Isolated polypeptides are provided that comprise a cholera toxin B subunit variant having one or more modifications to increase the expression of the polypeptide in a plant cell. Nucleic acids sequences, vectors, and plant cells for expressing the cholera toxin B subunit variant polypeptides are also provided. Further provided are methods for producing the cholera toxin B subunit variant polypeptides that include the steps of transforming a plant cell with a nucleic acid encoding the cholera toxin B subunit variant polypeptides expressing the variant polypeptides and purifying the polypeptides. Still further provided are methods of isolating the variant polypeptides that include the steps of obtaining a plant cell expressing the cholera toxin B subunit variant polypeptides extracting the cholera toxin B subunit variant polypeptides from the plant cell and purifying the cholera toxin B subunit variant polypeptides. Methods of eliciting an immune response are also provided.
