bLOOD CLOT AND PLATELET AGGREGATION INHIBITORS fROM THE SALIVA of Amblyommacajennense (ACARI: IXODIDAE)

Simons, S.M.(1),  Batista, I.F.C.(1), Faria, F.(1), Barros-Battesti, D.M.(2),Labruna, M.B.(3), Chudzinski-Tavassi, A.M.(1)

(1)Laboratório de Bioquímica e Biofísica,Instituto Butantan, São Paulo, SP, (2)Laboratório de Parasitologia e Entomologia, Instituto Butantan, São Paulo, SP, (3)USP - FMVZ-VPS – São Paulo, SP

Saliva of bloodsucker contains several substances that act on the platelet aggregation, protease control, vasoconstriction, among other physiological mechanisms.

Objective: to identify blood clotting and platelet aggregation inhibitors, from the saliva of the Amblyommacajennense ticks.

Methods:Crude saliva was obtained by Tatchellmethod with some modifications, and it was used to: check the 2D-electrophoreseis profile,inhibition of the platelet aggregation induced by collagen, and the inhibitors purification by gel filtration and ion-exchange chromatographs. The activity of the purified inhibitor on the prothrombinase complex was also analyzed.

Results: Amblyomma cajennense saliva contains proteins with pI between 3.37 to 6.64 and molecular mass 306 and 16 kDa. Concerning to the platelet aggregation induced by collagen, 35% of inhibition was observed, moreover, the results obtained in the flow cytometry experiments, performed also with the crude saliva suggested that the GP II-b is modified. The Factor Xa purified inhibitor is a 70 k Da protein that shows a IC₅₀ 0.13 nM, and is able to inhibit the FXa in the prothrombinase complex. A thrombin inhibitor in the crude saliva was also found but it was not visualized in the SDS-PAGE suggesting that it could be a peptide inhibitor.

Conclusion: Amblyommacajennensesaliva contains protease inhibitors, which are able to maintain the successful feeding and physiological systems of the tick.

Supported by: FAPESP

CORRESPONDENCE TO:

Simons, S.M., Laboratório de Bioquímica e Biofísica,Instituto Butantan, São Paulo, SP, 05503-900, Brasil, Email: smsimons@bol.com.br