Prevalence and titers of yellow fever virus neutralizing antibodies in previously vaccinated adults

Introduction: The World Health Organization (WHO) recommends one single dose of the Yellow Fever (YF) vaccine based on studies of antibody persistency in healthy adults. We assessed the prevalence and titers of YF virus neutralizing antibodies in previously vaccinated persons aged 60 years, in comparison to younger adults. We also evaluated the correlation between antibody titers and the time since vaccination among participants who received one vaccine dose, and the seropositivity among participants vaccinated prior to or within the past 10 years. Methods: previously vaccinated healthy persons aged 18 years were included. YF virus neutralizing antibody titers were determined by means of the 50% Plaque Reduction Neutralization Test. Results: 46 persons aged 60 years and 48 persons aged 18 to 59 years were enrolled. There was no significant difference in the prevalence of YF virus neutralizing antibodies between the two groups (p = 0.263). However, titers were significantly lower in the elderly (p = 0.022). There was no correlation between YF virus neutralizing antibody titers and the time since vaccination. There was no significant difference in seropositivity among participants vaccinated prior to or within the past 10 years. Conclusions: the clinical relevance of the observed difference in YF virus neutralizing antibody titers between the two groups is not clear

Avaliação da acurácia e confiabilidade do teste sorológico de neutralização por redução de placas de lise (micro PRNT) na detecção de anticorpos para o vírus da Febre Amarela

Submitted by Priscila Nascimento ([email protected]) on 2012-12-10T13:43:12Z No. of bitstreams: 1 marisol-simoes.pdf: 2202112 bytes, checksum: 3f9f53685909ddd3fdd381f8f3692f14 (MD5)Made available in DSpace on 2012-12-10T13:43:12Z (GMT). No. of bitstreams: 1 marisol-simoes.pdf: 2202112 bytes, checksum: 3f9f53685909ddd3fdd381f8f3692f14 (MD5) Previous issue date: 2011Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos. Rio de Janeiro, RJ, Brasil.A febre amarela é causada pelo vírus protótipo do gênero Flavivirus e é transmitida ao homem através da picada de mosquitos hematófagos infectados com o agente viral. A doença permanece endêmica em regiões das florestas tropicais da África e América do Sul, apesar da disponibilidade de vacinas eficazes contra o vírus da FA – 17D-204 e 17DD – consideradas seguras e altamente imunogênicas, capazes de induzir uma rápida resposta imune específica, com a formação de anticorpos neutralizantes que aparecem precocemente, são protetores e de longa duração. O teste de neutralização por redução de placas de lise (PRNT) é considerado o teste mais sensível e mais específico para a detecção e quantificação dos anticorpos neutralizantes, sendo o método de referência para a avaliação da resposta imune protetora após a vacinação. Este estudo avaliou a confiabilidade e a acurácia do micro PRNT50 (aplicado em placas de 96 poços) tomando como referência o PRNT 50 (aplicado em placas de 6 poços) e comparou o desempenho do micro PRNT50 com o micro PRNT90 (redução de 50% e 90% das placas de lise, respectivamente). Foram selecionados 200 soros de indivíduos brasileiros que participaram de um estudo clínico de dose-resposta da vacina 17DD produzida em Bio-Manguinhos. A repetibilidade foi aferida a partir de três repetições independentes do teste para cada um dos 200 soros por uma dupla operadora e o mesmo procedimento foi realizado pelas outras duas duplas operadoras, com a finalidade de determinar a reprodutibilidade do micro PRNT50 . Foram determinados o Coeficiente de Correlação Intraclasse (CCI) e o Coeficiente de Correlação de Pearson. As medidas de acurácia determinadas neste estudo foram sensibilidade, especificidade, acurácia global, prevalência e valores preditivos positivo (VPP) e negativo (VPN). A curva ROC também foi utilizada para determinar o melhor ponto de corte do micro PRNT50 . Na avaliação da repetibilidade, os CCIs das duplas operadoras variaram entre 0,62 e 0,76; e os coeficientes de correlação de Pearson apresentaram-se entre 0,62 e 0,78. Para a reprodutibilidade, o CCI obtido foi de 0,72 e os coeficientes de correlação de Pearson variaram entre 0,70 e 0,76. As melhores medidas de acurácia foram alcançadas considerando o ponto de corte para o micro PRNT50 de 2,9 Log 10 mUI/mL, o qual apresentou sensibilidade de 91,1%, especificidade de 72,9% e acurácia global de 78%. O melhor desempenho do micro PRNT50 com este ponto de corte foi ratificado pela análise da curva ROC. Considerando um cenário hipotético de surto de FA, a prevalência seria de 28%, com VPP de 56,7% e VPN de 95,5%. O micro PRNT50 apresentou níveis satisfatórios de confiabilidade e de acurácia, mas o micro PRNT90 mostrou desempenho superior com sensibilidade de 100%, especificidade de 94,7% e acurácia global de 95%. Modificações na metodologia do teste e alterações nos critérios de classificação nas leituras dos resultados obtidos serão importantes para melhorar a acurácia do micro PRNT.Yellow fever is caused by the prototype virus of the genus Flavivirus and it is transmitted to humans through the bite of bloodsucking mosquitoes infected with the viral agent. The disease remains endemic in tropical forest regions from Africa and South America, despite the availability of effective vaccines against yellow fever virus - 17D-204 and 17DD - considered safe and highly immunogenic, capable of inducing a rapid specific immune response, with the formation of neutralizing antibodies that appear early, are protective and long lasting. The plaque reduction neutralization test (PRNT) is considered the most sensitive and most specific test for detection and quantification of neutralizing antibodies, and the reference method for assessing the protective immune response after vaccination. This study evaluated the reliability and accuracy of micro PRNT50 (applied in 96-well plates) with reference to the PRNT50 (applied in 6-well plates) and compared the performance of the micro PRNT50 with the micro PRNT90. Two-hundred serum samples from Brazilian individuals who participated in a clinical study of dose-response of 17DD vaccine produced in Bio-Manguinhos were selected. The repeatability was measured from three independent repetitions of the test for each of the 200 sera by a dual operator and the same procedure was performed by the other two dual operators, in order to determine the reproducibility of the micro PRNT50. The intraclass correlation coefficient (ICC) and Pearson correlation coefficient were determined. Accuracy measures determined in this study were sensitivity, specificity, overall accuracy, prevalence and positive predictive values (PPV) and negative (NPV). The ROC curve was also used to determine the best cut-off point of micro PRNT50 . In the assessment of repeatability, ICCs for dual operators ranged from 0.62 to 0.76, and Pearson correlation coefficients were between 0.62 and 0.78. For reproducibility, the ICC obtained was 0.72 and the Pearson correlation coefficients ranged between 0.70 and 0.76. The best measures of accuracy were achieved considering the cut-off point for the micro PRNT50 of 2.9 log10 mIU/mL, which had a sensitivity of 91.1%, specificity of 72.9% and overall accuracy of 78%. The best performance of micro PRNT50 with this cut-off point was ratified by the ROC curve analysis. Considering a hypothetical scenario of an outbreak of YF, the prevalence would be 28%, with PPV of 56.7% and NPV of 95.5%. The micro PRNT50 showed satisfactory levels of reliability and accuracy, however the micro PRNT90 showed higher performance with sensitivity of 100%, specificity of 94.7% and overall accuracy of 95%. Modifications in the test methodology and changes in the classification criteria in the readings of the results obtained will be important to improve the accuracy of micro PRNT

Otimização, Padronização, Validação e Avaliação Comparativa de Testes de Quantificação dos Anticorpos Neutralizantes para o Vírus da Febre Amarela

Made available in DSpace on 2018-10-03T16:51:24Z (GMT). No. of bitstreams: 2 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) marisol_simoes_ioc_dout_2018.pdf: 32779637 bytes, checksum: 77022c85c6a92dba568ffa376159d8ef (MD5) Previous issue date: 2018Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.A febre amarela (FA) é uma doença infecciosa aguda, febril, causada pelo vírus protótipo do gênero Flavivirus. A doença permanece como grande problema de saúde pública, principalmente em regiões endêmicas da África e América do Sul. No Brasil, ondas alarmantes de epizootias e epidemias são registradas desde 2016. A vacinação é a maneira mais eficaz de prevenção e controle da FA. As vacinas disponíveis produzidas com as subcepas 17D-204 e 17DD são seguras e imunogênicas, induzindo a formação de anticorpos neutralizantes que aparecem precocemente, são protetores e de longa duração. Apesar de ser considerado referência para a análise da resposta imune protetora após a vacinação, a metodologia clássica do teste de neutralização por redução de placas de lise (PRNT) é trabalhoso, de difícil execução, requer recursos humanos, equipamentos e insumos específicos, além de um tempo longo para a sua finalização, mesmo na versão micro PRNT (em placas de 96 poços). Esta adaptação do método é mais operacional do que o PRNT (em placas de 6 poços), com maior capacidade de processamento das amostras. Mas, além das desvantagens semelhantes ao teste referência, apresenta a dificuldade de leitura das placas de lise por ser realizado em poços menores. A busca por um teste mais rápido, semiautomatizado e eficiente para a quantificação de anticorpos neutralizantes vem ao encontro das necessidades de aumento da capacidade e melhoria de análises das amostras de estudos clínicos O presente estudo objetivou não somente otimizar a metodologia já utilizada na rotina do Laboratório de Tecnologia Virológica para os estudos de avaliação de imunogenicidade das vacinas para FA (micro PRNT), mas também padronizar uma metodologia mais rápida e semiautomatizada denominada \03BCPRN-HRP. A partir da definição dos protocolos de execução, ambas as metodologias foram validadas com os parâmetros de precisão, exatidão, seletividade e robustez. Posteriormente à validação, 200 soros de indivíduos vacinados foram processados pelas três metodologias para a avaliação da concordância (Coeficiente de Correlação Intraclasse, CCI) dos testes índices (micro PRNT e \03BCPRN-HRP) com o teste referência (PRNT). Os critérios de análise predefinidos para todos os ensaios de validação foram alcançados pelas metodologias em placas de 96 poços. O micro PRNT apresentou concordância moderada a substancial com o PRNT tanto para os títulos em log10 da recíproca da diluição (CCI de 0,59 e 0,74) quanto para os títulos em log10 de mUI/mL (CCI de 0,48 e 0,65). O \03BCPRN-HRP apresentou concordância de fraca a moderada com o PRNT para os títulos em log10 da recíproca da diluição (CCI de 0,29 e 0,45). Mas, para os títulos em log10 mUI/mL, os estimadores de concordância apresentaram magnitude substancial a quase completa com o PRNT (CCI de 0,69 e 0,82). Os coeficientes de correlação linear obtidos para os testes índices foram muito próximos, sugerindo correlação moderada (r > 0,70) com o teste referência para os títulos em recíproca da diluição e em mUI/mL. Portanto, tanto o micro PRNT quanto o \03BCPRN-HRP podem ser utilizados na avaliação das vacinas para FA, gerando resultados confiáveis. O \03BCPRN-HRP destaca-se por ser um teste mais rápido, semiautomatizado e com maior capacidade de processamento de amostras.Yellow fever (YF) is an acute, febrile infectious disease caused by the prototype virus of the genus Flavivirus. The disease remains a major public health problem, especially in endemic areas in Africa and South America. In Brazil, alarming waves of epizootics and epidemics have been reported since 2016. Vaccination is the most effective way to prevent and control YF. The available vaccines produced with 17D-204 and 17DD substrains are safe and immunogenic, inducing the formation of neutralizing antibodies that appear early, are protective and long lasting. Although it is considered a reference for the analysis of the protective immune response after vaccination, the classical methodology of the plaque reduction neutralization test (PRNT) is labor intensive, difficult to execute, requires specific human resources, equipment and inputs, besides a long time for its finalization, even in the micro PRNT version (in 96-well plates). This adaptation of the method is more operational than the PRNT (in 6-well plates), with higher sample throughput. But, in addition to the disadvantages similar to the reference test, it presents the difficulty of reading plaques by being run in smaller wells. The search for a faster, semi-automated and efficient test for the quantification of neutralizing antibodies meets the needs of increasing throughput and improving analyzes of clinical trial samples The present study aimed not only to optimize the methodology already used in the routine of the Virological Technology Laboratory in the immunogenicity evaluation studies of the vaccines for YF (micro PRNT), but also to standardize a faster and semi-automated methodology called \03BCPRN-HRP. From the definition of the execution protocols, both methodologies were validated with the parameters of precision, accuracy, selectivity and robustness. After the validation, 200 sera of vaccinees were processed by the three methodologies for the evaluation of the agreement (Intraclass Correlation Coefficient, ICC) of the index tests (micro PRNT and \03BCPRN-HRP) with the reference test (PRNT). The predefined analysis criteria for all validation assays were achieved by methodologies in 96-well plates. The micro PRNT showed moderate to substantial agreement with the PRNT for both log10 titers of the reciprocal dilution (ICC of 0.59 and 0.74) and log10 mIU/mL titers (ICC of 0.48 and 0.65). The \03BCPRNHRP showed weak to moderate agreement with the PRNT for log10 titers of reciprocal dilution (ICC of 0.29 and 0.45). However, for log10 mIU/mL titers, the agreement estimators showed a substantial to almost complete magnitude with PRNT (ICC of 0.69 and 0.82). The linear correlation coefficients obtained for the index tests were very close, suggesting a moderate correlation (r> 0.70) with the reference test for titers in reciprocal dilution and in mIU/mL. Thus, both micro PRNT and \03BCPRN-HRP can be used to evaluate vaccines for YF, generating reliable results. The \03BCPRN-HRP stands out as being a faster, semi-automated and with a higher sample throughput

New data on the Late Cretaceous lizard Dicothodon bajaensis (Squamata, Borioteiioidea) from Baja California, Mexico reveals an unusual tooth replacement pattern in squamates

Abstract Borioteiioids comprise an extinct family of squamates that inhabited the Northern Hemisphere during the Cretaceous and were characterized by varying patterns of tooth replacement and dental morphology. Understanding the evolution of these tooth replacement patterns has, however, been largely hampered by an extremely fragmentary fossil record. Here we present new information on Dicothodon bajaensisfrom the Campanian of Baja California (Mexico), so far known only from isolated teeth and jaw fragments. Among abundant new materials there are ten maxillae and five dentaries belonging to distinct ontogenetic stages. Whereas juveniles display active tooth replacement, older specimens show no evidence of replacement. Dicothodon bajaensis is therefore inferred to have had arrested tooth replacement later in ontogeny. This provides the first evidence of cessation of tooth replacement during late ontogeny in lizards (living or extinct). This replacement type is also an evolutionary intermediate between the typical lizard replacement pattern, observed in some borioteiioids (e.g., Bicuspidon) and the complete absence of tooth replacement since early ontogeny as observed in other borioteiioids (e.g., Polyglyphanodon)

New data on the Late Cretaceous lizard Dicothodon bajaensis (Squamata, Borioteiioidea) from Baja California, Mexico reveals an unusual tooth replacement pattern in squamates

<div><p>Abstract Borioteiioids comprise an extinct family of squamates that inhabited the Northern Hemisphere during the Cretaceous and were characterized by varying patterns of tooth replacement and dental morphology. Understanding the evolution of these tooth replacement patterns has, however, been largely hampered by an extremely fragmentary fossil record. Here we present new information on Dicothodon bajaensisfrom the Campanian of Baja California (Mexico), so far known only from isolated teeth and jaw fragments. Among abundant new materials there are ten maxillae and five dentaries belonging to distinct ontogenetic stages. Whereas juveniles display active tooth replacement, older specimens show no evidence of replacement. Dicothodon bajaensis is therefore inferred to have had arrested tooth replacement later in ontogeny. This provides the first evidence of cessation of tooth replacement during late ontogeny in lizards (living or extinct). This replacement type is also an evolutionary intermediate between the typical lizard replacement pattern, observed in some borioteiioids (e.g., Bicuspidon) and the complete absence of tooth replacement since early ontogeny as observed in other borioteiioids (e.g., Polyglyphanodon).</p></div

Proteostasis Response to Protein Misfolding in Controlled Hypertension

Hypertension is the most determinant risk factor for cardiovascular diseases. Early intervention and future therapies targeting hypertension mechanisms may improve the quality of life and clinical outcomes. Hypertension has a complex multifactorial aetiology and was recently associated with protein homeostasis (proteostasis). This work aimed to characterize proteostasis in easy-to-access plasma samples from 40 individuals, 20 with controlled hypertension and 20 age- and gender-matched normotensive individuals. Proteostasis was evaluated by quantifying the levels of protein aggregates through different techniques, including fluorescent probes, slot blot immunoassays and Fourier-transform infrared spectroscopy (FTIR). No significant between-group differences were observed in the absolute levels of various protein aggregates (Proteostat or Thioflavin T-stained aggregates; prefibrillar oligomers and fibrils) or total levels of proteostasis-related proteins (Ubiquitin and Clusterin). However, significant positive associations between Endothelin 1 and protein aggregation or proteostasis biomarkers (such as fibrils and ubiquitin) were only observed in the hypertension group. The same is true for the association between the proteins involved in quality control and protein aggregates. These results suggest that proteostasis mechanisms are actively engaged in hypertension as a coping mechanism to counteract its pathological effects in proteome stability, even when individuals are chronically medicated and presenting controlled blood pressure levels

Prevalence and titers of yellow fever virus neutralizing antibodies in previously vaccinated adults

ABSTRACT Introduction: The World Health Organization (WHO) recommends one single dose of the Yellow Fever (YF) vaccine based on studies of antibody persistency in healthy adults. We assessed the prevalence and titers of YF virus neutralizing antibodies in previously vaccinated persons aged 60 years, in comparison to younger adults. We also evaluated the correlation between antibody titers and the time since vaccination among participants who received one vaccine dose, and the seropositivity among participants vaccinated prior to or within the past 10 years. Methods: previously vaccinated healthy persons aged 18 years were included. YF virus neutralizing antibody titers were determined by means of the 50% Plaque Reduction Neutralization Test. Results: 46 persons aged 60 years and 48 persons aged 18 to 59 years were enrolled. There was no significant difference in the prevalence of YF virus neutralizing antibodies between the two groups (p = 0.263). However, titers were significantly lower in the elderly (p = 0.022). There was no correlation between YF virus neutralizing antibody titers and the time since vaccination. There was no significant difference in seropositivity among participants vaccinated prior to or within the past 10 years. Conclusions: the clinical relevance of the observed difference in YF virus neutralizing antibody titers between the two groups is not clear

Emerging Infectious Diseases

Submitted by Nuzia Santos ([email protected]) on 2019-08-29T13:45:36Z No. of bitstreams: 1 17DD Yellow Fever Revaccination .pdf: 1335209 bytes, checksum: 7ab0df367d542e9e0b0d0acf6363a5d8 (MD5)Approved for entry into archive by Nuzia Santos ([email protected]) on 2019-08-29T13:53:35Z (GMT) No. of bitstreams: 1 17DD Yellow Fever Revaccination .pdf: 1335209 bytes, checksum: 7ab0df367d542e9e0b0d0acf6363a5d8 (MD5)Made available in DSpace on 2019-08-29T13:53:35Z (GMT). No. of bitstreams: 1 17DD Yellow Fever Revaccination .pdf: 1335209 bytes, checksum: 7ab0df367d542e9e0b0d0acf6363a5d8 (MD5) Previous issue date: 2019Fundação Oswaldo Cruz. Instituto René Rachou. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Instituto René Rachou. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Instituto René Rachou. Belo Horizonte, MG, Brasil / Universidade Federal de Minas Gerais. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Instituto René Rachou. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Instituto René Rachou. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Instituto René Rachou. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Instituto René Rachou. Belo Horizonte, MG, Brasil.Prefeitura de Belo Horizonte. Secretaria Municipal de Saúde. Belo Horizonte, MG, Brasil.Estado de Minas Gerais. Secretaria de Saúde. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Escola Nacional de Saúde Pública Sergio Arouca. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos Bio-Manguinhos . Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos Bio-Manguinhos . Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos Bio-Manguinhos . Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos Bio-Manguinhos . Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos Bio-Manguinhos . Rio de Janeiro, RJ, Brasil.Universidade Federal de Alfenas. Alfenas, MG, Brasil.Universidade de Brasília. Brasília, DF, Brasil.Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Brasília, DF, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Brasília, DF, Brasil.Fundação Oswaldo Cruz. Instituto René Rachou. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Instituto René Rachou. Belo Horizonte, MG, Brasil.We evaluated the duration of neutralizing antibodies and the status of 17DD vaccine–specific T- and B-cell memory following primary and revaccination regimens for yellow fever (YF) in Brazil. We observed progressive decline of plaque-reduction neutralization test (PRNT) seropositivity and of the levels of effector memory CD4+ and CD8+ T cells, as well as interferon-γ+CD8+ T cells, 10 years after primary vaccination. Revaccination restored PRNT seropositivity as well as the levels of effector memory CD4+, CD8+, and interferon-γ+CD8+ T cells. Moreover, secondary or multiple vaccinations guarantee long-term persistence of PRNT positivity and cell-mediated memory 10 years after booster vaccination. These findings support the relevance of booster doses to heighten the 17DD-YF–specific immune response to guarantee the long-term persistence of memory components. Secondary or multiple vaccinations improved the correlates of protection triggered by 17DD-YF primary vaccination, indicating that booster regimens are needed to achieve efficient immunity in areas with high risk for virus transmission