Advances in animal genome editing continue apace

Researchers celebrated two recent advancements in gene editing: approvals for pork from gene-edited pigs to enter the human food supply and a calf with reduced susceptibility to bovine viral diarrhea virus (BVDV).

The Food and Drug Administration (FDA) also announced a joint project with the National Institute of Standards and Technology (NIST) to create a new resource for researchers and companies developing innovative animal biotechnology products by using gene editing to alter animal genomes.

Gene-edited pigs

In early May, Washington State University (WSU) announced that the FDA had authorized gene-edited pigs from the College of Veterinary Medicine to be processed for human consumption—in this specific case.

The FDA authorization was limited to five pigs whose genomes were altered in such a way as to allow researchers to use the animals to sire offspring with traits from another male pig.

Dr. Jon Oatley, a professor in the School of Molecular Biosciences in WSU’s veterinary college, said in a statement, “The original intent in making these animals was to try to improve the way that we feed people. And we can’t do that unless we can work with the FDA system to get these animals actually into the food chain.”

Gene editing allows scientists to change an organism’s DNA more quickly than would occur naturally or through selective breeding. While several technologies have been developed to edit a genome, the most popular tool is CRISPR-Cas9, which is short for clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9. CRISPR was adapted from a naturally occurring genome editing system that bacteria use as an immune defense.

Dr. Oatley undertook the FDA Center for Veterinary Medicine’s (CVM) investigational food use authorization (IFUA) process for the gene-edited pigs to demonstrate that food made from the animals is safe to eat. An IFUA is issued after the FDA has evaluated any potential public health hazards and determined appropriate mitigations of those hazards are in place to ensure the safety of the edible products entering the human food chain.

The 2-year-old pigs were processed at the WSU Meat Lab, and the meat was inspected by the U.S. Department of Agriculture (USDA). Meat scientist Blake Foraker made some of the pork into sausages that were used in catering services that raise travel funds for the student members of the WSU Meat Judging team.

Securing the investigational approval for these five pigs required clearing a number of hurdles. The FDA waives some fees for nonprofits such as universities, but by the time the process was completed, Dr. Oatley’s team had spent two years and approximately $200,000 collecting data for this authorization.

“It’s important for a university to set the precedent by working with federal regulators to get these animals introduced into the food supply,” Dr. Oatley said, who is working toward FDA approval for a line of gene-edited pigs.

BVDV resistance

In related news, scientists have created the first gene-edited calf with reduced susceptibility to BVDV, one of the most significant viruses affecting bovine species throughout the world. This work provides the first example of gene editing in cattle to reduce the impact of a major viral disease.

The study, published in the May 2023 issue of PNAS Nexus, describes the results from a collaboration between the USDA’s Agricultural Research Service (ARS), the University of Nebraska–Lincoln (UNL), the University of Kentucky (UK), and industry partners, Acceligen and Recombinetics Inc.

According to the paper, “(Scientists) used CRISPR-mediated homology-directed repair and somatic cell nuclear transfer to produce a live calf with a six amino acid substitution in the BVDV binding domain of bovine CD46. The result was a gene-edited calf with dramatically reduced susceptibility to infection as measured by reduced clinical signs and the lack of viral infection in white blood cells.”

FDA partnership

Also in May, the FDA announced a joint project with the NIST in recognition that, with genome editing, there is a possibility of unintended alterations that might impact the health of the animal or the safety of meat, milk, or eggs from the animal.

Developers in the field have expressed the need for certain tools that can help them produce safe products. Namely, standardized measurements for characterizing both intended and unintended alterations in animals whose genomes have been altered using gene editing along with access to reference materials.

The FDA is funding and working on a project, headed by NIST, that will create these needed resources. Specifically, the project aims to generate standardized measurements for characterizing intentional genomic alterations (IGAs) in cattle and swine that are developed using gene editing.

These resources support the molecular characterization of gene-edited animals, which can apply to animals for a variety of uses, including animals for agriculture or human food use. In addition to helping developers, these methods and materials will also improve regulators’ confidence in developers’ evaluations, potentially reducing time to the marketplace, according to the FDA.

More information about the project will be posted on the FDA’s website later this year.