Data from: Dodging silver bullets: good CRISPR gene-drive design is critical for eradicating exotic vertebrates

Self-replicating gene drives that can spread deleterious alleles through animal populations have been promoted as a much needed but controversial ‘silver bullet’ for controlling invasive alien species. Homing-based drives comprise an endonuclease and a guide RNA that are replicated during meiosis via homologous recombination. However, their efficacy for controlling wild populations is threatened by inherent polymorphic resistance and the creation of resistance alleles via non-homologous end-joining (NHEJ) mediated DNA repair. We used stochastic individual-based models to identify realistic gene-drive strategies capable of eradicating vertebrate pest populations (mice, rats and rabbits) on islands. One popular strategy, a sex-reversing drive that converts heterozygous females into sterile males, failed to spread and required the ongoing deployment of gene-drive carriers to achieve eradication. Multiplexed guide RNAs could overcome inherent polymorphic resistance and were required for eradication success even when the probability of NHEJ was low. Strategies causing homozygotic embryonic non-viability or homozygotic female sterility produced high probabilities of eradication and were robust to NHEJ-mediated deletion of DNA sequence between multiplexed endonuclease recognition sites. The latter two strategies also purged the gene drive when eradication failed, therefore posing lower long-term risk should animals escape beyond target islands. Multiplexing guide RNAs will be necessary if this technology is to be useful for insular extirpation attempts; however, precise knowledge of homing rates will be required to design low-risk gene drives with high probabilities of eradication success.能够在动物种群中传播有害等位基因的自我复制基因驱动系统（self-replicating gene drives），被推崇为一种亟需且颇具争议的、用于防控外来入侵物种的“银弹”。归巢型基因驱动系统（homing-based drives）包含核酸内切酶（endonuclease）和向导RNA（guide RNA），二者可通过同源重组（homologous recombination）在减数分裂（meiosis）过程中完成复制。然而，其防控野生种群的效能受到固有多态性抗性的威胁，同时也会因非同源末端连接（NHEJ）介导的DNA修复过程产生抗性等位基因。本研究采用基于个体的随机模型（stochastic individual-based models），筛选出可用于根除岛屿上脊椎动物有害种群（小鼠、大鼠和兔）的切实可行的基因驱动策略。其中一种广受欢迎的策略——将杂合雌性（heterozygous females）转化为不育雄性（sterile males）的性别逆转型基因驱动——未能成功传播，需持续投放基因驱动载体种群方可实现根除。多重向导RNA（multiplexed guide RNAs）可克服固有多态性抗性，即便非同源末端连接概率较低，也仍是实现根除成功的必要条件。可导致纯合胚胎致死（homozygotic embryonic non-viability）或纯合雌性不育（homozygotic female sterility）的策略，不仅根除成功率极高，且对多重核酸内切酶识别位点间由NHEJ介导的DNA序列缺失具有鲁棒性。若根除失败，后两种策略还可清除种群中的基因驱动系统，因此若目标岛屿外出现种群逃逸，其长期风险更低。若要将该技术应用于岛屿种群根除尝试，多重向导RNA的使用必不可少；但要设计出低风险且高根除成功率的基因驱动系统，仍需精准掌握归巢速率（homing rates）相关数据。