Malaria mosquitoes suppressed in experiments that mimic the natural environment

The cage used in the study.Credit: Target malaria

Researchers have shown that “gene drive” technology, which promotes genetic modification that interferes with female reproduction, works in a natural environment.

A team led by researchers at Imperial College London, Polo GGB, and Liverpool School of Tropical Medicine was able to mimic a year-long experiment to control malaria-carrying mosquito populations. natural environment..

This is the first time that gene drives have been shown to be as effective as expected when tested over long periods of time in difficult ecological conditions.Results will be published today Nature Communications..

Despite the decline in malaria in recent decades, 2019 still has 229 million malaria cases, an increase over the previous year and 409,000 deaths.

Dr. Drew Hammond, co-author of the Imperial College London Department of Life Sciences and the Johns Hopkins Malaria Institute, said: A large gap in pesticide resistance and financing to parts of sub-Saharan Africa.

“Sadly, researchers estimate that COVID-19-related turmoil could double malaria mortality in 2020 and threaten decades of recession.

“Gene drives are self-contained, fast-acting technologies that work in tandem with existing tools such as mosquito nets, pesticides and vaccines, and have the potential to revolutionize the eradication of malaria.”

Aim for mosquitoes

The team selectively targeted Anopheles gambiel, a specific mosquito species responsible for the majority of malaria infections in sub-Saharan Africa. There are about 3,500 species of mosquitoes in the world, of which only a few can transmit malaria, and only a handful of them are responsible for the majority of malaria.

hope is mosquito Those with a gene drive will be released in the future as a new tool to spread corrections that impair women’s births and ultimately reduce the total number of malaria-carrying mosquitoes. malaria transmission.

Previously, imperial researchers said that gene drive technology could disrupt the population of Pacific cod in small cages within 7 to 11 generations, as gene drives would not give birth to all individuals. Was shown.

However, to test whether the gene drive is still widespread and causes the same population suppression in real conditions, the team is much larger to mimic the natural habitat of mosquitoes in the limited laboratory of Terni’s Polo GGB. I moved on to testing the technique in the cage. Italy.

Mimicking natural conditions

Testing in a large indoor cage that simulates the natural environment is for the World Health Organization and the National Institutes of Health Foundation to evaluate the effectiveness and safety of gene drive technology in physically restricted laboratories prior to opening. This is an important step in the development path proposed in. release.

Mosquito strains released into the wild must be able to compete with wild populations when used for vector control. The large cages used in the study contained hundreds of mosquitoes of various ages, representing a more natural and complex population structure.

Dedicated cages are also designed to mimic natural conditions in ways that small cages cannot achieve, inviting mosquitoes to complex mating, resting, foraging and spawning behavior not possible with small cages. .. ..

This was achieved not only by controlling temperature and humidity, but also by providing natural landmarks and special lighting designed to simulate sunrise and sunset to provoke herds.

Modified mosquitoes that carry the gene-drive element are released with an initial frequency of 12.5% ​​and 25% of the population, and researchers have shown how rapidly this element spreads and affects women’s childbirth and final population decline. I tracked it.

They found that each cage (2 at an initial frequency of 12.5% ​​and 2 at 25%) showed rapid spread of the gene drive and complete population collapse within a year.

Overcome resistance

The main barrier to the development of gene drives was the emergence of technology-resistant mutations. However, the strain tested here is the first and only strain that showed no signs of resistance in small or large tests. No new natural changes have occurred to counteract the effects of the gene drive.

Co-authors of Polo GGB and Dr. Tania Persampieri and Paola Pollegioni of the CNR-Research Institute on Terrestrial Ecosystems said: Additional “fitness costs” can be incurred if mosquitoes exhibit natural mating and spawning behavior and are affected in ways unpredictable from small cage studies.

“But no alterations were made to make the mosquito double sex gene resistant to our gene drive, suggesting that our alterations that promote female infertility are robust. “

Large-scale cage testing is a major step in the journey to release gene-drive-carrying mosquitoes into the wild, but before the team plans a field assessment, including more comprehensive ones, safety and Emphasize that there are still efficacy tests and potential technological developments Resistance testing and environmental risk assessment.

However, they state that the data obtained from this study are invaluable for future modeling aimed at predicting the spread of. Gene drive In certain areas, such as the site of Burkina Faso where the test facility was built.

Scientists develop new technologies that provide better control for managing malaria mosquitoes

For more information:
Andrew Hammond et al, Suppression of gene drive of mosquito populations in large cages as a bridge between the laboratory and the field, Nature Communications (2021). DOI: 10.1038 / s41467-021-24790-6

Quote: Malaria mosquitoes suppressed in an experiment that mimics the natural environment (July 28, 2021) are available from https: // 2021 Obtained July 28, 2014

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Malaria mosquitoes suppressed in experiments that mimic the natural environment

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