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1.
Rio de Janeiro; s.n; 2015. xiii,140 p. ilus, graf.
Thesis in English, Portuguese | LILACS | ID: lil-774261

ABSTRACT

Rhodnius prolixus é um dos principais insetos vetores de Trypanosomacruzi e de Trypanosoma rangeli na América Latina. A produção de peptídeosantimicrobianos (AMPs) no trato digestivo ou corpo gorduroso do inseto é vitalpara evitar a proliferação de microrganismos patogênicos além de manter ahomeostasia da microbiota nativa. O presente trabalho focou na modulação daimunidade humoral do intestino médio de R. prolixus desafiados oralmente coma bactéria Gram-positiva Staphylococcus aureus e Gram-negativa Escherichiacoli, além de seus tripanosomatídeos naturais T. rangeli e T. cruzi, considerandoa influência do desenvolvimento dos parasitas sobre a microbiota intestinal. Emcondições normais, a região anterior do intestino médio houve maior abundânciade transcritos de genes de lisozimas (lis) e defensinas (def), enquanto naposterior, do gene da prolixicina (prol). Insetos alimentados com bactérias Gramnegativasapresentaram maior quantidade de transcritos de defC e prol,enquanto a ingestão de bactérias Gram-positivas induziu a expressão de defA edefB no intestino médio. A infecção por T. rangeli cepa Macias diminuiu aatividade fenoloxidásica, os níveis de expressão de lisozimas e prolixicina, aomesmo tempo em que induziu aumento de atividade antibacteriana e dos níveisde defensina C no tubo digestivo do inseto, também modificando a composiçãode bactérias nativas...


Rhodnius prolixus is a major vector of Trypanosoma rangeli andTrypanosoma cruzi, in Latin America. The production of antimicrobial peptides(AMPs) in the midgut of the insect is vital to control possible infection, and tomaintain the microbiota already present in the digestive tract. This work focuseson the modulation of the humoral immune responses of the midgut of R. prolixusorally challenged with Gram positive and Gram negative bacteria as well with T.rangeli Macias strain, T. cruzi Dm 28c and Y strain, considering the influence ofthe parasites on the intestinal microbiota. Our results showed that the anteriormidgut contents of control insects contain a higher inducible antibacterial activityand AMPs transcript abundance than those of the posterior midgut. Insects orallyfed with Gram-negative bacteria presented higher amount of defC and proltranscripts, while the ingestion of Gram-positive induced defA and defBexpression in the midgut. T. rangeli Macias strain successfully colonized R.prolixus midgut through a decreasing in PO activities, prolixicin and lysozymelevels, while at the same time induced an increase in antibacterial activity andupregulated defC levels in the insect anterior midgut. T. rangeli infection alsodiminishes the amount of cultivable gut bacteria as well modified the compositionof indigenous microorganisms. Furthermore, different T. cruzi strains presentdistinct profiles of immune system and microbiota modulation in R. prolixusmidgut, where T. cruzi Dm 28c was able to induce an increase in defensin Cgenes and a depression in prolixicin genes, while drastically reduce the cultivablebacteria population. In the other hand T. cruzi Y was not competent to induceAMPs expression in the gut or considerably reduce the microbiota in the anteriormidgut...


Subject(s)
Animals , Antimicrobial Cationic Peptides , Rhodnius/immunology , Trypanosoma rangeli , Trypanosoma cruzi/immunology , Phagocytosis , Plant Root Nodulation
2.
Recife; s.n; 2006. 101 p. mapas, tab, graf.
Thesis in Portuguese | LILACS | ID: lil-527804

ABSTRACT

No presente estudo nós usamos microscopia eletrônica e confocal a laser para caracterizar morfologicamente os hemócitos de ninfas de quinto estádio em Rhodnius prolixus, bem como a resposta imune celular deste inseto contra partículas bióticas e abióticas ...


Subject(s)
Insecta/ultrastructure , Phagocytosis , Rhodnius/immunology , Animals
6.
Mem. Inst. Oswaldo Cruz ; 87(supl.5): 69-72, 1992.
Article in English | LILACS | ID: lil-128422

ABSTRACT

The effects of azadirachtin, a tetranortriterpenoid from the neem tree Aradirachta indica J. on both immunity and Trypanosoma cruzi interaction within Rhodniusprolixus and other triatomines, were presented Given through a blood meal, azadirachtin affected the immune reactivity as shown by a significant reduction in numbers of hemocytes and consequently nodule formation follwing challenge with Enterobacter cloacae ß12, reduction in ability to produce antibacterial activities in the hemolymph when injected with bacteria, and decreased ability to destroy the infection caused by inoculation of E. cloacae cells. A single dose of azadirachtin was able to block the development of T. cruzi in R. prolixus if given through the meal at different intervals, together with, before or after parasite infection. Similary, these results were observed with different triatomine species and different strains of T. cruzi. Azadirachtin induced a permanent resistance of the vector against reinfection with T. cruzi. The significance of these data is discussed in relation to the general mode of azadirachtin action in insects


Subject(s)
Rhodnius/immunology , Trypanosoma cruzi/drug effects
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