An Introduction to CRISPR: The Gene-Editing Breakthrough of Modern Biology
We must have come across the article on the use of CRISPR technology for cutting out HIV-1 DNA from human immune cells. Let’s now take a look into the history and working of this technique… CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a genome editing technology that allows precise modification of DNA in living organisms. It works like molecular scissors—cutting DNA at a specific location —and makes it possible to add, remove, or replace specific sequences. It was originally discovered as a defense mechanism in E. coli against viruses (bacteriophages) by Yoshizumi Ishino in 1987. Bacteria store small pieces of viral DNA in their CRISPR sequences to “remember” past infections—just like our B cells remember viruses. If the same virus attacks again, Cas proteins (cutting enzymes like Cas9, Cas12, Cas13, etc.) use this stored information to recognize and disable the viral DNA. The guide RNA (gRNA) carries the sequence that matches the target DNA. Step-by-step...