Immunity to Cas9 as an Obstacle to Persistent Genome Editing

In vivo genome editing with CRISPR-Cas9 systems is garnering widespread attention and enthusiasm for possible treatment of genetic disorders. However, the consequences of potential immunogenicity of the bacterial Cas9 protein have been the subject of considerable speculation. In fact, a fraction of the human population is positive for pre-existing immunity to the most commonly used Cas9 variants, presumably a result of exposure to these...