Plant-Derived Booster Vaccines or Adjuvants

Dear Colleagues, 

Plants have been used for millennia for medicinal purposes. Despite the development of chemically synthesised drugs, those of herbal origin still constitute one of foundations of modern pharmacotherapy. Moreover, biotechnology, including that based on genetic engineering, together with related sciences and advanced analytical tools, has opened new areas for the application of plant-derived products in biomedicine. Biopharmaceuticals may comprise both natural chemicals as well as recombinant proteins or other substances produced in plants with modified biosynthesis pathways. Among various types of biopharmaceuticals, vaccines remain one of the most important and most often produced in plant-based systems.

Plants offer an attractive platform for vaccines because of their low cost, safety (since they are innately free of human and zoonotic pathogens), and the option of oral immunisation. The primary idea for plant-based vaccines was to use raw tissues as “edible vaccines”. Although the efficacy of this vaccination method proved to be limited, mainly due to the mechanisms of GALT functioning and oral tolerance, emerged issues stimulated multidirectional studies on the improvement of plant-produced vaccines and their administration. These include the development of expression vectors adapted to various hosts, plant-material processing and formulation, as well as immunisation schemes. Eventually, it can be said that the initial concept of “edible vaccines” evolved to plant-derived orally administered booster vaccines. Such vaccines can be used even against blood-borne pathogens, where most often a systemic immune response is required, while the mucosal one may play a supplementary role. Recent examples of vaccines against hepatitis B, polio, or infectious bursal disease demonstrate that, although many factors still need to be established, not only plant-derived purified and injectable biopharmaceuticals, but also oral vaccines still have a promising potential.

Plants can serve not only as vaccine producers and carriers, but simultaneously as source of chemicals of immunostimulatory properties. Many natural plant compounds may act as mucosal or systemic adjuvants, as lectins, flavonoids, carotenoids, oils, or saponins, which are the key components of one of the most potent adjuvant and antigen delivery systems—ISCOMATRIX™. Apart from these, thanks to genetic engineering, plants can produce proteins enhancing immune response, acting as adjuvants, immunomodulators, epitope carriers, or structures combining these activities (e.g., LTB, CTB, interleukins, or various virus-like particles).

This Special Issue will focus on more recent studies dealing with plant-based booster vaccines, especially those that are orally administered, together with natural and recombinant adjuvants, including their production systems, processing, administration, effects on the immune system, and mechanisms of action. Toward this purpose, original research articles, reviews, and short communications are welcome.

Prof. Dr. Tomasz Pniewski
Guest Editor

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• plant-derived vaccine
• booster vaccine
• oral vaccine
• mucosal adjuvant
• systemic adjuvant
• virus-like particles
• immune response
• immunomodulatory effect
• plant expression system
• vaccine preparation