Assessing Risk of Unintended Antigen Occurrence in Food: A Case Instance for Maize-Expressed LT-B

ABSTRACT

Plant-based antigen production represents an innovative strategy for low cost vaccine production and delivery. Successfully advancing plant-made antigen production in open field systems requires understanding of confinement integrity and consequences of inadvertent occurrence in the food supply. The food safety implications of confinement loss and inadvertent antigen occurrence in the food supply can be effectively addressed using quantitative exposure assessment along with knowledge of properties of specific antigens. We report here a food safety risk assessment for the maize-expressed heat-labile enterotoxin subunit B of Escherichia coli (LT-B). In addition to dietary exposure assessment, food safety considerations for maize-expressed LT-B included assessment of allergenic potential, levels and sites of transgenic protein expression, history of use, post-translational glycosylation, protein processing and digestive stability, mammalian functionality and toxicity, and compositional characteristics of the transformed plant. As shown for LT-B, inadvertent occurrence in the food supply of a plant-produced antigen constitutes a minimal human health concern principally because of limited exposure potential.

Keywords:

• Escherichia coli
• enterotoxin subunit B
• vaccine
• transgenic
• confinement

ACKNOWLEDGEMENTS

We thank P. Song for conducting the allergen homology search for LT-B. This work has been supported through a grant from the Iowa State University Plant Sciences Institute.

Notes

^aReflecting total daily consumption of maize food and food forms (flour, meal, bran, and starch) determined from the Continuing Survey of Food Intake by Individuals (HNRC 1998; USEPA 2003).

^bNot pregnant or lactating.