FDA approves genetic alteration in pigs

A GalSafe pig (Courtesy United Therapeutics Corp.)

A genetically modified pig line has obtained the necessary federal approvals to be sold for medical purposes and for meat.

The change, approved by the Food and Drug Administration in December, removes detectable amounts of alpha-gal, a sugar molecule, from the surface of pig cells. Sugar is a rare allergy trigger, and its elimination could provide a new source of drugs, excipients, cosmetics and meat, according to an agency announcement.

Agency documents also indicate that tissues from pigs could provide candidate cells, tissues or organs for transplantation into human patients. Even for people without a specific alpha-gal allergy, alpha-gal in transplanted animal tissues can elicit hyperacute immune responses and at least contribute to transplant rejection.

The FDA regulates genetic modifications as drugs, and the approval applies to a single pig farm that can produce up to 1,000 pigs per year.

The approved Virginia-based company, Revivicor, is developing genetically modified pigs for use in the production of cells, organs and medical devices for human use, according to company information. The modification of this pig line, known as GalSafe pigs, inserts recombinant DNA to disrupt a gene linked to the production of alpha-gal.

Dewey Steadman, head of investor relations for Revivicor’s parent company, United Therapeutics Corp., said the breakthrough showed the potential to develop pork products in areas where alpha-gal could cause adverse effects in patients. patients with alpha-gal syndrome.

“We look forward to working with potential partners in the production of foods, drugs and medical devices to potentially bring these products to market,” he says. “This genetic modification is just one of ten modifications we are currently using in pigs for our preclinical xenotransplantation development program which we hope will one day help address the critical shortage of transplantable organs for humans in need. “

Unknown alpha-gal function

Uri Galili, PhD, is an immunologist and assistant professor at Rush Medical College in Chicago. He is the author of the 2017 book “The Natural Anti-Gal Antibody as Foe Turned Friend in Medicine” and a 2019 review article in the American Journal of Physical Anthropology which describes how inactivation of alpha- gal and the evolution of anti-gal antibodies have helped prevent the extinction of Old World primates during outbreaks of viruses containing alpha-gal epitopes. In the late 1980s, he and Bruce Macher, PhD, professor emeritus in the Department of Chemistry and Biochemistry at San Francisco State University, discovered alpha-gal epitopes and anti-gal antibodies and identified their reciprocal distribution.

Dr Galili said research has yet to reveal the biological role of the alpha-gal epitope or explain why it appeared in early mammals over 125 million years ago. But genetically engineered GalSafe pigs appear to be living normal lives, without the cataracts seen in his and Dr. Macher’s previous research on mice with a knockout gene for alpha-gal production.

FDA documents say agency officials have found no animal safety concerns beyond those expected in conventional pig farming.

GalSafe pigs had above average post-weaning survival rates compared to conventional herds, but the GalSafe herd had higher neonatal and pre-weaning rates. The report attributes these differences in early mortality rates, at least in part, to inbreeding among a small population of GalSafe pigs and high variability among the small number of dams and litters assessed.

Allergy acquired by ticks

Alpha-gal syndrome is an acquired allergy that can occur when certain ticks pass alpha-gal molecules into a person’s body, triggering an immune response that leads to an allergic reaction, according to FDA documents. The research involves solitary star and blacklegged ticks, according to the Centers for Disease Control and Prevention.

A scientific article published in May 2019 in Frontiers in Immunology indicates that researchers have identified alpha-gal in the salivary glands and saliva of solitary and blacklegged ticks. As solitary ticks spread from the southwestern United States to the east coast, a growing number of people have reported developing allergic reactions after eating red meat or dairy products, the article says.

Information from the CDC indicates that these allergic reactions can be life-threatening, and symptoms can occur three to six hours after a meal or other exposure to products containing alpha-gal, including subsequent tick bites. Symptoms may include hives, nausea, vomiting, difficulty breathing, low blood pressure, dizziness, fainting, and severe stomach pain.

Most of the reported allergies have occurred in people in the Southeastern United States, according to information from the CDC.

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About Teresa G. Wilson

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