The future of human cat allergy treatment may be in changing cats with food, vaccines or gene editing | Health

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PHILADELPHIA – Any cat lover who has watched an allergic friend react to a loved one knows the dark forces that lurk within this luxurious cat fur. Within minutes, an allergic person exposed to a cat can start sneezing and wheezing. Eyes watery and itchy. The misery is obvious.

Solutions for people who want to be around cats despite allergies are labor intensive, of questionable value, and sometimes contrary to common sense. How many emergency rooms would follow if we all tried to bathe our cats frequently?

This predicament sparked the imagination of researchers who see a lucrative market for better solutions in a country with more than 50 million cats in more than 20 million households. Some scientists are now taking a different approach to human pet allergies. Instead of trying to change allergic people or their surroundings, they are trying to change cats.

Purina began competing in the early days of the pandemic with a cat food – Pro Plan LiveClear – that is said to be able to reduce the protein that most allergy sufferers are sensitive to by 47% after three weeks.

“For me as a veterinarian, this is truly a groundbreaking and revolutionary pet food,” said Kurt Venator, Purina Chief Veterinary Officer. “We really believe this will help cats and people get closer.”

Another research group in Switzerland is working on a vaccine against the attacking protein called Fel d 1. And a team from Indoor Biotechnologies in Virginia is researching CRISPR gene editing techniques to turn off the gene that makes up Fel d 1. These two projects are years away from being realized.

Indoor Biotechnologies primarily detects, tests and cleans allergens. Martin Chapman, its president and CEO, had a long interest in cat allergens, but a fake company that marketed fake hypoallergenic cats until around 2015 caught his attention.

“It sort of turned out that there was a market for cats that would cost up to $ 7,000 apiece,” said Chapman, a former professor of medicine and microbiology at the University of Virginia.

Although some cats may end up in shelters because allergy sufferers cannot live with them, there is no doubt that many often prefer their cat to the comfort of their own, allergists said. They said it was rare for an allergic cat owner to abandon the cat or even ban it from the bedroom.

“I haven’t really met patients ready to get rid of their cats,” said Patrick Gleeson, an allergist with Penn Medicine. On the new cat food, he added, “I think there is a huge market for this product.”

Venator said an allergic cat owner who attended a Purina focus group said he bought a new couch every six months so he could remove allergens from his home and keep his cat.


Cat allergies affect 10 to 20% of adults. More than 90% of them react to Fel d 1. About 5% of adults are allergic to dogs, but many substances are implicated in these allergies. That makes modifying dogs a more complicated project. Researchers say allergies to fur animals are on the rise.

Fel d 1 is produced in the saliva, skin and anal glands of cats and is found in their tears. Cats spread it when they clean themselves. It writhes all over the house when they lose fur or flakes of skin. All cats manage, including hairless cats, although the amounts vary from cat to cat or even from day to day. Bruce Kornreich, director of the Cornell Feline Health Center, said there is evidence that uncastrated male cats make more of it than females or neutered males. There is no such thing as a hypoallergenic cat.

And there is no way to completely escape Fel d 1. It drives on people’s clothes to work and school. “It’s everywhere,” said James Wedner, an allergist at Washington University in St. Louis. He once saw five allergy sufferers working in a brand new office building. None had cats. He checked the building for mold, cockroaches and mice and found nothing. Then he found “incredibly high scores” in Fel d 1. Other workers brought in it, he said.

Nobody knows what role Fel d 1 plays in the cat’s body, so any attempt to get rid of it must take into account its effects on cats. Kornreich said there is speculation that Fel d 1 could protect the skin from pathogens. Another possibility is that it is involved in chemical signaling. Nicole Brackett, postdoctoral fellow at Indoor Biotechnologies, sequenced the genes that make up Fel d 1 in 50 domestic cats and some large and wild cats. She said that the genes in domestic cats are not “well conserved,” a sign that they are likely not essential.

Purina says its tests show its foods are safe.

LiveClear is already available in six flavors, including Weight Management, Senior and Sensitive Stomach. sells a 3.5 pound bag for $ 21.58. (A similar sized bag of non-specialized cat food could cost less than $ 10.) Allergen-reducing kitten food will hit the market in September, Venator said.

The company’s novel approach began about a decade ago when Ebenezer Satyaraj, a nutritional immunologist, learned that his daughter was allergic to cats. He discovered that chickens produce an antibody against Fel d 1, which can be found in their eggs. The company added the antibody to cat food. The resulting diet neutralized up to about half of the Fel d 1 produced by some cats.

This means that the treated cats will of course still make Fel d 1, which does not automatically mean that allergy sufferers will feel better around them. However, Wedner said that higher doses of an allergen generally cause more symptoms.

But Gleeson, who said Purina’s new food was “showing promise,” said doctors “don’t really know how much allergen reduction it takes to reduce symptoms”.

He said doctors often recommend getting rid of the cat – most patients won’t – or washing it weekly. “I haven’t spoken to patients who actually did that,” he said. You can also get rid of carpets, vacuum frequently, and get a HEPA air purifier. And they can try allergy shots. “This is another area where the evidence isn’t very good,” said Gleeson. Then there is medication.

Wedner led a small study by Washington University, funded by Purina, that found that some people with allergies could reliably tell the difference between blankets used by cats that ate LiveClear and cats that ate other foods. These heroic volunteers sat for three hours with the blankets in closed chambers designed for growing tomatoes. Her allergy symptoms were monitored every 15 minutes.

Wedner recently completed a larger study using real cats in people’s homes. It hasn’t been published yet so he couldn’t publish full results, but he said, “Patients were better off with food than without it.”

He also said that patients who do not participate in studies voluntarily indicate that the food helped them.

Elizabeth Knighton, a veterinarian with City Cat Vets in Philadelphia, said her mother was allergic to cats. “Although I’ve wanted a cat all my life, I didn’t get one until I was 11,” she said. Her mother didn’t want to let the cat into her room and had to get an allergy shot. “She always used an inhaler,” Knighton said.

She mentioned the new Purina food to some customers. “Because it’s so new, I don’t have any feedback yet,” she said. “I would like to know if I am recommending something that works.”


Saiba Animal Health, a Swiss company originally known as HypoPet, is going a very different route. They are working on a vaccine that will target the cat’s immune system against Fel d 1 proteins. The company’s research has shown that the HypoCat experimental vaccine lowers Fel d 1 in cat ruptures and reduces symptoms in 10 allergic cat owners.

Saiba also hopes to make a vaccine for dogs.

Kornreich said one concern with this type of vaccine is an improper immune response. “There is always a concern that the immune system can be stimulated to neutralize things that are not the target of interest,” he said.

As for the genetic approach, Indoor Biotechnologies’ Brackett achieved a 55% efficiency in eliminating Fel d 1 in a cat cell line. That’s a good price, she and Chapman said. “Cat cells are notoriously difficult to manipulate,” Brackett said.

The next step will be to see if they can reduce the allergen in cats’ salivary glands. Then comes the really hard part: figuring out how genetic treatment can be done on embryos or adult cats. You will keep an eye on the techniques that other CRISPR researchers are testing.

“Right now there seems to be a significant hurdle for CRISPR,” said Chapman.

Knighton, the Philadelphia veterinarian, said she was more comfortable with the special food that Fel d 1 neutralizes after the cat has done it than with major biological changes in cats. “I’m very careful about something that tells your body to attack something your body is doing,” she said.