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

Abstract

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.

An Insight into the Sialotranscriptome of Triatoma matogrossensis, a Kissing Bug Associated with Fogo Selvagem in South America

“…Like other triatomines that have been studied, [18][19][20][21][22] T. matogrossensis is most probably capable of counteracting host hemostatic responses triggered to prevent blood loss following tissue injury, such as vasoconstriction, blood coagulation, and platelet aggregation. 23 The molecular diversity of hematophagous insect saliva presents a rich field for the discovery of novel pharmacologically active compounds and for understanding evolutionary mechanisms leading to insect adaptation to this feeding habit.…”

“…This pattern has been found in all previously reported sialotranscriptomes of triatomine bugs. 19,21,22,63,64 Lipocalins are a large and heterogeneous group consisting of Figure 1. Phylogram of the salivary inositol phosphatases from bloodsucking Hemiptera.…”

Dimiconin, a novel coagulation inhibitor from the kissing bug, Triatoma dimidiata, a vector of Chagas disease

“…Recently, a large number of transcripts from the salivary glands of T. dimidiata were sequenced, and transcripts (Td60 and Td101) coding for a lipocalin protein homologous to triabin, a thrombin inhibitor identified from T. pallidipennis saliva, were identified (Kato et al, 2010). In the present study, a recombinant protein was produced from the transcript Td60, and its biological activity was characterized.…”

“…They feed directly from the blood vessel for 20-30min efficiently regardless of the host hemostatic response, suggesting the presence of strong and unique bioactive substances in their saliva (Martínez-Ibarra et al, 2001). To discover unique pharmacologically active agents, salivary components of triatomine bugs have been explored in Rhodnius prolixus (Ribeiro et al, 2004), Triatoma brasiliensis (Santos et al, 2007), Triatoma infestans (Assumpção et al, 2008), Triatoma dimidiata (Kato et al, 2010) and Dipetalogaster maxima (Assumpção et al, 2011) by transcriptome analyses of the salivary gland. Characteristically, their salivary components were found to be rich in lipocalins, a large group of extracellular proteins that bind and transport small hydrophobic molecules.…”

“…Triabin is a lipocalin protein identified from the saliva of Triatoma pallidipennis and functions as an inhibitor of thrombin, resulting in the inhibition of thrombin-induced platelet aggregation as well as blood coagulation (Noeske-Jungblut et al, 1995 (Noeske-Jungblut et al, 1994), R. prolixus aggregation inhibitor 1 (RPAI-1) as a platelet aggregation inhibitor in R. prolixus (Francischetti et al, 2000), and triafestin-1 and -2 as plasma kallikrein-kinin system inhibitors in T. infestans (Isawa et al, 2007). Recently, a transcriptome-based analysis of the salivary gland of T. dimidiata resulted in the identification of transcripts homologous to T. pallidipennis triabin, an inhibitor of thrombin activity (Kato et al, 2010). In the present study, a recombinant T. dimidiata triabinlike protein (designated 'dimiconin') was prepared and its activity was characterized.…”