US company starts breeding of gene-edited pigs resistant to PRRS

08-03-2023 | |
gene-edited pigs
Other researchers state that if gene editing were complemented with widespread and sufficiently effective vaccination, that would help eradicate PRRS. Photo: Henk Riswick

Acceligen, a company in Minnesota, announced that it will start with breeding of gene-edited pigs that are resistant to Porcine Reproductive and Respiratory Syndrome (PRRS).

This breeding involves “deploying protein modifications” developed by Kansas State University. It is based on work from the University of Missouri (U of M) by Dr. Bob Rowland and his colleagues.

Rowland explained that the idea of achieving resistance to PRRS through gene editing goes back 20 years. He and his colleagues published a paper in 2002 about removing a protein through gene editing in pigs to make their organs suitable for transplantation to humans.

At that time, other researchers described proteins likely responsible for the PRRS virus entering and infecting the lungs of pigs. “Similar to the molecule on the cell surface that resulted in rejection of an organ,” Roland explained, “the molecule responsible for PRRS virus infection may also be located on the surface of the cell.” In June of 2002, he filed a disclosure with the University of Missouri describing how scientists could remove the gene responsible for susceptibility.

Gene-editing not a sole solution?

However, in late 2021, researchers based in Scotland and New Zealand stated that gene editing alone will not eradicate PRRS. They surmised that whilst “recent production of gene-edited pigs that are fully resistant to the PRRS virus have raised expectations for eliminating this deadly disease, our models predict that disease elimination on a national scale would be difficult to achieve if gene editing was used as the only disease control.” However, they said elimination could be possible within 3 to 6 years “if gene editing were complemented with widespread and sufficiently effective vaccination.”

US approvals: a review

In March 2022, the FDA made its first decision on gene-edited livestock. It provided an enforcement discretion ruling (a ‘low risk determination’) for 2 calves with a gene edit for ‘slick coats,’ which makes them more heat tolerant. The ruling was given to Recombinetics (parent company of Acceligen).

In 2020, ‘GalSafe’ pigs and ‘AquAdvantage’ salmon became the first genetically engineered (transgenic) livestock approved by the FDA for human consumption.

This genetic engineering technology involves insertion of foreign DNA into the genome, and these pigs and salmon are considered genetically modified organisms (GMO), like RoundUp Ready crops.

The Food and Drug Administration (FDA) approved the use of GalSafe pigs in the production of drugs, for organs/tissues for human transplant, and for meat to be consumed by people with the Alpha-Gal meat allergy. A still-active petition was started about a year ago asking that GalSafe pork be provided to these people.

Consumer study

In 2022, the first study to gauge public acceptance in the US for gene edited foods was released. The study showed “that when you have a new technology that people are not familiar with, other factors play a much bigger role [in acceptance], especially people’s social and ethical values, and whether they trust government and industry to protect them.”

Other gene editing developments

In 2020, a gene editing approach was proposed by researchers in Germany to stop African swine fever virus replication. Also in 2020, progress was reported in Germany, on the use of gene editing to end physical castration by removing genes associated with boar taint.

Treena Hein Correspondent