RESUMO
BACKGROUND: Alouatta spp. are highly susceptible to yellow fever (YF) infection and develop an often fatal disease. The threat posed by an outbreak started in 2016 leads us to investigate vaccination as a potential tool in preventing YF in non-human primates (NHP). METHODS: Susceptible howler monkeys were immunized with three different concentrations of the human Brazilian commercial YF17DD vaccine. Post-vaccination viremia/RNAemia, immunogenicity, and safety were characterized. RESULTS: The vaccine did not produce YF clinical manifestations in any of the NHPs. After immunization, all animals seroconverted demonstrating the ability of the YF vaccine to induce humoral response in Alouatta species. CONCLUSIONS: The present work has demonstrated the safe and immunogenic profile of the existing YF 17DD vaccine in howler monkeys. This knowledge may support further studies with other susceptible monkey species and provide a possible solution for controlling epizootics and preventing the devastation of endangered species.
Assuntos
Alouatta/imunologia , Imunogenicidade da Vacina , Vacina contra Febre Amarela/efeitos adversos , Animais , Feminino , Masculino , Especificidade da Espécie , Vacinas Atenuadas/efeitos adversos , Vacinas Atenuadas/imunologia , Vacina contra Febre Amarela/imunologiaRESUMO
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.
Assuntos
Imunidade , Imunização Secundária , Vacina contra Febre Amarela/imunologia , Febre Amarela/imunologia , Febre Amarela/prevenção & controle , Vírus da Febre Amarela/imunologia , Adolescente , Adulto , Idoso , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Brasil/epidemiologia , Vírus da Dengue/imunologia , Feminino , Humanos , Imunidade Celular , Imunoglobulina G/imunologia , Memória Imunológica , Masculino , Pessoa de Meia-Idade , Testes de Neutralização , Vigilância em Saúde Pública , Vacina contra Febre Amarela/administração & dosagem , Adulto JovemRESUMO
Although it is considered the reference for quantification of neutralizing antibodies, classical method of the plaque reduction neutralization test (PRNT) is labor intensive, requires specific equipment and inputs, besides a long time for its finalization, even in the micro-PRNT version (in 96-well plates). It has a higher sample throughput, however the smaller wells make the reading of plaques more difficult. With an immunoenzymatic revelation step and a semi-automated reading, the µFRN-HRP (micro Focus Reduction Neutralization - Horseradish Peroxidase) is a faster and more efficient test for the quantification of YF neutralizing antibodies. This study aimed to standardize, validate, and compare it with the reference method in 6-well plates (PRNT). Once the execution protocol was standardized, precision, accuracy, selectivity, and robustness were evaluated to validate the µFRN-HRP. In addition, 200 sera of vaccinees were processed by the µFRN-HRP and by the micro-PRNT to compare with the reference test, estimating agreement by Intraclass Correlation Coefficient (ICC). The standardization and validation of the µFRN-HRP was carried out successfully. Weak to moderate agreement was observed between µFRN-HRP and PRNT for titers in reciprocal dilution, while the same comparison between the classical tests resulted in a better ICC. However, titers in milli-international units obtained by µFRN-HRP showed a substantial agreement with PRNT, while the agreement between micro-PRNT and PRNT was inferior. Therefore, µFRN-HRP can be used in the confirmation of natural YF infection and immune response to vaccination, replacing the micro-PRNT, gaining agility, while preserving the specificity of the result.
Assuntos
Anticorpos Neutralizantes , Febre Amarela , Humanos , Testes de Neutralização/métodos , Anticorpos Antivirais , Padrões de ReferênciaRESUMO
Chronic myeloid leukemia (CML) is a potentially fatal stem-cell cancer. P-glycoprotein (P-gp/ABCB1) activity has been described as a relevant factor in the chemotherapeutic failure and correlated to a poor prognosis in these malignancies. In the present study, we investigated the mechanism of the antineoplastic activity of 3ß-acetyl tormentic acid (3ATA), a triterpene isolated from C. lyratiloba, on Lucena-1, an MDR leukemia cell line, that overexpressed P-gp/ABCB1. Results showing that this triterpene induced DNA-fragmentation, activation of caspase-3 and cytochrome c release indicated that its activity is mediated by the activation of the intrinsic pathway of apoptosis. Interestingly, this triterpene did not interfere with P-gp/ABCB1 expression or activity, indicating that induction of death is not mediated by any effect on this protein. Moreover, the results show that none of the others triterpenes from C. lyratiloba were able to modulate the activity of P-gp/ABCB1. Together these results suggest 3ATA and the other triterpenes as a promising material for the development of anti-neoplastic drugs for leukemia and other tumors independent of P-gp/ABCB1 activity or expression.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Cecropia , Resistencia a Medicamentos Antineoplásicos , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Triterpenos/farmacologia , Subfamília B de Transportador de Cassetes de Ligação de ATP , Antineoplásicos Fitogênicos/isolamento & purificação , Caspase 3/metabolismo , Cecropia/química , Citocromos c/metabolismo , Relação Dose-Resposta a Droga , Ativação Enzimática , Humanos , Células K562 , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Fatores de Tempo , Triterpenos/isolamento & purificaçãoRESUMO
Yellow fever is a disease caused by the prototype virus of the genus Flavivirus and remains endemic in tropical forest regions from Africa and South America, despite the availability of effective vaccines. These are 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 is considered the most sensitive and specific test for quantification of neutralizing antibodies, and the reference method for assessing the protective immune response after vaccination. This study evaluated the reliability (repeatability and reproducibility) and accuracy (sensitivity, specificity and overall accuracy) of micro-PRNT50 and compared its performance with the micro-PRNT90. Although the micro-PRNT50 has showed satisfactory levels of reliability (ICCs ranged from 0.62 to 0.NorNormas e Manuais Técnicosas e Manuais Técnicos6 for repeatability and 0.72 for reproducibility) and accuracy (sensitivity of 91.1%, specificity of 72.9% and overall accuracy of 78%), the micro-PRNT90 showed higher performance, with ICCs for repeatability ranged from 0.78 to 0.79 and 0.81 for reproducibility, 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.
Assuntos
Anticorpos Antivirais/análise , Testes de Neutralização , Ensaio de Placa Viral , Vírus da Febre Amarela/imunologia , Humanos , Limite de Detecção , Reprodutibilidade dos Testes , Vírus da Febre Amarela/crescimento & desenvolvimentoRESUMO
Multidrug resistance (MDR) is considered the main cause of cancer chemotherapy failure and patient relapse. The active drug efflux mediated by transporter proteins of the ABC (ATP-binding cassette) family is the most investigated mechanism leading to MDR. With the aim of inhibiting this transport and circumventing MDR, a great amount of work has been dedicated to identifying pharmacological inhibitors of specific ABC transporters. We recently showed that 3ß-acetyl tormentic acid (3ATA) had no effect on P-gp/ABCB1 activity. Herein, we show that 3ATA strongly inhibited the activity of MRP1/ABCC1. In the B16/F10 and Ma104 cell lines, this effect was either 20X higher or similar to that observed with MK571, respectively. Nevertheless, the low inhibitory effect of 3ATA on A549, a cell line that expresses MRP1-5, suggests that it may not inhibit other MRPs. The use of cells transfected with ABCC2, ABCC3 or ABCC4 showed that 3ATA was also able to modulate these transporters, though with an inhibition ratio lower than that observed for MRP1/ABCC1. These data point to 3ATA as a new ABCC inhibitor and call attention to its potential use as a tool to investigate the function of MRP/ABCC proteins or as a co-adjuvant in the treatment of MDR tumors.
Assuntos
Resistência a Múltiplos Medicamentos , Resistencia a Medicamentos Antineoplásicos , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Triterpenos/química , Animais , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Haplorrinos , Humanos , Melanoma Experimental , Camundongos , Proteína 2 Associada à Farmacorresistência Múltipla , Células NIH 3T3RESUMO
The Yellow Fever (YF) vaccination is recommended for people living in endemic areas and represents the most effective strategy to reduce the risk of infection. Previous studies have warned that booster regimens should be considered to guarantee the long-term persistence of 17DD-YF-specific memory components in adults living in areas with YF-virus circulation. Considering the lower seroconversion rates observed in children (9-12 months of age) as compared to adults, this study was designed in order to access the duration of immunity in single-dose vaccinated children in a 10-years cross-sectional time-span. The levels of neutralizing antibodies (PRNT) and the phenotypic/functional memory status of T and B-cells were measured at a baseline, 30-45 days, 1, 2, 4, 7, and 10 years following primary vaccination. The results revealed that a single dose induced 85% of seropositivity at 30-45 days and a progressive time-dependent decrease was observed as early as 2 years and declines toward critical values (below 60%) at time-spans of ≥4-years. Moreover, short-lived YF-specific cellular immunity, mediated by memory T and B-cells was also observed after 4-years. Predicted probability and resultant memory analysis emphasize that correlates of protection (PRNT; effector memory CD8+ T-cells; non-classical memory B-cells) wane to critical values within ≥4-years after primary vaccination. Together, these results clearly demonstrate the decline of 17DD-YF-specific memory response along time in children primarily vaccinated at 9-12 months of age and support the need of booster regimen to guarantee the long-term persistence of memory components for children living in areas with high risk of YF transmission.
Assuntos
Imunidade/imunologia , Vacina contra Febre Amarela/imunologia , Febre Amarela/imunologia , Febre Amarela/prevenção & controle , Vírus da Febre Amarela/imunologia , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Linfócitos B/imunologia , Linfócitos T CD8-Positivos/imunologia , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Imunização Secundária/métodos , Lactente , Masculino , Vacinação/métodosRESUMO
Yellow fever (YF) is a viral disease transmitted by mosquitoes and endemic mostly in South America and Africa with 20-50% fatality. All current licensed YF vaccines, including YF-Vax® (Sanofi-Pasteur, Lyon, France) and 17DD-YFV (Bio-Manguinhos, Rio de Janeiro, Brazil), are based on live attenuated virus produced in hens' eggs and have been widely used. The YF vaccines are considered safe and highly effective. However, a recent increase in demand for YF vaccines and reports of rare cases of YF vaccine-associated fatal adverse events have provoked interest in developing a safer YF vaccine that can be easily scaled up to meet this increased global demand. To this point, we have engineered the YF virus envelope protein (YFE) and transiently expressed it in Nicotiana benthamiana as a stand-alone protein (YFE) or as fusion to the bacterial enzyme lichenase (YFE-LicKM). Immunogenicity and challenge studies in mice demonstrated that both YFE and YFE-LicKM elicited virus neutralizing (VN) antibodies and protected over 70% of mice from lethal challenge infection. Furthermore, these two YFE-based vaccine candidates induced VN antibody responses with high serum avidity in nonhuman primates and these VN antibody responses were further enhanced after challenge infection with the 17DD strain of YF virus. These results demonstrate partial protective efficacy in mice of YFE-based subunit vaccines expressed in N. benthamiana. However, their efficacy is inferior to that of the live attenuated 17DD vaccine, indicating that formulation development, such as incorporating a more suitable adjuvant, may be required for product development.
Assuntos
Modelos Animais de Doenças , Vacina contra Febre Amarela/biossíntese , Febre Amarela/prevenção & controle , Animais , ELISPOT/métodos , Humanos , Camundongos/imunologia , Testes de Neutralização/métodos , Febre Amarela/tratamento farmacológico , Vacina contra Febre Amarela/imunologia , Vacina contra Febre Amarela/uso terapêutico , Vírus da Febre Amarela/imunologiaRESUMO
In this investigation, machine-enhanced techniques were applied to bring about scientific insights to identify a minimum set of phenotypic/functional memory-related biomarkers for post-vaccination follow-up upon yellow fever (YF) vaccination. For this purpose, memory status of circulating T-cells (Naïve/early-effector/Central-Memory/Effector-Memory) and B-cells (Naïve/non-Classical-Memory/Classical-Memory) along with the cytokine profile (IFN/TNF/IL-5/IL-10) were monitored before-NV(day0) and at distinct time-points after 17DD-YF primary vaccination-PV(day30-45); PV(year1-9) and PV(year10-11). A set of biomarkers (eEfCD4; EMCD4; CMCD19; EMCD8; IFNCD4; IL-5CD8; TNFCD4; IFNCD8; TNFCD8; IL-5CD19; IL-5CD4) were observed in PV(day30-45), but not in NV(day0), with most of them still observed in PV(year1-9). Deficiencies of phenotypic/functional biomarkers were observed in NV(day0), while total lack of memory-related attributes was observed in PV(year10-11), regardless of the age at primary vaccination. Venn-diagram analysis pre-selected 10 attributes (eEfCD4, EMCD4, CMCD19, EMCD8, IFNCD4, IL-5CD8, TNFCD4, IFNCD8, TNFCD8 and IL-5CD4), of which the overall mean presented moderate accuracy to discriminate PV(day30-45)&PV(year1-9) from NV(day0)&PV(year10-11). Multi-parameter approaches and decision-tree algorithms defined the EMCD8 and IL-5CD4 attributes as the top-two predictors with moderated performance. Together with the PRNT titers, the top-two biomarkers led to a resultant memory status observed in 80% and 51% of volunteers in PV(day30-45) and PV(year1-9), contrasting with 0% and 29% found in NV(day0) and PV(year10-11), respectively. The deficiency of memory-related attributes observed at PV(year10-11) underscores the conspicuous time-dependent decrease of resultant memory following17DD-YF primary vaccination that could be useful to monitor potential correlates of protection in areas under risk of YF transmission.
Assuntos
Anticorpos Antivirais/sangue , Biomarcadores/sangue , Vacinação , Vacina contra Febre Amarela/imunologia , Febre Amarela/prevenção & controle , Vírus da Febre Amarela/imunologia , Adolescente , Adulto , Idoso , Linfócitos B/imunologia , Linfócitos T CD8-Positivos/imunologia , Citocinas/sangue , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Tempo , Febre Amarela/imunologia , Febre Amarela/virologia , Adulto JovemRESUMO
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 ï³ 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 ï³ 18 years were included. YF virus neutralizing antibody titers were determined by means of the 50% Plaque Reduction Neutralization Test. RESULTS:: 46 persons aged ï³ 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.
Assuntos
Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Vacina contra Febre Amarela/imunologia , Febre Amarela/prevenção & controle , Vírus da Febre Amarela/imunologia , Adolescente , Adulto , Fatores Etários , Idoso , Brasil , Feminino , Humanos , Imunoglobulina M/sangue , Masculino , Pessoa de Meia-Idade , Febre Amarela/imunologia , Adulto JovemRESUMO
Technological innovations in vaccinology have recently contributed to bring about novel insights for the vaccine-induced immune response. While the current protocols that use peripheral blood samples may provide abundant data, a range of distinct components of whole blood samples are required and the different anticoagulant systems employed may impair some properties of the biological sample and interfere with functional assays. Although the interference of heparin in functional assays for viral neutralizing antibodies such as the functional plaque-reduction neutralization test (PRNT), considered the gold-standard method to assess and monitor the protective immunity induced by the Yellow fever virus (YFV) vaccine, has been well characterized, the development of pre-analytical treatments is still required for the establishment of optimized protocols. The present study intended to optimize and evaluate the performance of pre-analytical treatment of heparin-collected blood samples with ecteola-cellulose (ECT) to provide accurate measurement of anti-YFV neutralizing antibodies, by PRNT. The study was designed in three steps, including: I. Problem statement; II. Pre-analytical steps; III. Analytical steps. Data confirmed the interference of heparin on PRNT reactivity in a dose-responsive fashion. Distinct sets of conditions for ECT pre-treatment were tested to optimize the heparin removal. The optimized protocol was pre-validated to determine the effectiveness of heparin plasma:ECT treatment to restore the PRNT titers as compared to serum samples. The validation and comparative performance was carried out by using a large range of serum vs heparin plasma:ECT 1:2 paired samples obtained from unvaccinated and 17DD-YFV primary vaccinated subjects. Altogether, the findings support the use of heparin plasma:ECT samples for accurate measurement of anti-YFV neutralizing antibodies.
Assuntos
Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Anticoagulantes/sangue , Coleta de Amostras Sanguíneas/métodos , Celulose/análogos & derivados , Monitoramento de Medicamentos/métodos , Heparina/sangue , Testes de Neutralização , Vacinação , Vacina contra Febre Amarela/administração & dosagem , Febre Amarela/prevenção & controle , Vírus da Febre Amarela/imunologia , Adolescente , Adulto , Idoso , Biomarcadores/sangue , Celulose/química , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Ensaio de Placa Viral , Febre Amarela/sangue , Febre Amarela/diagnóstico , Febre Amarela/virologia , Adulto JovemRESUMO
BACKGROUND: Yellow fever vaccine (YFV) induces weaker immune responses in HIV-infected individuals. However, little is known about YFV responses among antiretroviral-treated patients and potential immunological predictors of YFV response in this population. METHODS: We enrolled 34 antiretroviral therapy (ART)-treated HIV-infected and 58 HIV-uninfected adults who received a single YFV dose to evaluate antibody levels and predictors of immunity, focusing on CD4(+) T-cell count, CD4(+)/CD8(+) ratio, and Human Pegivirus (GBV-C) viremia. Participants with other immunosuppressive conditions were excluded. RESULTS: Median time since YFV was nonsignificantly shorter in HIV-infected participants than in HIV-uninfected participants (42 and 69 months, respectively, P = 0.16). Mean neutralizing antibody (NAb) titers was lower in HIV-infected participants than HIV-uninfected participants (3.3 vs. 3.6 log10mIU/mL, P = 0.044), a difference that remained significant after adjustment for age, sex, and time since vaccination (P = 0.024). In HIV-infected participants, lower NAb titers were associated with longer time since YFV (rho: -0.38, P = 0.027) and lower CD4(+)/CD8(+) ratio (rho: 0.42, P = 0.014), but not CD4(+) T-cell count (P = 0.52). None of these factors were associated with NAb titers in HIV-uninfected participant. GBV-C viremia was not associated with difference in NAb titers overall or among HIV-infected participants. CONCLUSIONS: ART-treated HIV-infected individuals seem to have impaired and/or less durable responses to YFV than HIV-uninfected individuals, which were associated with lower CD4(+)/CD8(+) ratio, but not with CD4(+) T-cell count. These results supports the notion that low CD4(+)/CD8(+) ratio, a marker linked to persistent immune activation, is a better indicator of functional immune disturbance than CD4(+) T-cell count in patients with successful ART.
Assuntos
Fármacos Anti-HIV/uso terapêutico , Anticorpos Antivirais/sangue , Relação CD4-CD8 , Infecções por HIV/imunologia , Vacina contra Febre Amarela/imunologia , Adulto , Anticorpos Neutralizantes/sangue , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Estudos de Casos e Controles , Feminino , Infecções por HIV/tratamento farmacológico , Humanos , Contagem de Linfócitos , Masculino , Pessoa de Meia-Idade , Carga ViralRESUMO
BACKGROUND: HIV-infected individuals have deficient responses to Yellow Fever vaccine (YFV) and may be at higher risk for adverse events (AE). Chronic immune activation-characterized by low CD4/CD8 ratio or high indoleamine 2,3-dioxygenase-1 (IDO) activity-may influence vaccine response in this population. METHODS: We prospectively assessed AE, viremia by the YFV virus and YF-specific neutralizing antibodies (NAb) in HIV-infected (CD4>350) and -uninfected adults through 1 year after vaccination. The effect of HIV status on initial antibody response to YFV was measured during the first 3 months following vaccination, while the effect on persistence of antibody response was measured one year following vaccination. We explored CD4/CD8 ratio, IDO activity (plasma kynurenine/tryptophan [KT] ratio) and viremia by Human Pegivirus as potential predictors of NAb response to YFV among HIV-infected participants with linear mixed models. RESULTS: 12 HIV-infected and 45-uninfected participants were included in the final analysis. HIV was not significantly associated with AE, YFV viremia or NAb titers through the first 3 months following vaccination. However, HIV-infected participants had 0.32 times the NAb titers observed for HIV-uninfected participants at 1 year following YFV (95% CI 0.13 to 0.83, p = 0.021), independent of sex, age and prior vaccination. In HIV-infected participants, each 10% increase in CD4/CD8 ratio predicted a mean 21% higher post-baseline YFV Nab titer (p = 0.024). Similarly, each 10% increase in KT ratio predicted a mean 21% lower post-baseline YFV Nab titer (p = 0.009). Viremia by Human Pegivirus was not significantly associated with NAb titers. CONCLUSIONS: HIV infection appears to decrease the durability of NAb responses to YFV, an effect that may be predicted by lower CD4/CD8 ratio or higher KT ratio.
Assuntos
Relação CD4-CD8 , Infecções por HIV/imunologia , Imunogenicidade da Vacina , Cinurenina/sangue , Triptofano/sangue , Vacina contra Febre Amarela/imunologia , Febre Amarela/prevenção & controle , Adulto , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/sangue , Feminino , Infecções por HIV/virologia , Humanos , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Viremia , Febre Amarela/imunologia , Febre Amarela/virologia , Vacina contra Febre Amarela/efeitos adversos , Vírus da Febre Amarela/imunologiaRESUMO
A single vaccination of Yellow Fever vaccines is believed to confer life-long protection. In this study, results of vaccinees who received a single dose of 17DD-YF immunization followed over 10 y challenge this premise. YF-neutralizing antibodies, subsets of memory T and B cells as well as cytokine-producing lymphocytes were evaluated in groups of adults before (NVday0) and after (PVday30-45, PVyear1-4, PVyear5-9, PVyear10-11, PVyear12-13) 17DD-YF primary vaccination. YF-neutralizing antibodies decrease significantly from PVyear1-4 to PVyear12-13 as compared to PVday30-45, and the seropositivity rates (PRNT≥2.9Log10mIU/mL) become critical (lower than 90%) beyond PVyear5-9. YF-specific memory phenotypes (effector T-cells and classical B-cells) significantly increase at PVday30-45 as compared to naïve baseline. Moreover, these phenotypes tend to decrease at PVyear10-11 as compared to PVday30-45. Decreasing levels of TNF-α(+) and IFN-γ(+) produced by CD4(+) and CD8(+) T-cells along with increasing levels of IL-10(+)CD4(+)T-cells were characteristic of anti-YF response over time. Systems biology profiling represented by hierarchic networks revealed that while the naïve baseline is characterized by independent micro-nets, primary vaccinees displayed an imbricate network with essential role of central and effector CD8(+) memory T-cell responses. Any putative limitations of this cross-sectional study will certainly be answered by the ongoing longitudinal population-based investigation. Overall, our data support the current Brazilian national immunization policy guidelines that recommend one booster dose 10 y after primary 17DD-YF vaccination.
Assuntos
Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Linfócitos B/imunologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Vacina contra Febre Amarela/imunologia , Febre Amarela/prevenção & controle , Vírus da Febre Amarela/imunologia , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Brasil , Humanos , Memória Imunológica/imunologia , Interferon gama/sangue , Fator de Necrose Tumoral alfa/sangue , Vacinação , Febre Amarela/virologiaRESUMO
A vacinação contra a febre amarela (YF) é recomendada para pessoas que vivem em áreas endêmicas e representa a estratégia mais eficaz para reduzir o risco de infecção. Estudos anteriores alertaram que os regimes de reforço devem ser considerados para garantir a persistência a longo prazo dos componentes de memória específicos da 17DD-YF em adultos que vivem em áreas com circulação do vírus da YF. Considerando as menores taxas de soroconversão observadas em crianças (9 a 12 meses de idade) em comparação aos adultos, este estudo foi desenvolvido para acessar a duração da imunidade em crianças vacinadas em dose única em um período de 10 anos de seção transversal . Os níveis de anticorpos neutralizantes (PRNT) e o status fenotípico / de memória funcional das células T e B foram medidos no início, 30 a 45 dias, 1, 2, 4, 7 e 10 anos após a vacinação primária. Os resultados revelaram que uma dose única induziu 85% de soropositividade entre 30 e 45 dias e uma diminuição progressiva dependente do tempo foi observada em apenas 2 anos e diminui para valores críticos (abaixo de 60%) em períodos de tempo ≥ 4 anos . Além disso, a imunidade celular específica de YF de curta duração, mediada pelas células T e B de memória, também foi observada após 4 anos. A análise de probabilidade prevista e a memória resultante enfatizam que os correlatos de proteção (PRNT; células T CD8 + com memória efetiva; células B com memória não clássica) diminuem para valores críticos dentro de ≥4 anos após a vacinação primária. Juntos, esses resultados demonstram claramente o declínio da resposta da memória específica da 17DD-YF ao longo do tempo em crianças vacinadas principalmente entre 9 e 12 meses de idade e suportam a necessidade de um regime de reforço para garantir a persistência a longo prazo dos componentes da memória para crianças que vivem em áreas com alto risco de transmissão YF.
Assuntos
Febre Amarela , Criança , Anticorpos NeutralizantesRESUMO
Nesta investigação, as técnicas melhoradas por máquina foram aplicadas para trazer insights científicos para identificar um conjunto mínimo de biomarcadores relacionados à memória fenotípica / funcional para o acompanhamento pós-vacinação da vacinação contra a febre amarela (FA). Para este propósito, o estado de memória das células T circulantes (Naïve / efetor-precoce / Memória-Central / Memória Efetiva) e células B (Naïve / memória não clássica / memória clássica) juntamente com o perfil de citocinas (IFN / TNF / IL-5 / IL-10) foram monitorizados antes do NV (dia 0) e em pontos de tempo distintos após a vacinação primária com 17DD-YF - VP (dia30-45); PV (ano1-9) e PV (ano10-11). Um conjunto de biomarcadores (eEfCD4; EMCD4; CMCD19; EMCD8; IFNCD4; IL-5CD8; TNFCD4; IFNCD8; TNFCD8; IL-5CD19; IL-5CD4) foi observado em PV (dia30-45), mas não em NV (dia0) , com a maioria deles ainda observada em VP (ano1-9). Deficiências de biomarcadores fenotípicos / funcionais foram observadas em NV (dia 0), enquanto a falta total de atributos relacionados à memória foi observada na PV (ano10-11), independentemente da idade na vacinação primária. Análise de diagrama de Venn pré-selecionada 10 atributos (eEfCD4, EMCD4, CMCD19, EMCD8, IFNCD4, IL-5CD8, TNFCD4, IFNCD8, TNFCD8 e IL-5CD4), dos quais a média geral apresentou moderada precisão para discriminar PV (dia30-45) e PV (year1-9) de NV (day0) e PV (year10-11). Abordagens multi-parâmetro e algoritmos de árvore de decisão definiram os atributos EMCD8 e IL-5CD4 como os dois principais preditores com desempenho moderado. Juntamente com os títulos PRNT, os dois principais biomarcadores levaram a um status de memória resultante observado em 80% e 51% dos voluntários em PV (dia30-45) e PV (ano1-9), contrastando com 0% e 29% encontrados em NV ( day0) e PV (year10-11), respectivamente. A deficiência de atributos relacionados à memória observada na PV (year10-11) ressalta a diminuição conspícua dependente do tempo da memória resultante após a vacinação primária com 17DD-YF, que pode ser útil para monitorar potenciais correlatos de proteção em áreas sob risco de transmissão da FA.
Assuntos
Febre Amarela , VacinasRESUMO
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.