Immunogenicity comparison of three multi-epitope proteins expressed in Escherichia coli against swine foot-and-mouth disease virus serotype A

Abstract:

[Objective] A multi-epitope protein vaccine of foot-and-mouth disease virus (FMDV) serotype A was developed to provide a safe and effective candidate vaccine for the prevention and control of FMD in pigs. [Methods] We designed and synthesized multi-epitope immunogenic genes A10, IA10 and FA10 based on the results of previous experiments and the global epidemiological information of FMDV serotype A. The expressed proteins were emulsified with ISA 201 adjuvant to immunize pigs. Serum IgG antibody titers were detected by liquid phase blocking ELISA at 0, 14 and 28 days post-immunization. All pigs were challenged with virulent FMDV A/HNLY4/2014 after a single inoculation. [Results] Three recombinant proteins were successfully expressed in E. coli and specific bands of approximately 35, 57 and 64 kDa, which were consistent with the expected size of the recombinant proteins A10, IA10 and FA10, respectively. The recombinant proteins were also recognized specifically by the anti-FMDV (type A) antibodies. A10+201 induced lower level of total IgG antibodies than the inactivated vaccine, but higher than other groups. All pigs (100%) immunized with A10+201 and inactivated vaccine were completely protected against virulent FMDV challenge. Four out of five pigs (80%) immunized with IA10+201 and FA10+201 were protected and only one out of five pigs (20%) immunized with A10 and FA10 were protected. All pigs inoculated with PBS+201 were unprotected. [Conclusion] A10+201 conferred the greatest protection against FMDV serotype A challenge in pigs and can be further evaluated as a candidate vaccine.