Reck J, Berger M, Marks F S, Zingali R B, Canal C W, Ferreira C A S, Guimarães J A, Termignoni C
Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
Parasitology. 2009 Sep;136(11):1339-49. doi: 10.1017/S0031182009990618. Epub 2009 Jul 23.
Ticks are blood-feeding arthropods widely distributed in the world and vectors of several diseases. As haematophagy demands evasion strategies and repeatedly infested hosts develop protective immune responses, we investigated the mechanisms of the Rhipicephalus (Boophilus) microplus saliva anti-haemostatic activity and the possible relationship between the acquired natural anti-tick host resistance and anti-haemostatic action. For this purpose, we studied the effects of R. microplus saliva on different pathways of haemostasis and tested whether repeated infested bovine sera (RIBS) are able to abolish salivary anti-haemostatic activities. R. microplus saliva (i) displays inhibitory activity upon collagen-induced platelet aggregation; (ii) inhibits the induction of endothelial pro-coagulant state; and (iii) reduces thrombogenesis in vivo. RIBS were shown to be able to partially block the delay of coagulation and the anti-thrombotic effect of saliva, and to totally abolish the modulation of endothelium activation. Conversely, RIBS has no effect on the inhibition of platelet aggregation. These results show, for the first time, the neutralization ability of sera from acquired resistance hosts against tick anti-haemostatics. Moreover, this is the first report of a haematophagous parasite able to modulate endothelial cell pro-coagulant state, and addresses the presence of anti-platelet and anti-thrombotic activity in R. microplus saliva.
蜱是吸血节肢动物，广泛分布于世界各地，是多种疾病的传播媒介。由于吸血需要逃避策略，且反复受侵袭的宿主会产生保护性免疫反应，我们研究了微小牛蜱唾液的抗止血活性机制以及获得性天然抗蜱宿主抵抗力与抗止血作用之间的可能关系。为此，我们研究了微小牛蜱唾液对不同止血途径的影响，并测试了反复受侵袭的牛血清（RIBS）是否能够消除唾液的抗止血活性。微小牛蜱唾液（i）对胶原诱导的血小板聚集具有抑制活性；（ii）抑制内皮促凝状态的诱导；（iii）在体内减少血栓形成。结果表明，RIBS能够部分阻断凝血延迟和唾液的抗血栓作用，并完全消除对内皮激活的调节。相反，RIBS对血小板聚集的抑制没有影响。这些结果首次表明获得性抗性宿主血清对蜱抗止血剂的中和能力。此外，这是关于吸血寄生虫能够调节内皮细胞促凝状态的首次报道，并阐述了微小牛蜱唾液中存在抗血小板和抗血栓活性。
