The first gene-edited chickens are scheduled to hatch at the Roslin Institute at The University of Edinburgh in Scotland. The designer birds have been modified to resist flu, which spreads rapidly among CAFO (concentrated animal feeding operation) birds and has the potential to be transmitted to humans.
“If we could prevent influenza virus crossing from wild birds into chickens, we would stop the next pandemic at source,” Wendy Barclay, a virologist at Imperial College London, said in a news release.1 The simplest way to stop the widespread transmission of bird flu would be to change the way chickens are raised, putting them outdoors on pasture as opposed to crowded in disease-ridden CAFOs.
But researchers discovered in 2016 that the ANP32 gene in chickens codes for a protein that flu viruses depend on,2 and cells without the gene were impervious to flu. Since then, they’ve been on a mission to change the gene in live chickens, and now it appears they’ve succeeded.
Gene-Edited Chickens Created
In order to create the transgenic chickens, scientists used the gene-editing technology known as CRISPR, or Clustered Regularly Interspaced Short Palindromic Repeat. Unlike genetically engineered (GE) foods, which may have genes from other species inserted, gene editing involves altering an organism’s DNA.
They targeted part of the ANP32 gene in order to create the flu-resistant chickens. “We have identified the smallest change that will stop the virus in its tracks,” Barclay said.3 Already, however, they’re anticipating that the public may be less than enthusiastic about gene-edited chickens on the dinner table.
People eat food from farmed animals that have been altered by decades of traditional breeding,” Barclay told Reuters. “But they might be nervous about eating gene edited food.”4 Indeed, just as is the case with genetically modified organisms (GMOs), there remain many unknowns about gene editing as it pertains to human health and the environment.
Further, foods produced via gene-editing are not subject to regulation by the U.S. Department of Agriculture (USDA) or other regulatory agencies — although an advisory board recommended gene-edited foods could not be labeled organic.5
In fact, in March 2018, the USDA released a statement noting that it would not regulate CRISPR-edited crops, stating, “With this approach, USDA seeks to allow innovation when there is no risk present.”6
Gene editing, with its loose regulation, accessibility and quick results, has been called the next “food revolution,”7 at least for plant foods, but it’s unclear whether the same will hold true for animals. In the U.S., it’s been proposed that gene-edited foods do not need to be labeled, either, but the European Union ruled that they should be regulated the same as GMOs.
Gene Editing Causes Side Effects in Animals
Gene-editing technologies are relatively new, but they’re moving ahead at a feverish pace. With the innovation, however, have come a few setbacks that should, at least, raise a few red flags.
Researchers have used CRISPR-Cas9 and other gene-editing technologies to create cows that can tolerate warmer temperatures (so they can be raised in the tropics), goats with longer cashmere wool and rabbits and pigs with bigger, leaner muscles.
Serious side effects resulted, however, including enlarged tongues in the rabbits.8,9 Among pigs that were altered by deleting the myostatin (MSTN) gene, which limits muscle growth, the larger muscles came along with an extra vertebrate in 20 percent of the gene-edited animals.
“This phenomenon has never been reported in other MSTN–mutant animals,” the researchers said,10 and therein lies the problem. While scientists have made great strides in mapping out genomes of entire organisms, much remains unknown about the purpose of individual genes and how they interact with one another.
As such, making tweaks to genes, even those intended to be precise, often lead to surprising and unintended consequences.
GE Foods Could Affect Gene Expression Patterns in Humans
In the U.S., the Food and Drug Administration (FDA) considers most genetically edited (GE) foods to be “substantially equivalent” to non-GE foods and, as such, categorizes them as “generally recognized as safe,” with no need for premarket approval.11 Yet, there is much we don’t know about the fate of GE foods, and GE food-derived DNA, once they enter our bodies.
Research published in Food and Chemical Toxicology revealed, however, that DNA from food not only can survive harsh processing and digestive conditions, but “DNA fragments up to a few hundred base pairs can survive and reach blood and tissues of human and animal consumers.”12
“There is limited evidence of food-born DNA integrating into the genome of the consumer and of horizontal transfer of GM crop DNA into gut-bacteria,” the researchers added.
Vertical gene transfer, or vertical inheritance (i.e., natural reproduction), is the transmission of genes from the parent generation to offspring via sexual or asexual reproduction, such as breeding a male and female from one species.
By contrast, horizontal gene transfer involves injecting a gene from one species into a completely different species, which yields unexpected and often unpredictable results. Mae-Wan Ho, director of the Institute of Science in Society, stated:13
“It is now clear that horizontal transfer of GM DNA does happen, and very often. Evidence dating from the early 1990s indicates that ingested DNA in food and feed can indeed survive the digestive tract, and pass through the intestinal wall to enter the bloodstream. The digestive tract is a hot spot for horizontal gene transfer to and between bacteria and other microorganisms.
Recent evidence obtained with direct detection methods indicates that horizontal transfer of GM DNA is routinely underestimated, largely because the overwhelming majority of bacteria in the environment and particularly in the gut cannot be cultured.
… Higher organisms including human beings are even more susceptible to horizontal gene transfer than bacteria, because unlike bacteria, which require sequence homology (similarity) for incorporation into the genome, higher organisms do not.”
The Food and Chemical Toxicology study also found that micro-ribonucleic acid (micro-RNA) from GE foods may enter the body and affect gene expression in different organs.
According to Ho, “One type of nucleic acids, the microRNAs (miRNAs), are specifically involved in gene silencing via a vastly complex and flexible process that changes according to the environmental context. Consequently, GMOs based on miRNAs have many potentially adverse off-target effects, which are radically unpredictable and uncontrollable.”14
While GMO foods and gene-edited foods are not technically the same, similar concerns exist for both technologies. Jaydee Hanson, an analyst at advocacy group the Center for Food Safety, told National Geographic that gene editing is essentially “the new kind of genetic engineering, whether you call it transgenic [GMO] or not.”15
GMO Chickens Produced to Make Cheaper Drugs
Scientists at The University of Edinburgh’s Roslin Institute (the institute responsible for creating the first cloned animal, Dolly the sheep) have also created GE chickens that have genes added to code for IFNalpha2a, a human protein with anticancer and antiviral effects, and macrophage-CSF, a protein that helps produce white blood cells.16
The chickens lay eggs with anticancer effects in the whites, and the researchers believe the substances could be extracted and used as a cost-effective method of drug production. Previously, researchers introduced DNA coding for the malaria parasite into the goat genome linked to milk production.
The experiments were geared toward producing an “edible” malaria vaccine, with the ultimate goal being that children drinking the milk would become vaccinated in the process.
Animals Being Gene-Edited for Disease Prevention and More
The Roslin Institute’s flu-free chickens are just one example of gene-editing technology at work. Researchers have also snipped out a section of pig DNA intended to prevent porcine reproductive and respiratory syndrome (PRRS) — a common and often fatal ailment among CAFO pigs.17 Such edits are permanent and passed down to other generations.
In another project, this one funded by the U.S. Department of Agriculture, researchers have added the SRY gene to cattle, which results in female cows that turn into males, complete with larger muscles, a penis and testicles, but no ability to make sperm.18 Male (or male-like) cattle are more valuable to the beef industry because they get bigger, faster, allowing companies to make greater profits in less time.
Other biotech companies have taken to targeting genes intended to ease animal suffering, which they believe may soften regulators and consumers who are wary of the technology. “It’s a better story to tell,” Tammy Lee, CEO of Recombinetics, told the New York Post.19
The company has snipped out the genes responsible for growing horns in dairy cows, for instance, which means they wouldn’t be subjected to the inhumane ways the horns are currently removed (with no pain relief).
Are Gene-Edited Foods in Your Supermarket?
The first gene-edited foods are expected to begin selling in the U.S. in 2019.20 Among the possibilities are “heart healthy” soybean oils, fiber-rich or low-gluten wheat or nonbrowning mushrooms. As for gene-edited animals, the FDA proposed to classify animals with edited or engineered DNA as drugs, prompting backlash from the biotech industry,21 which doesn’t want such foods labeled.
As for whether or not these foods are safe to eat, no one knows, but what is known is that gene editing produces off-target edits or, in other words, unintended changes to DNA.
When researchers at the U.K.’s Wellcome Sanger Institute systematically studied mutations from CRISPR-Cas9 in mouse and human cells, large genetic rearrangements were observed, including DNA deletions and insertions, near the target site. The DNA deletions could end up activating genes that should stay “off,” such as cancer-causing genes, as well as silencing those that should be “on.”22
Whether the government decides to classify gene-edited foods similarly to GMOs or conventional foods remains to be seen, but without labels you’ll have no way of knowing whether the food you eat has been genetically edited or not.
Jennifer Kuzma of the Genetic Engineering and Society Center at North Carolina State University estimated that about 20 gene-edited crops may hit the U.S. market in the next five years, to say nothing of the potential for gene-edited animals over that time.23
As it stands, all gene-edited crops are excluded from organic certification, so for now the best way to avoid gene-edited foods, if you so choose, is to purchase organic.
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