Before the commercialized vaccine was introduced, people mostly use traditional ways such as medicinal plants to battle infectious diseases. Plants that have antibiotic properties such as ginger, echinacea kill some pathogens and benefit the immune system. But using plants as vaccine factories is a relatively new idea because plants do not produce pathogens or human proteins. Not until plant genetic engineering technologies have been in the playing for the past 3 decades which allows foreign gene expression in plant systems. Plants can accumulate very large biomass in fields or greenhouse settings, without complex bioreactor, thus they can produce high amounts of recombinant proteins at a very low cost. Plant vaccines are generally considered much safer than using bacteria, fungal, and mammalian cell cultures because of no other biocontamination of animal’s origin and no live pathogens. There are several successful examples, such as the Protalix, an Israeli company, has developed plant-based biopharmaceuticals in cultured transgenic carrot or tobacco cells, and has received approval from the United States Food and Drug Administration (FDA) of the United States for taliglucerase alfas for Gaucher’s Disease.
Various plants such as tobacco, rice, maize, potato, alfalfa, lettuce, tomato, carrot, peanut, and soybean are used as hosts for foreign gene expression. Cereal crops are promising for vaccine production because seeds are in high amounts of protein and oil, vaccines in seeds can stand over very long storage periods without deterioration in quality. Oral plant-based vaccines are ideal because the manufacturing process is simple, no additional medical devices are needed; and the antigen immunogenicity activities are preserved in the gastrointestinal tract. Oral plant-based vaccines have been developed in edible plants, including rice, maize, potato, lettuce, and carrot. Once these vaccines pass through the gastric environment and reach the small intestine, antigens are incorporated into M cells in the follicle-associated epithelium (FAE) for the induction of mucosal and systemic immune response. The injection type needs further purification process which is most suitable for infections via a systemic or respiratory route. These antigens are often produced in tobacco plants using a transient expression. The choice of the plant species and technology depends on vaccine types and administration routes.
As the coronavirus disease 2019 (COVID-19) continues to spread, people around the world are anxious to know when we might have a vaccine to stop it. Although more than 100 possible vaccines in various stages are under development, there is currently no vaccine to prevent the COVID-19. Many of the preclinical programs exist on paper rather than in reality. Front runners such as adenovirus vaccine, mRNA vaccine, inactivated virus, and protein subunit are entering phase1 or 2. Virologists are not very optimistic that hundreds of millions of doses of vaccine might be ready for roll-out by the end of 2020.
Tobacco giants, British American Tobacco (BAT), the company that manufactures global cigarette brands such as Lucky Strike, Pall Mall, Newport, and Camel cigarettes, says it’s using tobacco plants in the manufacturing process of its experimental COVID-19 vaccine. Its biotech subsidiary, Kentucky BioProcessing (KBP), has been completing pre-clinical testing and the potential vaccine has been shown to produce a positive immune response. The vaccine candidate is progressing to the next stage which will be Phase 1 human clinical trials pending FDA authorization. The company’s goal is to produce from 1 million to 3 million doses of a coronavirus vaccine per week. People argue that smoking raises the amount of an enzyme called angiotensin-converting enzyme 2 (ACE2) present in the human lungs —which is a problem since the novel coronavirus binds to ACE2. However, we should not worry about that because the protein subunit produced in tobacco cells needs to be purified before injection administration.
Thanks to plant biotechnology we are able to manufacture substances from plants by introducing designed genetic material into their genome. This contains information that enables the production of medicines such as antibodies, vaccines, and other products. Hopes are high the technique, which harnesses the plant’s cells could eventually help pave the way to producing a COVID-19 vaccine. It can produce large amounts of the required protein, is low-cost compared to other methods, and is safe. Plants are very useful as they are capable of expressing viral proteins or nucleic acids without having to work with the causative virus.