NADPH Phagocyte Oxidase Knockout Mice Control Trypanosoma cruzi Proliferation, but Develop Circulatory Collapse and Succumb to Infection

•NO is considered to be a key macrophage-derived cytotoxic effector during Trypanosoma cruzi infection. On the other hand, the microbicidal properties of reactive oxygen species (ROS) are well recognized, but little importance has been attributed to them during in vivo infection with T. cruzi. In order to investigate the role of ROS in T. cruzi infection, mice deficient in NADPH phagocyte oxidase (gp91phox−/− or phox KO) were infected with Y strain of T. cruzi and the course of infection was followed. phox KO mice had similar parasitemia, similar tissue parasitism and similar levels of IFN-γ and TNF in serum and spleen cell culture supernatants, when compared to wild-type controls. However, all phox KO mice succumbed to infection between day 15 and 21 after inoculation with the parasite, while 60% of wild-type mice were alive 50 days after infection. Further investigation demonstrated increased serum levels of nitrite and nitrate (NOx) at day 15 of infection in phox KO animals, associated with a drop in blood pressure. Treatment with a NOS2 inhibitor corrected the blood pressure, implicating NOS2 in this phenomenon. We postulate that superoxide reacts with •NO in vivo, preventing blood pressure drops in wild type mice. Hence, whilst superoxide from phagocytes did not play a critical role in parasite control in the phox KO animals, its production would have an important protective effect against blood pressure decline during infection with T. cruzi

Análise da expressão genica em Trypanosoma cruzi: caracterização de mRNAs e clonagem de genes que codificam para sequências transcritas em diferentes estágios evolutivos do parasita

BV UNIFESP: Teses e dissertaçõe

Aspectos genético-moleculares da resistência mediada por plasmídios em Salmonella typhimurium

BV UNIFESP: Teses e dissertaçõe

Caracterização de um fragmento genômico de Trypanosoma cruzi complementar a diferentes espécies específicas de ARNs mensageiros mas diferente da seqüência líder

We have isolated a clone of Trypanosoma cruzi genimic DNA, lambda 3b2-5, which contains sequences that are reiterated in the genome. Northtern blot analysis showed that clone 3b2-5 hybridizes to 1,200-5,000 bases different mRNA species. The number of mRNAs species hybridized to clone 3b2-5 exceeds its coding capacity showing that this clone carries sequences that are common to several mRNAs species and conserved in the poly A(+) RNA. These sequences are not homologous to the T. cruzi spliced leader sequence, since clone 3b2-5 hybridize to a synthetic 20 nucleotice complementary to the spliced leader sequence. Clone 3b2-5 does not hybridize to DNA and RNA from several genera of Trypanosomatidae and other Trypanosoma species indicating that it carries T. cruzi species-specific sequences.Foi isolado um clone recombinante (lambda 3b2-5) de ADN genômico de Trypanosoma cruzi, o qual contém seqüências que estão reiteradas no genoma. Análise através da técnica de Northern blot mostrou que o clone 3b2-5 hibridiza com diferentes espécies de ARNs mensageiros de 1.200 a 5.000 bases. O número de espécies de ARNs mensageiros que hibridiza com o clone3b2-5 excede sua capacidade codante, sugerindo que este clone apresenta seqüências que são comuns a muitas espécies de ARNs mensageiros e conservadas no ARN poliadenilado. Estas seqüências não são homológas a seqüência líder presente nos ARNs de T. cruzi, pois, o clone 3b2-5 não hibridiza com um nucleotídeo sintético complementar a seqüência líder. O clone 3b2-5 não hibridiza com o ADN e ARN de diferentes gêneros de tripanosomatídeos e outras espécies de tripanosomas indicando que ele apresenta seqüências específicas para o T. cruzi.Escola Paulista de Medicina Departamento de Microbiologia, Imunologia e ParasitologiaUNIFESP, EPM, Depto. de Microbiologia, Imunologia e ParasitologiaSciEL