22 September 2021

Edible vaccines – the biotechnological future of medicine?

Vaccines are a way of protecting the body against diseases caused by specific bacteria or viruses. These are biological preparations containing appropriate antigens, the presence of which allows for the imitation of a natural infection, thanks to which the body develops a protective immunity during contact with a real bacteria or virus.

In recent times, they have aroused more and more controversy, but still remain the best and in many cases obligatory way to protect the body, especially in children. However, with the advancement of science and medicine, alternatives to the traditional and unpleasant injectable vaccines emerge. This alternative is the so-called edible vaccines.

What do the vaccines contain?

Vaccines are based on the delivery of the appropriate antigens, but they can be administered in a variety of forms. In the case of live attenuated vaccines, those used against chicken pox or, for example, tuberculosis, vaccines include whole, but weakened or pathogenic microorganisms such as bacteria and viruses. There are also vaccines that are doses of whole but dead microbial cells. These types of vaccines are used against rabies or hepatitis A.

It is also possible to dose fragments or the most pathogenic microbial elements, as well as vaccines containing inactivated bacterial toxins. In addition to antigens, vaccines include adjuvants that delay the release of the antigen used, most often aluminum compounds. Additional elements are also preservatives as well as auxiliary and stabilizing substances.

What are edible vaccines?

Edible vaccines, unlike traditional injections, are administered orally. It is a revolutionary idea that uses split, modern methods of biotechnology. Edible vaccines are the use of plants by genetically modifying them, thanks to which they will gain the ability to produce immunogenic antigens.

They are a much nicer form of vaccine administration and certainly much more attractive in the eyes of children. However, this is not a form that is suitable for all vaccinations. Only a few can be administered in this way due to the path of the administered antigen through the digestive system. The most important thing in vaccinations is the body’s response to its administration. In the digestive system, some antigens can be damaged and the vaccine will not be effective.

The process of making edible vaccines

The basis for the possibility of producing edible vaccines was the discovery of the properties of the Agrobacterium tumefaciens bacteria, which by attacking plant roots transfers a fragment of its DNA to them. Based on this discovery, a detailed process was developed leading to the development of vaccines for humans and animals. In the initial stage, genetic engineering is used to introduce into the bacteria a DNA fragment that encodes a given antigen.

The next stage is the incubation of the prepared bacteria together with the plant fragment, which will later become the source of the vaccine. Only leaf or organ scraps are used for incubation, from which the entire plant can then be grown. The incubation process is followed by a selection process aimed at isolating the explants that have taken the bacteria. In the next stages, the whole plant is restored and finally, you can start eating it. This is how, among others, transgenic potato tubers containing cholera antigens.

Which edible plant vaccines are already known?

Although the use of biotechnology and genetic modification of plants for the production of edible vaccines is relatively new, a number of such vaccines have already been developed. So far, a way has been found to use modification of the genotype of a potato tuber or a lettuce leaf to prevent hepatitis B.

Transgenic tomatoes also help to gain immunity against hepatitis B, but they are also protective against rabies. Tobacco is used to produce both antibacterial vaccines, acting on the Vibrio cholerae subunit, but also antiviral vaccines aimed at immunizing the body against rabies and hepatitis B. Other edible plant vaccines are corn kernels and alfalfa leaves, created to protect organisms, not humans, but animals.

Participation of Polish scientists in the production of plant vaccines

Even though edible vaccines are a novelty that uses special technologies and many of us might doubt our country’s capabilities in this regard, it is a pleasant surprise how much we are involved in this. One of the first edible vaccines was created in the studio of Professor Andrzej Legocki. This product was lettuce, which produced the white hepatitis B virus. Its effectiveness in immunizing the body against jaundice was proven in 1999.

Research on transgenic lettuce is still carried out at the Institute of Plant Genetics and the Institute of Biotechnology and Antibiotics. The Institute of Biochemistry and Biophysics of the Polish Academy of Sciences conducts research on genetically modified carrots. The aim of the research is to create a vaccine against the bacteria Helicobacter pylori, which causes stomach ulcers.

Edible vaccines and the benefits of their production

The first and greatest positive feature that distinguishes edible vaccines from those commonly used is the form of their administration. Avoiding an unpleasant injection will be a good solution for every patient. Another advantage of the new technologies is the avoidance of additional ingredients found in currently used vaccines. It is the aluminum compounds, which are a component of a large part of vaccines, that causes so many doubts and controversies. Edible vaccines, resulting from genetic modification of plants and giving them the ability to produce antigens, do not require the addition of aluminum compounds.

Another undoubted advantage of the use of biotechnology methods is the low production costs and the ease of storage of such vaccines. The aim would be to convert the plants into capsules, thus avoiding the need for a skilled worker administering the vaccine by injection. It would also be easier to store without the use of special containers and low temperatures.

Edible Vaccines – Could GMO Be Harmful?

What is GMO? GMO stands for Genetically Modified Organisms, which means genetically modified organisms. Edible vaccines and the GMO that are used in their production are modern technologies that still raise many doubts. Most of them are mainly due to the fear of the unnatural. Genetic modification is still associated with something unknown and harmful. In practice, however, genetic modifications are only a technology of giving plants new features, such as, for example, the production of antigens.

Most of the concerns are related to the short period of occurrence of such vegetation, which has limited the ability to accurately understand their impact on the human body. The detrimental effect of such genotype changes has not been proven so far and the production of transgenic plants is very low. The very frequent “non-GMO” slogans on food products are not, however, a way to distinguish specific, exceptional products, but a clever marketing method that takes advantage of consumer uncertainty.

Will edible vaccines soon replace traditional ones?

The production of edible vaccines based on genetically modified plants brings with it a number of unquestionable benefits. At the moment, however, this is a new technology and so far such vaccines remain in the preclinical research phase. Their effectiveness is mainly studied in mice and it will take a long time before they are permanently introduced into vaccinology.

The aim of the research is to learn about genetically modified foods as much as possible. Biotechnology changes plants by introducing a foreign gene, which may be associated with undesirable, harmful effects. If further research does not prove harmfulness of GMO, edible vaccines will remain the great hope of vaccinology. If it is possible to achieve the effectiveness of this form of vaccination in the case of more bacteria and viruses, we may face a medical revolution and a global decline in the incidence of some infectious diseases.

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