â€œIt seems gene editing is going to eliminate all disease,â€� said HBOâ€™s John Oliver, â€œOr kill every last one of us.â€�1 Heâ€™s referring to gene-editing tools such as CRISPR, or Clustered Regularly Interspaced Short Palindromic Repeat, and TALEN (Transcription Activator-Like Effector Nuclease), which are being used for everything from disease treatment to agriculture.
Unbeknownst to many, CRISPR technology has already been used to tinker with crops, including both plants and animal farming. In addition to altering the taste of foods, CRISPR is being used to extend shelf life and create foods that resist certain bacteria and viruses.2
Even chicken â€” a staple food in diets around the world â€” has been eyed for gene editing due to avian leucosis virus, and a â€œCRISPRâ€� chicken may be coming to your dinner plate soon.
Avian Leukosis Virus Widespread in CAFO Poultry
Avian leukosis virus (ALV) has been plaguing the CAFO (concentrated animal feeding operation) poultry industry since it was first identified in 1991.3 The disease causes tumors to develop in the birds, along with symptoms such as weakness, loss of appetite, diarrhea and depression.4
The last major ALV outbreak occurred in 2018 in China, leading to high mortality rates among infected chickens.5 However, the virus is present in CAFO chickens worldwide, leading to an estimated millions of pounds of losses annually.6
The U.S. Department of Agriculture (USDA) once required that chickens that show signs of ALV or â€œlesionsâ€� (tumors) must be removed from processing so they do not enter the food chain.7
However, the National Chicken Council petitioned the USDAâ€™s Food Safety and Inspection Service in March 2019 asking to â€œtreat lesions that could be suspected as being caused by avian leukosis as a trimmable condition and not a condition that requires whole bird condemnation.â€�8
July 16, 2020, FSIS accepted the petition, stating, â€œWe have determined that current scientific evidence supports treating avian leukosis as a trimmable condition and that the actions requested in your petition would reduce regulatory burdens on the industry.â€�9
Despite the significant regulatory change â€” which means chickens riddled with tumors may still end up in the food supply as long as theyâ€™re â€œtrimmedâ€� â€” researchers have been looking toward gene editing as another way to eradicate ALV from CAFO poultry flocks.
Scientists Use CRISPR to Tackle Avian Leukosis
In 2018, researchers with the Czech Academy of Sciences determined that, because ALVs use specific receptor proteins to gain entry into cells, such receptors would make good targets for â€œbiotechnological manipulationâ€� in order to create poultry resistant to the virus, which they attempted using CRISPR-Cas 9.10
CRISPR gene-editing technology brought science fiction to life with its ability to cut and paste DNA fragments, potentially eliminating serious inherited diseases. CRISPR-Cas9, in particular, has gotten scientists excited because,11 by modifying an enzyme called Cas9, the gene-editing capabilities are significantly improved.
In their 2018 study, published in the journal Viruses, the scientists noted that â€œCRISPR/Cas9-mediated knock-out or the fine editing of ALV receptor genes might be the first step in the development of virus-resistant chickens.â€�12 In a separate study published in PNAS in January 2020, the researchers demonstrated that CRISPR-Cas9 was effective in rendering chickens resistant to the J subgroup of ALV. They noted:13
â€œWe introduced a single amino acid deletion into the gene encoding the receptor that is required for avian leukosis virus subgroup J to infect chicken cells. Here, we demonstrate that this mutation confers the resistance of chickens to avian leukosis virus subgroup J, an important pathogen in poultry. In addition, we present highly efficient genome-editing technology in chicken.â€�
They added that no visible side effects were apparent after the process, which involved deleting tryptophan residue number 38 of chNHE1 (W38), a critical amino acid for virus entry. The word â€œvisibleâ€� is key, however, as many unexpected changes may still occur that arenâ€™t immediately recognizable, and itâ€™s possible for those changes to be transferred to other organisms or generations.
In an interview with Yale Insights, Dr. Greg Licholai, a biotech entrepreneur and a lecturer at Yale, explained that this could even lead to problems that are worse than the â€œcure,â€� like antibiotic resistance or incurable diseases:14
â€œThatâ€™s probably the biggest fear of CRISPR. Humans manipulating the genetic code, and those manipulations get passed on generation to generation to generation.
We think we know what weâ€™re doing, we think weâ€™re measuring exactly what changes weâ€™re doing to the genes, but thereâ€™s always the possibility that either we miss something or our technology canâ€™t pick up on other changes that have been made that havenâ€™t been directed by us.
And the fear then is that those changes lead to antibiotic resistance or other mutations that go out into the population and would be very difficult to control. Basically creating incurable diseases or other potential mutations that we wouldnâ€™t really have control over.â€�
Gene-Edited Chickens Also Exist That Resist Flu
Influenza spreads rapidly among CAFO birds and has the potential to be transmitted to humans. 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.
Scientists, however, turned to biotechnology instead, using CRISPR to target part of the ANP32 gene, which codes for a protein that flu viruses depend on,15 in order to create flu-resistant chickens.16
Flu- and ALV-resistant chickens are just two examples 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) â€” 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 USDA, 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.19 One company snipped out the genes responsible for growing horns in dairy cows, for instance, which means they wouldnâ€™t be subjected to the inhumane ways the horns are currently removed (with no pain relief).
As for gene-edited animals, the FDA proposed to classify animals with edited or engineered DNA as drugs,20 prompting backlash from the biotech industry,21 which doesnâ€™t even want such foods labeled. This isnâ€™t the case for gene-edited plants, however, which have largely escaped regulation.
Gene-Edited Mushrooms and Lax Regulations
A number of gene-edited plant foods have also been developed or proposed, including non-browning mushrooms, which were created by Yinong Yang, a plant pathologist at Pennsylvania State University, in 2016 using CRISPR-Cas9. Although the â€œfrankenfungi,â€� as itâ€™s been called, has never before existed in nature, it would require no USDA approval because it does not contain foreign DNA.
“Our genome-edited mushroom has small deletions in a specific gene but contains no foreign DNA integration in its genome,” Yang said in Penn Stateâ€™s Ag Science Magazine. “Therefore, we believed that there was no scientifically valid basis to conclude that the CRISPR-edited mushroom is a regulated article based on the definition described in the regulations.”22
Weeks after the USDA notified Yang that the gene-edited non-browning mushrooms would not require approval, it also ruled that DuPont Pioneerâ€™s CRISPR-Cas9-edited corn would also be able to bypass regulatory approval.23
The rule, known as the “Sustainable, Ecological, Consistent, Uniform, Responsible, Efficient” (SECURE) rule,24 was finalized in May 2020 and maintained the status that crops edited using CRISPR-Cas9 and other similar technologies would be non-regulated.25
Are You Already Eating Gene-Edited Soybean Oil?
A gene-edited soybean oil created by biotech company Calyxt was picked up by its first user â€” a Midwest company with both restaurant and foodservice locations, which is using it for frying as well as in dressings and sauces â€” in 2019.26 Calyxtâ€™s soybean oil, Calyno,27 contains two inactivated genes, resulting in an oil with no trans fats, increased heart-healthy oleic acid and a longer shelf life.
As of February 2019, more than 100 farmers in the Midwest were reportedly growing Calyxtâ€™s high-oleic soybeans on more than 34,000 acres.28 In an update released February 7, 2020, Calyxt stated it had contracted 100,000 soybean acres in the U.S. for 2020, which represented 178% growth from the year prior.29
It also received its first purchase order from a customer targeting four of its primary markets (foodservice, food ingredients, animal nutrition and industrial,) and is now offering 1-gallon jugs of its Calyno cooking oil directly to consumers.30
Calyxt has also developed a high-fiber wheat, which has been declared a non-regulated article and may launch as early as 2020 or 2021.31 In short, gene-edited foods are already on the market and expanding with fervor, while the health and environmental risks remain completely unknown.
Unexpected Consequences, Risks Uncovered
Gene-editing, for all of its intended precision, isnâ€™t an exact science. In animals, gene editing has led to unexpected side effects, including enlarged tongues and extra vertebrate.32,33
Further, when researchers at the U.K.â€™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 â€œoff,â€� such as cancer-causing genes, as well as silencing those that should be â€œon.â€�34
Without a label requirement, thereâ€™s no way for consumers to know whether theyâ€™re eating gene edited soybean oil â€” or one of the many future gene edited products likely to hit the market, like â€œCRISPR chicken.â€� For now, however, gene-edited foods cannot be labeled organic, which is one more reason why seeking out organic and, even better, biodynamic foods, is so important.