Identification of Continuous Human B-Cell Epitopes in the Envelope Glycoprotein of Dengue Virus Type 3 (DENV-3)

BACKGROUND:Dengue virus infection is a growing global public health concern in tropical and subtropical regions of the world. Dengue vaccine development has been hampered by concerns that cross-reactive immunological memory elicited by a candidate vaccine could increase the risk of development of more severe clinical forms. One possible strategy to reduce risks associated with a dengue vaccine is the development of a vaccine composed of selected critical epitopes of each of the serotypes. METHODOLOGY/PRINCIPAL FINDINGS:Synthetic peptides were used to identify B-cell epitopes in the envelope (E) glycoprotein of dengue virus type 3 (DENV-3). Eleven linear, immunodominant epitopes distributed in five regions at amino acid (aa) positions: 51-65, 71-90, 131-170, 196-210 and 246-260 were identified by employing an enzyme- linked immunosorbent assay (ELISA), using a pool of human sera from dengue type 3 infected individuals. Peptides 11 (aa51-65), 27 and 28 (aa131-150) also reacted with dengue 1 (DENV-1) and dengue 2 (DENV-2) patient sera as analyzed through the ROC curves generated for each peptide by ELISA and might have serotype specific diagnostic potential. Mice immunized against each one of the five immunogenic regions showed epitopes 51-65, 131-170, 196-210 and 246-260 elicited the highest antibody response and epitopes131-170, 196-210 and 246-260, elicited IFN-gamma production and T CD4+ cell response, as evaluated by ELISA and ELISPOT assays respectively. CONCLUSIONS/SIGNIFICANCE:Our study identified several useful immunodominant IgG-specific epitopes on the envelope of DENV-3. They are important tools for understanding the mechanisms involved in antibody dependent enhancement and immunity. If proven protective and safe, in conjunction with others well-documented epitopes, they might be included into a candidate epitope-based vaccine

Description of a Prospective 17DD Yellow Fever Vaccine Cohort in Recife, Brazil

From September 2005 to March 2007, 238 individuals being vaccinated for the first time with the yellow fever (YF) -17DD vaccine were enrolled in a cohort established in Recife, Brazil. A prospective study indicated that, after immunization, anti-YF immunoglobulin M (IgM) and anti-YF IgG were present in 70.6% (IgM) and 98.3% (IgG) of the vaccinated subjects. All vaccinees developed protective immunity, which was detected by the plaque reduction neutralization test (PRNT) with a geometric mean titer of 892. Of the 238 individuals, 86.6% had IgG antibodies to dengue virus; however, the presence of anti-dengue IgG did not interfere significantly with the development of anti-YF neutralizing antibodies. In a separate retrospective study of individuals immunized with the 17DD vaccine, the PRNT values at 5 and 10 years post-vaccination remained positive but showed a significant decrease in neutralization titer (25% with PRNT titers < 100 after 5 years and 35% after 10 years)

The Microcephaly Epidemic Research Group Paediatric Cohort (MERG-PC): A Cohort Profile.

This cohort profile aims to describe the ongoing follow-up of children in the Microcephaly Epidemic Research Group Paediatric Cohort (MERG-PC). The profile details the context and aims of the study, study population, methodology including assessments, and key results and publications to date. The children that make up MERG-PC were born in Recife or within 120 km of the city, in Pernambuco/Brazil, the epicentre of the microcephaly epidemic. MERG-PC includes children from four groups recruited at different stages of the ZIKV microcephaly epidemic in Pernambuco, i.e., the Outpatient Group (OG/n = 195), the Microcephaly Case-Control Study (MCCS/n = 80), the MERG Pregnant Women Cohort (MERG-PWC/n = 336), and the Control Group (CG/n = 100). We developed a comprehensive array of clinical, laboratory, and imaging assessments that were undertaken by a 'task force' of clinical specialists in a single day at 3, 6, 12, 18 months of age, and annually from 24 months. Children from MCCS and CG had their baseline assessment at birth and children from the other groups, at the first evaluation by the task force. The baseline cohort includes 711 children born between February 2015 and February 2019. Children's characteristics at baseline, excluding CG, were as follows: 32.6% (184/565) had microcephaly, 47% (263/559) had at least one physical abnormality, 29.5% (160/543) had at least one neurological abnormality, and 46.2% (257/556) had at least one ophthalmological abnormality. This ongoing cohort has contributed to the understanding of the congenital Zika syndrome (CZS) spectrum. The cohort has provided descriptions of paediatric neurodevelopment and early epilepsy, including EEG patterns and treatment response, and information on the frequency and characteristics of oropharyngeal dysphagia; cryptorchidism and its surgical findings; endocrine dysfunction; and adenoid hypertrophy in children with Zika-related microcephaly. The study protocols and questionnaires were shared across Brazilian states to enable harmonization across the different studies investigating microcephaly and CZS, providing the opportunity for the Zika Brazilian Cohorts Consortium to be formed, uniting all the ZIKV clinical cohorts in Brazil

Previous dengue or Zika virus exposure can drive to infection enhancement or neutralisation of other flaviviruses

Submitted by Ana Beatriz Oliveira ([email protected]) on 2019-09-20T12:15:36Z No. of bitstreams: 1 Previous dengue or Zika virus exposure can drive to infection.pdf: 720255 bytes, checksum: b461dd8eab962758ca4f956a764907ab (MD5)Approved for entry into archive by Ana Beatriz Oliveira ([email protected]) on 2019-09-20T13:15:53Z (GMT) No. of bitstreams: 1 Previous dengue or Zika virus exposure can drive to infection.pdf: 720255 bytes, checksum: b461dd8eab962758ca4f956a764907ab (MD5)Made available in DSpace on 2019-09-20T13:15:53Z (GMT). No. of bitstreams: 1 Previous dengue or Zika virus exposure can drive to infection.pdf: 720255 bytes, checksum: b461dd8eab962758ca4f956a764907ab (MD5) Previous issue date: 2019Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (Facepe) (grant BFP-0117-2.11/13), for granting RASO a visiting research fellowship and EFO-F (grant APQ 1380-5.05/15) and CNPq (DCR-0003-5.05/16), and to Louisa F. Ludwig-BegallUniversidade Federal da Paraíba. Departamento de Fisiologia e Patologia. João Pessoa, PB, Brasil.Fundação Oswaldo Cruz. Instituto Aggeu Magalhães. Departamento de Virologia. Recife, PE, Brasil / Charité-Universitätsmedizin. Berlin. Berlin, Germany.Universidade Federal da Paraíba. Hospital Universitário Lauro Wanderley. Serviço de Doenças Infecciosas e Parasitárias. João Pessoa, PB, Brasil / Universidade Federal da Paraíba. Escola Técnica de Saúde. Grupo de Estudos e Pesquisas em Imunologia Humana. João Pessoa, PB, Brasil.Universidade Federal de Pernambuco. Departamento de Medicina Clínica. Recife, PE, Brasil.Fundação Oswaldo Cruz. Instituto Aggeu Magalhães. Departamento de Virologia. Recife, PE, Brasil / University of Pittsburgh. Center for Vaccine Research. Department of Infectious Diseases and Microbiology. Pittsburgh, PA, USA.Fundação Oswaldo Cruz. Instituto Aggeu Magalhães. Departamento de Virologia. Recife, PE, Brasil.Fundação Oswaldo Cruz. Instituto Aggeu Magalhães. Departamento de Virologia. Recife, PE, Brasil.BACKGROUND Dengue virus (DENV) has circulated in Brazil for over 30 years. During this time, one serotype has cyclically replaced the other, until recently, when all four distinct serotypes began to circulate together. Persistent circulation of DENV for long time periods makes sequential infections throughout a person’s life possible. After primary DENV infection, life-long immunity is developed for the infecting serotype. Since DENV and Zika virus (ZIKV) are antigenically similar, the possibility of cross-reactions has attracted attention and has been demonstrated in vitro. OBJECTIVE The aim of this study was to investigate whether immune-sera from DENV and ZIKV infected patients would crossreact in vitro with other Flaviviridae family members. METHODS Cross-reaction of the studied samples with yellow fever virus (YFV), West Nile virus (WNV), Rocio virus (ROCV), Saint Louis virus (SLEV) and Ilheus virus (ILHV) has been investigated by plaque reduction neutralisation test (PRNT) and the antibody-dependent enhancement (ADE) by flow-cytometry. FINDINGS Antibodies against ZIKV and DENV virus cross-reacted with other flaviviruses either neutralising or enhancing the infection. Thus, viral entrance into FcRFcɣRII-expressing cells were influenced by the cross-reactive antibodies. ZIKV or DENV immune sera enhanced cellular infection by WNV, ILHV, ROCV and SLEV. Finally, DENV immune sera presented higher neutralising activity for YFV and SLEV. While ZIKV immune sera neutralised WNV, ILHV and ROCV with high frequencies of positivity. MAIN CONCLUSIONS The co-circulation of those viruses in the same area represents a risk for the development of severe infections if they spread throughout the country. Successive flavivirus infections may have an impact on disease pathogenesis, as well as on the development of safe vaccine strategies

ROC curves generated by Medcalc Software, 8.2 version.

<p>(A) Peptides 15, 16, 28, 29, 30, 31, 32, 40, 50 and its power to discriminate between DENV-3 infections and non dengue. (B) Peptides 11, 27, 28 and its power to differentiate DENV-3 infection from dengue infection of other serotypes.</p

T-cell response through ELISPOT assay for IFN-γ elicited in Balb/c mice immunized with the envelope epitopes identified in human.

<p>The T cell response was assessed using total splenocytes harvested from immunized mice as well as from CD8+ T cell enriched splenocytes (CD4+T cell-depleted) or CD4+ T enriched splenocytes (CD8+ T cell -depleted). In asterisk are the groups considered positive in all mice analyzed based upon the following criteria: spot forming cells (SFC) less 2 standard deviation (SD) was greater than the average of the background plus 2 SD; and the average of the experimental peptides was greater than 10 SFCs per 10⁶ cells. The result shown is the average and standard deviation from two different mice.</p