A total of 50 models were generated for the tag-less CFA/I/II/IV MEFA proteins. The one with the top conformer score showed a structure similar to backbone CFA/I CfaB subunit (Figure 2). Epitopes of the CFA/I, CS1, CS2, CS3, CS4, CS5 and CS6 in the tag-less MEFA protein were surface-exposed (Figure 2).