ASP-2/Trans-sialidase chimeric protein induces robust protective immunity in experimental models of Chagas' disease.

Immunization with the Amastigote Surface Protein-2 (ASP-2) and Trans-sialidase (TS) antigens either in the form of recombinant protein, encoded in plasmids or human adenovirus 5 (hAd5) confers robust protection against various lineages of Trypanosoma cruzi. Herein we generated a chimeric protein containing the most immunogenic regions for T and B cells from TS and ASP-2 (TRASP) and evaluated its immunogenicity in comparison with our standard protocol of heterologous prime-boost using plasmids and hAd5. Mice immunized with TRASP protein associated to Poly-ICLC (Hiltonol) were highly resistant to challenge with T. cruzi, showing a large decrease in tissue parasitism, parasitemia and no lethality. This protection lasted for at least 3 months after the last boost of immunization, being equivalent to the protection induced by DNA/hAd5 protocol. TRASP induced high levels of T. cruzi-specific antibodies and IFNγ-producing T cells and protection was primarily mediated by CD8+ T cells and IFN-γ. We also evaluated the toxicity, immunogenicity, and efficacy of TRASP and DNA/hAd5 formulations in dogs. Mild collateral effects were detected at the site of vaccine inoculation. While the chimeric protein associated with Poly-ICLC induced high levels of antibodies and CD4+ T cell responses, the DNA/hAd5 induced no antibodies, but a strong CD8+ T cell response. Immunization with either vaccine protected dogs against challenge with T. cruzi. Despite the similar efficacy, we conclude that moving ahead with TRASP together with Hiltonol is advantageous over the DNA/hAd5 vaccine due to pre-existing immunity to the adenovirus vector, as well as the cost-benefit for development and large-scale production.

Differential requirement of neutralizing antibodies and T cells on protective immunity to SARS-CoV-2 variants of concern.

The current COVID-19 vaccines protect against severe disease, but are not effective in controlling replication of the Variants of Concern (VOCs). Here, we used the existing pre-clinical models of severe and moderate COVID-19 to evaluate the efficacy of a Spike-based DNA vaccine (pCTV-WS) for protection against different VOCs. Immunization of transgenic (K18-hACE2) mice and hamsters induced significant levels of neutralizing antibodies (nAbs) to Wuhan and Delta isolates, but not to the Gamma and Omicron variants. Nevertheless, the pCTV-WS vaccine offered significant protection to all VOCs. Consistently, protection against lung pathology and viral load to Wuhan or Delta was mediated by nAbs, whereas in the absence of nAbs, T cells controlled viral replication, disease and lethality in mice infected with either the Gamma or Omicron variants. Hence, considering the conserved nature of CD4 and CD8 T cell epitopes, we corroborate the hypothesis that induction of effector T-cells should be a main goal for new vaccines against the emergent SARS-CoV-2 VOCs.

Promotion of neutralizing antibody-independent immunity to wild-type and SARS-CoV-2 variants of concern using an RBD-Nucleocapsid fusion protein.

Both T cells and B cells have been shown to be generated after infection with SARS-CoV-2 yet protocols or experimental models to study one or the other are less common. Here, we generate a chimeric protein (SpiN) that comprises the receptor binding domain (RBD) from Spike (S) and the nucleocapsid (N) antigens from SARS-CoV-2. Memory CD4+ and CD8+ T cells specific for SpiN could be detected in the blood of both individuals vaccinated with Coronavac SARS-CoV-2 vaccine and COVID-19 convalescent donors. In mice, SpiN elicited a strong IFN-γ response by T cells and high levels of antibodies to the inactivated virus, but not detectable neutralizing antibodies (nAbs). Importantly, immunization of Syrian hamsters and the human Angiotensin Convertase Enzyme-2-transgenic (K18-ACE-2) mice with Poly ICLC-adjuvanted SpiN promotes robust resistance to the wild type SARS-CoV-2, as indicated by viral load, lung inflammation, clinical outcome and reduction of lethality. The protection induced by SpiN was ablated by depletion of CD4+ and CD8+ T cells and not transferred by antibodies from vaccinated mice. Finally, vaccination with SpiN also protects the K18-ACE-2 mice against infection with Delta and Omicron SARS-CoV-2 isolates. Hence, vaccine formulations that elicit effector T cells specific for the N and RBD proteins may be used to improve COVID-19 vaccines and potentially circumvent the immune escape by variants of concern.

Profile of Brazilian inpatients with COVID-19 vaccine breakthrough infection and risk factors for unfavorable outcome.

Objective: To characterize the epidemiological and clinical profile of individuals more likely to become infected with SARS-CoV-2 after the fully vaccination schedule in order to profile priority groups to receive a booster dose in situations of vaccine doses shortage as well as for maintenance of personal protective care. Methods: This cross-sectional study used data from hospitalized COVID-19 patients aged ≥18 years, who had been fully vaccinated and had a SARS-CoV-2 infection positive diagnosis collected from the SIVEP-Gripe database (Influenza Epidemiological Surveillance Information System) from January 18, 2021 to September 15, 2021. Demographic data, clinical symptoms and preexisting medical conditions (comorbidities) were analyzed. The primary outcome was in-hospital death. Results: The majority of hospitalized patients with vaccine breakthrough infection were ≥60 years old, male, with critical or severe COVID-19. The fatality rate was extremely high (50.27%) and more pronounced in elderly groups. The most prevalent symptoms were cough, dyspnea, respiratory distress, and low blood oxygen saturation. The most frequent comorbidities were heart disease and diabetes. High fatality rates were observed among patients admitted to the intensive care units (72.88%) and those who required invasive mechanical ventilation (87.82%). The main risk factors for an unfavorable outcome were older age, respiratory compromise, inactivated virus vaccine immunization, and preexisting medical conditions. Conclusions: We characterized the profile of hospitalized Brazilian patients with COVID-19 vaccine breakthrough infection and the risk factors for an unfavorable outcome. These data allow to identify priority groups to receive a booster dose and to continue using personal protection.

Profile of Brazilian inpatients with COVID-19 vaccine breakthrough infection and risk factors for unfavorable outcome

[ABSTRACT]. Objective. To characterize the epidemiological and clinical profile of individuals more likely to become infected with SARS-CoV-2 after the fully vaccination schedule in order to profile priority groups to receive a booster dose in situations of vaccine doses shortage as well as for maintenance of personal protective care. Methods. This cross-sectional study used data from hospitalized COVID-19 patients aged ≥18 years, who had been fully vaccinated and had a SARS-CoV-2 infection positive diagnosis collected from the SIVEP-Gripe database (Influenza Epidemiological Surveillance Information System) from January 18, 2021 to September 15, 2021. Demographic data, clinical symptoms and preexisting medical conditions (comorbidities) were analyzed. The primary outcome was in-hospital death. Results. The majority of hospitalized patients with vaccine breakthrough infection were ≥60 years old, male, with critical or severe COVID-19. The fatality rate was extremely high (50.27%) and more pronounced in elderly groups. The most prevalent symptoms were cough, dyspnea, respiratory distress, and low blood oxygen saturation. The most frequent comorbidities were heart disease and diabetes. High fatality rates were observed among patients admitted to the intensive care units (72.88%) and those who required invasive mechanical ventilation (87.82%). The main risk factors for an unfavorable outcome were older age, respiratory compromise, inactivated virus vaccine immunization, and preexisting medical conditions. Conclusions. We characterized the profile of hospitalized Brazilian patients with COVID-19 vaccine breakthrough infection and the risk factors for an unfavorable outcome. These data allow to identify priority groups to receive a booster dose and to continue using personal protection.

[RESUMEN]. Objetivo. Caracterizar el perfil clínico y epidemiológico de las personas con mayores probabilidades de contraer la infección por el SARS-CoV-2 luego de tener el esquema completo de vacunación, con el fin de definir los grupos de prioridad para la aplicación de la dosis de refuerzo en situaciones de escasez de dosis de vacunación, así como para el mantenimiento de los equipos de protección personal. Métodos. En este estudio transversal se emplearon datos de pacientes mayores de 18 años hospitalizados con COVID-19 que habían recibido la pauta completa de vacunación y tenían un diagnóstico positivo de infección por SARS-CoV-2, recabados de la base de datos SIVEP-Gripe (Sistema de Información de Vigilancia Epidemiológica de la Gripe) en el periodo comprendido entre el 18 de enero del 2021 y el 15 de septiembre del 2021. Se analizaron datos demográficos, síntomas clínicos y trastornos médicos preexistentes (comorbilidades). El resultado primario fue la muerte hospitalaria. Resultados. La mayoría de los pacientes vacunados hospitalizados fueron varones mayores de 60 años con infección crítica o grave por el virus de la COVID-19. La tasa de letalidad fue extremadamente elevada (50,27 %) y más pronunciada en los grupos de edad avanzada. Los síntomas más prevalentes fueron tos, disnea, dificultad respiratoria y baja saturación de oxígeno en sangre. Las comorbilidades más frecuentes fueron las cardiopatías y la diabetes. Se observaron altas tasas de letalidad entre los pacientes ingresados en las unidades de cuidados intensivos (72,88 %) y los que necesitaron ventilación mecánica invasiva (87,82 %). Los principales factores de riesgo para un resultado desfavorable fueron la edad avanzada, dificultades respiratorias, inmunización con vacunas de virus inactivados y trastornos médicos preexistentes. Conclusiones. Se caracterizaron el perfil de los pacientes brasileños vacunados hospitalizados con COVID-19 por infección irruptiva de vacuna y los factores de riesgo de un resultado desfavorable. Estos datos permiten identificar los grupos de prioridad para recibir la dosis de refuerzo y continuar utilizando protección personal.

[RESUMO]. Objetivo. Caracterizar o perfil epidemiológico e clínico dos indivíduos mais propensos a se infectar com SARS-CoV-2 após o esquema vacinal completo, a fim de traçar o perfil dos grupos prioritários para receberem uma dose de reforço em situações de escassez de doses vacinais, bem como para manutenção dos cuidados de proteção individual. Métodos. Este estudo transversal utilizou dados de pacientes hospitalizados com COVID-19 com idade ≥18 anos, esquema vacinal completo e diagnóstico positivo de infecção por SARS-CoV-2, coletados do banco de dados SIVEP-Gripe (Sistema de Informação da Vigilância Epidemiológica da Gripe) de 18 de janeiro a 15 de setembro de 2021. Foram analisados dados demográficos, sintomas clínicos e problemas médicos preexistentes (comorbidades). O desfecho primário foi óbito intra-hospitalar. Resultados. A maioria dos pacientes hospitalizados com infecção devido a escape vacinal tinha ≥60 anos, era do sexo masculino e tinha um quadro de COVID-19 grave ou gravíssimo. A letalidade foi extremamente alta (50,27%) e mais pronunciada nos grupos de pessoas idosas. Os sintomas mais prevalentes foram tosse, dispneia, desconforto respiratório e baixa saturação de oxigênio no sangue. As comorbidades mais frequentes foram cardiopatia e diabetes. Altas taxas de letalidade foram observadas entre os pacientes internados em unidades de terapia intensiva (72,88%) e os que precisaram de ventilação mecânica invasiva (87,82%). Os principais fatores de risco para um desfecho desfavorável foram idade avançada, comprometimento respiratório, imunização com vacina de vírus inativado e problemas médicos preexistentes. Conclusões. Caracterizamos o perfil dos pacientes brasileiros hospitalizados com infecção por COVID-19 devido a escape vacinal e os fatores de risco para desfecho desfavorável. Esses dados permitem identificar grupos prioritários para receber dose de reforço e continuar os cuidados de proteção individual.

A temporal study of Brazilian pregnant and postpartum women vulnerability for COVID-19: Characteristics, risk factors and outcomes.

BACKGROUND: During the COVID-19 second wave in Brazil, there has been a significant increase in the number of daily cases and deaths, including pregnant and postpartum women. We assess risk factors and outcomes for this priority group compared to the COVID-19 non-pregnant cohort in two epidemic waves. METHODS: In this retrospective cohort study we evaluated data of hospitalized pregnant, postpartum, and nonpregnant women aged 15-44 years, between epidemiological weeks 2020-8 and 2021-15, who tested positive for SARS-CoV-2, retrieved from the Influenza Epidemiological Surveillance Information System maintained by Ministry of Health of Brazil. We analysed in-hospital case fatality rate, crude and adjusted risk ratios on different outcomes aiming to compare data in two waves. FINDINGS: The study included pregnant women (n = 7,132), postpartum women (n = 2,405) and nonpregnant women (n = 76,278) hospitalized with COVID-19. Case fatality rates of pregnant women were lower in both waves compared to nonpregnant women, but higher among postpartum women. The risk for admission to the intensive care unit and invasive mechanical ventilation requirement in both waves was significantly higher among postpartum women compared to nonpregnant women. Cardiac disease, diabetes, obesity, and asthma were the most frequent underlying medical conditions in all patient groups. These comorbidities were significantly less frequent among pregnant women. INTERPRETATION: Pregnant women with COVID-19 are at lower risk of poor outcome compared to nonpregnant women. On the other hand, postpartum women are at higher risk of adverse outcomes compared to pregnant and nonpregnant women, especially during the second wave. There was a significant increase in the in-hospital case fatality rate for all patient groups during the second wave of COVID-19. FUNDING: This study was financed in part by CAPES, CNPq, FAPEMIG and UFSJ.

Profile of Brazilian inpatients with COVID-19 vaccine breakthrough infection and risk factors for unfavorable outcome / Perfil de los pacientes brasileños vacunados hospitalizados por COVID-19 y factores de riesgo de un resultado desfavorable / Perfil de pacientes brasileiros internados com infecção por COVID-19 devido a escape vacinal e fatores de risco para desfecho desfavorável

ABSTRACT Objective. To characterize the epidemiological and clinical profile of individuals more likely to become infected with SARS-CoV-2 after the fully vaccination schedule in order to profile priority groups to receive a booster dose in situations of vaccine doses shortage as well as for maintenance of personal protective care. Methods. This cross-sectional study used data from hospitalized COVID-19 patients aged ≥18 years, who had been fully vaccinated and had a SARS-CoV-2 infection positive diagnosis collected from the SIVEP-Gripe database (Influenza Epidemiological Surveillance Information System) from January 18, 2021 to September 15, 2021. Demographic data, clinical symptoms and preexisting medical conditions (comorbidities) were analyzed. The primary outcome was in-hospital death. Results. The majority of hospitalized patients with vaccine breakthrough infection were ≥60 years old, male, with critical or severe COVID-19. The fatality rate was extremely high (50.27%) and more pronounced in elderly groups. The most prevalent symptoms were cough, dyspnea, respiratory distress, and low blood oxygen saturation. The most frequent comorbidities were heart disease and diabetes. High fatality rates were observed among patients admitted to the intensive care units (72.88%) and those who required invasive mechanical ventilation (87.82%). The main risk factors for an unfavorable outcome were older age, respiratory compromise, inactivated virus vaccine immunization, and preexisting medical conditions. Conclusions. We characterized the profile of hospitalized Brazilian patients with COVID-19 vaccine breakthrough infection and the risk factors for an unfavorable outcome. These data allow to identify priority groups to receive a booster dose and to continue using personal protection.

RESUMEN Objetivo. Caracterizar el perfil clínico y epidemiológico de las personas con mayores probabilidades de contraer la infección por el SARS-CoV-2 luego de tener el esquema completo de vacunación, con el fin de definir los grupos de prioridad para la aplicación de la dosis de refuerzo en situaciones de escasez de dosis de vacunación, así como para el mantenimiento de los equipos de protección personal. Métodos. En este estudio transversal se emplearon datos de pacientes mayores de 18 años hospitalizados con COVID-19 que habían recibido la pauta completa de vacunación y tenían un diagnóstico positivo de infección por SARS-CoV-2, recabados de la base de datos SIVEP-Gripe (Sistema de Información de Vigilancia Epidemiológica de la Gripe) en el periodo comprendido entre el 18 de enero del 2021 y el 15 de septiembre del 2021. Se analizaron datos demográficos, síntomas clínicos y trastornos médicos preexistentes (comorbilidades). El resultado primario fue la muerte hospitalaria. Resultados. La mayoría de los pacientes vacunados hospitalizados fueron varones mayores de 60 años con infección crítica o grave por el virus de la COVID-19. La tasa de letalidad fue extremadamente elevada (50,27 %) y más pronunciada en los grupos de edad avanzada. Los síntomas más prevalentes fueron tos, disnea, dificultad respiratoria y baja saturación de oxígeno en sangre. Las comorbilidades más frecuentes fueron las cardiopatías y la diabetes. Se observaron altas tasas de letalidad entre los pacientes ingresados en las unidades de cuidados intensivos (72,88 %) y los que necesitaron ventilación mecánica invasiva (87,82 %). Los principales factores de riesgo para un resultado desfavorable fueron la edad avanzada, dificultades respiratorias, inmunización con vacunas de virus inactivados y trastornos médicos preexistentes. Conclusiones. Se caracterizaron el perfil de los pacientes brasileños vacunados hospitalizados con COVID-19 por infección irruptiva de vacuna y los factores de riesgo de un resultado desfavorable. Estos datos permiten identificar los grupos de prioridad para recibir la dosis de refuerzo y continuar utilizando protección personal.

RESUMO Objetivo. Caracterizar o perfil epidemiológico e clínico dos indivíduos mais propensos a se infectar com SARS-CoV-2 após o esquema vacinal completo, a fim de traçar o perfil dos grupos prioritários para receberem uma dose de reforço em situações de escassez de doses vacinais, bem como para manutenção dos cuidados de proteção individual. Métodos. Este estudo transversal utilizou dados de pacientes hospitalizados com COVID-19 com idade ≥18 anos, esquema vacinal completo e diagnóstico positivo de infecção por SARS-CoV-2, coletados do banco de dados SIVEP-Gripe (Sistema de Informação da Vigilância Epidemiológica da Gripe) de 18 de janeiro a 15 de setembro de 2021. Foram analisados dados demográficos, sintomas clínicos e problemas médicos preexistentes (comorbidades). O desfecho primário foi óbito intra-hospitalar. Resultados. A maioria dos pacientes hospitalizados com infecção devido a escape vacinal tinha ≥60 anos, era do sexo masculino e tinha um quadro de COVID-19 grave ou gravíssimo. A letalidade foi extremamente alta (50,27%) e mais pronunciada nos grupos de pessoas idosas. Os sintomas mais prevalentes foram tosse, dispneia, desconforto respiratório e baixa saturação de oxigênio no sangue. As comorbidades mais frequentes foram cardiopatia e diabetes. Altas taxas de letalidade foram observadas entre os pacientes internados em unidades de terapia intensiva (72,88%) e os que precisaram de ventilação mecânica invasiva (87,82%). Os principais fatores de risco para um desfecho desfavorável foram idade avançada, comprometimento respiratório, imunização com vacina de vírus inativado e problemas médicos preexistentes. Conclusões. Caracterizamos o perfil dos pacientes brasileiros hospitalizados com infecção por COVID-19 devido a escape vacinal e os fatores de risco para desfecho desfavorável. Esses dados permitem identificar grupos prioritários para receber dose de reforço e continuar os cuidados de proteção individual.

CD4+ T cells apoptosis in Plasmodium vivax infection is mediated by activation of both intrinsic and extrinsic pathways.

BACKGROUND: Reduction in the number of circulating blood lymphocytes (lymphocytopaenia) has been reported during clinical episodes of malaria and is normalized after treatment with anti-malaria drugs. While this phenomenon is well established in malaria infection, the underlying mechanisms are still not fully elucidated. In the present study, the occurrence of apoptosis and its pathways in CD4+ T cells was investigated in naturally Plasmodium vivax-infected individuals from a Brazilian endemic area (Porto Velho - RO). METHODS: Blood samples were collected from P. vivax-infected individuals and healthy donors. The apoptosis was characterized by cell staining with Annexin V/FITC and propidium iodide and the apoptosis-associated gene expression profile was carried out using RT2 Profiler PCR Array-Human Apoptosis. The plasma TNF level was determined by ELISA. The unpaired t-test or Mann-Whitney test was applied according to the data distribution. RESULTS: Plasmodium vivax-infected individuals present low number of leukocytes and lymphocytes with a higher percentage of CD4+ T cells in early and/or late apoptosis. Increased gene expression was observed for TNFRSF1B and Bid, associated with a reduction of Bcl-2, in individuals with P. vivax malaria. Furthermore, these individuals showed increased plasma levels of TNF compared to malaria-naive donors. CONCLUSIONS: The results of the present study suggest that P. vivax infection induces apoptosis of CD4+ T cells mediated by two types of signaling: by activation of the TNFR1 death receptor (extrinsic pathway), which is amplified by Bid, and by decreased expression of the anti-apoptotic protein Bcl-2 (intrinsic pathway). The T lymphocytes apoptosis could reflect a strategy of immune evasion triggered by the parasite, enabling their persistence but also limiting the occurrence of immunopathology.