A blood meal-induced Ixodes scapularis tick saliva serpin inhibits trypsin and thrombin, and interferes with platelet aggregation and blood clotting.

Autor: Ibelli AM; Texas A & M University AgriLife Research, Department of Entomology, 2475 TAMU, College Station, TX 77843, USA; Federal University of São Carlos, Graduate Program in Genetics and Evolution, Brazil., Kim TK; Texas A & M University AgriLife Research, Department of Entomology, 2475 TAMU, College Station, TX 77843, USA., Hill CC; Texas A & M University AgriLife Research, Department of Entomology, 2475 TAMU, College Station, TX 77843, USA., Lewis LA; Texas A & M University AgriLife Research, Department of Entomology, 2475 TAMU, College Station, TX 77843, USA., Bakshi M; Texas A & M University AgriLife Research, Department of Entomology, 2475 TAMU, College Station, TX 77843, USA., Miller S; Texas A & M University AgriLife Research, Department of Entomology, 2475 TAMU, College Station, TX 77843, USA; College Station High School, Science Department-Biology, 4002 Victoria Ave, College Station, TX 77845, USA., Porter L; Texas A & M University AgriLife Research, Department of Entomology, 2475 TAMU, College Station, TX 77843, USA., Mulenga A; Texas A & M University AgriLife Research, Department of Entomology, 2475 TAMU, College Station, TX 77843, USA. Electronic address: a-mulenga@tamu.edu.
Jazyk: angličtina
Zdroj: International journal for parasitology [Int J Parasitol] 2014 May; Vol. 44 (6), pp. 369-79. Date of Electronic Publication: 2014 Feb 28.
DOI: 10.1016/j.ijpara.2014.01.010
Abstrakt: Ixodes scapularis is a medically important tick species that transmits causative agents of important human tick-borne diseases including borreliosis, anaplasmosis and babesiosis. An understanding of how this tick feeds is needed prior to the development of novel methods to protect the human population against tick-borne disease infections. This study characterizes a blood meal-induced I. scapularis (Ixsc) tick saliva serine protease inhibitor (serpin (S)), in-house referred to as IxscS-1E1. The hypothesis that ticks use serpins to evade the host's defense response to tick feeding is based on the assumption that tick serpins inhibit functions of protease mediators of the host's anti-tick defense response. Thus, it is significant that consistent with hallmark characteristics of inhibitory serpins, Pichia pastoris-expressed recombinant IxscS-1E1 (rIxscS-1E1) can trap thrombin and trypsin in SDS- and heat-stable complexes, and reduce the activity of the two proteases in a dose-responsive manner. Additionally, rIxscS-1E1 also inhibited, but did not apparently form detectable complexes with, cathepsin G and factor Xa. Our data also show that rIxscS-1E1 may not inhibit chymotrypsin, kallikrein, chymase, plasmin, elastase and papain even at a much higher rIxscS-1E1 concentration. Native IxscS-1E1 potentially plays a role(s) in facilitating I. scapularis tick evasion of the host's hemostatic defense as revealed by the ability of rIxscS-1E1 to inhibit adenosine diphosphate- and thrombin-activated platelet aggregation, and delay activated partial prothrombin time and thrombin time plasma clotting in a dose-responsive manner. We conclude that native IxscS-1E1 is part of the tick saliva protein complex that mediates its anti-hemostatic, and potentially inflammatory, functions by inhibiting the actions of thrombin, trypsin and other yet unknown trypsin-like proteases at the tick-host interface.
(Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
Externí odkaz: