Biotechnology has been used to improve crop performance for decades and growers have become familiar with how it works and why it matters.
But for livestock producers, biotechnology, in the form of gene editing for improved disease resistance, is still new. Two experts say that how we talk about it now matters for the future of animal health, innovation and the next generation of farmers.
“‘GMO’ is such a frustratingly nebulous term,” says Dr. Alison Van Eenennaam, professor of cooperative extension in Animal Biotechnology and Genomics at the University of California Davis. “The trouble is with the letter O – ‘organism’. It could describe anything, really – a traditionally out-crossed apple, for instance, is technically a genetically modified organism. I’m a scientist. I like precision.”
She says what most people really mean when they refer to Genetically Modified Organisms (GMO) are things that have been genetically engineered, such as Bt corn where genes from a soil bacteria were introduced to the corn genome. A feature of GMO technology is that it’s random where the introduced genes insert themselves into the plant’s genome.
While this technology has been beneficial for plant breeders, Van Eenennaam says genetic engineering in this form is prohibitively expensive for the animal industry. That’s why recent advances in gene editing technology are so exciting for this sector.
“Genetic engineering, or GMO, is where we introduce a construct randomly into a genome,” she says. “Gene editing is making targeted changes to the genome. It’s not using DNA from other organisms; nothing foreign is being introduced.”
Known as CRISPR (Clustered Regulatory Interspaced Short Palindromic Repeats), gene editing lets scientists precisely delete or change a small portion of an organism’s own DNA to achieve a specific, predictable outcome – such as resistance to a disease. That precision, that ability to alter a genome at a specific point, recently made gene editing a uniquely powerful tool in the field of swine health with the development of disease-resistant pigs.
Porcine reproductive and respiratory syndrome (PRRS) is a serious, deadly virus that affects pigs worldwide. While it can have major financial impact for producers, it can have a huge emotional toll on them, too, since an outbreak often means many animal deaths.
Using gene editing, scientists were able to remove a specific snippet of the pig’s DNA which is the binding site for the PRRS virus. No binding site, no PRRS infections – period. It’s nothing short of revolutionary.
Gene editing as medicine
The gene edit used to breed the PRRS-resistant pig was developed by PIC and was approved by the U.S. Food and Drug Administration in early 2025. Full commercialization is waiting on other major pork producing countries, like Canada, Mexico and Japan to approve the technology in their markets. Dr. Jason Hocker, for one, can’t wait for that day.
“Pre-commercialization, we’re still in the throes of PRRS,” says Hocker, a swine vet with Audubon Manning Veterinary Clinic (AMVC) in Iowa. “It’s an RNA virus, so it’s always mutating. It’s very challenging, and it can feel like a losing battle with Mother Nature being always one step ahead.”
Hocker says vaccines have been tried but aren’t very effective because the virus replicates in unpredictable ways. “All our vaccine technology today just can’t keep up with it. That’s why we’re very excited about this next frontier of medicine.”
And he’s very clear that gene editing to achieve PRRS resistance, is medicine. “PRRS is the most significant disease we deal with in terms of cost, pig health and mortality and the emotional tax on farmers. These are the therapies of the future,” says Hocker. “We have to be intentional about communicating that.”
It is easy to see how a gene edited pig can be seen as a potential solution because it’s not something that has to be done with every pig in every generation. Rather, a PRRS-resistant pig will pass that trait on to its offspring through traditional breeding.
“It’s a synergistic addition to conventional breeding, not a replacement for it,” says Van Eenennaam.
Hocker agrees: “Gene editing eliminates the receptor that the virus binds to, then we use selective breeding like we’ve always done to get PRRS-resistant herds.”
Why start with gene editing for PRRS?
Van Eenennaam says gene editing isn’t a panacea for all the things animal breeders might like to select for. PRRS happens to map to a single gene on the pig genome, so editing that one piece of genetic material is straightforward, or at least more straightforward than trying to edit for problems that are multigenic, like mastitis in cows.
“It’s been years of work sequencing the pig genome, narrowing the focus to the genes of interest and finding the right one,” says Van Eenennaam. “That investment is now beginning to pay dividends. PRRS kills a lot of pigs. I’m glad that disease resistance is the first cab off the rank when it comes to this technology.”
For Hocker, it’s about more than healthy pigs today, it’s about the future of agriculture.
“Farming is a noble profession,” he says. “We produce the food, fuel, pharmaceuticals, fibre – things that everyone needs but only two per cent of us are doing it. So how do we talk to the rest of the world about what’s important to us, so they understand? We have to find a value proposition that’s bigger than just for the industry. We have to show the next generation of farmers that we are here, we are relevant, we do care and want to be on the cutting edge of technology.”
He thinks the conversations about gene editing become more nuanced when human health is involved, and that’s something the ag industry can learn from.
“The victories in human therapies and medicine make me more excited about what could be in animal science,” he says. “It’s worth fighting for. Let’s embrace this then learn how to talk about it.”
For more information about gene editing and the development of PIC’s PRRS-Resistant Pig, visit PIC PRRS-Resistant Pig
