Cas9 In Genetically Modified Food Unlikely to Cause Food Allergy

Cas9 in Genetically Modified Food Is Unlikely to Cause Food Allergy

Osamu Nakajima,* Tomoko Nishimaki-Mogami, and Kazunari Kondo

Two major scientific topics of controversy remain widely discussed: genetically modified organisms (GMOs) and the CRISPR-Cas genetic modification system.  The two are meshed together and examined by Osamu Nakajima and his colleagues.  To understand the premise of this article and the major scientific question at hand, it is first necessary that each topic be examined in broad detail. 

            GMOs have been widely inspected for their potential harmful effects on the human population via consumption of such genetically modified foods.  However, although extensive research links genetically modified organisms to everything from food allergies to cancer, there is no conclusive evidence/law that states that genetically modified food is harmful for human consumption.  Genetically modification of food usually involves a certain editing of the organism’s genetic material in order to provide a new and likely desirable trait. This editing typically consists of artificial insertion of foreign DNA (containing a specific trait) into the organism to be modified.  These desirable traits can range from making a tomato appear more deep red and therefore more aesthetically pleasing to the customer, to making a corn plant drought or pest resistant in order to increase yields. 

            However, often times this modification technology that is used may not be so artificial after all!  Specifically, the CRISPR-Cas system, short for Clustered Regularly Interspaced Short Palindromic Repeats, was originally an immune defense that was first discovered in bacteria in order to prevent against viral infection.  When a virus first attaches to a bacterial cell, it releases its genetic material into the bacterial host cell that is now infected.  Following infection, short segments of viral DNA can become integrated into the bacterial host’s DNA at the CRISPR site.  If this cell becomes infected with another virus that contains this same DNA segment, the bacteria will recognize it and use a protein known as Cas to cut the viral DNA, therefore inactivating it and preventing bacterial cell death.

            By using this CRISPR-Cas system for genetic modification, it allows researchers to selectively delete or insert specific segments of DNA that will produce the desired trait in the organism.  The researchers in the paper introduced above focus on the CRISPR-Cas9 system in regards to digestibility and thermal stability upon human consumption of these genetically modified foods.  Specifically, they discovered that the Cas9 system was not stable at high temperatures and is degraded easily, suggesting that it is highly unlikely that it would not be degraded in the stomach upon digestion.  Additionally, they discussed the possibility of GMOs in processed food, but proved that heat treatment during food processing that is required would also degrade the Cas9 system.  If the Cas9 system were to aggregate, or clump together, there would be extensive toxicity, yet there was no evidence of aggregation, but rather, degradation.

  With any genetic modification system, it is imperative that it be analyzed for food safety, allergenicity, and the possibility for mutations to arise as a result of the editing. Another potential concern that resulted from the study included the genetic modification system existing in plants being backcrossed. Backcrossing is achieved by taking a plant hybrid (one that is genetically modified) with a parent or one that is genetically similar in order to create a desired end product.  If this backcrossing occurs, the clones that do not contain the Cas9 in their genome will be selected.  However, if the backcrossing is not performed, then it will remain in the plant, meaning the general public will be consuming the genetically modified plant unknowingly and unwillingly if they choose to do so. 

After analyzing the incorporation of the Cas9 gene into GMOs for food use, it was found to lack the ability to produce an allergenic response and therefore is unlikely to cause human food allergy upon consumption of these GMOs.  However, despite these experiments, it is important to note the possibility of this genome modification system in causing a potential food allergy.