A review on edible vaccines and their prospects

For a long time, vaccines have been the main mode of defense and protection against several bacterial, viral, and parasitic diseases. However, the process of production and purification makes them expensive and unaffordable to many developing nations. An edible vaccine is when the antigen is expressed in the edible part of the plant. This reduces the cost of production of the vaccine because of ease of culturing. In this article, various types of edible vaccines that include algal and probiotics in addition to plants are discussed. Various diseases against which research has been carried out are also reviewed. This article focused on the conception of edible vaccines highlighting the various ways by which vaccines can be delivered.

[Production of chimeric tir-intimin protein from E. coli O157:H7 in the tobacco [Nicotiana tobbacum] plant and its immunological evaluation in an animal model]

Escherichia coli [E.coli] O157:H7 is one of the most important pathogenic causes of hemorrhagic colitis in humans. Cattle are the main reservoirs of this bacteria and vaccination is a key mechanism for its control. The intimin, translocated intimin receptor [tir], and EspA proteins are virulence factors expressed by the LEE locus of enterohemorrhagic E. coli. EspA protein is a member of the type III secretion system [TTSS] needle complexes that delivers the tir protein into the host cell. Surface arrayed intimin docks the bacterium to the translocated intimin receptor [Tir]. This intimate linkage is the starting point for attachment and effacing lesions. We hypothesize that the chimeric recombinant forms of two of these three effectors, as edible-based immunogens, would reduce colonization of E. coli O157:H7 in the mice model. We constructed a synthetic gene [it] composed of eae [i] and tir [t] attached together by a peptide linker. The synthetic gene [it] was codon optimized based on the tobacco [Nicotiana tobbacum] plant and cloned into plant expression vectors adjacent to CaMV35S promoters for expression in transgenic tobacco plants. The antigen produced in this plant was orally fed to mice. Immunization of the mice model by the transgenic plant that contained the divalent immunogen showed the presence of IgG antibodies against E. coli O157:H7. This method could be an effective tool for protecting against E. coli O157:H7 hemorrhagic colitis

Transgenic lettuce seedlings carrying hepatitis B virus antigen HBsAg

The obtainment of transgenic edible plants carrying recombinant antigens is a desired issue in search for economic alternatives viewing vaccine production. Here we report a strategy for genetic transformation of lettuce plants (Lactuca sativa L.) using the surface antigen HBsAg of hepatitis B virus. Transgenic lettuce seedlings were obtained through the application of a regulated balance of plant growth regulators. Genetic transformation process was acquired by cocultivation of cotyledons with Agrobacterium tumefaciens harboring the recombinant plasmid. It is the first description of a lettuce Brazilian variety "Vitória de Verão" genetically modified.

Edible vaccines: current status and future.

Edible vaccines hold great promise as a cost-effective, easy-to-administer, easy-to-store, fail-safe and socioculturally readily acceptable vaccine delivery system, especially for the poor developing countries. It involves introduction of selected desired genes into plants and then inducing these altered plants to manufacture the encoded proteins. Introduced as a concept about a decade ago, it has become a reality today. A variety of delivery systems have been developed. Initially thought to be useful only for preventing infectious diseases, it has also found application in prevention of autoimmune diseases, birth control, cancer therapy, etc. Edible vaccines are currently being developed for a number of human and animal diseases. There is growing acceptance of transgenic crops in both industrial and developing countries. Resistance to genetically modified foods may affect the future of edible vaccines. They have passed the major hurdles in the path of an emerging vaccine technology. Various technical obstacles, regulatory and non-scientific challenges, though all seem surmountable, need to be overcome. This review attempts to discuss the current status and future of this new preventive modality.