Hammond Andrew M, Kyrou Kyros, Bruttini Marco, North Ace, Galizi Roberto, Karlsson Xenia, Kranjc Nace, Carpi Francesco M, D'Aurizio Romina, Crisanti Andrea, Nolan Tony
Dept. of Life Sciences, Imperial College London, London, United Kingdom.
Polo d'Innovazione Genomica, Genetica e Biologia, Siena, Italy.
PLoS Genet. 2017 Oct 4;13(10):e1007039. doi: 10.1371/journal.pgen.1007039. eCollection 2017 Oct.
Gene drives have enormous potential for the control of insect populations of medical and agricultural relevance. By preferentially biasing their own inheritance, gene drives can rapidly introduce genetic traits even if these confer a negative fitness effect on the population. We have recently developed gene drives based on CRISPR nuclease constructs that are designed to disrupt key genes essential for female fertility in the malaria mosquito. The construct copies itself and the associated genetic disruption from one homologous chromosome to another during gamete formation, a process called homing that ensures the majority of offspring inherit the drive. Such drives have the potential to cause long-lasting, sustainable population suppression, though they are also expected to impose a large selection pressure for resistance in the mosquito. One of these population suppression gene drives showed rapid invasion of a caged population over 4 generations, establishing proof of principle for this technology. In order to assess the potential for the emergence of resistance to the gene drive in this population we allowed it to run for 25 generations and monitored the frequency of the gene drive over time. Following the initial increase of the gene drive we observed a gradual decrease in its frequency that was accompanied by the spread of small, nuclease-induced mutations at the target gene that are resistant to further cleavage and restore its functionality. Such mutations showed rates of increase consistent with positive selection in the face of the gene drive. Our findings represent the first documented example of selection for resistance to a synthetic gene drive and lead to important design recommendations and considerations in order to mitigate for resistance in future gene drive applications.
基因驱动在控制具有医学和农业重要性的昆虫种群方面具有巨大潜力。通过优先偏向自身遗传，基因驱动能够迅速引入遗传性状，即便这些性状会对种群产生负面的适合度效应。我们最近基于CRISPR核酸酶构建体开发了基因驱动，其设计目的是破坏疟蚊中雌性生育力所必需的关键基因。在配子形成过程中，该构建体会将自身及相关的基因破坏从一条同源染色体复制到另一条同源染色体，这一过程称为归巢，可确保大多数后代继承该驱动。此类驱动有潜力导致持久、可持续的种群抑制，不过预计它们也会对蚊子产生强大的抗性选择压力。其中一种种群抑制基因驱动在4代内迅速侵入了一个封闭种群，为该技术建立了原理验证。为了评估该种群中对基因驱动产生抗性的可能性，我们让其繁殖了25代，并随时间监测基因驱动的频率。在基因驱动最初增加之后，我们观察到其频率逐渐下降，同时在靶基因处出现了由核酸酶诱导的小突变扩散，这些突变对进一步切割具有抗性并恢复了其功能。此类突变的增加速率与面对基因驱动时的正选择一致。我们的研究结果代表了首个关于对合成基因驱动产生抗性的选择的记录实例，并为未来基因驱动应用中减轻抗性问题带来了重要的设计建议和考量。
