Identificação e caracterização funcional de atividade apirásica nas salivas de triatomíneos vetores da Doença de Chagas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Blood-feeding arthropods are able to constraints barriers imposed by host defenses, due to the presence of a wide range of antihemostatic factors in their saliva, including vasodilators, antiplatelet factors and anticoagulant. The main Chagas disease transmission mechanism is contamination of a host by faeces from triatominae infected. Triatoma infestans Klug, 1834, the main vector of Chagas disease in Brazil, expresses several apyrases in its saliva that inhibit the vertebrate host platelet aggregation. We show in this report that the 88, 82 E 79 kDa apyrases of the insect are antigenically different and localize within the salivary gland D2 unit. The content of one D2 unit, and not that of the others, was able to mediate fully inhibition of platelet aggregation induced by ADP, from 1 mL of human blood. In addition, we identified for the first time apyrase activities in the saliva of Rhodnius brethesi Matta, 1919; Rhodnius milesi Carcavallo, Rocha, Galvão, Jurberg &Valente 2001; Rhodnius pictipes Stal, 1872 e Rhodnius robustus Larrousse, 1927. The tests, which were accomplished at 37 C and pH 8,3, revealed that these apyrase activities are dependent upon Ca+2 . The apyrase activities present in the salivary glands of R. brethesi e R. pictipes were then partially purified on an Oligo dT Cellulose column. To identify proteins related to apyrase activity, salivary gland content and eluted fractions from the Oligo dT column were submitted to SDS-PAGE enzimography without previous boiling or reduction of the samples. This experiment allowed the identification of 44-45 kDa protein bands displaying both ATPase and ADPase activities. In vitro platelet aggregation assays showed that the content of 0,5 salivary gland pair R. brethesi, R. milesi, R. pictipes e R. robustus completely abolished platelets aggregation induced by ADP. Differently fromf T. infestans apirases, Rhodnius spp. express apyrases of low molecular masses that arent members of the 5nucleotidase family. The wide distribution of apyrases in the saliva of Chagas disease vectors and other arthropods indicate that these enzymes play an important role during the hematophagous process.

ASSUNTO(S)

agregação plaquetória apirase bioquimica doença de chagas

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