Egg Allergy is Over! With Gene Editing, Scientists Now Eliminate Egg Allergy

Scientists have achieved a significant breakthrough by developing a chicken egg that holds the potential to be consumed safely by individuals with allergies to egg whites. Allergy to chicken eggs ranks among the most common allergies in children, with some individuals carrying this sensitivity into adulthood. Symptoms of egg white allergies can range from vomiting and stomach cramps to breathing difficulties, hives, and swelling. Moreover, this allergy can pose limitations on receiving certain flu vaccines.

Utilizing genome editing technology, researchers have successfully created an egg variant lacking the protein responsible for triggering egg white allergies. The specific protein, known as ovomucoid, accounts for approximately 11% of the total protein content in egg whites.

A paper published in Food and Chemical Toxicology in April 2023 presented the research findings concerning the food safety profile of this modified egg, named OVM-knockout.

“To use OVM-knockout chicken eggs as food, it is important to evaluate their safety as food. In this study, we examined the presence or absence of mutant protein expression, vector sequence insertion, and off-target effects in chickens knocked out with OVM by platinum transcription activator-like effector nucleases (TALENs),” said Ryo Ezaki, an assistant professor at the Graduate School of Integrated Sciences for Life at Hiroshima University in Hiroshima, Japan.

Egg Allergy is Over! With Gene Editing, Scientists Now Eliminate Egg Allergy

In order to develop OVM-knockout eggs, the researchers employed a method to identify and eliminate the ovomucoid protein present in egg whites. They utilized TALENs, which were designed to target a specific RNA segment called exon 1, responsible for encoding certain proteins. Eggs generated through this technique were thoroughly examined to ensure the absence of ovomucoid protein, mutant ovomucoid protein, or any unintended effects.

The eggs exhibited the intended frameshift mutation, a genetic alteration achieved by adding or removing nucleotide bases in a gene, and none expressed mature ovomucoid proteins. Rigorous testing involving anti-ovomucoid and anti-mutant ovomucoid antibodies was conducted to detect any trace of the protein, and no evidence of ovomucoid was found in the eggs. This signifies that the mutant ovomucoids cannot generate new allergens, a crucial step in assessing the safety profile of the eggs.

Unlike other gene editing tools like CRISPR, which may induce unintended mutations, the whole-genome sequencing of the modified egg whites revealed that the mutations, presumed to be off-target effects, were not localized to regions encoding proteins.

“The eggs laid by homozygous OVM-knockout hens showed no evident abnormalities. The albumen contained neither the mature OVM nor the OVM-truncated variant,” said Ezaki. “The potential TALEN-induced off-target effects in OVM-knockout chickens were localized in the intergenic and intron regions. Plasmid vectors used for genome editing were only transiently present and did not integrate into the genome of edited chickens. These results indicate the importance of safety evaluations and reveal that the eggs laid by this OVM knockout chicken solve the allergy problem in food and vaccines.”

Moving forward, the researchers will continue to validate the safety profile of OVM-knockout eggs. As even a small amount of ovomucoid can trigger severe reactions in highly allergic individuals, additional immunological and clinical studies will be conducted to determine the safety of these eggs. Currently, it has been determined that OVM-knockout eggs are less allergenic than standard eggs and can be safely utilized in heat-treated foods suitable for individuals with egg allergies.

“The next phase of research will be to evaluate the physical properties and processing suitability of OVM-knockout eggs, and to confirm their efficacy through clinical trials,” said Ezaki. “We will continue to conduct further research toward the practical application of allergy-reduced eggs.”

References: “Transcription activator-like effector nuclease-mediated deletion safely eliminates the major egg allergen ovomucoid in chickens” by Ryo Ezaki, Tetsushi Sakuma, Daisuke Kodama, Ryou Sasahara, Taichi Shiraogawa, Kennosuke Ichikawa, Mei Matsuzaki, Akihiro Handa, Takashi Yamamoto, and Hiroyuki Horiuchi, 6 March 2023, Food and Chemical Toxicology.
DOI: 10.1016/j.fct.2023.113703