Triatoma infestans, the main vector of Chagas disease, has nearly been eliminated from Brazil. Nevertheless, other triatominae species are involved in the domiciliation process, including Triatoma rubrovaria in Rio Grande do Sul State (RS). Previous studies showed that 1.6% of the T. rubrovaria specimens collected at the rural district of Quaraí, RS, were naturally infected by Trypanosoma cruzi. In this study, five T. cruzi isolates obtained from infected triatomines were characterized molecularly and biologically. Genotyping of the T. cruzi isolates showed that they belong to lineage IIc of T. cruzi (TCIIc). Biological characterization showed miotropism and myositis during acute and chronic phases of infection, respectively. Virulence and mortality rates were variable among isolates. To our knowledge, this study corresponds to the first characterization of T. cruzi isolates from T. rubrovaria and the first description of TCIIc in the sylvatic cycle of T. cruzi from the southern region of Brazil.

Introduction:To evaluate the efficacy of vitamin C in reducing the consequences generated by the production of free radicals in the acute and chronic phases of Chagas disease, two different doses of ascorbic acid were administered orally to 60 mice infected by Trypanosoma cruzi QM2 strain. Methods: The animals were divided into six groups: G1, G2, and G3 for the acute phase study, and G'1, G'2, and G'3 for the chronic stage. The groups G1 and G'1 received 8.6x10 -4 mg/g of vitamin C daily, whereas G2 and G'2 received 7.14x10 -3 mg/g daily. The other groups, G3 and G'3, were considered placebos and received 10µL of mineral water. Results: The study of the acute phase showed statistically significant differences between G1 and the other groups at various count days of the parasitemia evolution. The multiplying parasite was slower in G1 until the 11 th day, but on the 22 nd day it had greater parasitemia than in G2 and G3, and from the 36 th day on, parasitemia stabilized at higher levels. However, when the histopathology of acute and chronic phases is considered, one does not note significant differences. Conclusions: The administration of two different doses of vitamin C was not able to protect mice and to contain the oxidative stress caused by free radicals formed by the metabolism of oxygen (reactive oxygen species) and nitrogen (reactive nitrogen species). Keywords: Ascorbic acid. T. cruzi. Parasitemia. Free radicals. RESUMOIntrodução: Para avaliar a eficácia da vitamina C em reduzir as consequências geradas pela produção de readicais livres na fase aguda e crônica da doença de Chagas, duas diferentes dosagens de ácido ascórbico foram administradas oralmente para 60 camundongos infectados pela cepa QM2 de Trypanosoma cruzi. Métodos: Estes animais foram divididos em seis grupos: G1, G2 e G3 para o estudo da fase aguda e G'1, G'2 e G'3 para o estudo da fase crônica. Diariamente, G1-G'1 recebeu 8.6 x 10 -4 mg/g de vitamina C, G2-G'2 recebeu 7.14 x 10 -3 mg/g. Os outros grupos, G3-G'3, foram considerados placebos e receberam 10µL of de água mineral. Resultados: O estudo da fase aguda mostrou diferenças estatisticamente significativas entre G1 e os outros grupos em vários dias de contagens na evolução da parasitemia, e até o 11 o dia a multiplicação parasitária foi menor em G1, mas no 22 o dia ele tinha parasitemia maior que G2 e G3, e a partir do 36 o , a parasitemia estabilizou em altos níveis. Quando considerado o histopatológico da fase aguda e crônica, não foi notado, entretanto, diferença significativa. Conclusões: Assim, foi encontrado que a administração de duas diferentes dosagens de vitamina C não foi capaz de proteger o camundongo e conter o estresse oxidativo causado pelos radicais livres formados pelo metabolismo do oxigênio (ROS) e nitrogênio (RNS). Palavras-chaves: Acido ascórbico. T. cruzi. Parasitemia. Radicais livres.

SUMMARYThe tissue changes that occur in Chagas disease are related to the degree of oxidative stress and antioxidant capacity of affected tissue. Studies with vitamin C supplementation did not develop oxidative damage caused by Chagas disease in the host, but other studies cite the use of peroxiredoxins ascorbate -dependent on T. cruzi to offer protection against immune reaction. Based on these propositions, thirty "Swiss" mice were infected with T. cruzi QM1 strain and treated with two different vitamin C doses in order to study the parasitemia evolution, histopathological changes and lipid peroxidation biomarkers during the acute phase of Chagas disease. The results showed that the parasite clearance was greater in animals fed with vitamin C overdose. There were no significant differences regarding the biomarkers of lipid peroxidation and inflammatory process or the increase of myocardium in animals treated with the recommended dosage. The largest amount of parasite growth towards the end of the acute phase suggests the benefit of high doses of vitamin C for trypomastigotes. The supplementation doesn't influence the production of free radicals or the number of amastigote nests in the acute phase of Chagas disease.

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ARTIGO/ARTICLEAtualmente, após as campanhas de combate ao Triatoma infestans e sua conseqüente eliminação do domicílio e peridomicílio, triatomíneos silvestres estão se candidatando a assumir a condição de vetores do Trypanosoma cruzi no ambiente domiciliar 22 .Triatoma rubrovaria, espécie silvestre, hoje encontrada no Brasil apenas nas regiões do centro ao sul e oeste do Estado do Rio Grande do Sul 14 15 , aparentemente, nas proximidades das residências, está ocupando o espaço anteriormente colonizado pelo T. infestans 2 21 . ) tiveram a reação de precipitina não reagente para os anti-soros testados, 4 (30,8%) positivos para anti-soro de roedor, 4 (30,8%) para anti-soro de cabra e 1 (7,7%) para anti-soro de porco e humano. Palavras-chaves: Trypanosomatidae. Trypanosoma cruzi. Triatoma rubrovaria. Reservatórios. Rio Grande do Sul. ABSTRACTRupestrian triatomines were captured in six Quaraí city localities, RS, to verify the level of Trypanosomatidae infection, as well as the animal reservoir. The capture occurred in a wild environment and 453 samples were collected, which were identified and separated by nymphal instar. 421 (92.9%) samples of Triatoma rubrovaria, 26 (5.7%) of Triatoma circummaculata and 6 (1.3%) of Panstrongylus tupynambai were collected. Only 13 samples (4.2%) of Triatoma rubrovaria presented Trypanosomatidae infection. After mice and LIT culture inoculation, five strains of Trypanosoma cruzi were isolated. Of these triatomines, 4 (30.8%) displayed no reagent precipitin for the antiserum tested, 4 (30.8%) were positive for rodent antiserum, 4 (30.8%) were positive for goat antiserum and 1 (7.7%) were positive for human and pig antiserum.

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Introduction:In order to examine the effectiveness of vitamin C (ascorbic acid) in combating the oxidative insult caused by Trypanosoma cruzi during the development of the chronic phase of Chagas disease, Swiss mice were infected intraperitoneally with 5.0 × 104 trypomastigotes of T. cruzi QM1strain.Methods:Mice were given supplements of two different doses of vitamin C for 180 days. Levels of lipid oxidation (as indicated by thiobarbituric acid reactive substances-TBARS), total peroxide, vitamin C, and reduced glutathione were measured in the plasma, TBARS, total peroxide and vitamin C were measured in the myocardium and histopathologic analysis was undertaken in heart, colon and skeletal muscle.Results:Animals that received a dose equivalent to 500 mg of vitamin C daily showed increased production of ROS in plasma and myocardium and a greater degree of inflammation and necrosis in skeletal muscles than those that received a lower dose or no vitamin C whatsoever.Conclusion:Although some research has shown the antioxidant effect of vitamin C, the results showed that animals subject to a 500 mg dose of vitamin C showed greater tissue damage in the chronic phase of Chagas disease, probably due to the paradoxical actions of the substance, which in this pathology, will have acted as a pro-oxidant or pro-inflammatory.

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