genome-of-indian-cobra-sequenced

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

Need

  • Accidental contact with snakes leads 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”: the Indian cobra (Naja naja), common krait (Bungarus caeruleus), Russell’s viper (Daboia russelii), and saw-scaled viper (Echis carinatus).
  • 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 a snakebite. But antivenom available today does not target these toxins
  • The existing anti-venom efficacy varies against the venom of the Big 4. 
  • While the common antivenom is marketed against the saw-scaled viper and the common cobra, it fell short against some neglected species and also against one of the “big four”-  the common krait.
  • Genome sequencing is ostensibly the process of determining the complete DNA sequence of an organism's genome
  • This entails sequencing all of an organism's chromosomal DNA as well as DNA contained in the mitochondria and, for plants, in the chloroplast.

Antivenom development process-related issues 

  • Antivenom is currently produced by a century-old process.
  • The process involves the injection of a small amount of venom into a horse or a sheep which produces antibodies that are then collected and developed into antivenom.
  • The process is riddled with complications, expensive, cumbersome.

Side effects due to injection of anti-venom:

  • The human immune system recognizes the horse derived antivenom as foreign hence the human body mounts an antibody response which leads to what is called serum sickness.
  • This also increases the risk of a severe allergic reaction.

Significance of the Genome sequencing in evolving new antivenom   

  • High-quality genomes of venomous snakes will enable the generation of a comprehensive catalog of venom-gland-specific toxin genes that can be used for the development of synthetic anti-venom of defined composition.
  • It will help in targeting the 19 specific toxins in the snake venom that will lead to a safe and effective antivenom for treating Indian cobra bites.

This high-quality genome allowed us to study various aspects of snake venom biology, including venom-gene genomic organization, genetic variability, evolution and expression of key venom genes.

Challenges

  • It wouldn't address the huge volume and variety of snakebites in India, as In India bites from 60 of 270 species of Indian snakes are known to kill or maim.
  • These big 4 species are not found in northeastern India but the region reports a significant number of snake bites. That implies we need new kinds of anti-venom against species here. 
  • The krait in Punjab produces a venom chemically different from the krait in South India.
  • The Sind krait from western India is over 40 times more potent than that of the Spectacled cobra, making it the most toxic Indian snake. There is no mechanism effectively neutralize the venom of this species as well.

“Sequence information of the genes that code for venom proteins is very important for the production of recombinant antivenoms. However, there is a very long way to go from genomes to effective anti-snake venoms.”

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