What If You Could Make Your Cat Hypoallergenic?

The first thing to know is that allergen-free cats are a myth. sorry.

that’s why everyone Cats – long-haired, short-haired, and hairless – secrete a little bit of a virulent protein called Fel d 1, found in saliva and sebaceous glands, that causes most cat allergies. Some cats shed 80 times more than others of the same breed; Nobody knows why. Some shed more than a month and less in the following month. Some strains may actually be lower on average than Fel d 1, but the evidence is sparse. Back in the 2000s, a startup that claimed to have shamefully bred hypoallergenic cats collapsed, leaving some clients with pets that still make them feel bad and others who shelled out thousands of dollars up front with no cats at all. This means that the demand for allergen-free cats is high. It is just that no one has succeeded in breeding one.

But where ancient breeding failed, scientists are now turning to biotechnology. In recent years, a combination of science fiction strategies have been targeted in Fel d 1: a cable coated with an egg yolk derivative that neutralizes allergens, a vaccine that uses cucumber mosaic viruses to trick cats’ immune systems, and a gene therapy that deletes the Fel d 1 gene from cats’ DNA using a technology CRISPR Editing. This dish is, in fact, available on store shelves as Purina’s Pro Plan LiveClear cat food. The vaccine has already been tested on more than 100 cats. And although a viable gene therapy is elusive, the scientists were able to delete Fel d 1 from cat cells in a petri dish.

None of these strategies will completely eliminate Fel d 1 in a cat, but they may reduce allergen levels enough to avoid itchy eyes and sneezing. (By the way, Hypoallergenic is often used colloquially to mean “allergen-free,” but it technically just means “reduce allergy.”) This reduction may be enough to allow allergy sufferers to keep their beloved cats. “I used to, in my younger days, say, ‘Oh, you really need to get rid of your cat,’” says William Nesch, an allergist in Georgia. “That made me very unpopular.” Allergists like him now suggest cat owners try allergy pills. Or allergy shots at themselves—and to brush with a HEPA filter, bathe their cat regularly, and keep them out of the bedroom.

While these strategies largely target humans, modern biotechnology ideas are all aimed at shaping the cat according to human desires. This may not be new. These ideas incorporate state-of-the-art technology, but they also might be the next logical step in our millennia-old relationship with cats, during which we’ve transformed a wild killer into Fluffy who sharply nods for food at 8 p.m. and snuggles in bed.

Even a century ago, pet cats would spend most of their time outside. A cat that is used exclusively indoors is a fairly recent development – made possible by the invention of the litter. And only when the cats got close to us physically did all the little bits of Fel d 1 turn into a problem.


Ebenezer Satyaraj, director of molecular nutrition for Nestlé parent company Purina, first started thinking about how to use cat food against Fel d 1 more than a decade ago. He told me the main idea is that cats spend a lot of time taking care of themselves. Normally, this behavior spreads the saliva in their saliva all over their fur, which in turn spreads over your sofa, jacket, bed, etc., etc., etc., but what if you could interrupt this process by feeding cats something that would be negated? d 1 in their mouths?

Satyraj and his team settled on the idea of ​​using anti-Fel d 1 proteins purified from egg yolks, which are made by injecting a chicken with Fel d 1. Its immune system treats Fel d 1 like a piece of foreign pathogens, mounting antibodies that bind and neutralize it. These antibodies end up in the yolk as a means of passing protection to the chicks. But it can also, remarkably, act as a kind of transmission of immunity between species: there is an additive to pig feed, for example, made with egg yolk antibodies intended to protect against E. coli. In this case, Satyraj wanted the egg yolk antibodies to neutralize the D1 gene on cats — ultimately, choosing the chicken’s immune system to protect allergic humans.

It worked. The egg yolk coating on Purina cat food reduces the amount of allergens shed by an average of 47 percent. The goal here, says Satyraj, is to get Fel d 1 levels below the threshold to reduce allergy symptoms — that may not be enough for everyone, but it should be enough for some. A study in humans with allergies found that using Purina cat food helped reduce congestion and itchy eyes. How well the kibble works depends on how much Fel d 1 the cat starts and how sensitive the owner is to even small amounts of allergens. And any effect only lasts as long as he continues to feed them Purina food.

The second idea of ​​making cats more resistant to allergies involves tapping into the strength of the cat’s immune system, as the effects may last longer. In 2013, scientists at the University of Zurich founded a company, now called Saiba Animal Health, to make a cat vaccine that reduces Fel d 1 secretion. They used a multipart strategy originally developed for human vaccines: Hide the Fel d 1 protein inside the shell of cucumber mosaic virus, Which in turn is embedded with a little tetanus toxin. This tricks a cat’s immune system into thinking Fel d 1 is part of a virus, says Gary Jennings, Saiba’s chief operating officer. Once vaccinated, the cat starts making antibodies that neutralize Fel d 1. Their allergen levels had actually decreased over several weeks, and Saiba found that owners of cats with allergies were able to spend more time petting their vaccinated cats. The company has since licensed the technology to a large animal health company — for which Jennings says he cannot disclose it — to collect the data needed to gain regulatory approval.

Both the doctors and veterinarians I spoke to thought such a vaccine would exist in an interesting limited space: Was a vaccine given to cats to treat humans considered an animal vaccine or a human vaccine? Who even regulates it? Jennings tells me that based on conversations with the Food and Drug Administration and the European Medicines Agency, both will oversee the vaccine as an animal vaccine — but in a slightly different way. The FDA needs to make sure the vaccine doesn’t harm cats and works on humans, but the EMA wants to weigh the harm and benefit to the cat itself.

How do we weigh the risks of treating a pet versus the comfort and happiness of its owner? This question seemed very new for a second, until I realized that the novelty of a vaccine against cat allergy only made the question seem so. We used to pluck cats’ claws to spare our furniture. (No longer accepted). We still remove testicles or ovaries to reduce sexual behaviors that might make them annoying as house pets. (Totally acceptable, very encouraging.) Can you even say that surgery or a vaccine benefits the cat itself, if the pet is modified to become a more suitable indoor pet, making its owner happier and more toned?

To judge the potential harms of targeting Fel d 1, we also need a better understanding of the protein and what exactly it does in cats. Unfortunately, “no one really knows the answer,” says Drew Wegner, an Atlanta veterinarian who specializes in cats. Scientists hypothesized that Fel d 1 might act like a pheromone for social cues. This may mean that it is less important to house cats, especially those who live alone. Male cats also tend to produce more Fel d 1, and neutralizing them actually reduces their levels three to five times – which means we’re already routinely changing cats’ Fel d 1 production. The large variation in levels of allergens from one cat to another indicates that reducing them should not have serious consequences. Indeed, studies in cats fed the antiviral 1 food and those given the vaccine did not find significant adverse effects associated with reduced levels of the protein.


But what if you went even further, erasing the gene that encodes Fel d 1 from cats’ DNA? Nicole Brackett, a researcher at Indoor Biotechnologies, is using powerful new gene-editing technology CRISPR to delete the gene from cat cells. As part of this work, she was researching the role of Fel d 1 in all cats, both domesticated and wild. I’ve found that the genetic sequence of Fel d1 varies enormously from species to species – say from tiger to lion – but also from cat to cat. The fact that it is not conserved over the course of evolution suggests that it “may not be functionally necessary for the cat,” Brackett says.

Indoor Biotechnologies’ goal is not to genetically engineer new cats without Fel d 1, as the company is not interested in entering the cat breeding business. Instead, Brackett and her colleagues hope to lay the groundwork for gene therapy in the form of an injection that deletes villi D1 from enough cells to lower the cat’s overall production. In the lab, Brackett was able to eliminate Fel d 1 from up to 55 percent of cat cells in a petri dish. That reduction might be enough to make a cat allergic, she says, if a pet goes to the vet for a new injection of the gene therapy every few months or once a year. However, many challenges remain. Brackett tested CRISPR in a type of cell commonly used in labs because it grows so well – but it comes from cat kidneys and doesn’t naturally produce Fel d 1. So you still need to make sure CRISPR works in saliva and oil gland cells, then figure out how to smuggle a mechanism CRISPR to those cells inside a living animal – which remains a major mystery to human CRISPR treatments.

But scientists have come a long way already. Indoor Biotechnologies President and CEO Martin Chapman was part of the original team that first isolated the gene for Fel d 1, in the 1990s. However, he says he remembers thinking, Wouldn’t it be cool if we could delete these genes? But that was not possible with technology at the time. All of these new ideas for dealing with cat allergy are based on breakthroughs in other areas: CRISPR, of course, but also the development of egg yolk antibodies, and the invention of new strategies for making human vaccines. In the 21st century, biotechnology is so quietly touching so many aspects of our lives that it’s no surprise that it’s coming to our pets as well.

The indoor cat is indeed a markedly different creature from the first wild cats that roamed around human settlements hunting rodents. We have shaped cats according to our lifestyles, and will continue to do so as long as they are popular pets. In the end, we may have a cat that is truly allergen-free.

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