Apyrases are nucleoside triphosphate-diphosphohydrolases (EC 3.6.1.5) present in a variety of organisms. The apyrase activity found in the saliva of hematophagous insects is correlated with the prevention of ADPinduced platelet aggregation of the host during blood sucking. Purification of apyrase activity from the saliva of the triatomine bug Triatoma infestans was achieved by affinity chromatography on oligo(dT)-cellulose and gel filtration chromatography. The isolated fraction includes five N-glycosylated polypeptides of 88, 82, 79, 68 and 67 kDa apparent molecular masses. The isolated apyrase mixture completely inhibited aggregation of human blood platelets. Labeling with the ATP substrate analogue 5-p-fluorosulfonylbenzoyladenosine showed that the five species have ATP-binding characteristic of functional apyrases. Furthermore, tandem mass spectroscopy peptide sequencing showed that the five species share sequence similarities with the apyrase from Aedes aegypti and with 5-nucleotidases from other species. The complete cDNA of the 79-kDa enzyme was cloned, and its sequence confirmed that it encodes for an apyrase belonging to the 5-nucleotidase family. The gene multiplication leading to the unusual salivary apyrase diversity in T. infestans could represent an important mechanism amplifying the enzyme expression during the insect evolution to hematophagy, in addition to an escape from the host immune response, thus enhancing acquisition of a meal by this triatomine vector of Chagas' disease.Hematophagy in triatomines (Hemiptera: Reduviidae) is associated with the presence of biochemical compounds in the salivary glands that are essential for obtaining blood meals. Indeed, most blood-feeding arthropods have salivary components with vasodilatory, anti-clotting, and anti-platelet aggregation activities that are capable of inhibiting hemostatic reactions of the host (1-4).Host platelet aggregation is considered to be an important hemostatic barrier against insect feeding, because it can stop the bleeding of small blood vessels regardless of other clotting factors (5, 6). Rhodnius prolixus, a triatomine, neutralizes and overrides platelet aggregation induced by collagen, thrombin, thromboxane A 2 , and ADP (7-10). Similarly, collagen-and thrombin-induced platelet aggregation is inhibited by, respectively, pallidipin and triabin, both of which are present in the saliva of Triatoma pallidipennis (11,12). However, the importance of ADP as a common mediator of platelet aggregation pathways is evidenced by the presence on the vascular endothelium surface of the CD39 apyrase, which limits platelet aggregation by hydrolyzing ADP, thus preventing thrombus formation (13). Thus, studying insect apyrases may lead to alternative strategies against the diseases they transmit, as well as new pharmaceutical tools for platelet aggregation-associated disorders. Apyrase removes inorganic phosphate from ATP and ADP, and thus prevents platelet aggregation (6,8,14). Apyrase activity has been characterized in the saliva of Anopheles st...

Abstract. The Triatoma infestans salivary gland proteins (TSGP) can induce local and systemic hypersensitivity reactions in humans. IgG antibodies against TSGP were present in higher levels in sera of Chagas disease patients, and in individuals living in triatomine-infested areas than in controls living in triatomine-free areas. TSGP-specific IgG 1 was found in sera of Chagas patients, and of individuals living in triatomine-infested rural areas, and uniquely specific IgG 4 was present in sera of Chagas patients living in triatomine-infested areas, reactive against TSGP. Unique specificities were not detected in sera of individuals reacting against the ubiquitous mosquito Culex quinquifasciatus saliva proteins (CSGP). In conclusion, IgG 1 reactive against TSGP is the main antibody present in individuals living in the triatomine-infested study areas. Also, IgG 4 is found in the sera of insect-transmitted Chagas disease patients living in study areas.

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SummaryLack of conservation of the Amazon tropical rainforest has imposed severe threats to its human population living in newly settled villages, resulting in outbreaks of some infectious diseases. We conducted a seroepidemiological survey of 1100 inhabitants of 15 villages of Paço do Lumiar County, Brazil. Thirty-five (3%) individuals had been exposed to Trypanosoma cruzi (Tc), 41 (4%) to Leishmania braziliensis (Lb) and 50 (4.5%) to Leishmania chagasi (Lc) infections. Also, 35 cases had antibodies that were cross-reactive against the heterologous kinetoplastid antigens. Amongst these, the Western blot assays revealed that 11 (1%) had Tc and Lb, that seven (0.6%) had Lc and Tc, and that 17 (1.6%) had Lb and Lc infections. All of these cases of exposures to mixed infections with Leishmania sp, and eight of 11 cases of Tc and Lb were confirmed by specific PCR assays and Southern hybridizations. Two cases had triple infections. We consider these asymptomatic cases showing phenotype and genotype markers consistent with mixed infections by two or more kinetoplastid flagellates a high risk factor for association with Psychodidae and Triatominae vectors blood feeding and transmitting these protozoa infections. This is the first publication showing human exposure to mixed asymptomatic kinetoplastid infections in the Amazon.

An epidemiological chain involving Trypanosoma