Recently scientists have sequenced one of the deadliest snake’s genome, the Indian cobra.This development as many others in the field of science can be revolutionary as it promises a cure for snake bites.
Thousands of people worldwide are bitten by snakes and for now anti venoms are the only cure. About 4 lakh of the bitten people end up with an amputated body part and around 1 lakh end up dying. With these statistics and the fact that science has had many advances in the recent past. It is high time we find more cheaper, readily available cure for snake venom.
Snake venom is a yellow coloured fluid stored in the modified salivary gland of the snakes. Snakes use their venom to kill and immobilize their prey. The venom acts on the central nervous system, break down the cell and tissues leading to paralysis, tissue death , internal bleeding. Snake venom is a deadly combination of proteins, enzymes and other molecular compounds.
Although snake venom is composed of a complex cocktail of toxin, mostly they can be classified as
They affect the nervous system by distrupting the chemical signals(neurotransmitters) between the neurons.They may reduce neurotransmitter production or block neurotransmitter reception sites. Other snake neurotoxins work by blocking voltage-gated calcium channels and voltage-gated potassium channels. These channels are important for the transduction of signals along neurons. Neurotoxins cause muscle paralysis which may also result in respiratory difficulty and death.
These toxins destroy the cells, tissue and ultimately lead to necrosis. Some tissue may experience liquefactive necrosis in which the tissue is partially or completely liquefied. Cytotoxins help to partially digest the prey before it is even eaten. Cytotoxins are usually specific to the type of cell they impact. Cardiotoxins are cytotoxins that damage heart cells. Myotoxins target and dissolve muscle cells. Nephrotoxins destroy kidney cells. Many venomous snake species have a combination of cytotoxins and some may also produce neurotoxins or hemotoxins.They also trigger apoptosis in the cells. The bite site is the most affected.
They disrupt the blood coagulation process, by causing the red blood cells to burst open.These toxins also interrupt which the blood coagulation factors.Ultimately these toxins lead to internal bleeding, tissue death, organ death, kidney damage.
HOW IS ANTIVENOM PRODUCED?
Anti venom is generally produced by extracting the snake venom and producing antibodies by injecting them into animals such as horses. These antibodies are then purified from the animal blood and used as antivenom in case of humans.
The problem here is that we have to extract snake venom to create antibodies. The snakes produce venom in very small quantities, making production of huge amount of antibodies very difficult. Also this makes the antivenom very expensive and not so easily available due to its high demand and less quantity.
A vial of antivenom costs about Rs 500 and a snake bite needs 25 vials or more to neutralize the snake bite effect.
Using modern biotechnological sequencing technology to sequence the snake genome has also helped in knowing the venom gland genome. This can help us in recognizing the genes that produce the venom protein and generate antibodies in large scale.
Researchers, of the sequenced genome found 12,346 genes expressed in the venom glands, what they call the “venom-ome” of the animal. Of these, they found 139 toxin genes, the ones that perform the biological reactions specific to toxins. Then they designated 19 of these genes as “venom-ome specific,” expressed only in the venom gland, and that are responsible for a wide range of symptoms in humans, including heart-function problems, paralysis, nausea, blurred vision, internal bleeding and death.
Using recombinant protein technology the scientist hope to produce antivenom effective against the venom of Indian cobra and related species. This also paves a way of creating a combination of genes to produce a broad spectrum antivenom , which can be used for a wide spectrum of snake venom.