CRISPR-Cas9-based gene drive systems possess the inherent capacity to spread progressively throughout target populations. Here we describe two self-copying (or active) guide RNA-only genetic elements, called e-CHACRs and ERACRs. These elements use Cas9 produced in trans by a gene drive either to inactivate the cas9 transgene (e-CHACRs) or to delete and replace the gene drive (ERACRs). e-CHACRs can be inserted at various genomic locations and carry two or more gRNAs, the first copying the e-CHACR and the second mutating and inactivating the cas9 transgene. Alternatively, ERACRs are inserted at the same genomic location as a gene drive, carrying two gRNAs that cut on either side of the gene drive to excise it. e-CHACRs efficiently inactivate Cas9 and can drive to completion in cage experiments. Similarly, ERACRs, particularly those carrying a recoded cDNA-restoring endogenous gene activity, can drive reliably to fully replace a gene drive. We compare the strengths of these two systems.

基于 CRISPR-Cas9 的基因驱动系统具有在目标人群中逐步传播的固有能力。在这里，我们描述了两个自我复制（或主动）指导 RNA-only 遗传元件，称为 e-CHACRs 和 ERACRs。这些元件使用由基因驱动反式产生的 Cas9来灭活cas9转基因 (e-CHACR) 或删除和替换基因驱动 (ERACR)。e-CHACR 可以插入到不同的基因组位置并携带两个或多个 gRNA，第一个复制 e-CHACR，第二个使 cas9 突变和失活转基因。或者，将 ERACR 插入与基因驱动相同的基因组位置，携带两个 gRNA，在基因驱动的两侧切割以切除它。e-CHACRs 可以有效地使 Cas9 失活，并可以在笼式实验中完成。同样，ERACR，特别是那些携带重新编码的 cDNA 恢复内源基因活性的 ERACR，可以可靠地驱动以完全取代基因驱动。我们比较了这两个系统的优势。