The ex vivo effects of Bitis arietans venom on the ultrastructure, platelet activity and viscoelastic properties of human blood

Abstract

Background: In 2017, venomous snake bites were recognised and categorised as a category A neglected tropical disease (NTD), by the World Health Organization. Statistics show that between 81 000 and 138 000 fatalities occur annually due to snakebite envenomation. Puff Adder snake bites continue to pose a threat to human health as they can have negative effects on the body's physiology, but very little is known about the coagulative changes that its venom induces in humans, other than the cytotoxic and thrombolytic properties of the Puff Adder venom. Objectives: In this analytical, laboratory-based study the effects of Puff Adder venom on blood coagulopathy were studied. The objectives were to examine fibrin fibres, platelets, and red blood cell (RBC) ultrastructure using scanning electron microscopy (SEM), measure platelet activation using flow cytometry and evaluate whole blood (WB) clot kinetics with thromboelastography® (TEG®). Methods: Red blood cell ultrastructural morphology was studied along with platelet activation and clot formation using SEM. Platelet activation was measured using flow cytometry, after which TEG® was used to analyse the viscoelastic properties of whole blood clot kinetics. The WB was exposed to a final venom concentration of 2.0 nanograms/microlitre (ng/μL).

Results: This study demonstrated that exposure to snake venom significantly affects red blood cell (RBC) morphology, platelet activation, and clot structure. Echinocytes and membrane blebbing along with platelet-rich aggregates were observed in venom-exposed samples and the viscoelastic profile in venom-treated blood samples indicated hypocoagulation. Decreased interaction between the fibrin fibre network and RBCs was seen in SEM micrographs, along with broken fibrin fibres and “melting” of fibres into each other. Conclusion: The study’s findings confirms that Puff Adder venom interferes with platelet function and affects fibrin clot formation. These insights can improve the understanding of the effect these venoms have on human coagulation, allowing for the creation of a venom profile for identification in snakebite victims. Further research is required into the toxins and their underlying mechanisms that cause these effects.