Mosquitoes that can't spread malaria could help eradicate the disease

The scientific breakthrough could transform health.
Deniz Yildiran

Malaria, which infected 241 million people in 2020, is a serious case that’s still around to take lives today. According to WHO, the African region was home to 96 percent of deaths. However, since not every country in the world is able to provide health care services to its citizens to treat malaria, which is transmitted through a certain type of mosquito, the science community has been trying other ways to eradicate the disease. And they might be close to the solution.

Researchers from the Transmission:Zero team at Imperial College London have designed a technique that enables mosquitoes to produce compounds in their guts that stunt the growth of parasites. This way, parasites cannot reach the salivary glands of mosquitoes, hence be passed on in a bite before they die, a press release reveals.

This technique got the job done in a lab setting, decreasing the malaria spread. Scientists are hopeful that it could do the same in nature. The technique is also planned to be combined with the existing gene drive technology in the long run, which could further spread the modification to reduce the transmission of the disease.

The results of the technology in the lab have been published in the journal Science Advances.

"Since 2015, the progress in tackling malaria has stalled. Mosquitoes and the parasites they carry are becoming resistant to available interventions such as insecticides and treatments, and funding has plateaued. We need to develop innovative new tools," Co-first author of the study Dr. Tibebu Habtewold, from the Department of Life Sciences at Imperial, said.

Modification process

The team at Transmission:Zero genetically modified Anopheles gambia, the main mosquito species that carry the disease in sub-Saharan Africa. When the mosquito bites and sucks blood, it produces two molecules called antimicrobial peptides in its guts; then, the peptides impair the malaria parasite's development.

Parasites are delayed from jumping to the next stage, where they're expected to reach salivary glands; in the meantime, most mosquitoes are expected to die in nature.

"For many years, we have been trying to no avail to make mosquitoes that cannot be infected by the parasite or ones that can clear all the parasites with their immune system. Delaying parasite's development inside the mosquito is a conceptual shift that has opened many more opportunities to block malaria transmission from mosquitoes to humans," co-first author of the study Astrid Hoermann, from the Department of Life Sciences at Imperial, said.

Study Abstract:

Gene drives hold promise for the genetic control of malaria vectors. The development of vector population modification strategies hinges on the availability of effector mechanisms impeding parasite development in transgenic mosquitoes. We augmented a midgut gene of the malaria mosquito Anopheles gambiae to secrete two exogenous antimicrobial peptides, magainin 2 and melittin. This small genetic modification, capable of efficient nonautonomous gene drive, hampers oocyst development in both Plasmodium falciparum and Plasmodium berghei. It delays the release of infectious sporozoites, while it simultaneously reduces the life span of homozygous female transgenic mosquitoes. Modeling the spread of this modification using a large-scale agent-based model of malaria epidemiology reveals that it can break the cycle of disease transmission across a range of transmission intensities.

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