Synthetic peptide vaccines against foot-and-mouth disease. II. Comparison of the response of guinea-pigs, rabbits and mice to various formulations.

The immune response of guinea-pigs to vaccination with either of two aphthovirus-specific synthetic peptides was investigated. One peptide copied the sequence of amino acids 141 to 160 from the VP1 of aphthovirus strains O1BFS 1860 and O1 Kaufbeuren (O peptide), the other copied the equivalent sequence from aphthovirus strain A24 Cruzeiro (A peptide). The immune response was enhanced when the peptides were conjugated to a carried protein, but the choice of carrier protein and cross-linking agent was not critical in obtaining enhancement. The response was greatest when the peptide or peptide-carrier conjugate was adjuvanted in Freund's complete adjuvant (FCA). The O peptide was poorly immunogenic and did not confer protection against challenge with infectious virus, whereas the A peptide had good immunogenicity and did confer protection. This reflected the relative immunogenicity of the parent viruses. Rabbits, three strains of guinea-pigs and seven strains of mice were vaccinated with the O peptide conjugated to keyhole limpet haemocyanin (KLH). Considerable variation was observed between the responses of each strain and it is proposed that this relates to their repertoire of immune response genes.