A new study of CRISPR-Cas9 found that many people carry existing immunities to the proteins the widely used gene-editing method uses, which could render genetic treatments useless or harmful. The new discovery, published at bioRxiv, made investors jittery and sent some CRISPR shares plummeting, the news site Stat reported.
Researchers obtain the proteins used to edit DNA from bacteria that frequently infect humans such as Staphylococcus aureus and Streptococcus pyogenes.
Scientists hope one day to use CRISPR to treat a wide variety of genetic diseases in humans. But when the researchers tested the blood of 22 newborns and 12 adults, they found that the majority carried antibodies against those bacteria that could attack and destroy a gene-editing treatment.
The bacteria do not always cause disease, and most people come in contact with them at some point in time and may then develop immunities.
Some studies show that 40 percent of people carry S. aureus and 20 percent of children test positive for S. pyogenes.
Researchers not involved with the study told Stat they do not find the results alarming. Many of the human clinical trials that scientists plan to conduct will involve removing cells from patients, editing the DNA, and then returning the cells to the patient’s body. Such a procedure would inject few or no CRISPR proteins back into the patient for the immune system to detect. The researchers also said studies using different proteins that could avoid an immune response are already underway. —J.B.