Khushboo Negi and Samakshi Verma

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) has shown a promising approach for the treatment of HIV-1 (Human Immunodeficiency Virus). With its unparalleled capacity to induce precise genetic alterations, the CRISPR/Cas9 system — first identified as an adaptive immune defence mechanism in bacteria and archaea — has quickly revolutionised the field of genome editing itself. The basic idea of CRISPR arrays is to store bits of viral DNA that the prokaryotic host comes into contact with. These bits are subsequently converted into short RNAs. Through the use of complementary sequences in invasive nucleic acids, Cas9 endonuclease works as molecular scissors to cause specific Double-strand Breaks (DSBs) in DNA. Through a single guide RNA (sgRNA), Cas9 is guided to a particular genomic locus that has the Protospacer Adjacent Motif (PAM) sequence. It is a site which helps in the determination of the target for CRISPR/Cas9. Upon recognition, the Cas9 nuclease generates a DSB near the PAM site. This targeted cleavage forms the molecular basis for editing genomes in a highly specific and efficient manner…read more on NOPR