Humoral and cellular immune responses induced by the urease-derived peptide Jaburetox in the model organism Rhodnius prolixus

MOYETTA NATALIA; FRUTTERO LEONARDO; COSTE GRAHL MATHEUS; UBERTI AUGUSTO; CARLINI CELIA REGINA

Maceió

Congreso; XXVI Congreso Brasilero IX Congreso Latinoamericano de Entomología.; 2016

Plant ureases are multifunctional proteins with functions independent of the catalytic activity, such as exocytosis induction and entomotoxic effects. Previous studies in Rhodnius prolixus, one of the main vectors of the Chagas? disease in Latin America, demonstrated that the treatment with the urease of Canavalia ensiformis (Jack Bean Urease, JBU) induced aggregation of the hemocytes, disruption of the cytoskeleton and darkening of the hemolymph, suggesting the activation of the defense system. Nevertheless, the available information on the ureases mechanism of action on the immune system of insects is very limited. The immune innate response of insects comprises cellular and humoral defenses including phagocytosis, encapsulation, melanization, synthesis of proteins and anti-microbial peptides, as well as the activation of the pro-phenoloxidase (pro-PO) cascade. PO enzymes participate in the melanization associated to the ecdysis and the encapsulation of pathogens in the hemolymph, in addition to producing quinones that are toxic for microorganisms. In this work, we used biochemical and cellular biology approaches to evaluate if the ureases and Jaburetox (JBTX, peptide recombinant derived of the JBU) can trigger an immune response in R. prolixus. In vivo and vitro Jaburetox treatments induced aggregation of hemocytes in fifth instar nymphs and adults, and EDTA incubations indicated that the cellular response was dependent on extracellular cations. Ureases of soybean and from the pathogens Helicobacter pylori also induced hemocyte aggregation in vitro. Finally, PO activity increased upon Jaburetox injections as determined bv L-DOPA spectrophotometry assays. The elucidation of the action mechanisms that explain the entomotoxicity of ureases and derived peptides is fundamental for the development of biotechnological applications directed to rational insect control.