Presentation of foreign antigenic determinants at the bacterial cell surface using the TraT lipoprotein

The TraT protein is an oligomeric outer membrane lipoprotein, specified by plasmids of the IncF group, that is very highly exposed at the bacterial cell surface. We have investigated the feasibility of using the protein as a carrier of foreign antigenic determinants by genetic insertion of the C3 epitope of type 1 poliovirus into defined sites in the protein. Several of the hybrid proteins constructed had features characteristic of the native protein and one in particular retained the ability of function in surface exclusion and genetic suppression assays as well as to assemble into oligomers. Our results suggest that the TraT protein can be used to transport and present foreign antigenic determinants at the cell surface.