Bacterial Toxin Fusion Proteins Elicit Mucosal Immunity against a Foot-and-Mouth Disease Virus Antigen When Administered Intranasally to Guinea Pigs

Figure 2

(a) Predicted structure of vaccine constructs. Wild-type LT binds to GM1 receptors upon pentamerization of LT-B and translocates the toxic LT-A subunit into host cells. LTA2B-GH is predicted to pentamerize in a similar fashion to the wild-type toxin, thereby, presenting five copies of the G-H loop to the host. ntPE-LTA2B-GH additionally contains ntPE in place of LT-A1 in order to expand receptor repertoire of the vaccine. (b) Amino acid sequence of the “TCA” peptide. The N-terminus consists of a promiscuous T-helper cells epitope from VP4 of FMDV (bold), followed by linking amino acids GG (underlined), “site C” from VP1 (bold), another linker sequence (PPS, underlined), and site A (the G-H loop). (c) GM1 ELISA to illustrate the pentamerization of LTA2B-GH and ntPE-LTA2B-GH. Microtiter plates were coated with GM1 and incubated with CTB, TCA peptide, ntPE, LTA2B-GH, and ntPE-LTA2B-GH. Then they were tested with anti-G-H, anti-CTB and anti-ntPE antibodies to illustrate the GM1-binding capacity of fusion proteins. ***𝑃 value < 0.001 according to ANOVA and post-hoc Tukey-Kramer multiple comparison test.