As the buzz of the mosquito-stuffed summer starts to fade – at least for the Northern Hemisphere – some researchers think they’ve found a solution that could stop the pesky insects spreading dangerous diseases. It focuses on a concept called a “gene drive” that aims to drive targeted mosquito populations right out of existence. The goal is to eliminate troublesome insects in areas where they’re spreading catastrophic diseases.
Destroying a wild population of insects is a weighty proposition. But consider this: in 2016, there were around 216 million malaria cases and an estimated 445,000 malaria-related deaths worldwide, mostly of children under five years old. You may not realize there are more than three-thousand species of mosquitoes. Only 40 of them carry malaria. If even one of those species can be successfully eliminated, it could save lives of some of the most vulnerable people in the world.
So what’s the plan? Gene drives — they are genetic edits that not only get passed down, they are able to promote themselves so they’re almost guaranteed to be inherited.
The scientists first select a gene associated with the trait of interest. In this case, that could be a gene associated with fertility. Researchers then insert a CRISPR-based system that uses its gene-editing capabilities to replace the organism’s existing copies of the gene with an altered version during early development. This universal replacement seeks to guarantee the alteration gets passed along to the next generation.
Researchers have explored using gene drives in aggressive ways with disease-causing insects. One set of scientists incorporated a gene drive aimed at reducing the number of offspring of Anopheles gambiae mosquitoes – one of the species known to transmit malaria in sub-Saharan Africa.
In that study, the gene drive successfully passed down to nearly all of the An. gambiae offspring, spreading through an entire captive population in just four generations. But the insects quickly evolved mutations that restored their fertility and blocked the gene drive’s spread.
However, a recent round of experiments carried out the task much more effectively. By targeting a different fertility gene, a team from Imperial College London managed to crash caged populations of the mosquito species in only 7-11 generations, with no sign of resistant mutations.
Researchers warn it will still be another 5-10 years before the gene drive even gets tested in the wild, but there’s clearly a path forward for the technique.
Still trepidation remains. Some scientists warn that once a gene drive gets released into the wild, it could become incredibly difficult to predict how far it would reach or precisely how it might impact the broader ecosystem.
Scientists believe gene drives could develop into an effective means of controlling pest populations from mosquitoes to rats, but the biotechnology still has ground to cover before it’s ready, and even then, it looks like Mother Nature will always be fighting to stay one step ahead.
To schedule a media interview with Dr. Neil Lamb or to invite him to speak at an event or conference, please contact Margetta Thomas by email at mthomas@hudsonalpha.org or by phone: Office (256) 327-0425 | Cell (256) 937-8210
References:
Hammond A. et al. The creation and selection of mutations resistant to a gene drive over multiple generations in the malaria mosquito. PLOS Genetics (2017) doi:10.1371/journal.pgen.1007039
Kyrou K. et al. A CRISPR–Cas9 gene drive targeting doublesex causes complete population suppression in caged Anopheles gambiae mosquitoes. Nature Biotechnology (2018) doi:10.1038/nbt.4245
