Snake Venoms and Other Toxic Components Affecting Thrombosis and Hemostasis

Blood coagulation and platelet aggregation are the primary host defense systems against invasion by nonself factors such as viruses and pathogens. Some exogenous proteins/peptides from snake venoms and the saliva of hematophagous organisms target blood coagulation and platelet aggregation systems. Many unique proteins/peptides that do not exist in mammals have been isolated from various snake venoms and the salivary glands of leeches and ticks. These compounds specifically attack critical molecules of prey and hosts to disrupt and destroy their homeostatic systems. Such potent and highly specific exogenous proteins/peptides have thus been indispensable in elucidating the complex physiology of mammalian blood coagulation and platelet aggregation. This chapter provides an overview of the structures and functions of snake venom toxins, salivary proteins of hematophagous organisms, and also some bacteria-derived proteins that affect blood coagulation and platelet aggregation.