Plant-Based Vaccines: A Promising Alternative Approach for Vaccine Production
Plant-based Vaccines
Naufan Cmi
History and Advantages of Plant-Based Vaccine Production
Plants have long been investigated as a means for producing vaccines and therapeutics due to a number of key advantages over traditional production methods. While the concept of plant-based vaccines dates back to the late 1980s, research and development in this area has accelerated in recent decades. Some of the main benefits of plant-based production include lower costs, scalability, and easier storage and distribution.
Plants Based Vaccines provide a very cost-effective platform for manufacturing biologics compared to egg- or cell-based systems. They do not require expensive fermentation equipment or facilities compliant with good manufacturing practices. Furthermore, plants can be grown on a large scale in greenhouses or fields, allowing for mass production to meet global demand. It is estimated that a single acre of plant biomass could potentially produce hundreds of kilograms of target proteins.
The stability of plant cells also means that vaccines produced within plants do not require strict cold chain requirements for storage and transport. This makes plant-based vaccines highly suitable for use in low-resource settings that lack reliable refrigeration infrastructure. Thermostable plant vaccines could reach more vulnerable communities currently facing difficulties accessing life-saving immunizations.
Expression of Vaccine Antigens in Plants
Various plant species have been utilized as bioreactors for recombinant protein expression, with tobacco, potato, and legumes being among the most widely investigated. The first step is introducing a gene encoding the desired antigen protein into the plant genome using Agrobacterium-mediated transformation or particle bombardment. The gene is regulated by a strong, constitutive promoter to maximize yield.
Once successfully integrated and expressed, the antigen protein will accumulate inside different plant tissues depending on the chosen promoters. For instance, using chloroplast promoters results in high levels of antigen accumulation within chloroplasts. Cytoplasmic and nuclear promoters target expression to other subcellular locations such as the cytoplasm, endoplasmic reticulum, vacuoles, or storage organs. Tissues commonly harvested for antigen purification include leaves, fruits, tubers, and seeds.
Some examples of disease antigens that have been reconstituted in plants include the Ebola virus glycoprotein, rotavirus VP6 proteins, Norwalk virus capsid proteins, and anthrax protective antigen. Studies show these antigens produced the expected immune response in animal models when administered as an edible vaccine or injectable subunit vaccine. Overall, plants have proven capable of functioning as mini-factories to produce diverse subunit vaccine components.
Plant-Based Vaccines in Clinical Trials and Beyond
With encouraging preclinical data accumulated over decades, several plant-produced vaccine candidates have now entered clinical testing. One of the lead projects is Medicago's coronavirus-like particle (CoVLP) vaccine against COVID-19, which is currently in Phase 3 trials. Initial results indicate the plant-derived VLP elicits a promising antibody response comparable to other authorized vaccines.
Another key player is the biotech company iBio, which has ongoing Phase 1/2 trials for its plant-produced influenza VLP vaccine IBIO-200. Their VLP technology offers scalability and easier production compared to egg-based flu vaccines. Preliminary data again found IBIO-200 to be well-tolerated and immunogenic in healthy adults.
On the regulatory front, the first plant-based vaccine approval could happen as soon as 2022. The FDA has granted Fast Track status to Medicago's COVID-19 VLP candidate, reflecting its confidence in this novel expression platform. Positive Phase 3 results would support an accelerated review pathway and potential authorization. As for Canadian regulators, they have stated plant-produced vaccines meeting appropriate standards could receive approval in Canada.
Going forward, plant-based systems offer the ability to rapidly manufacture large amounts of numerous vaccine candidates during an outbreak scenario. Researchers are also investigating fusion of antigens to facilitate single-dose immunization or combinations targeting multiple pathogens. With continued validation from late-stage clinical testing, plant vaccines could emerge as a competitive force to help address unmet global vaccination needs.
Concluding Thoughts
In summary, plant molecular pharming represents an innovative solution for sustainable vaccine development and production. Compared to traditional egg- and cell-based methods, plant platforms provide economic and logistical advantages due to quicker scale-up, lower costs, and thermostability. Decades of preclinical studies have demonstrated a wide array of disease antigens can be safely expressed in plants and induce protective immune responses in animal models.
Now with Phase 3 trials ongoing for leading anti-COVID and influenza candidates, the first regulatory approvals of plant-produced vaccines may occur within the next year or two. As the technology continues advancing, plant bioreactors have great potential to become a principal means of affordable mass manufacturing for both existing and novel vaccines globally. With their benefits, plant-based vaccines show significant promise to improve immunization coverage worldwide.
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About Author:
Money Singh is a seasoned content writer with over four years of experience in the market research sector. Her expertise spans various industries, including food and beverages, biotechnology, chemical and materials, defense and aerospace, consumer goods, etc.
