London: Scientists have genetically modified mosquitoes with the ability to slow the growth of malaria-causing parasites in their guts, which could help prevent the disease’s transmission to humans in advance. These engineered mosquitoes produce compounds that inhibit the growth of the malaria-causing parasites, which are then unlikely to reach the mosquito’s salivary glands and pass into the bite before the insects die.Also Read – Swine flu, dengue, malaria cases on the rise in Mumbai: BMC urges everyone to follow guidelines
Researchers at the Institute for Disease Modeling at the Bill & Melinda Gates Foundation have developed a model that can assess the impact of such changes when used in a variety of African settings. They found that the change in question can be effective even where transmission is high.
While the technique is described in a paper published in the journal Science Advances. Shown to dramatically reduce the likelihood of malaria transmission in a lab setting, if proven safe and effective in real-world settings, it could provide a powerful new tool to help eliminate malaria.
The disease is transmitted to people by female mosquitoes after biting a person infected with the malaria parasite. The parasite then develops into its next stage in the mosquito’s gut and travels to its salivary glands, ready to infect the next person the mosquito bites.
However, only 10 percent of mosquitoes survive long enough for the parasite to develop sufficiently to become infectious. By extending the time it takes for the parasite to develop in the gut, the team aimed to stretch the odds even further.
Researchers in Transmission: Imperial College London, UK. The team at XERO genetically modified the main malaria-carrying species of mosquito in sub-Saharan Africa, Anopheles gambiae, such that the mosquito produces antimicrobial peptides in its gut when it takes a blood meal. .
These peptides inhibit the growth of the malarial parasite by interfering with the parasite’s energy metabolism and also, shorten the lifespan of mosquitoes and further inhibit their ability to pass on the parasite.
By the time the next parasite stage can reach the mosquito salivary glands, most mosquitoes in nature are expected to die.
“We need to develop innovative new tools because mosquitoes and the parasites they carry are becoming resistant to available interventions, such as insecticides and treatments, and funding,” said Tibebu Hebtevold, co-first author of the study.
“Delaying the development of the parasite in the mosquito opens up many more opportunities to block the transmission of malaria from mosquitoes to humans,” said Astrid Horman, co-first author of the study.
To use genetic modification to stop the spread of malaria in the real world, it needs to be spread from lab-raised mosquitoes to wild people. The innovation is designed in such a way that it can be combined with existing gene drive’ technology to spread the change and drastically reduce the transmission of malaria.
“Gene drive is a powerful weapon that, together with drugs, vaccines and mosquito control, can help stop the spread of malaria and save human lives,” said study co-lead author Professor George Christofides.
Gene drives can be added to mosquitoes that cause the anti-parasite genetic modification to be preferentially inherited, allowing it to spread more widely in any natural population.
Being new, however, any field trial will require extremely careful planning to minimize risks.
The Transmission:Zero team, therefore, is creating two separate but compatible strains of modified mosquitoes, one with an anti-parasite modification and the other with a gene drive.
They can then test the anti-parasitic modification on its own, adding to the gene drive only when it is shown to be effective.
With partners in Tanzania, the team set up a facility to breed and control genetically modified mosquitoes and conduct some of the first tests. This includes collecting parasites from locally infected school children, to ensure that the modification works against parasites circulating in the respective communities.
They also fully risk assess any potential release of modified mosquitoes, consider any potential risks and ensure they have buy-in from the local community. But they are optimistic that their intervention could eventually help eradicate malaria.
Malaria is one of the most devastating diseases globally, threatening half of the world’s population. In 2021 alone, it infected 241 million and killed 627,000 people, mostly children under the age of five in sub-Saharan Africa, the researchers said.
