Hug and cry. When will genetically modified cats appear?

Domestic cats are one of the most allergic animals. Allergy to them affects 15% of children and adults, and symptoms range from rhinoconjunctivitis to severe asthma. About 95% of allergic reactions are caused by the body’s response to the Fel d 1 protein produced by the salivary, sebaceous, perianal and lacrimal glands in cats. Expression levels of this protein vary depending on the breed, sex, and other characteristics of the animal, but truly hypoallergenic cats are not yet available.

They can be created using genetic engineering. Researchers at the American biotech company ImBio have found a way to inhibit the production of the Fel d 1 protein using genetic editing. The study was published in the journal CRISPR Journal.

Earlier attempts to reduce Fel d 1 production included the development of a special diet and the creation of a vaccine based on a viral vector. Also, scientists tried to breed separate breeds of genetically modified hypoallergenic cats. The study’s authors took a different route, undertaking the development of a method that would make any currently living cat hypoallergenic.

“It’s very costly to create a separate hypoallergenic cat line for consumers and patients,” explains ImBio researcher Nicole Brackett, lead author of the study. “We believe it makes more commercial and ethical sense to develop a treatment for existing cats rather than raising and selling allergen-free cats.”

The role of Fel d 1 in cats is still unclear. However, analysis of the genes encoding this protein in wild and domestic cats has shown that these genes do not affect survival and may not play a significant role.

For the experiments, the scientists used testicular, ovarian and uterine tissues obtained by sterilizing 50 domestic cats. Using CRISPR/Cas9 genetic editing technology, which allows the DNA to be cut in the right place and any fragments added or removed, the researchers removed the CH1 and CH2 genes, which encode the Fel d 1 protein, from the cat genome. production of protein. The researchers did not notice any effect on the expression of other proteins.

The authors note that it is unclear how much Fel d 1 production needs to be reduced for a cat to not cause allergies. Previous experiments with a protein-reducing cat food showed that a 47% reduction in Fel d 1 in a cat’s secretions was sufficient to reduce allergy symptoms by 30%. However, this effect is significant only in direct interaction with the animal – if the protein accumulates in the house dust, it will continue to cause allergic reactions.

“Given that nearly all patients with cat allergy experience symptoms at a threshold level of 8 µg Fel d 1 per gram of house dust and the allergen can accumulate in house dust at levels >1000 mcg/g, the clinical impact of moderate allergen reduction may be minimal,” the researchers wrote. .

Another experimental way to combat feline allergies is to inject patients with monoclonal antibodies to Fel d 1, which will prevent it from binding to immunoglobulins. In previous studies, this method reduced the severity of symptoms by approximately 60% in half of the subjects. Scientists hope that blocking Fel d 1 production will protect almost everyone from allergies.

“Our data demonstrate the practical application of CRISPR technology in allergy or veterinary research and highlight the unique intersection of evolutionary biology, genomic engineering, and therapeutic development,” the authors write.

The researchers hope in the future they will be able to create a drug that can be administered to a cat, for example, by injection. Meanwhile, they moved from testing on cell cultures and tissues to experiments on live cats. The scientists involved will examine in more detail how the absence of Fel d 1 will affect the animals themselves.