Scientists create transgenic egg that does not cause allergy – 05/20/2023 – Science

Eggs that can be consumed by those who are allergic to this food have just become a reality in the laboratory, say Japanese researchers. Using a precise DNA-editing method, the team of scientists at the University of Hiroshima created chickens whose eggs do not produce the egg white protein responsible for most cases of allergy.

Detailed analyzes of the non-allergenic egg have just been published in the specialized journal Food and Chemical Toxicology. In the study, led by Ryo Ezaki, the group of scientists showed that it is possible to “turn off” the production of ovomucoid protein, which corresponds to just over a tenth of the protein content of egg whites.

Allergic people who consume ovomucoid protein may have episodes of vomiting, breathing problems and swelling in the body, among other symptoms. The molecule is still present in flu vaccines produced from chicken eggs, which often means that people with allergies end up not receiving this immunization.

Ezaki and his colleagues started the egg production process by modifying the DNA of chicken embryos, using molecules designated by the acronym Talens. Roughly speaking, they can be compared to molecular scissors, being able to recognize specific sequences of DNA “letters” and cut them relatively precisely.

In the case of the stretch of DNA that contains the recipe for the production of the ovomucoid protein, the use of Talens produced a mutation that completely messed up the reading of the molecular recipe by the organism.

Imagine, for example, a cookbook in which the phrase “Add milk” was read from the third letter of the first word, becoming “fresh milk”. The phrase would no longer make sense — and, in the case of DNA, that means that the ovomucoid protein is no longer produced by the organism of the genetically modified chickens.

“In order to be able to use the eggs of these hens in food, their safety must be evaluated first”, Ezaki highlighted in an official statement about the study. Therefore, the Japanese team used a series of molecular biology techniques to understand how genetic modification affected the characteristics of the eggs.

They used, for example, antibodies designed to adhere to the ovomucoid protein, and none of them managed to “catch” any piece of that molecule when they were applied to the egg whites of chickens whose DNA had been altered.

In addition, the researchers conducted a complete analysis of the chicken’s DNA, verifying that the gene editing techniques do not appear to have modified functional regions other than the one linked to the ovomucoid protein.

“The eggs laid by the hens did not show any obvious abnormality,” said Ezaki.

According to the researcher, current data already allow for the conclusion that genetically modified eggs can be consumed by allergic people when used as ingredients in cooked foods.

However, as even very small amounts of the ovomucoid protein are capable of causing reactions in some people, the Japanese team plans to carry out more safety tests before considering that the eggs can be consumed in natura without fear.

Still about allergies

Allergic reactions deserve attention from the first symptoms and can lead to anaphylaxis, a condition characterized by the presence of symptoms in more than one organ. In some cases, there is airway compromise and cardiovascular symptoms, eventually resulting in anaphylactic shock—a sudden drop in blood pressure that can be fatal.