Snake venom serine protease from Vipera ammodytes and Vipera berus (SVSP)

Snake venom serine proteases (SVSPs) from Vipera ammodytes and Vipera berus are critical enzymatic toxins that primarily target the host's hemostatic system. These enzymes often function as thrombin-like enzymes (TLEs) or kallikrein-like proteases, mimicking endogenous factors to disrupt blood coagulation and blood pressure regulation (UniProt P0DPS3; MDPI Toxins 2024, 16(6), 255). By directly cleaving fibrinogen or activating other clotting factors like Factor X, they induce venom-induced consumptive coagulopathy (VICC), leading to systemic hemorrhage and potentially fatal hypotension (NIH/PMC6024332). In V. ammodytes (the nose-horned viper) and V. berus (the common European adder), SVSPs are major components of the venom proteome and are essential targets for therapeutic intervention (ResearchGate: Composition of V. berus berus venom proteins). Current treatment relies on the administration of antivenoms, such as ViperaTAb or Zagreb antivenom, which contain purified antibody fragments that neutralize these proteases (NIH/PMC8066110). While antivenoms are effective, they carry risks of hypersensitivity reactions and may not fully address local tissue damage if administered late. Research into small-molecule inhibitors like nafamostat suggests they could serve as adjunct treatments to delay the onset of severe coagulopathy by competitively inhibiting the SVSP active site (NIH/PMC7763118).

Other names

Thrombin-like enzymeTLEKallikrein-like proteaseFibrinogenolytic enzymeNikobinVaSP1Viper venom serine proteaseVVSP

Antivenoms provide passive immunity by using specific antibodies or antibody fragments (Fab or F(ab')2) to bind and neutralize the enzymatic activity of snake venom serine proteases, preventing them from interacting with host substrates like fibrinogen and facilitating their clearance from the bloodstream. Small-molecule inhibitors like nafamostat act as competitive inhibitors that bind to the active site of the serine protease, blocking its catalytic function and preventing the cleavage of coagulation factors.