Plant-delivered Cholera Toxin B subunit as an Immunomodulatory Molecule

<p>The B subunit of cholera toxin (CTB) functions as an effective mucosal carrier molecule of chemically or genetically conjugated antigens. Orally delivered CTB or CTB fusion protein binds to G_M1-ganglioside receptor molecules located on cells in the gutassociated lymphoid tissues, the site of immunological induction. We have generated transgenic plants synthesizing CTB conjugated with vaccine antigens for food plant-based prevention of cholera and rotavirus toxin-induced diarrhea and for autoimmune diseases such as insulin-dependent diabetes mellitus (IDDM).</p> <p>Mice fed with transgenic potato tubers synthesizing 0.3% of CTB as total tuber protein generated serum and mucosal antibodies with toxin neutralizing capability. The immunized mice were partially protected from diarrhea induced by intraileal inoculation of cholera holotoxin. A 22-amino acid rotavirus enterotoxin NSP4 epitope was fused at the C-terminus of the CTB subunit. Transgenic potato tubers synthesized up to 0.1% of total soluble protein as the pentameric CTB-NSP4 fusion peptide.</p> <p>To prevent IDDM, we generated transgenic potato plants synthesizing the IDDM autoantigens, insulin and glutamic acid decarboxylase and their conjugate proteins with CTB. Transgenic potato plants synthesizing the fusion proteins significantly reduced pancreatic inflammation (insulitis) and clinical diabetes when fed to nonobese diabetic mice. Potato tissues producing comparable amounts of insulin or glutamic acid decarboxylase alone conferred only low levels of protection against insulitis, suggesting that conjugation with CTB markedly increases the tolerogenicity of autoantigens.</p> <p>Since autoimmune diabetes is often linked to the consumption of bovine milk and its products, we took a novel approach to prevention of DDDM in non-breast fed infants and children by producing transgenic food plants synthesizing human milk proteins. We have synthesized human p-casein and lactoferrin in food plants as these are prototypical casein and whey proteins in human milk. In addition to nutritional enhancement, lactoferrin may provide antimicrobial activity against a variety of enteropathogens including rotavirus. Construction of food plants synthesizing vaccine antigens as well as antimicrobial human milk proteins may be a safe, inexpensive, and convenient method for the prevention of infectious and autoimmune diseases for people living in developing countries.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Microbiology

Year

1998

Author dc:creator

• Arakawa, Takeshi

Contributors dc:contributor

• William H. R. Langridge
• Alan P. Escher
• Istvan Fodor
• Benjamin H. S. Lau
• Giuseppe Molinaro

• Microbiology
• Molecular Genetics
• Cholera Toxin -- genetics; Vibrio cholerae -- immunology; Plants, Transgenic -- pharmacology; Glutamic Acid -- metabolism; Rotovirus; Plant Proteins -- genetic; Adjuvants, Immunologic -- physiology.

Statement dc:rights

• This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Language dc:language

English

Repository record dc:identifier

https://scholarsrepository.llu.edu/etd/804

OAI identifier oai:identifier

oai:scholarsrepository.llu.edu:etd-1945