Edible vaccine protects mice against Escherichia coli heat-labile enterotoxin (LT): potatoes expressing a synthetic LT-B gene

• Published in: Vaccine Vol. 16; no. 13; pp. 1336 - 1343
• Main Authors: Mason, Hugh S., Haq, Tariq A., Clements, John D., Arntzen, Charles J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.1998; Elsevier
• Subjects: Administration, Oral; Animals; Antibodies, Bacterial - biosynthesis; Bacterial Toxins - genetics; Bacterial Toxins - immunology; Bacterial Vaccines - administration & dosage; Bacterial Vaccines - genetics; Bacterial Vaccines - immunology; Bacteriology; Base Sequence; Biological and medical sciences; diarrhoeal-disease; E. coli; Eating; enterotoxin-LT-B; Enterotoxins - genetics; Enterotoxins - immunology; Escherichia coli - genetics; Escherichia coli - immunology; Escherichia coli Proteins; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Immunity, Mucosal; Mice; Microbiology; Molecular Sequence Data; mouse; plant-vaccine; Plants, Genetically Modified; potato; RNA, Messenger - biosynthesis; Solanum tuberosum - genetics; Solanum tuberosum - metabolism; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies; Vaccines, Synthetic - administration & dosage; Vaccines, Synthetic - genetics; Vaccines, Synthetic - immunology; mouse; plant-vaccine; enterotoxin-LT-B; diarrhoeal-disease; potato; E. coli; Delivery system; Solanum tuberosum; Escherichia coli; Rodentia; Oral administration; Foodstuff; Vaccine; Subunit; Feeding; Potato; Vertebrata; Mammalia; Immunogenicity; Mouse; Dicotyledones; Angiospermae; Enterotoxin; Bacteria; Spermatophyta; Transgenic plant; Tuber plant; Solanaceae; Recombinant protein; Enterobacteriaceae
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/S0264-410X(98)80020-0

The authors have designed and constructed a plant-optimized synthetic gene encoding the Escherichia coli heat-labile enterotoxin B subunit (LT-B), for use in transgenic plants as an edible vaccine against enterotoxigenic E. coli. Expression of the synthetic LT-B gene in potato plants under the control of a constitutive promoter yielded increased accumulation of LT-B in leaves and tubers, as compared to the bacterial LT-B gene. The plant-derived LT-B assembled into native pentameric structures as evidenced by its ability to bind ganglioside. The authors demonstrated immunogenicity by feeding mice the raw tubers and comparing the anti-LT-B serum IgG and faecal IgA to that produced in mice gavaged with bacterial LT-B. Mice were fed three weekly doses of 5 g tuber tissue containing either 20 or 50 μg LT-B, or gavaged weekly with 5 μg of LT-B from recombinant E. coli. One week after the third dose, mice immunized with potato LT-B had higher levels of serum and mucosal anti-LT-B than those gavaged with bacterial LT-B. Mice were challenged by oral administration of 25 μg LT, and protection assessed by comparing the gut/carcass mass ratios. Although none of the mice were completely protected, the higher dose potato vaccine compared favourably with the bacterial vaccine. These findings show that an edible vaccine against E. coli LT-B is feasible.