VP1 B–C and D–E loops of bovine enterovirus cluster B can effectively display foot-and-mouth disease virus type O-conserved neutralizing epitope

Abstract

On the basis of generation of an infectious cDNA clone for the BHM26 strain of bovine enterovirus cluster B (BEV-B), 22 sites on different loops of the BHM26 capsid were selected according to an alignment of its sequence with the structural motifs of BEV-A strain VG-5-27 for insertion of the foot-and-mouth disease virus (FMDV) type O-conserved neutralizing epitope 8E8. Two recombinant viruses, rBEV-A1 and rBEV-DE, in which the FMDV epitope was inserted into the VP1 B–C or D–E loops, were rescued by transfection of BHK-21 cells with the in vitro-transcribed RNA of the recombinant BHM26 genome-length cDNA constructs. The two epitope-inserted viruses were genetically stable and exhibited growth properties similar to those of their parental virus in BHK-21 and IBRS-2 cells, which are susceptible to both BEV and FMDV. However, the two recombinant BEVs (rBEVs) had a significantly lower growth titre than those of the parental virus BHM26 in MDBK and Marc145 cells, which are susceptible to BEV but not to FMDV. These results indicated that insertion of the FMDV epitope into the VP1 B–C or D–E loops of the BEV particle altered the replication properties of BEV. In addition, the two rBEVs were sensitive to neutralization by the FMDV type O-specific mAb 8E8, and anti-FMDV IgG antibodies were induced in mice by intramuscular inoculation with the rBEV-A1 and rBEV-DE viruses. Our results demonstrate that the VP1 B–C and D–E loops of the BEV-B particle can effectively display a foreign epitope, making this an attractive approach for the design of BEV-vectored and epitope-based vaccines.