Acquisition of venom in snakes is due to their evolved pancreatic secretion, specialised in immobilising, killing and digesting the prey. Anti-venom, based on the principle of acquired immunity, has long been used worldwide to save patients from, previously fatal, snake bites.
Anti-venom production process
Small amounts of venom are injected into animals (horses, rabbits, sheep, goats and chickens are most used), which are targeted by their immune system producing antibodies. The dosage increases as the animal becomes more immune to the venom, stimulating more production of antibodies in the animals’ bloodstream. The serum is taken from the animal, by removing RBCs, and further purified for human use. The downside of this treatment is that serum sickness can occur which is caused by the human body attacking the proteins in anti-venom.
Anti-venoms can be monovalent (containing only one kind of antibody) or polyvalent (many), and stored up to 3 years if well refrigerated.
Future of anti-venom?
In 2003, Biochemists in VMSRF (Vittal Mallya Scientific Research Foundation) was working on producing anti-venom from chicken eggs. Young chickens are immunised with venom and the dosage is slowly increased. The result is antibodies accumulating in the eggs which can be used, instead of extracting blood from horses or other animals, to make anti-venom. This provides a more humane and cheaper alternative but this technology still requires refining before being used for mass production.
Scientists working at Liverpool School of Tropical Medicine in the UK had made an anti-venom that is not directly derived from snakes.
An analysis of active DNA when a snake (in this experiment, a carpet viper is used) is replenishing its venom leads is done and the genes for the venom are collected. The sequences, coding for the proteins exposed on the outside of the venom molecules, are joined together and are used to produce proteins that are similar to the venom on the outside, but harmless. The manufactured proteins are then injected into animal subjects to produce anti-venom.
The benefits of this technique are that the anti-venom produced is more potent than those made using the original method, and that it can be polyvalent. However, the major drawback is the cost for manipulating the DNA whereas the production method now (though still quite expensive) is more cost effective.
http://www.reptilepark.com.au/venom_snake.asp
http://www.kingsnake.com/elapids/antivenom_manufactures.htm
http://www.newscientist.com/article.ns?id=dn9277&feedId=online-news_rss20
http://news.nationalgeographic.com/news/2003/02/0211_030211_snakeeggs_2.html
And for those who loved the article of the guy from Darwin who got bitten 9 times by the same snake, here’s the link to it:
http://www.darwinawards.com/stupid/stupid1999-18.html
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