Why in News?

An international team of researchers have sequenced the genome of the Indian cobra, in the process identifying the genes that define its venom.

What is the significance?

• This genome sequence can provide a blueprint for developing more effective anti-venom.
• The cobra genome sequence is of really high quality.
• Sequence information of the genes that code for venom proteins is very important for the production of recombinant anti-venoms.

Are existing anti-venoms not effective enough?

• Their efficacy varies, besides producing side effects.
• In India, the challenge has been producing anti-venom for the species known collectively as the “big four”,
  1. The Indian cobra (Naja naja),
  2. Common krait (Bungarus caeruleus),
  3. Russell’s viper (Daboia russelii), and
  4. Saw-scaled viper (Echis carinatus).
• Common anti-venom is marketed for the treatment of bites from the “big four”, but its effectiveness came under question in a recent study.
• The common anti-venom worked against the saw-scaled viper and the common cobra.
• But this anti-venom fell short against some neglected species and also against one of the “big four” - the common krait.
• Facts - Accidental contacts with snakes lead to over 100,000 deaths across the world every year.
• India alone accounts for about 50,000 deaths annually, and these are primarily attributed to the “big four”.

Why has production of effective anti-venom been challenging?

• Venom is a complex mixture of an estimated 140-odd protein or peptides.
• Only some of these constituents are toxins that cause the physiological symptoms seen after snakebite.
• But anti-venom available today does not target these toxins specifically.
• Anti-venom is currently produced by a century-old process.
• In this process, a small amount of venom is injected into a horse or sheep, which produces antibodies that are then collected and developed into anti-venom.

What are the issues with this ‘horse technique’?

• This is expensive, cumbersome technique and comes with complications.
• Some of the antibodies raised from the horse may be completely irrelevant.
• The horse also has a lot of antibodies floating in its blood that have nothing to do with the venom toxins.
• One more problem with horse antibodies is that our immune system recognises it as foreign and when anti-venom is given our body mounts an antibody response. This leads to what is called serum sickness.

How does decoding the genome help?

• In the Indian cobra genome, the researchers have identified 19 key toxin genes, the only ones that should matter in snakebite treatment.
• They stress the need to leverage this knowledge for creation of safe and effective anti-venom using synthetic human antibodies.
• The next step would be obtaining the genomes and the venom gland genes from the other three of the “big four” and the deadly African species.
• However, there is a very long way to go from genomes to effective anti-snake venoms.