Modification of CRISPR guide RNA structure prevents immune response in target cells
(PHYSorg.com Biology)

CRISPR-mediated genome editing has become a powerful tool for modeling of disease in various organisms and is being developed for clinical applications. Preassembled Cas9 ribonucleoproteins (RNPs) composed of the recombinant Cas9 protein and in vitrotranscribed (IVT) guide RNA complexes can be delivered into cells without risk of foreign DNA integration into the host genome and with fewer off-target effects. However, in a study published today in Genome Research, scientists discovered in vitro-transcribed gRNAs, containing a 5` triphosphate (5`ppp) moiety, activate the immune response in human cells leading to cell death.