The two genes for the protein mainly responsible for allergic reactions to cats have been deleted from cat cells using CRISPR gene editing. It is a first step towards creating hypoallergenic cats, says US-based company InBio.
“The estimated timeline for this is several years,” says Nicole Brackett, who leads the CRISPR cat team at InBio.
About 15 per cent of people have allergic reactions to cats. The main cause of this is a small protein called Fel d 1 that is secreted by salivary and skin glands. It is spread over cats’ fur when felines clean themselves and can become airborne as the fur dries. What, if anything, Fel d 1 does for cats isn’t known.
All cats produce Fel d 1, but a 2019 study found that levels in saliva vary greatly among typical domestic cats. It is often claimed that some specific breeds are less likely to trigger allergies, but no scientific studies have confirmed this.
Fel d 1 consists of two different subunits, and there are two genes – called CH1 and CH2 – encoding each subunit. When Brackett and her colleagues compared the sequences of the CH1 and CH2 genes in domestic cats with those in other cat species such as lions, tigers, cougars and fishing cats, they found many changes.
Because the sequence of genes with key functions tends to change little if at all, this suggests that Fel d 1 isn’t essential. The only way to find out for sure, however, will be to see what happens to cats that cannot produce any Fel d 1.
Next, the team deleted either the CH1 or the CH2 gene from cat cells growing in culture using the CRISPR genome editing technique. The next step will be to delete all copies of the two genes at once, and to confirm that this prevents cells making the Fel d 1 protein. Only then the team will try to create cats that lack the genes.
“[We have] no particular cat breeds in mind at the moment,” says Brackett.
In the 2000s, at least two other companies announced plans to modify moggies to eliminate Fel d 1, but neither managed it. However, achieving this is now more feasible thanks to the development of CRISPR in 2012.
Some other companies are exploring alternative ways of reducing Fel d 1, such as a vaccine that makes cats produce antibodies that mop up Fel d 1 before it is secreted.
Journal reference: The CRISPR Journal, DOI: 10.1089/crispr.2021.0101
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