I see no mention of what I thought was the primary obstacle to using CRISPR to modify whole organisms: pre-existing immunity to the CRISPR machinery. Identific

I see no mention of what I thought was the primary obstacle to using CRISPR to modify whole organisms: pre-existing immunity to the CRISPR machinery. Identification of preexisting adaptive immunity to Cas9 proteins in humans https://www.nature.com/articles/s41591-018-0326-x https://www.nature.com/articles/s41591-018-0326-x Immunity to Cas9 as an Obstacle to Persistent Genome Editing https://www.cell.com/molecular-therapy-family/molecular-therapy/fulltext/S1525-0016(20)30241-0 https://www.cell.com/molecular-therapy-family/molecular-ther... Evasion of Pre-Existing Immunity to Cas9: a Prerequisite for Successful Genome Editing In Vivo? https://link.springer.com/article/10.1007/s40472-019-00237-2 https://link.springer.com/article/10.1007/s40472-019-00237-2