People like cats. Up to 15 percent of the population are allergic to them, however, largely thank to a particular allergen called Fel d 1, which is produced by your kitty's salivary, sebaceous, perianal and lachrymal glands. Natural Fel d 1 production levels vary between cats, some producing more than 100 times what others do.
If you're allergic to cats, this substance is likely responsible for somewhere between 60-90 percent of your immune response, and the associated asthma attacks. This has long been known – indeed, some 18 years ago, we covered an American company called Allerca that claimed it was breeding cats specifically to select for low levels of this protein. Allerca went out of business in 2015, after a rather damning ABC News report discovered these "hypoallergenic cats" were not only no more or less allergenic than any other cat, but indeed they were simply random cats being bought from shelters and sold on to customers the next day.
Still, the idea of a hypoallergenic cat persists, and Virginia-headqurtered biotechnology company InBio has completed a proof of principle study using CRISPR-Cas9 gene editing, finding that "Fel d 1 is both a rational and viable candidate for gene deletion, which may profoundly benefit cat allergy sufferers by removing the major allergen at the source."
Researchers identified two DNA target regions, which it dubbed CH1 and CH2, which looked like good candidates for CRISPR editing. They tested the CRISPR-CAS9 process on feline epithelial cells, finding editing efficiencies between 52.2-77.6 percent, with no evidence of off-target editing at four DNA sites that were predicted as possible places where editing errors might occur.
Genetic analysis across eight different cat species showed widely variable natural amounts of these two gene sequences, potentially explaining the natural variability of Fel d 1 levels, and leading the researchers to conclude that it's probably non-essential to the survival of cats, and thus a good target for gene deletion.
From here, the researchers plan to continue work on this idea. First, they'll try replicating the CRISPR edits in primary feline cells that express Fel d 1, then they'll move to live trials in cats. Eventually, the team hopes to develop a treatment that can be used to render adult cats hypoallergenic, while also studying the Fel d 1 protein where it occurs in other animals, searching for its evolutionary purpose and biological functions.
So it's promising news for sneezy cat lovers plagued by asthma, but there's a way to go just yet before you can get your mog CRISPR-snipped. In the meanwhile, the researchers note that the HypoCat vaccine seems to be able to go some way toward reducing Fel d 1 and the associated immune response in cat owners with allergies, and a monoclonal antibody treatment for humans has been shown to reduce allergy symptom severity by about 60 percent in around half of patients tested. So there are multiple approaches underway.
The study is open access in the CRISPR Journal. Hear lead researcher Nicole Brackett speak about the process in detail in the video below.
Source: InBio