CRISPR-Cas13 is an RNA targeting and editing system based on the bacterial immune system that protects them from viruses. Cas13, previously known as C2c2, is the effector protein that targets and cleaves invading nucleic acids from viruses in type VI CRISPR-Cas systems. The CRISPR-Cas13 system is analogous to the CRISPR-Cas9 system. However, unlike Cas-9 which targets DNA, Cas-13 targets and cleaves single stranded RNA. Cas-13 was first discovered in L. shahii, a species of the Leptotrichia bacteria while researchers were looking for previously unidentified CRISPR systems. Members of Cas13, Cas13a and Cas13b are being developed for therapeutic gene correction at the RNA level and detection of viral pathogens.