A repertoire of the dominant transcripts from the salivary glands of the blood-sucking bug, Triatoma dimidiata, a vector of Chagas disease.

Triatoma (T.) dimidiata is a hematophagous Hemiptera and a main vector of Chagas disease. The saliva of this and other blood-sucking insects contains potent pharmacologically active components that assist them in counteracting the host hemostatic and inflammatory systems during blood feeding. To describe the repertoire of potential bioactive salivary molecules from this insect, a number of randomly selected transcripts from the salivary gland cDNA library of T. dimidiata were sequenced and analyzed. This analysis showed that 77.5% of the isolated transcripts coded for putative secreted proteins, and 89.9% of these coded for variants of the lipocalin family proteins. The most abundant transcript was a homologue of procalin, the major allergen of T. protracta saliva, and contributed more than 50% of the transcripts coding for putative secreted proteins, suggesting that it may play an important role in the blood-feeding process. Other salivary transcripts encoding lipocalin family proteins had homology to triabin (a thrombin inhibitor), triafestin (an inhibitor of kallikrein-kinin system), pallidipin (an inhibitor of collagen-induced platelet aggregation) and others with unknown function.