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Brasiliensin: A novel intestinal thrombin inhibitor from Triatoma brasiliensis (Hemiptera : Reduviidae) with an important role in blood intake

Araujo, R. N., Campos, I. T. N., Tanaka, A. S., Santos, A., Gontijo, N. F., Lehane, Mike and Pereira, M. H. (2007) 'Brasiliensin: A novel intestinal thrombin inhibitor from Triatoma brasiliensis (Hemiptera : Reduviidae) with an important role in blood intake'. International Journal for Parasitology, Vol 37, Issue 12, pp. 1351-1358.

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Every hematophagous invertebrate studied to date produces at least one inhibitor of coagulation. Among these, thrombin inhibitors have most frequently been isolated. In order to study the thrombin inhibitor from Triatoma brasiliensis and its biological significance for the bug, we sequenced the corresponding gene and evaluated its biological function. The T. brasiliensis intestinal thrombin inhibitor, termed brasiliensin, was sequenced and primers were designed to synthesize double strand RNA (dsRNA). Gene knockdown (RNAi) was induced by two injections of 15 mu g of dsRNA into fourth instar nymphs. Forty-eight hours after the second injection, bugs from each group were allowed to feed on hamsters. PCR results showed that injections of dsRNA reduced brasiliensin expression in the anterior midgut by approximately 71% in knockdown nymphs when compared with controls. The reduction in gene expression was confirmed by the thrombin inhibitory activity assay and the citrated plasma coagulation time assay which showed activity reductions of similar to 18- and similar to 3.5-fold, respectively. Knockdown nymphs ingested approximately 39% less blood than controls. In order to confirm the importance of brasiliensin in blood ingestion, fourth instar nymphs were allowed to ingest feeding solution alone or feeding solution containing 15 U of thrombin prior to blood feeding. Fifty-five percent less blood was ingested by nymphs which were fed thrombin prior to blood feeding. The results suggest that anticoagulant activity in the midgut is an important determinant of the amount of blood taken from the host. The role of anticoagulants during blood ingestion is discussed in the light of this novel insight. (c) 2007 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Item Type: Article
Uncontrolled Keywords: triatomine triatoma brasiliensis rna interference brasiliensin feeding efficiency thrombin inhibitor intestinal anti-coagulant bug rhodnius-prolixus rna interference anticoagulant expression infestin cloning insect saliva cdna gene
Subjects: QX Parasitology > Insects. Other Parasites > QX 503 Hemiptera (e.g., Bedbugs)
QX Parasitology > Insects. Other Parasites > QX 650 Insect vectors
Faculty: Department: Groups (2002 - 2012) > Vector Group
Digital Object Identifer (DOI):
Depositing User: Ms Julia Martin
Date Deposited: 06 Sep 2010 14:05
Last Modified: 06 Feb 2018 13:01


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