SUMMARY
A single dose of foot-and-mouth disease (fmd) virus protein 1 (vp1) peptide, expressed in Escherichia coli as a fusion protein with 190 amino acids (aa) of the LE' protein of the tryptophan operon of E coli, elicited an immune response in steers sufficient to withstand the challenge of exposure to animals with acute fmd. The 58-μg dose of viral peptide, composed of a segment of the vp1 from the A12 strain (A12) of FMD virus (fmdv; A1232dimer) in a tandem repeat configuration of aa137 through 168 and emulsified with oil adjuvant, elicited a serologic response in cattle equivalent to that obtained using conventional whole virus vaccines. Two groups of swine were vaccinated, 1 with the A12-32dimer as used in cattle and 1 with aa131 through 157 from vp1 of the A24 strain (A24) of fmdv (A24-peptide), expressed in the same system as A12-32dimer, but as a single copy per molecule. In swine, the 58-μg dose of the A12-32dimer repeated at 28 days was an effective immunogen; all swine were protected against A12 and, in addition, the vaccine protected 50% of the swine against A24. The 29-μg dose of A24-peptide, administered according to the same schedule, elicited protection against A24 in 50% of the vaccinates and, in addition, protected 25% of those vaccinates against A12. The serologic response elicited by A12-32dimer against A24 virus was considerably greater than the response elicited by A24-peptide against A12 virus. The evidence of multiple immunogenic epitopes between aa131 and aa168 was evaluated.
