/virologia , Animais , Quimera , Humanos , Vacinação , Vacinas Atenuadas/imunologia
14.
Viruses ; 13(8)2021 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-34452312

RESUMO

The four serotypes of the mature dengue virus can display different morphologies, including the compact spherical, the bumpy spherical and the non-spherical clubshape morphologies. In addition, the maturation process of dengue virus is inefficient and therefore some partially immature dengue virus particles have been observed and they are infectious. All these viral particles have different antigenicity profiles and thus may affect the type of the elicited antibodies during an immune response. Understanding the molecular determinants and environmental conditions (e.g., temperature) in inducing morphological changes in the virus and how potent antibodies interact with these particles is important for designing effective therapeutics or vaccines. Several techniques, including cryoEM, site-directed mutagenesis, hydrogen-deuterium exchange mass spectrometry, time-resolve fluorescence resonance energy transfer, and molecular dynamic simulation, have been performed to investigate the structural changes. This review describes all known morphological variants of DENV discovered thus far, their surface protein dynamics and the key residues or interactions that play important roles in the structural changes.


Assuntos
Variação Antigênica , Antígenos Virais/química , Antígenos Virais/genética , Vírus da Dengue/imunologia , Dengue/virologia , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Anticorpos Facilitadores , Antígenos Virais/imunologia , Vacinas contra Dengue/imunologia , Vírus da Dengue/química , Vírus da Dengue/classificação , Vírus da Dengue/genética , Humanos , Sorogrupo , Proteínas do Envelope Viral/genética
15.
PLoS Negl Trop Dis ; 15(7): e0009557, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34324505

RESUMO

With increasing geographic spread, frequency, and magnitude of outbreaks, dengue continues to pose a major public health threat worldwide. Dengvaxia, a dengue live-attenuated tetravalent vaccine, was licensed in 2015, but post hoc analyses of long-term data showed serostatus-dependent vaccine performance with an excess risk of hospitalized and severe dengue in seronegative vaccine recipients. The World Health Organization (WHO) recommended that only persons with evidence of past dengue infection should receive the vaccine. A test for pre-vaccination screening for dengue serostatus is needed. To develop the target product profile (TPP) for a dengue pre-vaccination screening test, face-to-face consultative meetings were organized with follow-up regional consultations. A technical working group was formed to develop consensus on a reference test against which candidate pre-vaccination screening tests could be compared. The group also reviewed current diagnostic landscape and the need to accelerate the evaluation, regulatory approval, and policy development of tests that can identify seropositive individuals and maximize public health impact of vaccination while avoiding the risk of hospitalization in dengue-naive individuals. Pre-vaccination screening strategies will benefit from rapid diagnostic tests (RDTs) that are affordable, sensitive, and specific and can be used at the point of care (POC). The TPP described the minimum and ideal characteristics of a dengue pre-vaccination screening RDT with an emphasis on high specificity. The group also made suggestions for accelerating access to these RDTs through streamlining regulatory approval and policy development. Risk and benefit based on what can be achieved with RDTs meeting minimal and optimal characteristics in the TPP across a range of seroprevalences were defined. The final choice of RDTs in each country will depend on the performance of the RDT, dengue seroprevalence in the target population, tolerance of risk, and cost-effectiveness.


Assuntos
Vacinas contra Dengue/imunologia , Dengue/diagnóstico , Dengue/prevenção & controle , Testes Imediatos , Testes Sorológicos/métodos , Vacinação , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Dengue/imunologia , Humanos , Programas de Rastreamento/métodos , Padrões de Referência , Sensibilidade e Especificidade , Vacinas Atenuadas
16.
Elife ; 102021 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-34219653

RESUMO

Background: Sanofi-Pasteur's CYD-TDV is the only licensed dengue vaccine. Two phase three trials showed higher efficacy in seropositive than seronegative recipients. Hospital follow-up revealed increased hospitalisation in 2-5- year-old vaccinees, where serostatus and age effects were unresolved. Methods: We fit a survival model to individual-level data from both trials, including year 1 of hospital follow-up. We determine efficacy by age, serostatus, serotype and severity, and examine efficacy duration and vaccine action mechanism. Results: Our modelling indicates that vaccine-induced immunity is long-lived in seropositive recipients, and therefore that vaccinating seropositives gives higher protection than two natural infections. Long-term increased hospitalisation risk outweighs short-lived immunity in seronegatives. Independently of serostatus, transient immunity increases with age, and is highest against serotype 4. Benefit is higher in seropositives, and risk enhancement is greater in seronegatives, against hospitalised disease than against febrile disease. Conclusions: Our results support vaccinating seropositives only. Rapid diagnostic tests would enable viable 'screen-then-vaccinate' programs. Since CYD-TDV acts as a silent infection, long-term safety of other vaccine candidates must be closely monitored. Funding: Bill & Melinda Gates Foundation, National Institute for Health Research, UK Medical Research Council, Wellcome Trust, Royal Society. Clinical trial number: NCT01373281 and NCT01374516.


Assuntos
Vacinas contra Dengue/imunologia , Vírus da Dengue/classificação , Dengue/prevenção & controle , Modelos Biológicos , Adolescente , Teorema de Bayes , Criança , Pré-Escolar , Dengue/patologia , Vacinas contra Dengue/efeitos adversos , Humanos , Sorogrupo , Análise de Sobrevida
17.
Nat Immunol ; 22(8): 958-968, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34267374

RESUMO

Antibody-dependent enhancement (ADE) is an important safety concern for vaccine development against dengue virus (DENV) and its antigenically related Zika virus (ZIKV) because vaccine may prime deleterious antibodies to enhance natural infections. Cross-reactive antibodies targeting the conserved fusion loop epitope (FLE) are known as the main sources of ADE. We design ZIKV immunogens engineered to change the FLE conformation but preserve neutralizing epitopes. Single vaccination conferred sterilizing immunity against ZIKV without ADE of DENV-serotype 1-4 infections and abrogated maternal-neonatal transmission in mice. Unlike the wild-type-based vaccine inducing predominately cross-reactive ADE-prone antibodies, B cell profiling revealed that the engineered vaccines switched immunodominance to dispersed patterns without DENV enhancement. The crystal structure of the engineered immunogen showed the dimeric conformation of the envelope protein with FLE disruption. We provide vaccine candidates that will prevent both ZIKV infection and infection-/vaccination-induced DENV ADE.


Assuntos
Anticorpos Facilitadores/imunologia , Antígenos Virais/imunologia , Reações Cruzadas/imunologia , Vacinas contra Dengue/imunologia , Dengue/prevenção & controle , Zika virus/imunologia , Aedes , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Linfócitos B/imunologia , Chlorocebus aethiops , Cricetinae , Vírus da Dengue/imunologia , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Receptor de Interferon alfa e beta/genética , Vacinação , Células Vero , Infecção por Zika virus/imunologia , Infecção por Zika virus/prevenção & controle
18.
Front Immunol ; 12: 574411, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34211454

RESUMO

Dengue virus (DENV) poses a serious threat to global health as the causative agent of dengue fever. The virus is endemic in more than 128 countries resulting in approximately 390 million infection cases each year. Currently, there is no approved therapeutic for treatment nor a fully efficacious vaccine. The development of therapeutics is confounded and hampered by the complexity of the immune response to DENV, in particular to sequential infection with different DENV serotypes (DENV1-5). Researchers have shown that the DENV envelope (E) antigen is primarily responsible for the interaction and subsequent invasion of host cells for all serotypes and can elicit neutralizing antibodies in humans. The advent of high-throughput sequencing and the rapid advancements in computational analysis of complex data, has provided tools for the deconvolution of the DENV immune response. Several types of complex statistical analyses, machine learning models and complex visualizations can be applied to begin answering questions about the B- and T-cell immune responses to multiple infections, antibody-dependent enhancement, identification of novel therapeutics and advance vaccine research.


Assuntos
Linfócitos B/imunologia , Vacinas contra Dengue/imunologia , Vírus da Dengue/fisiologia , Dengue/imunologia , Linfócitos T/imunologia , Anticorpos Neutralizantes/metabolismo , Anticorpos Antivirais/metabolismo , Anticorpos Facilitadores , Antivirais/uso terapêutico , Inteligência Artificial , Simulação por Computador , Dengue/tratamento farmacológico , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Aprendizado de Máquina , Proteínas do Envelope Viral/imunologia
19.
Pediatr Infect Dis J ; 40(8): 774-781, 2021 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-34250977

RESUMO

BACKGROUND: Incorporating dengue vaccination within existing vaccination programs could help improve dengue vaccine coverage. We assessed the immunogenicity and safety of a quadrivalent human papillomavirus (HPV) vaccine administered concomitantly or sequentially with a tetravalent dengue vaccine (CYD-TDV) in healthy children 9-13 years of age in Malaysia. METHODS: In this phase IIIb, open-label, multicenter study (NCT02993757), participants were randomized 1:1 to receive 3 CYD-TDV doses 6 months apart and 2 doses of quadrivalent HPV vaccine concomitantly with, or 1 month before (sequentially), the first 2 CYD-TDV doses. Only baseline dengue-seropositive participants received the 3 doses. Antibody levels were measured at baseline and 28 days after each injection using an enzyme-linked immunosorbent assay for HPV-6, -9, -16 and -18, and the 50% plaque reduction neutralization test for the 4 dengue serotypes; immunogenicity results are presented for baseline dengue-seropositive participants. Safety was assessed throughout the study for all participants. RESULTS: At baseline, 197 of 528 (37.3%) randomized participants were dengue-seropositive [n = 109 (concomitant group) and n = 88 (sequential group)]. After the last HPV vaccine dose, antibody titers for HPV among baseline dengue-seropositive participants were similar between treatment groups, with between-group titer ratios close to 1 for HPV-6 and 0.8 for HPV-11, -16, and -18. After CYD-TDV dose 3, dengue antibody titers were similar between treatment groups for all serotypes [between-group ratios ranged from 0.783 (serotype 2) to 1.07 (serotype 4)]. No safety concerns were identified. CONCLUSIONS: The immunogenicity and safety profiles of CYD-TDV and quadrivalent HPV vaccines were unaffected when administered concomitantly or sequentially in dengue-seropositive children.


Assuntos
Vacinas contra Dengue/administração & dosagem , Vacina Quadrivalente Recombinante contra HPV tipos 6, 11, 16, 18/administração & dosagem , Imunogenicidade da Vacina , Segurança do Paciente , Vacinas Combinadas/administração & dosagem , Adolescente , Criança , Vacinas contra Dengue/imunologia , Feminino , Vacina Quadrivalente Recombinante contra HPV tipos 6, 11, 16, 18/imunologia , Humanos , Programas de Imunização/métodos , Malásia/epidemiologia , Masculino , Vacinas Combinadas/imunologia
20.
PLoS Negl Trop Dis ; 15(7): e0009606, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34310614

RESUMO

An effective and widely used vaccine could reduce the burden of dengue virus (DENV) around the world. DENV is endemic in Puerto Rico, where the dengue vaccine CYD-TDV is currently under consideration as a control measure. CYD-TDV has demonstrated efficacy in clinical trials in vaccinees who had prior dengue virus infection. However, in vaccinees who had no prior dengue virus infection, the vaccine had a modestly elevated risk of hospitalization and severe disease. The WHO therefore recommended a strategy of pre-vaccination screening and vaccination of seropositive persons. To estimate the cost-effectiveness and benefits of this intervention (i.e., screening and vaccination of seropositive persons) in Puerto Rico, we simulated 10 years of the intervention in 9-year-olds using an agent-based model. Across the entire population, we found that 5.5% (4.6%-6.3%) of dengue hospitalizations could be averted. However, we also found that 0.057 (0.045-0.073) additional hospitalizations could occur for every 1,000 people in Puerto Rico due to DENV-naïve children who were vaccinated following a false-positive test results for prior exposure. The ratio of the averted hospitalizations among all vaccinees to additional hospitalizations among DENV-naïve vaccinees was estimated to be 19 (13-24). At a base case cost of vaccination of 382 USD, we found an incremental cost-effectiveness ratio of 122,000 USD per QALY gained. Our estimates can provide information for considerations to introduce the CYD-TDV vaccine in Puerto Rico.


Assuntos
Análise Custo-Benefício , Vacinas contra Dengue/economia , Vacinas contra Dengue/imunologia , Dengue/epidemiologia , Dengue/prevenção & controle , Vacinação/economia , Humanos , Porto Rico/epidemiologia
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