Snake venom toxins affecting haemostasis have facilitated extensively the routine assays of haemostatic parameters in the coagulation laboratory.
Snake venom thrombin-like
enzymes (SVTLE) are used for
fibrinogen/
fibrinogen breakdown product assay and for the detection of
fibrinogen dysfunction. SVTLE are not inhibited by
heparin and can thus can be used for assaying
antithrombin III and other haemostatic variables in
heparin-containing samples.
Snake venoms are a rich source of
prothrombin activators and these are utilised in
prothrombin assays, for studying dysprothrombinaemias and for preparing
meizothrombin and non-enzymic forms of
prothrombin. Russell's viper (Daboia russelli)
venom (RVV) contains toxins which have been used to assay blood clotting factors V, VII, X,
platelet factor 3 and, importantly, lupus
anticoagulants (LA). Other
prothrombin activators (from the taipan, Australian brown snake and saw-scaled viper) have now been used to assay LA.
Protein C and
activated protein C resistance can be measured by means of RVV and
Protac, a fast acting inhibitor from Southern copperhead
snake venom and
von Willebrand factor can be studied with
botrocetin from
Bothrops jararaca venom. The
disintegrins, a large family of
Arg-Gly-Asp (RGD)-containing
snake venom proteins, show potential for studying
platelet glycoprotein receptors, notably, GPIIb/IIIa and Ib.
Snake venom toxins affecting haemostasis are also used in the therapeutic setting:
Ancrod (from the Malayan pit viper, Calloselasma rhodostoma), in particular, has been used as an
anticoagulant to achieve 'therapeutic defibrination'. Other
snake venom proteins show promise in the treatment of a range of haemostatic disorders.