Uruguay wants to use gene drives to eradicate devastating screwworms

On a warm, sunny day in Montevideo, Uruguay, the air is smogless and crisp. Inside a highly secured facility at the National Institute of Agricultural Research (INIA) are a sophisticated gene gun, giant microscopes, and tens of thousands of gene-edited flies, their bright blue wings fluttering against the walls of their small, white, netted cages.

These flies—shown to me on video by an INIA veterinarian, Alejo Menchaca—are a new weapon that may soon be unleashed against an enemy that kills cattle and costs the livestock industry millions of dollars every year: the New World screwworm, a parasite common in parts of South America and the Caribbean.

When a female screwworm fly attacks cattle, it lays eggs, which hatch and turn into worm-like larvae that screw down into the host animal, feeding on flesh along their way and damaging the animal’s skin. Left untreated, the animals eventually die in excruciating agony.

But Menchaca and colleagues have a plan. Using the genome-editing system CRISPR, they’ve developed what’s known as a gene drive, a type of genetic element that manipulates the reproductive process to spread farther and faster than an ordinary gene. They are about to move into the next stage of caged trials in the lab, with a view to eventually using the genetic tool to decimate the screwworm fly population. They have received a $450,000 grant from the Inter-American Development Bank (IDB) for the research.

“With gene drives, we can control these pests in precise and effective ways,” says Menchaca.

The scientific team in Uruguay poses in a lab.
COURTESY OF ALEJO MENCHACA

Gene drives occur naturally in the wild, but the technology for making them deliberately is new and still pretty controversial. CRISPR allows scientists to cut specific genes in any organism’s DNA and replace them with new sequences. It can be used to tweak an animal’s DNA in a way that affects the species’ survival, often by making the females sterile, when it spreads in the population through breeding.

Some organizations have been trying to develop gene drives to eradicate mosquitoes. Target Malaria, supported by the Seattle-based Bill & Melinda Gates Foundation (BMGF), is currently the most advanced gene-drive project in the world. But even then, they have never gone beyond caged trials. The process of getting permission for field release efforts has crawled.

In 2020, the INIA researchers received permission from the Uruguayan government to test their techniques through the country’s existing National Program for Control of Screwworms. Right now, they’re experimenting with different components of the gene drive in gene-edited screwworm flies in the lab. The plan is to create a population of male screwworms with edited versions of genes that are essential for fertility in the female screwworms. When the engineered males are released into the wild, they should mate with females and pass on that gene.

Over successive generations, more and more female screwworms will inherit copies of the gene drive and become sterile, causing a population crash.

“The thing that’s attractive is if you knock a gene drive into the female, you could disrupt female development,” says Maxwell Scott, an entomologist at North Carolina State University who is working with the Uruguayan team. “It’s potentially a very efficient system.”

The situation is urgent. In July of last year, Panama declared a state of animal health emergency amid outbreaks of cattle screwworm throughout the country. And this February, more than 200 cases of screwworm attacks on animals were reported in Costa Rica, prompting the government to declare an emergency as well. In Uruguay, screwworm flies cost the livestock industry $40 million to $154 million a year. Agricultural export is the linchpin of Uruguay’s economy—over 80% of the goods the nation exports are agricultural products. Beef, which accounts for 20% of that, is worth $2.5 billion a year.

That makes the country’s search for new tools to combat the pests even more critical, says Carmine Paolo De

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By: Abdullahi Tsanni
Title: Uruguay wants to use gene drives to eradicate devastating screwworms
Sourced From: www.technologyreview.com/2024/02/16/1088505/uruguay-gene-drives-screwworms/
Published Date: Fri, 16 Feb 2024 14:00:00 +0000

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