Humans love dogs, but petting them can leave some people sneezing and wheezing. About 15% of the world’s population lives with a dog allergy, which can increase the risk of hay fever and asthma. The main culprit is Can f 1, a protein found mainly in dog saliva. Right now, staying away from furry friends or getting regular immunotherapy shots or tablets is the only way to deal with the symptoms.
In a recent study published in The CRISPR Journal, researchers wanted to explore whether it is possible to eliminate dog allergies by targeting them directly at their biological source. Rather than focus on treating human symptoms, they wanted to see whether dogs could be genetically edited to stop producing the allergen altogether.
They used CRISPR-Cas9 to make a tiny, highly precise cut in the Can f 1 gene in dog skin cells and inserted a single extra DNA building block at the site. That small change scrambled the gene’s instructions, switching it off so it could no longer produce the Can f 1 allergen protein. The edited DNA was then introduced into mature eggs from donor beagles. The result was two female beagle puppies, Alfie and Bailey, born from cloned embryos.
When researchers tested their saliva, hair and dander, they found no detectable trace of the Can f 1 allergen protein.
Editing the allergen out
Dog allergies should never be taken lightly. Symptoms can start small—a runny nose, itchy eyes or skin hives—but they can quickly escalate into serious asthma attacks and breathing difficulties that require medical attention. Keeping the home clean and limiting contact with dogs can help, but it rarely solves the problem.
Dog allergens spread easily and stick around on furniture, clothes and in the air, so avoiding them completely is nearly impossible. Therefore, real solutions are needed, not just workarounds, for anyone who lives with a dog or regularly visits family or friends with one.
Most current approaches to dog allergies work by adjusting the human immune response. This study took a different route, going straight to the source of the problem. Researchers started with ordinary skin cells, called fibroblasts, taken from a beagle, then used CRISPR-Cas9 to edit the Can f 1 gene directly.
To turn the edited cells into living dogs, they used a cloning technique called somatic cell nuclear transfer (SCNT). It involved removing the original genetic material from mature dog eggs and replacing it with genetic material from the new Can f 1-mutant cells. Twenty-five embryos were transferred to a surrogate mother dog, which gave birth to pups with the edited genetic change.
Whole-genome and targeted Can f 1 sequencing found that the gene-editing process did not cause any unintended genetic damage to the puppies’ DNA. Because this was a proof-of-concept study aimed at silencing Can f 1 in dogs, the researchers could not be certain whether the genetic change might have any negative effects on the dogs’ health. As a precaution, the puppies were kept under strict veterinary observation from birth.
The team ran biochemical tests on saliva, hair and dander samples from the gene-edited dogs, a normal beagle, a standard poodle and a goldendoodle to directly detect the allergen protein. While the protein was easily detected in the other dogs, including the poodles and goldendoodles advertised as hypoallergenic breeds, it was completely absent in the edited ones.
Then came the real test: finding out whether the beagles caused a reaction. Using a standard skin prick device, the team applied protein extracts from each dog to a volunteer’s arm and observed any reaction.
The results were striking. The volunteer broke out in allergic bumps after exposure to the normal beagle and even the supposed hypoallergenic breeds, but the gene-edited dogs triggered no reaction.
This study demonstrates that it is technically possible to directly shut down the major dog allergen in a living animal. However, before this approach can be used commercially, researchers will need to establish its long-term safety, ensure careful oversight of animal welfare and meet all regulatory requirements.