We concluded from this and our earlier work that biosynthetically produced FMDV VP1-specific fusion proteins are effective vaccines. Whether this method of vaccine production can be extended to many other immunogenic proteins from other organisms is not known. Some problems that could be expected to occur with bacterially produced antigens are that the immunogenic site may not be properly exposed or the peptide sequence(s) within that site may not be able to form into the correct configuration. This could be caused by hydrophobic or hydrophilic interactions in the fusion protein that do not occur in the protein at the virus surface. Also, the immunogenic site may require disulfide bonding to bring two distant parts of a protein or two different peptide chains into close proximity to form an antigenic site, as demonstrated by the studies of Atassi et al. for lysozyme-using synthetic peptides. In summary, the use of genetically programmed bacteria is a promising avenue to vaccine manufacture. For FMD, biosynthetic protein vaccines have significant advantages over current whole-virus technology.