Practice question

Edible vaccines utilize transgenic plants as low-cost production and oral delivery systems synthesizing recombinant immunogens in edible tissues. Concept pioneered by Charles Arntzen 1990 proposing foods containing antigens could be eaten eliminating purification, cold chain, sterile needles, medical personnel and hazardous waste associated with injections. Plant transformation via Agrobacterium tumefaciens binary vector carrying antigen gene driven by constitutive CaMV 35S promoter or tissue specific patatin, glutelin for seed accumulation, plus signal peptide targeting to endoplasmic reticulum for glycosylation and stability. Plants such as potato, tomato, lettuce, rice, banana accumulate antigen at 0.01-0.3 percent total soluble protein in leaves tubers fruits seeds. Bioencapsulation within plant cell wall composed of cellulose lignin protects antigen from gastric acidic pH 1-2 and pepsin digestion until arrival in small intestine where gut microbiota cellulases degrade wall releasing antigen near Peyer's patches M cells that translocate antigen to underlying dendritic cells initiating mucosal IgA and systemic IgG. Advantages include scalability agriculture hectares, oral tolerance risk if dose too low causing regulatory T cell induction, and need for dose standardization fruit size variability challenges. Nonetheless plant made vaccines promise for livestock and developing regions.