Induction of immunogenicity by live attenuated Leishmania donovani centrin deleted parasites in dogs

AbstractZoonotic visceral leishmaniasis, caused by the intracellular protozoan parasite Leishmania infantum, is a neglected tropical disease that is often fatal when untreated. Dogs are considered the main reservoir of L. infantum in zoonotic VL as the presence of infected dogs may increase the risk for human infection. Canine visceral leishmaniasis (CVL) is a major veterinary and public health problem in Southern Europe, Middle East and South America. Control of animal reservoirs relies on elimination of seropositive dogs in endemic areas. However, treatment of infected dogs is not considered a favorable approach as this can lead to emergence of drug resistance since the same drugs are used to treat human infections. Therefore, vaccination against CVL remains the best alternative in control of the animal reservoirs. In this study, we present data on the immunogenicity profile of a live attenuated parasite LdCen−/− in a canine infection model and compared it to that of Leishmune®, a commercially available recombinant vaccine. The immunogenicity of the LdCen−/− parasites was evaluated by antibody secretion, production of intracytoplasmic and secreted cytokines, activation and proliferation of T cells. Vaccination with LdCen−/− resulted in high immunogenicity as revealed by the higher IgGTotal, IgG1, and IgG2 production and higher lymphoproliferative response. Further, LdCen−/− vaccinated dogs showed higher frequencies of activated CD4+ and CD8+ T cells, IFN-γ production by CD8+ T cells, increased secretion of TNF-α and IL-12/IL-23p40 and decreased secretion of IL-4. These results contribute to the understanding of immunogenicity elicited by live attenuated L. donovani parasites and, consequently, to the development of effective vaccines against visceral leishmaniasis

Profile of Central and Effector Memory T Cells in the Progression of Chronic Human Chagas Disease

Chagas disease is a parasitic infection caused by protozoan Trypanosoma cruzi that affects approximately 11 million people in Latin America. The involvement of the host's immune response on the development of severe forms of Chagas disease has not been fully elucidated. Studies on the immune response against T. cruzi infection show that the immunoregulatory mechanisms are necessary to prevent the deleterious effect of excessive immune response stimulation and consequently the fatal outcome of the disease. A recall response against parasite antigens observed in in vitro peripheral blood cell culture clearly demonstrates that memory response is generated during infection. Memory T cells are heterogeneous and differ in both the ability to migrate and exert their effector function. This heterogeneity is reflected in the definition of central (TCM) and effector memory (TEM) T cells. Our results suggest that a balance between regulatory and effectors T cells may be important for the progression and development of the disease. Furthermore, the high percentage of central memory CD4+ T cells in indeterminate patients after stimulation suggests that these cells may modulate host's inflammatory response by controlling cell migration to tissues and their effector role during chronic phase of the disease

Aspects of the ecology and behaviour of phlebotomines in endemic area for visceral leishmaniasis in State of Minas Gerais

Submitted by Nuzia Santos ([email protected]) on 2012-12-11T16:05:42Z No. of bitstreams: 1 5. Aspectos da ecologia e do comportamento de flebotomíneos em.pdf: 39803 bytes, checksum: 56419ee60fd6f80a21af5ff9ec964244 (MD5)Made available in DSpace on 2012-12-11T16:05:42Z (GMT). No. of bitstreams: 1 5. Aspectos da ecologia e do comportamento de flebotomíneos em.pdf: 39803 bytes, checksum: 56419ee60fd6f80a21af5ff9ec964244 (MD5) Previous issue date: 2005Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Belo Horizonte, MG, Brasil.Universidade Federal de Minas Gerais. Belo Horizonte, MG, Brasil.Fundação Nacional de Saúde. Belo Horizonte, MG, BrasilFaculdade de Medicina do Triângulo Mineiro. Uberaba, MG, BrasilFundação Oswalo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, BrasilFundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, BrasilFundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, BrasilFundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, BrasilO comportamento e hábitos alimentares de algumas espécies da flebotomíneos têm sido útil na compreensão da epidemiologia das leishmanioses. No município de Porteirinha (MG), foram realizadas capturas mensais sistematizadas utilizando-se 28 armadilhas luminosas tipo CDC, durante o período de janeiro a dezembro de 2002. Foram capturadas14 espécies de flebotomíneos, totalizando 1.408 exemplares. De acordo com o ambiente, os resultados obtidos mostraram que o peridomicílio apresentou a maior (53,3%) porcentagem dos espécimens encontrados na região, embora parte (46,7%) da fauna também tenha sido encontrada no intradomicílio. O repasto sanguíneo de 38 fêmeas de Lutzomyia longipalpis, provenientes do campo, foi identificado através da reação de precipitina. Os resultados indicam que Lutzomyia longipalpis foi a espécie predominante (65,1%), mostrando-se oportunista, podendo sugar uma ampla variedade de vertebrados.Studies on the behavioral and feeding habits of some species of phlebotominae sand flies have contributed to the comprehension of the epidemiology of leishmaniasis. In the present work, systematic captures were performed monthly in the municipality of Porteirinha (MG) using 28 light traps (CDC) from January to December 2002. Fourteen different species of phlebotomine were captured in a total of 1,408 specimens. The highest percentage of individuals (53.3%) was collected in the peridomicile against 46.7% in the intradomicile. Lutzomyia longipalpis was the predominant species in that region. The blood feeding of 38 females of this species from the field was analyzed by precipitin reaction. The results indicated that Lutzomyia longipalpis is an opportunist (65.1%) species that feeds on a wide variety of vertebrates in nature

Cytokine responses 5 weeks after immunization with <i>LdCen</i>^<i>-/-</i> parasites and LJM19.

<p>Immune response in the ear tissue of immunized hamsters was measured. The expression of mRNA encoding IFN-γ (A), iNOS (B), IL-12 (C), IL-4 (D) and IL-10 (E) was evaluated by qPCR. The data were normalized to β-Actin expression. (F) Fold increase of the cytokines compared to BSA (G4) group. Statistical differences (<i>p</i><0.05) are indicated in letters (a: G1).</p

Specific antibody production 5 weeks after immunization.

<p>ELISAs using plates coated with SLA from <i>L</i>. <i>donovani</i> were performed to detect production of total IgG (A), IgG₁ (B), IgG₂ (C) and the ratio IgG₂/IgG₁ (D). The OD values representing antibody concentration are shown on the <i>y</i>-axis, and the error bars indicate the standard deviation. Dotted lines represent the cut-off value. Statistical differences (<i>p</i><0.05) are indicated in letters (a: G1 and b: G2).</p

Specific antibody production 1 month after challenge.

<p>ELISAs using plates coated with SLA from <i>L</i>. <i>donovani</i> were performed to detect production of total IgG (A), IgG₁ (B), IgG₂ (C) and the ratio IgG₂/IgG₁ (D). The antibody OD values are shown on the <i>y</i>-axis, and the error bars indicate the standard deviation. Dotted lines represent the cut-off value. Statistical differences (<i>p</i><0.05) are indicated in letters (a: G1).</p

Table_1_Retrospective cohort study to evaluate the continuous use of anticholesterolemics and diuretics in patients with COVID-19.DOCX

PurposeThe purpose of this study is to evaluate the interference of the continuous use of drug classes in the expression of biomarkers during the first week of hospitalization and in the prognosis of patients with COVID-19.MethodsThe patients diagnosed with COVID-19 and confirmed with SARS-CoV-2 by RT-qPCR assay underwent the collection of fasting whole blood samples for further analysis. Other data also extracted for this study included age, sex, clinical symptoms, related comorbidities, smoking status, and classes of continuous use. Routine serum biochemical parameters, including alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, C-reactive protein, N-terminal fragment of B-type natriuretic peptide, and cardiac troponin, were measured.ResultsIn this cross-sectional study, a total of 176 patients with COVID-19 hospitalizations were included. Among them, 155 patients were discharged (88.5%), and 21 patients died (12%). Among the drug classes evaluated, we verified that the continuous use of diuretic 4.800 (1.853–11.67) (p = 0.0007) and antihypercholesterolemic 3.188 (1.215–7.997) (p = 0.0171) drug classes presented a significant relative risk of death as an outcome when compared to the group of patients who were discharged. We evaluated biomarkers in patients who used continuous antihypercholesterolemic and diuretic drug classes in the first week of hospitalization. We observed significant positive correlations between the levels of CRP with cardiac troponin (r = 0.714), IL-6 (r = 0.600), and IL-10 (r = 0.900) in patients who used continuous anticholesterolemic and diuretic drug classes and were deceased. In these patients, we also evaluated the possible correlations between the biomarkers AST, NT-ProBNP, cardiac troponin, IL-6, IL-8, and IL-10. We observed a significantly negative correlations in AST levels with NT-ProBNP (r = −0.500), cardiac troponin (r = −1.00), IL-6 (r = −1.00), and IL-10 (r = −1.00) and a positive correlation with IL-8 (r = 0.500). We also observed significant negative correlation in the levels of NT-ProBNP with IL-10 (r = −0.800) and a positive correlation with cardiac troponin (r = 0.800). IL-6 levels exhibited positive correlations with cardiac troponin (r = 0.800) and IL-10 (r = 0.700).ConclusionIn this study, we observed that hospitalized COVID-19 patients who continued using anticholesterolemic and diuretic medications showed a higher number of correlations between biomarkers, indicating a poorer clinical prognosis. These correlations suggest an imbalanced immune response to injuries caused by SARS-CoV-2.</p

Image_1_Retrospective cohort study to evaluate the continuous use of anticholesterolemics and diuretics in patients with COVID-19.TIF

PurposeThe purpose of this study is to evaluate the interference of the continuous use of drug classes in the expression of biomarkers during the first week of hospitalization and in the prognosis of patients with COVID-19.MethodsThe patients diagnosed with COVID-19 and confirmed with SARS-CoV-2 by RT-qPCR assay underwent the collection of fasting whole blood samples for further analysis. Other data also extracted for this study included age, sex, clinical symptoms, related comorbidities, smoking status, and classes of continuous use. Routine serum biochemical parameters, including alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, C-reactive protein, N-terminal fragment of B-type natriuretic peptide, and cardiac troponin, were measured.ResultsIn this cross-sectional study, a total of 176 patients with COVID-19 hospitalizations were included. Among them, 155 patients were discharged (88.5%), and 21 patients died (12%). Among the drug classes evaluated, we verified that the continuous use of diuretic 4.800 (1.853–11.67) (p = 0.0007) and antihypercholesterolemic 3.188 (1.215–7.997) (p = 0.0171) drug classes presented a significant relative risk of death as an outcome when compared to the group of patients who were discharged. We evaluated biomarkers in patients who used continuous antihypercholesterolemic and diuretic drug classes in the first week of hospitalization. We observed significant positive correlations between the levels of CRP with cardiac troponin (r = 0.714), IL-6 (r = 0.600), and IL-10 (r = 0.900) in patients who used continuous anticholesterolemic and diuretic drug classes and were deceased. In these patients, we also evaluated the possible correlations between the biomarkers AST, NT-ProBNP, cardiac troponin, IL-6, IL-8, and IL-10. We observed a significantly negative correlations in AST levels with NT-ProBNP (r = −0.500), cardiac troponin (r = −1.00), IL-6 (r = −1.00), and IL-10 (r = −1.00) and a positive correlation with IL-8 (r = 0.500). We also observed significant negative correlation in the levels of NT-ProBNP with IL-10 (r = −0.800) and a positive correlation with cardiac troponin (r = 0.800). IL-6 levels exhibited positive correlations with cardiac troponin (r = 0.800) and IL-10 (r = 0.700).ConclusionIn this study, we observed that hospitalized COVID-19 patients who continued using anticholesterolemic and diuretic medications showed a higher number of correlations between biomarkers, indicating a poorer clinical prognosis. These correlations suggest an imbalanced immune response to injuries caused by SARS-CoV-2.</p