Navegando por Autor "Nicoli, Jacques Robert"
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Item Adhesion on yeast cell surface as a trapping mechanism of pathogenic bacteria by Saccharomyces probiotics.(2012) Tiago, Fabiana da Conceição Pereira; Martins, Flaviano dos Santos; Souza, Éricka Lorenna de Sales e; Pimenta, Paulo Filemon Paolucci; Araújo, Helena Rocha Corrêa de; Castro, Ieso de Miranda; Brandão, Rogélio Lopes; Nicoli, Jacques RobertRecently, much attention has been given to the use of probiotics as an adjuvant for the prevention or treatment of gastrointestinal pathology. The great advantage of therapy with probiotics is that they have few side effects such as selection of resistant bacteria or disturbance of the intestinal microbiota, which occur when antibiotics are used. Adhesion of pathogenic bacteria onto the surface of probiotics instead of onto intestinal receptors could explain part of the probiotic effect. Thus, this study evaluated the adhesion of pathogenic bacteria onto the cell wall of Saccharomyces boulardii and Saccharomyces cerevisiae strains UFMG 905, W303 and BY4741. To understand the mechanism of adhesion of pathogens to yeast, cell-wall mutants of the parental strain of Saccharomyces cerevisiae BY4741 were used because of the difficulty of mutating polyploid yeast, as is the case for Saccharomyces cerevisiae and Saccharomyces boulardii. The tests of adhesion showed that, among 11 enteropathogenic bacteria tested, only Escherichia coli, Salmonella Typhimurium and Salmonella Typhi adhered to the surface of Saccharomyces boulardii, Saccharomyces cerevisiae UFMG 905 and Saccharomyces cerevisiae BY4741. The presence of mannose, and to some extent bile salts, inhibited this adhesion, which was not dependent on yeast viability. Among 44 cell-wall mutants of Saccharomyces cerevisiae BY4741, five lost the ability to fix the bacteria. Electron microscopy showed that the phenomenon of yeast–bacteria adhesion occurred both in vitro and in vivo (in the digestive tract of dixenic mice). In conclusion, some pathogenic bacteria were captured on the surface of Saccharomyces boulardii, Saccharomyces cerevisiae UFMG 905 and Saccharomyces cerevisiae BY4741, thus preventing their adhesion to specific receptors on the intestinal epithelium and their subsequent invasion of the host.Item American trypanosomiasis (chagas' disease) in conventional and germfree rats and mice.(1987) Silva, Marcelo Eustáquio; Evangelista, Elísio Alberto; Nicoli, Jacques Robert; Bambirra, Eduardo Alves; Vieira, Enio CarlosItem Antigenic dietary protein guides maturation of the host immune system promoting resistance to Leishmania major infection in C57BL/6 mice.(2010) Amaral, Joana Ferreira do; Santos, Ana Cristina Gomes; Silva, Josiely Paula; Nicoli, Jacques Robert; Vieira, Leda Quercia; Faria, Ana Maria Caetano de; Silva, Juscilene Menezes daThe immature immune system requires constant stimulation by foreign antigens during the early stages of life to develop properly and to create efficient immune responses against later infections. We have previously shown that intake of antigenic dietary protein is critical for inducing maturation of the immune system as well as for the development of T helper type 1 (Th1) immunity. In this study, we show that administration of an amino acid (aa)-based diet during the development of the immune system subsequently resulted in inefficient control of Leishmania major infection in adult C57BL/6 mice. Compared with mice fed a control protein-containing diet, adult aa-fed mice showed a decreased interferon (IFN)-c response to parasite antigens and insufficient production of nitric oxide (NO), which is crucial to parasite death. However, no deviation towards Th2-specific immunity to L. major was observed. Phenotypic analysis of antigen-presenting cells (APCs) from aa-fed mice revealed deficient levels of the costimulatory molecules CD40 and CD80, and low levels of interleukin (IL)-12 produced by peritoneal macrophages, revealing an early stage of maturation of these cells. APCs isolated from aa-fed mice were unable to stimulate a Th1 response in vitro. Both phenotypic features of T cells from aa-fed mice and their ability to produce a Th1 response in the presence of mature APCs were unaffected when compared with T cells from control mice. The results presented here support the notion that regulation of Th1 immunity to infection includes environmental factors such as dietary proteins, which provide a natural source of stimulation that contributes to the process of maturation of APCs.Item Cruzamentos entre leveduras da fermentação da cachaça para a obtenção de novas estirpes : potencial para produção de cervejas.(2016) Figueiredo, Bruna Inez Carvalho de; Brandão, Rogélio Lopes; Saraiva, Margarete Alice Fontes; Moreira, Leandro Marcio; Nicoli, Jacques RobertNa fabricação de cervejas estilos Ale ou Lager, são utilizadas leveduras pertencentes às espécies Saccharomyces cerevisiae e Saccharomyces pastorianus, respectivamente. As cepas do estilo Lager fermentam em baixas temperaturas, produzem menores concentrações de compostos responsáveis por aroma e são consideradas de baixa fermentação, por flocularem. As cepas do estilo Ale fermentam a temperaturas mais elevadas, produzem altas concentrações de alcoóis superiores e ésteres e são consideradas de alta fermentação. O objetivo deste trabalho foi estudar a capacidade de esporulação, a característica reprodutiva, assim como a aplicação de técnicas de cruzamentos entre leveduras isoladas de dornas de fermentação da cachaça para a obtenção de novas estirpes com potencial para produção de cerveja. Das 128 cepas de leveduras caracterizadas quanto à freqüência e eficiência da esporulação, 121 leveduras (95%) apresentaram esporulação acima de 50%, sendo que quatorze não foram capazes de esporular. Vinte e quatro cepas apresentaram viabilidade de esporos acima de 91% e sete cepas não apresentaram viabilidade dos esporos. Apenas, três cepas de leveduras foram classificadas como heterotálicas: LBCM1073, LBCM1078 e LBCM1115. A partir dos resultados apresentados e de outros resultados do nosso grupo de pesquisa, como a caracterização da produção de compostos responsáveis pelo aroma, capacidade de fermentação de açúcares e de floculação, duas cepas foram selecionadas para cruzamentos. A cepa LBCM1078 apresenta capacidade de fermentação de maltose e alta produção de compostos responsáveis por aroma, enquanto a cepa LBCM1092 apresenta uma floculação constitutiva. A partir das duas técnicas de cruzamento desenvolvidas, entre células haplóides e entre células diplóides, 21 e 33 híbridos foram obtidos, respectivamente. Os híbridos foram avaliados quanto à capacidade de fermentação de maltose e a capacidade de floculação, sendo selecionadas três novas cepas para futuros experimentos de fermentação em condições similares à produção de cerveja.Item Effect of substrate and pH on the activity of proteases from Fusarium oxysporum var. lini.(1991) Castro, Ieso de Miranda; Lima, Angélica Alves; Paula, Carmem Aparecida de; Nicoli, Jacques Robert; Brandão, Rogélio LopesThe results obtained in this work suggest that both the pH (through selective inhibition) and the carbon source (through repression and acidification or alkalinization of the medium) may play an important role in the distribution of extracellular proteases in Fusarium oxysporum var. lini.Item Effect of the trehalose levels on the screening of yeast as probiotic by in vivo and in vitro assays.(2008) Martins, Flaviano dos Santos; Castro, Ieso de Miranda; Rosa, Carlos Augusto; Nicoli, Jacques Robert; Neves, Maria JoséProbiotics are viable defined microorganisms (bacteria or yeasts) that exert a beneficial effect on the health of the host when ingested in adequate amounts. Screening for such biotherapeutic agents is commonly performed by in vitro assays simulating gastrointestinal environment to determine the ability to survive in the digestive tract. In the present study, the possibility of extrapolation of data obtained in in vitro assays to in vivo conditions was studied using five Saccharomyces cerevisiae strains isolated from Brazilian Atlantic rain forest. Trehalose contents and survival after exposure to a combination of physiological stresses generally found in the gastrointestinal tract of humans were determined for the five yeasts and compared to the behavior of Saccharomyces boulardii, a well-known probiotic. The results were completed with the colonization capacity of the gastrointestinal tract of gnotobiotic mice by these yeast strains. Some results obtained by in vitro assays are not confirmed by in vivo experiments, indicating that the extrapolation cannot be always done.Item Germ-free mice produce high levels of interferon-gamma in response to infection with Leishmania major but fail to heal lesions.(2005) Oliveira, Marcia Rosa de; Tafuri, Wagner Luiz; Afonso, Luís Carlos Crocco; Oliveira, Milton Adriano Pelli de; Nicoli, Jacques Robert; Vieira, Etel Rocha; Scott, Phillip; Melo, Maria Norma; Vieira, Leda QuerciaIn order to investigate the importance of the host microbiota on differentiation of T cell subsets in response to infection, Swiss/NIH germ-free mice and conventional (microbiota-bearing) mice were infected with Leishmania major, and lesion development, parasite loads, and cytokine production were assessed. Germ-free mice failed to heal lesions and presented a higher number of parasites at the site of infection than their conventional counterparts. In addition, histopathological analysis indicated a higher density of parasitized macrophages in lesions from germ-free mice than in conventional mice. The initial production of interleukin (IL)-12 and interferon-gamma (IFN-c) in germ-free mice was comparable to the conventional controls. Also, germ-free mice produced elevated levels of IFN-c and lower levels of IL-4 throughout the course of infection, suggesting the development of a Th1 response. Macrophages from germ-free mice exposed to IFN-c and infected with amastigotes in vitro were not as efficient at killing parasites as macrophages from conventional animals. These observations indicate that the microbiota is not essential for the development of Th1 immune responses, but seems to be important for macrophage activation.Item Glucose induced activation of the plasma membrane ATPase in Fusarium oxysporum.(1992) Brandão, Rogélio Lopes; Castro, Ieso de Miranda; Passos, Jomar Becher dos; Nicoli, Jacques Robert; Thevelein, Johan MariaAddition of glucose and other sugars to derepressed cells of the fungus Fusarium oxysporum var. Zini triggered activation of the plasma membrane H+-ATPase within 5 min. Glucose was the best activator while galactose and lactose had a lesser effect. The activation was not prevented by previous addition of cycloheximide and it was fully reversible when the glucose was removed. The activation process in uiuo also caused changes in the kinetic properties of the enzyme. The non-activated enzyme had an apparent K, of about 3.2 mM for ATP whereas the activated enzyme showed an apparent K,,, of 0.26 mM. In addition, the pH optimum of the H+-ATPase changed from 6.0 to 7.5 upon activation. The activated enzyme was more sensitive to inhibition by vanadate. When F. oxysporum was cultivated in media containing glucose as the major carbon source, enhanced M+-ATPase activity was largely confined to the period corresponding to the lag phase, i.e. just before the start of acidification of the medium. This suggests that the activation process might play a role in the onset of extracellular acidification. Addition of glucose to F. oxysporum var. Zini cells also caused an increase in the cAMP level. No reliable increase could be demonstrated for the other sugars. Addition of proton ionophores such as DNP and CCCP at pH 5-0 caused both a large increase in the intracellular level of cAMP and in the activity of the plasma membrane H+- ATPase. Inhibition of the DNP-induced increase in the cAMP level by acridine orange also resulted in inhibition of the activation of plasma membrane H+-ATPase. These results suggest a possible causal relationship between the activity of F. oxysporum var. Zini plasma membrane H+-ATPase and the intracellular level of CAMP.Item Glucose-induced activation of plasma membrane H+-ATPase in mutants of the yeast Saccharomyces cerevisiae affected in cAMP metabolism, cAMP-dependent protein phosphorylation and the initiation of glycolysis.(1992) Passos, Jomar Becher dos; Vanhalewyn, Mieke; Brandão, Rogélio Lopes; Castro, Ieso de Miranda; Nicoli, Jacques Robert; Thevelein, Johan MariaAddition of glucose-related fermentable sugars or pro,tonophores to derepressed cells of the yeast Saccharomyces ceret'isiae causes a 3- to 4-fold activation of the plasma membrane H +-A'fPase within a few minutes. These conditions are known to cause rapid increases in the cAMP level. In yeast strains carrying temperature-sensitive mutations in genes required for cAMP .~jnthesis, incohati~a at the restrictive temperature reduced the extent of H+-ATPase activation, Incubation of nontemperature- sensitive strains, however, at such temperatures also caused reduction of H +-ATPase activation. Yeast strains which are specifically deficient in the glucose-induced cAMP increase (and not in basal cAMP synthesis) still showed plasma membrane H+-ATPase aCtivation. Yeast mutants with widely divergent activity levels of cAMP-dependent protein kinase displayed very similar levels of activation of the plasma membrane H +-A'l'Pase. This was also true for a yeast mutant carrying a deletion in the CDC25 gene. These results show that the cAlVlP-protein kinase A signaling pathway is not required for glucose activation of the H*-ATPase. They also contradict the specific requirement of the CDC25 gene product. Experiments with yeast strains carrying point or deletion mutations in the genes coding for the sugar phnsphorylating enzymes hexokinase Pl and Pll and glucokinase showed that activation of the H+-ATPase with glucose or fructose was completely dependent on the presence cf a kinase able m phnsphorylate the sugar. These and other data concerning the role of init,:al sugar metabolism in triggering activation are consistent with the idea that the glucose-induced activation pathways of cAMP-synthesis and H+-ATPase have a common initiation point.Item Identificação de um gene, provavelmente envolvido no transporte ativo de glicerol em Wickerhamomyces anomalus (Pichia anomala).(2015) Gomes, Lorena Soares; Brandão, Rogélio Lopes; Teixeira, Janaina Aparecida; Castro, Ieso de Miranda; Nicoli, Jacques RobertExistem micro-organismos capazes de utilizar o glicerol como fonte de carbono e energia, sendo assim, bastante atrativos como bioconversores do glicerol bruto gerado a partir da produção de biodiesel. Em Saccharomyces cerevisiaea via de metabolização do glicerol é bem definida, em que um sistema simporte de prótons, codificado pelo gene STL1, é preferencialmente utilizado na captação do glicerol quando fontes fermentáveis de carbono não estão presentes. O presente trabalho objetivou identificar o gene STL1 que codifica um provável transportador de glicerol em Wickerhamomyces anomalus LBCM105, cujo o genoma ainda não se encontra disponível em banco de dados. O gene identificado apresentou 1443 pb e 480 aminoácidos. A análise in sílico comparativa da região promotora identificou fatores de transcrição putativos associados à regulação de STL1 de W. anomalus LBCM105 e S. cerevisiae, sugerindo uma notável distinção entre os elementos putativos de ambos. A análise da arvore filogenética, construída a partir das sequências de proteínas Stl1 de diferentes leveduras, evidenciou uma maior similaridade entre o transportador putativo de W. anomalus LBCM105 e W. ciferrii, e uma maior distância em relação a S. cerevisiae. Após caracterização do gene STL1 de W. anomalus LBCM105, foram realizados análises da expressão gênica deste em condições de cultivo contendo glicose ou glicerol, como fonte de carbono. O gene STL1 apresentou uma expressão 23,76 vezes maior em glicerol em relação à condição de meio contendo glicose. A avaliação do transporte de glicerol pela W. anomalus LBCM105 evidenciou um transporte ativo em condições de cultivo contendo glicose ou glicerol, no entanto, Stl1p foi induzida em presença de glicerol. Os resultados apresentaram dados relevantes quanto à possível identificação do transportador de glicerol em W. anomalus LBCM105, evidenciando um potencial significativo na aplicação biotecnológica quanto ao consumo de glicerol bruto, resíduo da indústria de biodiesel, uma vez que demonstrou ser bastante eficiente na captação de glicerol.Item Influence of normal microbiota on some aspects of the immune response during experimental infection with Trypanosoma cruzi in mice.(2004) Duarte, Rinaldo; Silva, Andréia Marçal da; Vieira, Leda Quercia; Afonso, Luís Carlos Crocco; Nicoli, Jacques RobertTo study the influence of normal associated microbiota on systemic immunological responses during experimental Chagas’ disease, germ-free and conventional NIH Swiss mice were infected with Y strain of Trypanosoma cruzi. Although no statistical differences in mortality and parasitaemia were found, conventional mice showed IFN-ª, TNF-Æ and NO production (P , 0.05) by spleen cell cultures and higher blood levels of immunoglobulins of the IgG2a isotype (P , 0.05) when compared to their germ-free counterparts. Moreover, higher levels of IgG1 were also found in conventional animals. On the other hand, no differences in IL10 production were found between germ-free and conventional mice after infection (P , 0.05). Interestingly, spleen cell cultures from non-infected germ-free mice spontaneously produced higher levels of IL10 than cultures from conventional mice. Moreover, cultures from non-infected germ-free mice responded to T. cruzi antigens with IFN-ª production, contrary to cultures from conventional animals. In conclusion, the presence of the normal microbiota skews the immune response towards production of inflammatory cytokines during experimental infection with T. cruzi in mice. However, the increase in production of cytokines that is linked to resistance to this parasite did not alter the outcome of infection significantly, probably due to high virulence of the Y strain.Item Intracellular signal triggered by cholera toxin in Saccharomyces boulardii and Saccharomyces cerevisiae.(1998) Brandão, Rogélio Lopes; Castro, Ieso de Miranda; Bambirra, Eduardo Alves; Amaral, Sheila Coutinho; Fietto, Luciano Gomes; Trópia, Maria José Magalhães; Neves, Maria José; Santos, Raquel Gouvêa dos; Gomes, Newton Carlos Marcial; Nicoli, Jacques RobertAs is the case for Saccharomyces boulardii, Saccharomyces cerevisiae W303 protects Fisher rats against cholera toxin (CT). The addition of glucose or dinitrophenol to cells of S. boulardii grown on a nonfermentable carbon source activated trehalase in a manner similar to that observed for S. cerevisiae. The addition of CT to the same cells also resulted in trehalase activation. Experiments performed separately on the A and B subunits of CT showed that both are necessary for activation. Similarly, the addition of CT but not of its separate subunits led to a cyclic AMP (cAMP) signal in both S. boulardii and S. cerevisiae. These data suggest that trehalase stimulation by CT probably occurred through the cAMP-mediated protein phosphorylation cascade. The requirement of CT subunit B for both the cAMP signal and trehalase activation indicates the presence of a specific receptor on the yeasts able to bind to the toxin, a situation similar to that observed for mammalian cells. This hypothesis was reinforced by experiments with 125I-labeled CT showing specific binding of the toxin to yeast cells. The adhesion of CT to a receptor on the yeast surface through the B subunit and internalization of the A subunit (necessary for the cAMP signal and trehalase activation) could be one more mechanism explaining protection against the toxin observed for rats treated with yeasts.Item Investigating acid stress response in different saccharomyces strains.(2014) Brandão, Rogélio Lopes; Rosa, Júlio César Câmara; Nicoli, Jacques Robert; Almeida, Marcos Vinicius Simi; Carmo, Ana Paula do; Queiros, Heloa Teixeira; Castro, Ieso de MirandaYeast cells need to respond to a variety of stresses found in such different conditions as gastrointestinal tract after probiotic ingestion or fermentation vat during ethanol production. In the present study, H+ neutralisation capacity, membrane fatty acid composition, H+-ATPase activity, and cytosolic Ca2+ concentration were evaluated in yeast cells used for probiotic (Saccharomyces boulardii) and laboratory (Saccharomyces cerevisiae W303) purposes, as well as in some W303 mutant strains for ENA1 gene and S. cerevisiae BY4741. Results show that the H+ internal concentration of yeast is regulated by several systems, including the plasma membrane H+-ATPase, and that Ena1p has an important but undefined role in the cellular response to acid.Membrane fatty acid composition of S. cerevisiae W303 strain was affected by exposure to acidic pH, but the presence of 86mM NaCl prevented this effect, whereas membrane fatty acid composition of S. boulardii was unaffected by acidic pH. We also demonstrated that the acid stress response is dependent on calcium metabolism and blocked by FK 506.Item Lactobacillus delbrueckii UFV-H2b20 induces type 1 cytokine production by mouse cells in vitro and in vivo.(2009) Neumann, Elisabeth; Ramos, M. G.; Santos, Liliane Martins dos; Rodrigues, Ana Cristina Persichini; Vieira, Enio Carlos; Afonso, Luís Carlos Crocco; Nicoli, Jacques Robert; Vieira, Leda QuerciaItem The effect of iron deficiency and iron overload on the evolution of chagas disease produced by three strains of trypanosoma cruzi in CFW mice.(1990) Pedrosa, Maria Lúcia; Silva, Marcelo Eustáquio; Silva, Marcio Eustáquio; Silva, Marcílio Eustáquio de Castro; Nicoli, Jacques Robert; Vieira, Enio Carlosl. CFW mice were fed either on control diet or on iron-deficient diet. 2. After 5 months the mice were infected with CL, Y or YuYu strain of Trypanosoma cruzi. 3. On the fifth day after the infection, the mice on control diet were divided in three groups: one group remained as controls, two groups were injected either with desferrioxamine or iron-dextran. 4. The severity of the disease was evaluated by parasitemia and mortality. 5. The experimental groups were compared with the infected group fed on the control diet. 6. In mice fed on the iron-deficient diet, the disease was more severe for CL strain and less severe for Y and YuYu strains. 7. Treatment with desferrioxamine produced a less severe disease with YuYu strain and no difference with the other strains. 8. On treatment with iron-dextran, the disease became more severe with Y and CL strains; no effect was observed with YuYu strain. 9. These findings may be due to intraspecific differences among the strains.Item The effect of iron nutritional status on Trypanosoma cruzi infection in germfree and conventional mice.(1993) Pedrosa, Maria Lúcia; Nicoli, Jacques Robert; Silva, Marcelo Eustáquio; Silva, Marcio Eustáquio; Silva, Marcílio Eustáquio de Castro; Vieira, Leda Quercia; Bambirra, Eduardo Alves; Vieira, Enio Carlos1. Conventional (CV) and gnotobiotic (GN) female CFW mice were infected with the Y strain of Trypanosoma cruzi. 2. After infection, both CV and GN groups received injections of iron-dextran or desferrioxamine. Non-injected mice served as controls. 3. The parasitemia was more intense in iron-dextran-treated mice. 4. The iron levels in serum, liver, and spleen were: (a) not decreased by desferrioxamine and (b) increased by iron-dextran treatments. 5. An increase in leukocyte numbers was observed in all GN and CV groups after infection. 6. There was no difference in total iron binding capacity (TIBC) and iron saturation transferrin (IST) between GN and CV mice before infection. 7. In CV groups, after infection, TIBC was decreased whereas the levels of IST were increased; in GN the opposite occurred. 8. Trypanosome-specific IgG and IgM antibody levels were raised in the GN group but not in the CV group.Item Trypanosoma cruzi : influence of predominant bacteria from indigenous digestive microbiota on experimental infection in mice.(2005) Duarte, Rinaldo; Silva, A. M.; Vieira, Leda Quercia; Afonso, Luís Carlos Crocco; Nicoli, Jacques RobertTo verify the inXuence of some predominant components from indigenous microbiota on systemic immunological responses during experimental Chagas disease, germ-free NIH Swiss mice were mono-associated with Escherichia coli, Enterococcus faecalis, Bacteroides vulgatus or Peptostreptococcus sp. and then infected with the Y strain of Trypanosoma cruzi. All the mono-associations predominantly induced a Th1 type of speciWc immune response to the infection by T. cruzi. A direct correlation was observed between a higher survival rate and increased IFN-_ and TNF-_ production (P<0.05) in E. faecalis-, B. vulgatus-, and Peptostreptococcus- associated mice. Moreover, higher levels of anti-T. cruzi IgG1 and anti-T. cruzi IgG2a were also found in mono-associated animals after infection. On the other hand, with the exception of E. faecalis-associated mice, mono-association induced a lower IL-10 production after infection (P< 0.05) when compared with germ-free animals. Interestingly, spleen cell cultures from non-infected germ-free and mono-associated mice spontaneously produced higher levels (P< 0.05) of IL-10 than cultures from infected monoassociated mice, except again for E. faecalis-associated animals. In conclusion, the presence of the components of the indigenous microbiota skews the immune response towards production of inXammatory cytokines during experimental infection with T. cruzi in gnotobiotic mice. However, the degree of increase in production of cytokines depends on each bacterial component.Item Vitamin D overload and experimental Trypanosoma cruzi infection : parasitological and histopathological aspects.(1993) Silva, Marcelo Eustáquio; Silva, Marcílio Eustáquio de Castro; Nicoli, Jacques Robert; Bambirra, Eduardo Alves; Vieira, Enio Carlosl. Six groups of 45-day-old, 23.0 & 1.7 g, female Balb/c mice were inoculated intraperitoneally with 63, 252, 440, 630, 2520 or 6300 I.U. of vitamin D for 6 days. A seventh group was inoculated with saline. Each group consisted of 30 animals. 2. All animals inoculated with the doses of 2520 and 6300 and 70% of mice which received 630 I.U. of vitamin D died 21 days after the first administration of the vitamin. The LDm was 630 I.U. 3. The survivors were divided into two groups inoculated intraperitoneally with 5000 trypomastigotes of either Y or CL strain of Trypanosoma cruzi. 4. Based on the survival index on day 73 after infection, Vitamin D gave statistically significant protection (P < 0.01) for mice inoculated with doses of 63 or 430 I.U. of Y or CL strains, respectively. 5. On histopathological examination, inflammatory reaction and cellular and tissue parasitism were less intense in animals which received higher doses of vitamin D. 6. It is concluded that an overload of vitamin D had a protective effect against CL and Y strains of Trypanosoma cruzi infection in Balb/c mice.