ALVINA CLARA FELIX
Projetos de Pesquisa
Unidades Organizacionais
Departamento de Moléstias Infecciosas e Parasitárias, Faculdade de Medicina
LIM/52 - Laboratório de Virologia, Hospital das Clínicas, Faculdade de Medicina
LIM/52 - Laboratório de Virologia, Hospital das Clínicas, Faculdade de Medicina
13 resultados
Resultados de Busca
Agora exibindo 1 - 10 de 13
conferenceObject DENGUE IN SOUTHEASTERN BRAZIL: A LARGE OUTBREAK FOLLOWED BY A THREE-YEAR LOW INCIDENCE PERIOD. OBSERVATIONS FROM A PROSPECTIVE COHORT STUDY(2018) LUNA, Expedito; FIGUEIREDO, Gerusa; LEVI, Jose; CAMPOS, Sergio; FIGUEIREDO, Walter; COSTA, Angela; FELIX, Alvina; SOUZA, Nathalia; PANNUTI, Claudio- DETECTION OF HUMAN ANTI-ZIKA VIRUS IgG BY ELISA USING AN ANTIGEN FROM in vitro INFECTED VERO CELLS: PRELIMINARY RESULTS(2016) SUMITA, Laura Masami; RODRIGUES, Jaqueline Polizeli; FERREIRA, Noely Evangelista; FELIX, Alvina Clara; SOUZA, Nathalia Caroline Santiago; MACHADO, Clarisse Martins; ANDRADE JUNIOR, Heitor Franco deZika virus (ZKV) infection is a huge public health problem in Brazil because of the increased incidence of microcephaly in neonates from infected mothers. Detection of specific IgG antibodies in maternal serum samples constitutes an important approach for diagnosing ZKV infection and evaluating its relationship with neonatal microcephaly. However, as there is no serological test produced in Brazil to detect IgM and IgG antibodies against ZKV, we sought to examine specific IgG in serum samples from patients or suspected mothers to detect previous infection and to test for specificity with regard to flaviviral infections occurring in the same area. Brazilian Zika virus native antigens were obtained from infected Vero cell layers or free virions in the culture medium and then used in ELISA. We tested sera from eight ZKV RNA-diagnosed infected patients (ZKVR), seven neonates with microcephaly and their mothers after delivery (MM), 140 dengue virus IgM-positive (DM) and IgG (DG)-positive patients, and 100 yellow fever (YF)-vaccinated patients. According to the ELISA, ZKVR samples were mostly positive (7/8), and all the MM serum samples were positive for ZKV IgG (7/7). In contrast, cross-reactions for dengue or yellow fever-vaccinated patients were observed, including DM (48/95), DG (10/45) or YF (3/100) serum samples; however, these cross-reactions exhibited low antigen avidity so that 6 M urea largely removed this cross-reactivity, with only a few cross-reacting samples remaining (8/140). ELISA based on extracted virions was much more specific, with all ZKVR (8/8) and MM sera being positive for ZKV IgG (7/7) and only borderline cross-reactivity found for DM (6/95), DG (3/45) or YF (4/100)-vaccinated serum samples. This technique (ELISA) can identify specific IgG in ZKV-infected patients and may be helpful in diagnosing congenital infetions after maternal RNA virus clearance or in epidemiological studies.
- Cross reactivity of commercial anti-dengue immunoassays in patients with acute Zika virus infection(2017) FELIX, Alvina Clara; SOUZA, Nathalia C. Santiago; FIGUEIREDO, Walter M.; COSTA, Angela A.; INENAMI, Marta; SILVA, Rosangela M. G. da; LEVI, Jose Eduardo; PANNUTI, Claudio Sergio; ROMANO, Camila MaltaSeveral countries have local transmission of multiple arboviruses, in particular, dengue and Zika viruses, which have recently spread through many American countries. Cross reactivity among Flaviviruses is high and present a challenge for accurate identification of the infecting agent. Thus, we evaluated the level of cross reactivity of anti-dengue IgM/G Enzyme-Linked Immunosorbent Assays (ELISA) from three manufacturers against 122 serum samples obtained at two time-points from 61 patients with non-dengue confirmed Zika virus infection. All anti-dengue ELISAs cross reacted with serum from patients with acute Zika infection at some level and a worrisome number of seroconversion for dengue IgG and IgM was observed. These findings may impact the interpretation of currently standard criteria for dengue diagnosis in endemic regions.
conferenceObject A COHORT STUDY TO DETERMINE THE INCIDENCE OF ZIKA VIRUS INFECTION AMONG NEWBORNS, SANTOS, BRAZIL, 2016-2017(2017) LUNA, Expedito J.; ROMANO, Camila M.; ARAUJO, Evaldo S.; LEVI, Jose E.; OLIVEIRA, Olimpia N.; FERNANDES, Luis R.; FELIX, Alvina C.; SOUZA, Nathalia S.; FERNANDES, Joao H.; CAMPOS, Sergio R.; FRAGOSO, Danielli B.; PANNUTI, Claudio S.- Data on dengue incidence in South-eastern Brazil, 2014-2018(2020) LUNA, Expedito; FIGUEIREDO, Gerusa; LEVI, Jose; CAMPOS, Sergio; FELIX, Alvina; SOUZA, Nathalia; FIGUEIREDO, Walter; COSTA, Angela; CARDOSO, Maria; PANNUTI, ClaudioData from the routine surveillance systems have been extensively used to estimate the incidence of dengue. However, routine surveillance data frequently underestimate the diseases' incidence. Underreporting of dengue cases is related to the varying spectrum of its clinical presentation, with a large proportion of mild and asymptomatic infections, to its unspecific signs and symptoms, to the limitations of access to health care, and to the performance of the surveillance system itself [1-3]. In order to obtain accurate figures on dengue incidence, a cohort of children and adolescents was set up and followed during four years. The incidence of reported cases was used as a reference for the sample size calculation, which was stratified by age groups. A two-stage procedure was used to select the participants: census tracts were randomly selected, and within each one, a pre-determined number of children of each age group was randomly selected. The parents or legal guardians of the participating children and adolescents provided a written informed consent. In the first home visit, they responded to a questionnaire containing data on socio-demographic characteristics, housing, access to water, sewage, and garbage collection. Also, during the first visit a blood sample of the participating child/adolescent was collected for dengue baseline serology. Beginning in the week after the enrolment, the parent or legal guardian that was designated in the first visit received weekly phone calls for fever surveillance. If the child/adolescent had fever during the week, a nurse was dispatched to the family's home to collect more detailed data on the fever episode and collect a blood sample for dengue diagnosis (IgG, IgM, NS1 and PCR). If the dengue diagnosis was confirmed, a medical appointment was scheduled, and another blood sample for confirmatory tests was collected. It was also agreed that in every anniversary of their participation, they would receive another visit for a blood collection for dengue serology, regardless if they had a fever episode or a confirmed dengue diagnosis during the previous year. This article contains the description of the cohort's dataset. It is associated with the article published in Acta Tropica, under the title ""A cohort study to assess the incidence of dengue, Brazil, 2014-2018"" [4]. The associated article focused on the seroprevalence and incidence of dengue, and explored some associations between both outcomes and some explanatory variables. (C) 2020 The Authors.
- Evaluation of serological cross-reactivity between yellow fever and other flaviviruses(2019) SOUZA, Nathalia Caroline Santiago e; FELIX, Alvina Clara; PAULA, Anderson Vicente de; LEVI, Jose Eduardo; PANNUTI, Claudio Sergio; ROMANO, Camila MaltaObjectives: This study was performed to determine whether neutralizing antibodies against yellow fever virus (YFV) generated by YFV vaccine could interfere in the specificity of dengue virus (DENV) and Zika virus (ZIKV) IgG ELISA tests. Methods: Seventy-nine pairs of serum samples (pre- and post-vaccination), collected during the years 1997-1998 from children with no history of yellow fever disease who had been vaccinated against YFV, were tested. The seroconversion post-vaccination was evaluated through plaque reduction neutralization test (PRNT), and four different commercial ELISA kits were used for the detection of DENV and ZIKV IgG antibodies. Results: A cross-reactivity rate of 3.9% with DENV IgG antibodies was found only with the Dengue Virus IgG Dx Select kit (Focus Diagnostics). Conclusions: As several countries have local transmission of multiple arboviruses, the absence of cross-reactivity or minimum cross-reactivity of YFV neutralizing antibodies with DENV and ZIKV antigens is a relevant finding, since the interpretation of sero-epidemiological investigations would be seriously impacted in many regions where YFV vaccination is mandatory. (C) 2019 The Authors.
- A cohort study to assess the incidence of dengue, Brazil, 2014-2018(2020) LUNA, Expedito J. A.; FIGUEIREDO, Gerusa M.; LEVI, Jose E.; CAMPOS, Sergio R. S. L. C.; FELIX, Alvina Clara; SOUZA, Nathalia Santiago E; FIGUEIREDO, Walter M.; COSTA, Angela A.; CARDOSO, Maria R. A.; PANNUTI, Claudio S.The present cohort study was set up with the aim of determining the incidence of dengue among children and adolescents, from 2 to 16 years of age, living in Araraquara, South-Eastern Brazil, a city classified as a mid-level endemicity location for dengue. Enrollment took place from September 2014 to March 2015. Baseline socio-demographic data were collected, and a blood sample from the participant was drawn, for dengue serology. Families were contacted weekly for fever surveillance. If the child developed fever, a nurse visited the household to collect a blood sample. PCR, NS1 and IgM were used for dengue diagnosis. Parents or legal guardians of participating children provided a written informed consent. 3,514 children and adolescents were enrolled in the cohort. Dengue baseline seroprevalence was 12.2% (95%CI: 11.1 - 13.3). The incidence density of symptomatic dengue was 8.94 per 100 person/years in the first year of follow-up, 0.58 in the second, and 0.19 in the fourth. No cases were confirmed in the third year. Incidence was associated with age, sex, baseline seroprevalence and with living in a house as opposed to an apartment. This study provides relevant information on the epidemiology of dengue in mid-level transmission settings that may be useful to policymakers in the evaluation of control strategies.
conferenceObject RE-EMERGENCE OF DENV-2 IN THE STATE OF SAO PAULO, BRAZIL(2019) LUNA, Expedito J.; FIGUEIREDO, Gerusa M.; CAMPOS, Sergio R.; LEVI, Jose E.; FIGUEIREDO, Walter M.; COSTA, Angela A.; FELIX, Alvina C.; SOUZA, Nathalia S.; PANNUTI, Claudio S.conferenceObject ESTIMATING THE UNDERREPORTING OF DENGUE CASES, ARARAQUARA, BRAZIL, 2015(2017) LUNA, Expedito J.; FIGUEIREDO, Gerusa M.; CAMPOS, Sergio R.; LEVI, Jose E.; FIGUEIREDO, Walter M.; COSTA, Angela A.; FELIX, Alvina C.; SOUZA, Nathalia S.; CARDOSO, Maria R.; PANNUTI, Claudio S.conferenceObject INAPPARENT DENGUE VIRUS INFECTION INCIDENCE, SAO PAULO, BRAZIL, 2014-2015(2017) LUNA, Expedito J.; FIGUEIREDO, Gerusa M.; CAMPOS, Sergio R.; LEVI, Jose E.; FIGUEIREDO, Walter M.; COSTA, Angela A.; FELIX, Alvina C.; SOUZA, Ana C.; SOUZA, Nathalia C.; CARDOSO, Maria R.; PANNUTI, Claudio S.