Gene Edited Cats Will Not Cause Human Allergies

Researchers Are Closer to Creating Hypoallergenic Cats Using CRISPR Technology

The allergen-causing protein Fel d 1 was removed from feline cells using the gene-editing tool
www.smithsonianmag.com/smart-news/researchers-are-closer-to-creating-hypoallergenic-felines-180979832/



Elizabeth Gamillo
Daily Correspondent

March 31, 2022



After analyzing the DNA of 50 domestic cats, researchers identified regions along the two genes that code for Fel d 1 that the team could cut and edit with CRISPR. Courtesy of Elizabeth Gamillo

Thanks to CRISPR gene-editing technology, truly hypoallergenic cats could soon steal people's hearts and safely curl up on their laps without triggering sneezes, itchy eyes or other allergy symptoms.

InBio, a United States biotech company, has found a way to block genes responsible for a major cat allergen using CRISPR, a genetic engineering technique that allows scientists to add or remove bits of DNA at a specific location in an organism's genome. Gizmodo's Ed Cara reports the find is the first step toward hypoallergenic cats as healthy as felines with unedited genes. Details on the project called CRISPR Cat were published this month in The CRISPR Journal.

Fifteen percent of people have allergic reactions to cats that cause symptoms like sneezing, congestion, itchiness and watery eyes. The responses are caused by a small protein called Fel d 1 that cats secrete through their salivary and skin glands. When the furry felines clean themselves, the allergen is spread all over their fur and can become airborne when their coat dries, reports Michael Le Page for New Scientist. A cat's dander, or dried skin flakes, can also trigger allergic reactions.

It is claimed that some cat breeds are less likely to produce allergens, but no scientific studies have confirmed this, per New Scientist. All types of felines produce Fel d 1, but a 2019 study published in the Journal of Feline Medicine and Surgery found that the protein level in saliva varies in typical house cats.

The two genes that code for Fel d 1 are CH1 and CH2. Researchers at InBio are working on using CRISPR to create cats that produce little-to-no Fel d 1. After analyzing the DNA of 50 domestic cats, researchers identified regions along the two genes that the team could cut and edit with CRISPR, per Gizmodo. CRISPR technology uses an enzyme called Cas9 to cut the two strands of DNA at a target site on the genome so that sections of DNA can be inserted or deleted.

When the team compared the genes of the domestic cats with eight wild cat species, the researchers found variation between the groups, suggesting that Fel d 1 is not a needed gene for the cats to survive and removing it may not cause any health risks, Gizmodo reports.

"The gene sequences don't appear to be that well conserved over the course of evolution, which suggest things about whether or not the gene is essential," study author Nicole Brackett, a geneticist at InBio, told Heather McKenzie for BioSpace in 2021. "An essential gene, one that would be required for survival or viability, generally doesn't change much over evolution, and we're seeing change between the exotic and domestic cat that suggests that maybe those sequences are not conserved, and maybe the protein is not essential."

McKenzie and her colleagues then used the gene-editing tool, CRISPR, to delete either CH1 or CH2 in cat cells in a Petri dish. The researchers' next step is to delete copies of the two genes at once and confirm that this process eliminates the Fel d 1 protein from the cat cells. If this process is successful, only then will scientists try to create felines without these genes, per New Scientist.

Besides gene editing, there are other ways to reduce the Fel d 1 protein in felines. Purina has specialized line of pet food that reduces the amount of allergen in dander or fur by 47 percent on average after three weeks of use. Another company is developing vaccine that trains a cat's immune system to reduce levels of the protein. But the researchers argue that these methods won't eliminate the allergen completely, so gene-editing could be a tool to make truly hypoallergenic cats, per Gizmodo.



Elizabeth Gamillo 
Elizabeth Gamillo is a daily correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.