The CRISPR system is a prokaryotic immune system that is resistant to the invasion of foreign genetic material, such as phage viruses and foreign plasmids. At the same time, it provides acquired immunity to bacteria: when bacteria are invaded by viruses or foreign plasmids, they generate corresponding "memory" to resist their reinvasion. The CRISPR system recognizes foreign DNA and severs them to silence the expression of foreign genes.
Thanks to this precise targeting function, CRISPR has been developed as a powerful gene editing tool for gene precise editing. The genomic DNA of the cells to be edited was precisely cut with the participation of the guide RNA and the Cas9 protein. In 2013, Professor Zhang, Feng and the team led by Dr. Cong, Le successfully used the CRISPR/Cas9 system to implement genome editing in mammalian cells. This technology immediately gained great attention from academia, industry and capital.