Why in the News?

India launched its 1^st indigenous CRISPR-based gene editing therapy called BIRSA-101 for Sickle Cell Disease.

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• It has been developed by CSIR–Institute of Genomics & Integrative Biology (IGIB).
• It has been called BIRSA-101 as it has been dedicated to Bhagwan Birsa Munda on his 150th birth anniversary.
• A technology transfer agreement has been signed between CSIR-IGIB and Serum Institute of India which aims to enable scalable, affordable enFnCas9 CRISPR-based therapies for Sickle Cell Disease and other genetic disorders.

CRISPR Technology and Mechanism

• CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats
• It is a gene-editing technology to selectively modify the DNA of living organisms.

How does it work? 

• CRISPR leverages a natural defense mechanism of bacteria to cut DNA at a specific location. 
• When bacteria are attacked by a virus, they record a section of the virus's DNA in their own DNA.
• Storing part of the virus's genetic code allows the bacteria to "remember" it. 
• When the same type of virus attacks again, the bacteria use a specific CRISPR-associated protein number 9 (CAS9) to cut the virus's DNA, destroying the virus.
• In the laboratory, scientists use this same CRISPR/CAS9 system to identify and cut a specific DNA sequence.
• Main Components:
  • Cas9 Protein: The system uses a Cas protein called Cas9, which acts like molecular scissors to cut DNA.
  • Guide RNA: A guide RNA tells Cas9 where to cut, and the DNA is cut exactly at the spot chosen by this guide.
• Genome Editing Tools
  • CRISPR-Cas9: It uses a small piece of RNA to guide the Cas9 "cutting" protein to the exact spot in the DNA.
  • Homing Endonucleases (Meganucleases): These are natural enzymes that can find and cut long sections of DNA. 
  • Zinc-Finger Nucleases (ZFNs): They use special protein parts to find the right place in the DNA and then cut it.
  • TALE Nucleases (TALENs): These tools use two parts that come together to cut DNA at a chosen spot.