By Patti Wilson Contributing Editor
A multinational company, PIC, has developed a porcine reproductive and respiratory syndrome (PRRS) resistant line of swine through gene editing and gained approval of commercial marketing by the FDA. Brazil, Columbia and the Dominican Republic have also given positive determinations to the company. The breakthrough has taken ten years to accomplish and is a landmark for all agricultural livestock production.
What Is PRRS?
PRRS is a viral disease first reported in the United States and now found in Asia, Africa and Europe. There are two distinct clinical phases: reproductive failure and postweaning respiratory disease. Diagnosis is by serology or polymerase chain reaction laboratory test (PCR). There are no effective treatments, although modified-live vaccines provide partial protection against infection.
After infection of a naïve herd, exposure of all members of the breeding population is inconsistent, leading to development of naïve, exposed and persistently infected populations of sows.
An aside to cattle people: I cannot write this piece without being constantly reminded of BVD, also of ovine progressive pneumonia (OPP) in sheep.
The primary vector of transmission is the infected pig and contaminated semen. The virus may also be carried in the wind and by needles, boots and clothing. Mosquitoes and flies are guilty, as well.
The reproductive phase of PRRS involves stillborn pigs, mummified fetuses, premature farrowing and weak litters. Combined problems can lead to a 50 percent reduction in baby pig survival. The respiratory phase includes live piglets that develop a characteristic “thumping” respiratory pattern and severe pneumonia. The infection will set pigs up for susceptibility to a host of additional bacteria such as strep, staph, E.coli, salmonella and mycoplasma.
Infected herds have an increased need for antibiotics of over 200 percent. PRRS has cost the U.S. swine industry an estimated $1.2 billion per year in lost production.
What Is Gene Editing?
First, we must learn there is a huge difference between gene editing and genetic engineering. Genetic engineering alters an animal’s genetic code by exogenous manipulation. In other words, certain genes are swapped out for genes from a different species of animal. One of the huge challenges of both genetic engineering and gene editing is the predictable negative reaction and poor consumer acceptance of meat, milk and eggs due to safety considerations. One article I stumbled upon had the audacity (though not rare) to label any sort of genetic manipulation as production of “Frankenswine,” saying that no one knows the long-term effects on human health. For the record, the FDA has not given approval to any genetically engineered livestock and future approval seems unlikely.
A simply put piece written by Kevin Schultz in the May 12, 2025, Farm Progress website included, “As we have learned, whether we’re talking genetically modified grains or gene editing to deactivate the CD163 gene in pigs, the public perception can derail or at least make acceptance difficult. Regardless of how badly the U.S. swine industry needs such technology in its toolbox, complete consumer acceptance will dictate approval in the long run. If consumers don’t want pork from gene-edited pigs, then the greatest development in the world could be for naught.”
How, specifically, does gene editing differ from genetic engineering or producing a genetically modified organism (GMO)? In the case of PRRS, scientists can identify a specific critical protein, CD163, produced on the gene that PRRS requires to grow and cause infection. They are deleting this specific protein using gene editing technology, disabling the PRRS virus. The swine genome remains the same, sans a single letter of DNA. This trait is passed on to future generations. Thus, hogs are still hogs. The same can be said of genetically editing the horned gene from cattle. In this case, the horned gene was removed and replaced by a polled bovine gene. It did not involve foreign DNA from a different species of animal. Research has accomplished this goal; however, FDA approval still awaits for bovines.
Genetic engineering techniques were first developed in the 1970s. The more predictable and efficient gene editing technique emerged much later. In terms of government oversight and regulation, it is accepted more regularly in countries that are science based, as opposed to genetically engineered stock.
PIC, the founding company of the PRRS-resistant swine, hired Circana to conduct a survey of 1,000 U.S. participants, researching consumer acceptance of their gene edited pigs. They found a 72 percent acceptance of the PRRS-resistance idea and the added benefits it brings. It shines a bright spot on their company and shows we may have future genomic progress to look forward to.
The inherent uncertainty of gene editing, no matter how badly naysayers wish to deride it, seems unsubstantial to the potential limitless benefits.
Human Benefits
An example of human benefits derived from emerging livestock technology is the development of GalSafe Swine. The genetically edited livestock have been cleared by the FDA for therapeutics and human food. The administration’s news release from Dec. 14, 2020, explains that the IGA (intentional genomic alteration) in these swine eliminates alpha-gal sugar on the surface of pork cells. People with alpha-gal syndrome have allergic reactions to the alpha-gal sugar found in every red meat product. These swine are handled under far more stringent conditions than any conventional pork, so are not available to the general population, although they are safe for human consumption.
The sweet benefit from GalSafe Swine comes from their potential as a source of medical products such as heparin to thin blood and transplantable tissues and organs for humans that do not trigger immune rejection.
What About Humans Themselves?
On May 16 news broke about a baby in Philadelphia who was treated with the first personalized gene-editing drug. KJ Muldoon was born with a rare metabolic genetic disorder that prevented his liver from removing ammonia from his body.
According to the MIT Technology Revue, Antonio Regaldo wrote “that time and effort involved more than 45 scientists and doctors as well as pro bono assistance from several biotechnology companies. Musunura [the doctor] says he cannot estimate how much it cost in time and effort.”
The treatment was programmed to correct a single letter of DNA in Muldoon’s cells. The errant letter was found in the gene CPS1, which stopped it from making a vital enzyme in his liver.
As of this writing, the youngster had had three CRISPR treatments, no complications and was responding successfully to the procedure. His family is thrilled. His doctors caution that it is still very early in treatment and the child will need to be watched closely to understand the full effects of his therapy.
Human biotechnology companies are testing gene-editing work only on more common conditions like sickle cell disease. Companies are more likely to recover costs of research and development on frequently occurring genetic diseases; thousands of genetic conditions are so rare that companies could never recoup the expense of developing appropriate treatments. That situation alone is causing what some experts call “a growing crisis in gene-editing technology.”
These recent developments prove once again that livestock production does more than furnish food for a hungry population. People everywhere gain greatly from our constant efforts in care and technology. The inherent uncertainty of gene editing, no matter how badly naysayers wish to deride it, seems unsubstantial to the potential limitless benefits.
You may be wondering where the catchy CRISPR acronym comes from. It is short for “clustered regularly interspaced short palindromic repeats.” Just remember the word CRISPR; it’s a much more entertaining name.
