SUMMARY A single dose of foot-and-mouth disease ( fmd ) virus protein 1 ( vp 1) 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 vp 1 from the A12 strain (A12) of FMD virus ( fmdv ; A1232dimer) in a tandem repeat configuration of aa 137 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 aa 131 through 157 from vp 1 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 aa 131 and aa 168 was evaluated.
A DNA sequence coding for the immunogenic capsid protein VP3 of foot-and-mouth disease virus A12, prepared from the virion RNA, was ligated to a plasmid designed to express a chimeric protein from the Escherichia coli tryptophan promoter-operator system. When Escherichia coli transformed with this plasmid was grown in tryptophan-depleted media, approximately 17 percent of the total cellular protein was found to be an insoluble and stable chimeric protein. The purified chimeric protein competed equally on a molar basis with VP3 for specific antibodies to foot-and-mouth disease virus. When inoculated into six cattle and two swine, this protein elicited high levels of neutralizing antibody and protection against challenge with foot-and-mouth disease virus.
SUMMARY Four groups of 9 cattle each were vaccinated with 10, 50, 250, or 1,250 μg of foot-and-mouth disease ( fmd ) virus A12 VP1 fusion protein that was produced in Escherichia coli and emulsified in an oil adjuvant. The groups given the 10 and 50 μg of antigen were revaccinated at 15 weeks and were challenge exposed at 30 weeks; 5 of 9 and 7 of 9 cattle, respectively, were protected from fmd virus infection. The remaining 2 groups, vaccinated with 250 or 1,250 μg of antigen, were revaccinated at 32 weeks and were challenge exposed at 45 weeks; 8 of 9 and 9 of 9 cattle, respectively, were protected. The results indicated that the biosynthetic polypeptide fmd vaccine was effective using vaccination intervals frequently followed with conventional whole-virus vaccines.
The immunogenic capsid protein (VPt), circa 30 kilodaltons (kd), of foot-and-mouth disease virus was examined for (i) its ability to induce neutralizing antibody in guinea pigs after chemical modifications and CNBr or tryptic cleavages and (ii) N-terminal amino acid sequence homology across three virus types. The immunogenicity of VPt was inactivated by glutaraldehyde treatment, carboxymethylation and maleylation or citraconylation. However, de-citraconylation restored part of the lost activity. Cleavage of type A12 VPt with CNBr produced an immunogenic peptide of circa 13 kd. A slightly larger (ca. 16 kd) immunogenic doublet, VPτa¾, was obtained by tryptic cleavage of VPt in the virion. Sequence homologies of circa 85% were found between the first 26 amino acids at the N-terminus of VP chains from virus types A12 strain 119 (A12), C3 Resende (C311) and Oi Brugge (Oib).
