Animal venoms/toxins and the complement system

- Snakes have developed methods to cause complement activation: by enzymatic inactivation of C1-INH, direct enzymatic activation of C3, C4 and C5 and/or formation of a stable C3/C5 convertase.
- Ticks have developed complement inhibitors by preventing binding of properdin to the C3-convertase or protecting C5 from the C5-convertase.
- In cases where complement is involved in the pathology, common features include C-mediated renal pathology and C-dependent haemolysis.

Nature is a wealthy source of agents that have been shown to be beneficial to human health, but nature is also a rich source of potential dangerous health damaging compounds. This review will summarise and discuss the agents from the animal kingdom that have been shown to interact with the human complement (C) system. Most of these agents are toxins found in animal venoms and animal secretions. In addition to the mechanism of action of these toxins, their contribution to the field of complement, their role in human pathology and the potential benefit to the venomous animal itself will be discussed. Potential therapeutic applications will also be discussed.