Fusion proteins with multiple copies of the major antigenic determinant of foot-and-mouth disease virus protect both the natural host and laboratory animals.

Proteins consisting of one, two or four copies of the amino acid sequence 137 to 162, which contains the major immunogenic site of VP1 of foot-and-mouth disease virus, attached to the N-terminus of beta-galactosidase have been expressed in Escherichia coli cells. In guinea-pigs the protein containing one copy (P71) of the viral determinant elicited only low levels of neutralizing antibody whereas protective levels were elicited by the proteins containing two (P72) or four (P74) copies of the determinant. Single inoculations of the P72 and P74 proteins containing as little as 2 micrograms or 0.8 micrograms of peptide respectively were sufficient to protect all the animals against challenge infection. Moreover, the equivalent of 40 micrograms of peptide in P74 protected pigs against challenge infection after one inoculation.