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
4 resultados
Resultados de Busca
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- 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.
- SARS-CoV-2 reinfection caused by the P.1 lineage in Araraquara city, Sao Paulo State, Brazil(2021) ROMANO, Camila Malta; FELIX, Alvina Clara; PAULA, Anderson Vicente de; JESUS, Jaqueline Goes de; ANDRADE, Pamela S.; CANDIDO, Darlan; OLIVEIRA, Franciane M. de; RIBEIRO, Andreia C.; SILVA, Francini C. da; INEMAMI, Marta; COSTA, Angela Aparecida; LEAL, Cibele O. D.; FIGUEIREDO, Walter Manso; PANNUTI, Claudio Sergio; SOUZA, William M. de; FARIA, Nuno Rodrigues; SABINO, Ester CerdeiraReinfection by the severe acute respiratory syndrome coronavirus type 2 (SARS-COV-2) has been reported in many countries, suggesting that the virus may continue to circulate among humans despite the possibility of local herd immunity due to massive previous infections. The emergence of variants of concern (VOC) that are more transmissible than the previous circulating ones has raised particular concerns on the vaccines effectiveness and reinfection rates. The P.1 lineage was first identified in December 2020 in Manaus city and is now globally spread. We report the first case of reinfection of SARS-CoV-2 caused by the P.1 variant outside of Manaus. The potential of these new variants to escape naturally and vaccine-induced immunity highlights the need for a global vigilance.
- A spatial case-control study on symptomatic and inapparent primary dengue infections in an endemic city in Brazil(2024) FIGUEIREDO, Gerusa; CHIARAVALLOTI, Francisco; CAMPOS, Sergio; PELLINI, Alessandra Cristina Guedes; FELIX, Alvina Clara; LUNA, ExpeditoWe conducted a spatial case-control study nested in a dengue incidence cohort to explore the role of the spatial and socioeconomic factors in the proportion of symptomatic (cases) and inapparent primary dengue virus infections (controls). Cohort participants were children and adolescents (2 to 16 years of age) at the beginning of the follow-up. Case definitions were, for symptomatic cases, fever plus a positive lab result for acute dengue (NS1, RT-PCR, ELISA IgM/IgG), and for inapparent infection a positive result for dengue IgG (ELISA) in subjects without symptoms and with a previously negative result at baseline. The covariates included sociodemographic factors, residential location, and socioeconomic context variables of the census tracts of residence of cases and controls. We used principal component analysis to reduce the contextual covariates, with the component values assigned to each one based on their residences. The data were modeled in a Bayesian context, considering the spatial dependence. The final sample consisted of 692 children, 274 cases and 418 controls, from the first year of follow-up (2014-2015). Being male, older age, higher educational level of the head of the family and having a larger number of rooms in the household were associated with a greater chance of presenting dengue symptomatic infection at the individual level. The contextual covariates were not associated with the outcome. Inapparent dengue infection has extensive epidemiological consequences. Relying solely on notifications of symptomatic dengue infections underestimates the number of cases, preserves a silent source of the disease, potentially spreading the virus to unaffected areas.
- Zika virus infection among symptomatic patients from two healthcare centers in Sao Paulo State, Brazil: prevalence, clinical characteristics, viral detection in body fluids and serodynamics(2019) TOZETTO-MENDOZA, Tania Regina; AVELINO-SILVA, Vivian Iida; FONSECA, Silvia; CLARO, Ingra Morales; PAULA, Anderson Vicente de; LEVIN, Anna Sara; SABINO, Ester Cerdeira; MENDES-CORREA, Maria Cassia; FIGUEIREDO, Walter Manso; FELIX, Alvina Clara; SOUZA, Nathalia C. Santiago; COSTA, Angela Aparecida; INENAMI, Maria; SILVA, Rosangela M. Gasparetto da; LEVI, Jose Eduardo; ROMANO, Camila Malta; PARANHOS-BACCALA, Glaucia; SEGURADO, Aluisio Cotrim; MAYAUD, PhilippeZika virus (ZIKV) clinical presentation and frequency/duration of shedding need further clarification. Symptomatic ZIKV-infected individuals identified in two hospitals in Sao Paulo State, Brazil, were investigated regarding clinical characteristics, shedding in body fluids, and serodynamics. Ninety-four of 235 symptomatic patients (Site A: 58%; Site B: 16%) had Real-Time PCR-confirmed ZIKV infection; fever, headache and gastrointestinal symptoms were less frequent, and rash was more frequent compared to ZIKV-negative patients. Real-Time PCR in serum had worse performance compared to plasma, while urine had the highest sensitivity. Shedding in genital fluids and saliva was rare. IgM positivity was the highest <14 days after the symptoms onset (86%), decreasing >28 days (24%); IgG positivity increased >14 days (96%) remaining positive in 94% of patients >28 days. ZIKV prevalence varied importantly in two neighboring cities during the same transmission season. Urine Real-Time PCR can improve diagnostic sensitivity; serum testing is less useful. Accurate serological tests are needed to improve diagnosis and surveillance.