- Alpha-gal syndrome is a relatively new, tick-borne allergy to red meat and animal products.
- The molecule involved in the allergy is the same that causes humans to reject animal organ transplants.
- Genetically modified pigs can be used for transplants, as well as for alpha-gal-free meat.
For some people, a bite by the tiny lone star tick could mean the end of bacon and barbecues forever.
Alpha-gal syndrome (AGS) is a tick-borne disease that causes what may look like a sudden-onset red meat allergy. People who never had problems with meat before have reported that just one bite of pot roast sent them to the emergency room, and they didn't make the connection to ticks until later.
The syndrome is relatively new in the medical world, with the first 24 official cases of AGS described in 2009, but a growing number of cases have been reported across the Eastern and Central US over the past decade.
Scientists don't yet understand how or why the bite of a specific tick species sickens some people with AGS, while others walk away unscathed (or with a different tick-borne illness). But they've found one innovation that could improve the quality of life for people who suddenly have to avoid meat.
The answer may lie in the muscle and fat of genetically-modified pigs that were initially developed for organ transplants, Sarah Zhang recently wrote for the Atlantic. For months now, Revivicor, the biotech company behind the first pig-to-human heart transplant, has been sending other specialty pork products — think bacon, ham, and chops — to AGS sufferers free of charge in a bid to understand the roots of this odd disorder.
Genetically modified pigs lack the molecule that sets off the allergy
Pigs are just one of many mammal species that contain alpha-gal, a sugar molecule that sets them apart from humans and other primates.
Most humans can digest pork, beef, or lamb full of alpha-gal without a problem, but something about the bite of the lone star tick rallies the immune system in an unprecedented reaction to the marker. Some people with AGS are so sensitive that trace amounts of alpha-gal in dairy or gelatin, or even meat fumes, can cause a severe allergic reaction.
Alpha-gal is also involved in the rejection of animal-to-human organ transplants, since it alerts the immune system that the tissue came from a different species. So when scientists set out to make a pig that could be used as an organ donor, they genetically engineered a herd of alpha-gal-free swine.
The pigs used for the groundbreaking pig-heart transplant in January and separate attempts to transplant pig kidneys into brain-dead patients required a host of other genetic modifications to decrease the likelihood of rejection. But for people with AGS, just one tweak to the animal's genetic code could make a life-changing difference.
The pigs were FDA-approved as both food and medicine
When Steve Troxler, agriculture commissioner of North Carolina, learned about Revivicor's work with genetically modified pigs, he threw himself into getting alpha-gal-free pork approved by the Food and Drug Administration, he told the Atlantic. He said his AGS diagnosis got in the way of his barbecue-adjacent duties as commissioner, but his position and experience helped him navigate the complex approval process.
The GalSafe pig was officially approved two years later in December 2020, which is a relatively quick timeline. Since then, Reivivicor has been sending out free samples of GalSafe pork to people with AGS who opt in by order form. The company plans to sell the meat by mail-order, rather than in supermarkets, according to a news release from the FDA.
Troxler told the Atlantic the genetically modified pork tasted normal to him. The response from other people with AGS was mostly positive, Zhang wrote: no one had an allergic reaction from the modified meat, and people generally enjoyed the samples.
However, genetically modified pork can't solve all of the challenges that come with an AGS diagnosis. Many people with the syndrome have to change their lifestyles, avoiding restaurants with potential cross-contamination and even checking ingredients labels for pill capsules that might contain animal products. But GalSafe pigs could be the starting point for alpha-gal-free medical products as well, opening up a world of alternatives for people with AGS.