LTB and tuberculosis: To increase immunogenicity, the ESAT6 antigen was fused with other tuberculosis antigens (Ag85B and Mtb72F) [3, 20, 40, 41] or adjuvants (CTB: cholera toxin B subunit, LTB: Escherichia coli heat-labile enterotoxin B subunit, LipY: a cell wall protein, and ELP: elastin-like peptide) [3, 7, 42] and expressed in various plant species (Arabidopsis thaliana, tobacco, and lettuce).