WESTERN MAIL (Cardiff, UK) 03 December 13 Welsh scientists uncover the poison secrets of the world's longest venomous snake (Darren Devine)
Welsh scientists have sequenced the entire genome of the world’s longest poisonous snake - the iconic King Cobra.
The work at Bangor University, in North Wales, has helped explain how venom is produced and scientists say the toxins could form the basis of new drugs and address concerns over the enormous number of snake bites and deaths in tropical countries.
Leading the research Dr Nick Casewell, of Bangor’s School of Biological Sciences, analysed the genetic makeup of every venom protein produced by the King Cobra.
Dr Caswell, working alongside academics at Leiden University, Holland, and the University of Texas, Arlington, found the individual toxins in venom evolved from related proteins found elsewhere in the snake.
The toxins perform standard “biological housekeeping” tasks throughout the body like digestion.
Dr Casewell said: “The genes important to the venom glands have evolved rapidly in evolutionary terms. The reason why we see this change and subsequent variety found within relatively closely related snake species could be compared to an evolutionary arms race.
“As the prey becomes increasingly resistant to a toxin, so stronger or different variations of toxins may evolve to overcome such resistance.”
The process has led to the development of ‘suites’ of between 50-100 toxic proteins, and also causes major variations in venom between different snakes.
These differences are not only found between distinct major groups of venomous snakes, such as the elapids, which include cobras and mambas, but also within a single species in different regions.
This ‘venom variation’ can cause problems for medics wanting to deliver the correct antivenom treatment to people bitten by snakes.
King Cobras can grow to nearly six metres long.
It is estimated around 90,000 people die worldwide each year as the result of snakebite, with the vast majority in tropical regions.
Dr Casewell said toxins in snake venom have long been used to form the basis of drugs to treat conditions like high blood pressure, blood clots and heart attacks.
He hopes his work could lead to new medicines in five to 10 years.
Dr Casewell added: “Some snakes have what we call haemotoxic venom in that they affect the blood system and can cause clotting or breakdown clotting or drop your blood pressure or raise your blood pressure.
“So by identifying which of these proteins is responsible for these changes we can actually think about how we can manipulate them to turn them into medicine.”
Studies in the US have unveiled the therapeutic potential of snake toxins for treating strokes and brain aneurisms.
Biochemist Professor Frank Markland, of the University of Southern California, found injecting contortrostatin, a protein in southern copperhead snake venom, slows the development of breast cancer in mice.
Professor Markland said as well as inhibiting the growth of the tumour it also slowed the growth of blood vessels into the tumour that allow it to spread.
The protein also impaired the spread of the tumour to the lungs - where breast cancer spreads effectively.
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