Using genomics to find solutions to malaria
Using genomics to find solutions to malaria
Tags: Africa, Gene drive, Malaria, Selfish genetic elements, Target malariaMorgan Morris, Nature Africa, 2024.
Joel Odero’s experiences of malaria is wide and deep. Growing up in a village in Kenya, he not only contracted the disease numerous times, but was all too familiar with the relentless daily regimen of spraying insecticides and checking malaria nets were not ripped. Decades later, as a research scientist with the Ifakara Health Institute in Tanzania, he witnessed firsthand how, for many, that daily grind is still ongoing. As part of the institute’s teams that, between 2018 and 2022, spread out across the country to capture a range of malaria-transmitting mosquitoes for studying, he would collect samples from homes where people had to spray and check their nets every day. Odero is part of a generation of scientists trying to break the stranglehold of the Anopheles mosquitoes that transmit the disease-causing parasite. Their weapon of choice is genomics. It’s a challenge taken up by organizations like Target Malaria, a not-for-profit international research consortium featuring teams in Africa, the US and Europe, and funded by, among others, the Bill & Melinda Gates Foundation and Open Philanthropy. There, researchers’ game plan is simple: reduce the population numbers of the mosquitoes, specifically those of three related species responsible for most malaria transmissions in Africa – Anopheles gambiae, Anopheles coluzzii and Anopheles arabiensis.
To do so, they are looking to capitalize on a naturally occurring phenomenon, gene drive. Often described as “selfish genetic elements”, taking the form of bits of DNA code, genes are ‘driven’ when a gene that has a favorable effect becomes more prevalent in successive generations. Typically, with both humans and mosquitoes, offspring inherit two copies of any gene, one from each parent. As a result, there is a 50/50 chance of either of the two copies being passed on to later generations. Using gene drives, researchers are manipulating the bias that is introduced to that rate of inheritance so that a specific trait is nearly 100% guaranteed to be passed on. Gene-drive malaria research takes on many forms. Two of the most popular are known as ‘population replacement’ and ‘population suppression’. With population replacement, the aim is to modify the mosquitoes so that they are no longer vectors, aka transmitters, of the malaria parasite. With population suppression – which the work of Target Malaria falls under – the goal is to reduce the mosquito population.