Antihemostatic activity in salivary glands of the human body louse, Pediculus humanus humanus (Anoplura: Pediculidae)

A thrombin inhibitor, factor Xa inhibitor and apyrase activity were demonstrated in the salivary glands of Pediculus humanus humanus, Less than 0.15 mu g of salivary gland extracts (SGE), which is equivalent to approximately 0.15 lice salivary glands, caused 50% inhibition of thrombin activity, while 1 mu l of SGE was sufficient to double thrombin time using rat plasma, A single peak of thrombin inhibitor was eluted from the Mono Q column at a fraction corresponding to a protein with Mol, Wt. of about 7 kDa, The thrombin inhibitor was partially purified from the SGE by gel filtration chromatography and FPLC chromatography, and a single sharp peak of thrombin inhibitory activity was eluted, The results obtained from the FXa activity assay indicate the presence of a weak inhibitory activity against this coagulation factor in the salivary gland, The amount of SGE needed for FXa inhibition (IC50) was 500 times higher than that required for thrombin inhibition, Apyrase activity was also detected in the SGE using ADP as a substrate, These results indicate the presence of both anticoagulant and anti-platelet agents in the salivary gland of the human louse. Copyright (C) 1996 Elsevier Science Ltd