Gene drive technology is a genetic engineering technique that is capable of modifying genes so that they disobey natural rules of heredity. Gene drive systems are therefore referred to as selfish genetic elements that can be used to control the natural populations of an organism. Although the concept of gene drive was known to the scientists since the late 1880s, it did not find much application until recently. Moreover, with the availability of the CRISPR/Cas9 system, the use of gene drive technology has become easier than before. CRISPR/Cas9 system has also helped to understand the precise mechanism that results in the preferential increase in the desired/engineered trait.
A CRISPR/Cas9 based gene drive system consists of the engineered gene that is to be incorporated, Cas9 nuclease for cleaving host DNA, and sgRNA. The components are delivered into the host cell where the editing occurs and the naturally occurring gene is substituted by the engineered gene in both DNA strands. Gene drive system based on CRISPR/Cas9 can also edit or silence a specific gene. Thus, the genome no longer has the natural gene, instead only has the modified gene.
One of the applications of gene drive technology is the spread of disease-refractory genes into populations of mosquito to reduce their capability to spread diseases such as malaria to humans. Gene drive technology allows the rapid spread of the modified gene across the population, thus helping to override natural selection mechanisms that operate. Thus, gene drive is actually capable of modifying the natural evolutionary trajectory of a species, and when applied to mosquitoes, it can help in eradicating mosquitoes that are capable of transmitting diseases or suppressing mosquito population completely.
In 2015, George Church and his team first attempted to use CRISPR/Cas9 gene editing technology to create gene drive in yeast. In the same year, other researchers also reported their attempts to create a gene drive in the fruit fly. At the end of 2015, successful attempts to create gene drive altered mosquitoes were reported independently by two groups, one led by Anthony James, and the other led by Austin Burt and Andrea Crisanti.
Will gene drive be safe and effective? Will it have any negative impact on public health, the environment, and the ecosystem? How to decide the point when gene-drive modified organisms are to be released into the environment? What are the potential risks? These are some of the questions that need to be considered carefully to ensure the responsible use of gene drive technology.