CRISPR Cas9 is present in somewhat varying forms across many (all?) bacteria. I don’t have the quote to hand but I know CRISPR from bacteria that rarely or neve

CRISPR Cas9 is present in somewhat varying forms across many (all?) bacteria. I don’t have the quote to hand but I know CRISPR from bacteria that rarely or never come into contact with humans (think extremeophiles like deep sea thermal vent bacteria) doesn’t provoke an immune response, as it’s slightly different in form and novel to the human immune system. This is not a huge setback for CRISPR research. Also you could argue that the title is misleading, as stating that CRISPR evokes an immune response is inaccurate; CRISPR from a bacterium that frequently comes into contact with most humans evokes it, and not all CRISPRs are the same.