Haematophagous triatomine bugs produce a wide range of pharmacologically active compounds in their saliva to counteract vertebrate host haemostasis events such as coagulation, vasoconstriction and platelet aggregation, and to modulate vertebrate host immune-response. Proteins such as nucleoside triphosphate-diphosphohydrolases, commonly called apyrases, were found to be quite peculiar since they are specialized in neutralizing human platelet aggregation by hydrolysing ADP.
Triatoma infestans species were previously shown by our group to contain a salivary pool of five apyrases. Triatoma infestans and Panstrongylus megistus, in the Cerrado biome, and Rhodnius brethesi and R. robustus, in the Amazonian rainforest, are important Chagas disease vectors in Brazil. To investigate the possible presence of apyrases in the salivas of each of the four bug species above cited, proteomic analysis of salivary gland secretions was initiated.
Initially, immunodetection of SDS-PAGE separated salivary proteomes with anti-T. infestans apyrases serum revealed possible presence of such proteins in all of the four species. Experimental conditions for two-dimensional electrophoresis (2-DE) separation of the saliva proteomes were then optimized. Protein spots were also immunodetected in the 2-DE electroblotted gels by anti-T.infestans apyrases serum. The confirmation of their identity is currently under progress by MALDI-TOF MS, which was positive for T. infestans apyrases. For the salivas of the remaining three species, other approaches such as tandem mass spectrometry (MS/MS) and Edman chemical sequencing are soon going to be used as a second alternative strategy for protein identification.
The discovery of these potential apyrase-like proteins may suggest the implication of these proteins in the anti-platelet aggregation mechanism. Moreover, it will probably lead us to understanding the features of divergent evolution that have been associated with different triatomine’s biological behaviours.
Supported by CNPq (PIBIC) and PRONEX.