Propagation of seminal toxins through binary expression gene drives could suppress populations.

Gene drives can be highly effective in controlling a target population by disrupting a female fertility gene. To spread across a population, these drives require that disrupted alleles be largely recessive so as not to impose too high of a fitness penalty. We argue that this restriction may be relaxed by using a double gene drive design to spread a split binary expression system. One drive carries a dominant lethal/toxic effector alone and the other a transactivator factor, without which the effector will not act. Only after the drives reach sufficiently high frequencies would individuals have the chance to inherit both system components and the effector be expressed. We explore through mathematical modeling the potential of this design to spread dominant lethal/toxic alleles and suppress populations. We show that this system could be implemented to spread engineered seminal proteins designed to kill females, making it highly effective against polyandrous populations.

Facilitating the Conversation: Gene Drive Classification.

Gene drives are an emerging technology with tremendous potential to impact public health, agriculture, and conservation. While gene drives can be described simply as selfish genetic elements (natural or engineered) that are inherited at non-Mendelian rates, upon closer inspection, engineered gene drive technology is a complex class of biotechnology that uses a diverse number of genetic features to bias rates of inheritance. As a complex technology, gene drives can be difficult to comprehend, not only for the public and stakeholders, but also to risk assessors, risk managers, and decisionmakers not familiar with gene drive literature. To address this difficulty, we describe a gene drive classification system based on 5 functional characteristics. These characteristics include a gene drive's objective, mechanism, release threshold, range, and persistence. The aggregate of the gene drive's characteristics can be described as the gene drive's architecture. Establishing a classification system to define different gene drive technologies should make them more comprehensible to the public and provide a framework to guide regulatory evaluation and decisionmaking.