New Strategies Toward Edible Vaccines: An Overview

Abstract

With the ever growing population, advancements in edible vaccines and related technologies have seen a rise in popularity. Antigenic peptides incorporated into an edible part of a plant can be administered raw as a vaccine. While conventional vaccines have improved the quality of life by drastically reducing the onset of diseases, edible vaccines are able to perform the same with greater accessibility and at an affordable price. Low cost of production, ease of storage, transportation and administration are some of the many reasons behind the push for the development of edible vaccines. This article aims at giving an overview of the different plant systems used to produce vaccines in various experiments, as well as the merits and demerits of using that particular expression system. Further, the article elaborates on the problems faced in the production of edible vaccines and the measures adopted to surpass them. The major obstacle in the process is attaining a sufficiently large concentration of foreign antigen in the plant system. The article discusses various plant expression systems like banana, rice, alfalfa, mushroom, potato, tomato, pea, tobacco, and maize. When these were reviewed, it was found that the inability to produce the desired antigen concentration was one of the primary reasons why edible vaccines sometimes fail to generate the desired level of immune response in the recipient. We conclude with a promising solution to the problem by incorporating nano-technological advancements to the already existing protocols for edible vaccine development.

An edible vaccine development for coronavirus disease 2019: the concept

“…The first plant-derived rabies vaccine was produced in tomatoes and offered the advantages of high biomass yields and the increased containment by growth in greenhouses. Lettuce and bananas have also been utilized for the production of plant-based vaccines [ 8 9 10 ].…”

“…The current status of plant-based vaccine and their clinical evaluation are summarized in Table 1 [ 4 5 ]. The plant-based vaccine development idea was started 30 years ago and since then many vaccine proteins have been produced in plants for human and animal diseases [ 6 7 8 9 10 ]. Since more than 20 years, plant science has grown tremendously and shown great importance towards molecular pharming and have significant achievements in large scale with low cost production of recombinant proteins, enzymes, and pharmaceuticals compounds.…”

Disease Prevention: An Opportunity to Expand Edible Plant-Based Vaccines?

“…In that sense, edible vaccines appear to be more promising in terms of animal vaccination [4,5,96], although the quality and safety of raw plant materials need to be assured. Another limitation of edible vaccines is the uncertainty related to the calculation of adequate oral administration dosage, which may require several rounds of administration, increasing the final cost of its application [97,98]. As long as the production costs remain high and a proper estimation of necessary antigen concentration remains unresolved, the future of edible vaccines will be as uncertain as that of traditional oral vaccines.…”

“…This transgenic plant was developed based on the expression of a capsid protein of Norwalk virus. Protein accumulation of up to 8% of the soluble protein was observed in the unripened fruit, with lower accumulation in red ripened fruits [98,115]. Expression in plant seeds allowed storage of the antigenic peptide and thus generated a plant with a high yield of protein expression; the protein content was estimated at 20% to 40% [98,115], and thus extraction of the pharmaceuticals would not require extensive purification procedures [98].…”

“…Pea plants have also been used for expression of the hemagglutinin protein (H), a PA against rinderpest virus. The level of expression was determined by Western Blot and was observed to be between 0.12% to 49% of the total soluble protein in leaves [98,136]. Thus, further studies to optimize protein expression in transgenic peas are needed.…”