Protection of swine against foot-and-mouth disease with viral capsid proteins expressed in heterologous systems

Three groups of swine were each inoculated with a different antigen preparation of foot-and-mouth disease virus (FMDV) capsid proteins and challenged by contact exposure to animals infected with FMDV. One group of four animals was inoculated with an extract from cells infected with a recombinant baculovirus containing the FMDV P1-2A structural protein precursor gene and a portion of the P2 gene. Two out of four animals were protected from clinical disease, but not from virus replication. A second group of animals was inoculated with an extract from Escherichia coli that expressed FMDV proteins from a construct containing the P1-2A gene, a portion of the P2 gene and the 3C protease gene. Three out of four animals in this group did not develop clinical signs of FMD upon challenge and two of four were protected against virus replication. In contrast, inoculation of a third group of swine with an extract from E. coli expressing the same FMDV construct as present in the recombinant baculovirus failed to protect any of the four animals from generalized FMD.