Expression and Manufacture of Pharmaceutical Proteins in Genetically Engineered Horticultural Plants - Transgenic Horticultural Crops: Challenges and Opportunities - page 94

FIGURE 4.2 (See color insert.) .Human.volunteers.ate.transgenic.potatoes.in.a.clinical.
trial. study. by. Tacket. et. al. 238 . Transgenic. potatoes. expressing. LTB. antigen. were. peeled,.
diced,.and.consumed.by.human.volunteers..Non-transgenic.potatoes.were.used.as.negative.
controls.
vaccines. in. plant. tissue. will. circumvent. major. infrastructural. challenges. in. vac-
cine. storage,. distribution,. and. delivery. and. allow. the. realistic. implementation. of.
an.immunization.program.in.countries.where.the.“cold-chain”.and.other.medical.
supplies. are. limited. 116 . The. optimal. candidates. for. oral. subunit. vaccine. develop-
ment. in. plants. are. aggregated. pathogen. protein. complexes. as. they. are. naturally.
recognized.at.mucosal.sites..For.example,.viral.surface.proteins.that.assemble.into.
VLPs. spontaneously. and. bacterial. toxins. that. naturally. aggregate. to. form. multi-
meric.complexes.have.been.explored.as.plant-derived.oral.vaccine.candidates. 117-119 .
These.natural.mucosally.targeted.protein.complexes.have.also.been.studied.as.car-
riers.for.developing.other.plant-derived.oral.vaccines.as.they.can.be.linked.to.other.
antigens.by.protein.fusion.technologies. 99,120,121 .So.far,.moderate.success.has.been.
achieved. in. the. development. of. plant. oral. vaccines. as. many. vaccine. candidates.
have.been.expressed.in.edible.plant.parts,.and.ive.human.clinical.trials.have.been.
performed.with.orally.delivered.plant-produced.vaccines.(Table.4.2). 122-125 .Results.
from. clinical. trials. indicated. that. serum. antibodies. and,. in. some. cases,. mucosal.
antibodies.can.be.successfully.stimulated.by.plant-derived.oral.vaccines..Although.