Snake venom metalloproteinases:Their role in the pathogenesis of local tissue damage

https://who.int/bloodproducts/publications/antivenoms_toxicon_final.pdf

Report of a WHO workshop on the standardization and control of antivenoms.

The processes that drive the evolution of snake venom variability, particularly the role of diet, have been a topic of intense recent research interest. Here, we test whether extensive variation in venom composition in the medically important viper genus Echis is associated with shifts in diet. Examination of stomach and hindgut contents revealed extreme variation between the major clades of Echis in the proportion of arthropod prey consumed. The toxicity (median lethal dose, LD50) of representative Echis venoms to a natural scorpion prey species was found to be strongly associated with the degree of arthropod feeding. Mapping the results onto a novel Echis phylogeny generated from nuclear and mitochondrial sequence data revealed two independent instances of coevolution of venom toxicity and diet. Unlike venom LD50, the speed with which venoms incapacitated and killed scorpions was not associated with the degree of arthropod feeding. The prey-specific venom toxicity of arthropod-feeding Echis may thus be adaptive primarily by reducing venom expenditure. Overall, our results provide strong evidence that variation in snake venom composition results from adaptive evolution driven by natural selection for different diets, and underscores the need for a multi-faceted, integrative approach to the study of the causes of venom evolution.

/pdf/coevolution-of-diet-and-prey-specific-venom-activity-444vt5ks40.pdf

Coevolution of diet and prey-specific venom activity supports the role of selection in snake venom evolution

Snakebite envenoming from a global perspective: Towards an integrated approach.

Ethnobotanical survey of folk plants for the treatment of snakebites in Southern part of Tamilnadu, India.

In accordance with the recommendations of the report of a WHO Coordination Meeting on Venoms and Antivenoms, methods have been developed for the assessment of lethal, defibrinogenating, procoagulant, haemorrhagic, and necrotizing properties of venoms, and used to study 53 venoms from 30 different species of snakes of medical importance throughout the world The venoms studied included Echis carinatus (Iran), Naja naja kaouthia (Thailand), Notechis scutatus (Australia), Trimeresurus flavoviridis (Japan), Vipera russelli (Thailand), and Crotalus atrox (USA), which comprise six of the eight venoms designated by WHO as international reference venoms (IRVs) (C atrox venom replaced C adamanteus venom, as an adequate supply of the latter was not available) The tests used were simple and should be reproducible in other laboratories throughout the world Procedures for assaying neuromuscular paralytic activity and systemic myotoxic activity have yet to be developedThe tests will be used to assay the neutralizing potency of both international standard antivenoms (raised using the IRVs) and new and currently available commercial antivenoms Such studies should result in the production of more potent antivenoms for use in both developing and developed countries, and improve the understanding and management of snake bite throughout the world

R. D. G. Theakston

Papers

Development of simple standard assay procedures for the characterization of snake venom.