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Possible roadblock to CRISPR use in humans: we might be immune to it

posted by Jason Kottke   Jan 11, 2018

Researchers from Stanford have published a study showing that immunity might hinder the use of the CRISPR gene editing technique in humans. The Cas9 bacterial protein commonly used in CRISPR is found in and around human bodies, so many of those bodies have already built up an immunity to it. That means if you send Cas9 into a body to do some gene editing, that body’s immune system might attack and destroy it before it can do its work. Sarah Zhang wrote about the study for The Atlantic.

Porteus and his colleagues focused on two versions of Cas9, the bacterial protein mostly commonly used in CRISPR gene editing. One comes from Staphylococcus aureus, which often harmlessly lives on skin but can sometimes causes staph infections, and another from Streptococcus pyogenes, which causes strep throat but can also become “flesh-eating bacteria” when it spreads to other parts of the body. So yeah, you want your immune system to be on guard against these bacteria.

It sounds like this was something geneticists were well aware of but wasn’t common knowledge among non-technical CRISPR enthusiasts. As Chang notes, scientists are already employing strategies to route around the potential immunity roadblock:

Modify Cas9 or use a different CRISPR protein altogether: It may be possible to redesign Cas9 to hide it from the immune system or to find other bacterial proteins that can do the job of Cas9 without provoking the immune response. Many different bacteria have CRISPR systems. “We already have lots of Cas enzymes and could get many more,” George Church, a geneticist at Harvard and a founding scientific advisor of Editas, wrote in an email.