“What if I’m tired of answering questions about Dolly? Not at all, it was transformative,” explains Bruce Whitelaw, who runs the Roslin Institute on the outskirts of Edinburgh, Scotland, United Kingdom. Whitelaw, wearing a Scottish tartan jacket and tie, receives EL PAÍS and explains the new direction of his animal science research center: “Now we do fantastic science, we have created pigs resistant to porcine reproductive and respiratory syndrome. The number of ranchers who go bankrupt due to this disease is enormous. It’s a big impact, all right, but it won’t be as big as Dolly. “It was unique”
Although the institute remains attached to the name of a sheep, the first mammal cloned from an adult cell, they long ago abandoned animal cloning completely. They are currently dedicated to using the enormous power of genetic editing – CRISPR technology that modifies the intimacy of DNA in a cheap, simple and incredibly effective way – to create breeds of more robust farm animals, resistant to different types of production stress, such as heat or drought and, above all, disease.
The ailments studied at Roslin make up a whole list of misfortunes for livestock farming, poultry farming and, sometimes, for human health, that seems straight out of Oliver Twist: porcine reproductive and respiratory syndrome, classical swine fever, African swine fever, avian flu, West Nile virus, Newcastle disease, those caused by bacteria and complex pathogens such as toxoplasmas or trypanosomes. The new outbreaks of zoonotic diseases, those that manage to jump from animals to humans (like this summer in US dairy farms affected by bird flu in which they have been infected 14 people to date), once again demonstrate the close relationship between the health of farm animals and human life.
During the visit to the institute, the cackling of the nearly 600 chickens resounds, which quickly disappear carried by the powerful wind of the Scottish summer. Because it’s summer, but it’s Scotland. The National Avian Research Center is one of the jewels in the Roslin crown. There, together with geneticists from Imperial College London and the Pirbright Institute, they have created the first chickens in the world with some resistance to bird flu. In recent years, this disease has caused the death of hundreds of millions of birds around the world and has spread to mammals such as seals, sea lions, cows and mink, and caused several human deaths in what could be the worst crisis. of avian flu known in the world.
Using CRISPR to modify a single gene—responsible for producing a protein called ANP32A, which viruses hijack during infection—scientists have ensured that nine out of ten of these modified birds show no signs of infection when exposed to a high dose. typical of the flu virus. When exposed to the high dose, however, five in ten, half the group, become infected.
“Bird flu is a major threat to bird populations. Vaccination against the virus poses many challenges, with important practical and cost problems,” explains Mike McGrew, director of the chair of avian reproductive technologies at Roslin and one of the authors of that research. He adds: “Instead, gene editing offers a promising route towards permanent resistance to the disease, which could be transmitted from generation to generation, protecting poultry and reducing risks to humans and wild birds.” McGrew and his team are now trying to create chickens with modifications in three genes that, in preliminary laboratory tests, have been shown to block the virus completely.
The Roslin Institute, which employs around 450 researchers, was incorporated into the University of Edinburgh in 2008 after a time of financial hardship, and now occupies a sinuous, shiny building, like a snake’s skin, on the Easter Bush veterinary campus. , about 11 kilometers south of Edinburgh. It is surrounded by the bare mountains of the Pentland Hills, car dealerships and rows of new, identical houses, like clones.
Inside the institute there is an animal presence everywhere, even in the hall of the main building, where photos of researchers with chickens and pigs hang. Outside there is a veterinary hospital, an equine hospital; an innovation center, marked by a nearly five-meter steel sculpture in the shape of a horse’s head; and, of course, farms. Great expanses of eternally green meadows in the Scottish rain in which they hid Dolly of the curious. “The best place to hide a sheep: among a bunch of other sheep,” Whitelaw says with a smile. The farm staff pampered her so much that they had to put her on a diet.
Stop porcine respiratory syndrome
In addition to these animals with impenetrable eyes, at Roslin they research chickens, cows, rodents and salmon, but one of the current stars are pigs. Whitelaw and his colleagues have created pigs resistant to the virus that causes porcine reproductive and respiratory syndrome —PRRS, by its English acronym—, a disease that involves a productivity loss of 1.5 billion euros per year in Europe. To create it, they eliminated, using CRISPR, a small fragment of porcine DNA that caused a receptor on the outside of the cells, called CD163, to lack a type of anchor that the virus needs to enter the cell interior and multiply. Without it, the virus rebounds and remains at the doors, unable to unleash the infection.
For Whitelaw, “the challenge of these great changes, the manipulation of the genome, is to create animals that are as robust and productive as before the editing.” And he emphasizes: “With these pigs the only thing we have done is stop the entry of the virus, everything else is normal. “If you make animals resistant to this virus, for example, but they are not going to live as long for whatever reason, it no longer works.”
Pigs resistant to PPRS are now running around in Madison (Wisconsin, USA), on farms owned by the company Genus PLC to which Roslin’s team has licensed, and are in the process of being approved by the US Food and Drug Administration (FDA). , for its acronym in English). Whitelaw is optimistic and thinks they could be approved by the end of the year. “If Genus sells the semen of these pigs on the market in the near future it will have a tremendous impact. The number of animals affected by PRRS is millions and millions and millions, and many farmers are going bankrupt due to this disease,” says the director of the Roslin Institute.
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