Adeno-Associated Virus serotype 6 (AAV6) appears to be related to AAV1 by sequence analysis and shows the best transduction efficiency in pancreatic beta-cells compared to other AAV serotypes. AAV6 vectors are also particularly effective in the transduction of human prostate, breast, and liver cancer cells.Cas9 is an endonuclease enzyme that introduces a double stranded break into the DNA when recruited to a specific DNA sequence by the sgRNA (single guide RNA). This double stranded break is repaired in mammalian cells either through Non-Homologous End Joining or Homologous Recombination. Non-Homologous End Joining often results in the deletion or insertion of several base pairs at the cut site, which, when resulting in a frameshift, causes the functional inactivation of the gene.SaCas9 (Staphylococcus aureus CRISPR-associated protein 9) has demonstrated high cutting efficiency in mammalian cells, and its smaller size makes it ideal for packaging into AAV. SaCas9 recognizes a longer protospacer adjacent motif (PAM) site, 5'-NNGRRT-3', than the more traditional SpCas9 (Streptococcus pyogenes CRISPR-associated protein 9). These AAV particles constitutively express SaCas9 under the control of a CMV promoter.