Aspectos comportamentais, bioquímicos e moleculares envolvidos no processo de infecção de Triatoma infestans por Beauveria bassiana
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2015-07-22
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Universidade Federal de Goiás
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Triatoma infestans is the main vector of Chagas disease in Argentina, Bolívia and Paraguai. Beauveria bassiana is effective against all developmental stages of T. infestans. The dynamics of the host infection with B. bassiana has not been well studied yet and more basic research is necessary to elucidate aspects of this interaction. The present study characterized volatile organic compounds (VOC) secreted by T. infestans physically disturbed and infected with B. bassiana employing gas cromatography coupled to mass spectrometry. The expression of genes potentially involved in the biosynthesis of this volatiles (Ti-brnq and Ti-bckdc) was analysed according to the progress of infection with quantitative reverse transcription real-time (qPCR) methodology. The time-related expression of B. bassiana genes envolved in the biosynthesis of fungal toxins (BbtenS, BbbeaS, BbbslS) in nymphs treated with conidia or blastospores was measured, as well as the gene expression levels of insect proteins belonging to the humoral immune response (TiPPO, TiHL, TiDEF) in the same nymphs. Moreover, the influence of conidia on nymphal behavior was analysed. No clear repellent effect of conidia was found. Isobutyric acid was the most abundant VOC found, however, significant effect of the fungal on propionic acid secretion was found 1–3 days after treatment (a.t.). Ti-brnq and Ti-bckdc expression was higher 4 d a.t. than at 10 d a.t. in both conidial concentrations tested, but a significant effect of the time was found only with the first gene. In individuals immersed in the higher conidial concentration the expression of BbtenS and BbbeaS peaked 3 and 12 days a.t. respectively, and 9 days a.t with individuals treated with the lower concentration. In blastospore-injected nymphs, these genes peaked 24 h a.t. and in dead insect exposed in humid chamber. A significant effect of time on the expression of TiPPO in nymphs immersed in both conidial concentrations was found. TiDEF and TiHL peaked 6 days a.t. to both conidial concentration tested. In insects injected with blastospores significant increase in the expression pattern of all genes was found at the lower dose tested. Results emphasized the importance to elucidate better the dynamics of infection of T. infestans with B. bassiana in order to develop biological control estrategies of these vectors with entomopathogenic fungi.
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LOBO, L. S. Aspectos comportamentais, bioquímicos e moleculares envolvidos no processo de infecção de Triatoma infestans por Beauveria bassiana. 2015. 96 f. Tese (Doutorado em Medicina Tropical e Saúde Publica) - Universidade Federal de Goiás, Goiânia, 2015.