Daboia siamensis factor X activator metalloproteinase (RVV-X) (RVV-X)

Daboia siamensis factor X activator metalloproteinase (RVV-X) is a potent procoagulant enzyme found in the venom of the Eastern Russell's viper (Daboia siamensis). It is a heterotrimeric P-IIIc snake venom metalloproteinase (SVMP) composed of a catalytic heavy chain containing metalloproteinase, disintegrin-like, and cysteine-rich domains, and two C-type lectin-like light chains (UniProt: P0C2P1, P0C2P2, P0C2P3; PubMed: 23567015). The enzyme's primary biological function is the highly specific activation of blood coagulation Factor X into Factor Xa by cleaving the Arg194-Ile195 bond in the Factor X heavy chain (PubMed: 11469735). This activation occurs independently of the physiological tenase complex (Factor VIIIa/IXa) and calcium ions, leading to rapid and uncontrolled thrombin generation. Clinically, this results in venom-induced consumptive coagulopathy (VICC), a life-threatening condition characterized by the depletion of clotting factors, such as fibrinogen, and systemic hemorrhage (WHO Snakebite Guidelines; PubMed: 30114433). RVV-X is a primary target for neutralization by therapeutic antivenoms, and research is ongoing into small-molecule inhibitors like DMPS (dimercapto-1-propanesulfonic acid) and marimastat to mitigate its enzymatic activity in the field (PubMed: 32503855). Additionally, it serves as a critical reagent in diagnostic assays such as the Dilute Russell's Viper Venom Time (dRVVT) used to detect lupus anticoagulants and assess Factor X deficiency (StatPearls: Lupus Anticoagulant).

Other names

Russell's viper venom factor X activatorRVV-XFactor X-activating enzyme from Daboia siamensisDsV-FXADaboia siamensis venom factor X activator

Therapeutic agents target this molecule through antibody-mediated neutralization (antivenom) or by chelating the essential zinc ion in the metalloproteinase catalytic site, thereby preventing the proteolytic activation of Factor X.