IMMUNOGENICITY OF A MYCOBACTERIAL T-CELL EPITOPE EXPRESSED IN OUTER-MEMBRANE PROTEIN PHOE OF ESCHERICHIA-COLI

The outer membrane protein PhoE of Escherichia coli can be used for th e expression of foreign antigenic determinants. Previously, a T-cell e pitope of the 65 kDa heat shock protein (hsp65) of Mycobacterium tuber culosis, comprising amino acids 180 to 188, was expressed in PhoE. The hybrid protein induced proliferation of epitope-specific T-cell clone s in vitro. In this report, the potential of the hybrid protein to ind uce an in vivo T-cell response against the 180-188 T-cell epitope was assessed. Popliteal lymph node cells, isolated from rats immunized wit h PhoE containing the hsp65 epitope, showed high proliferative respons es to a synthetic peptide consisting of amino acids 180 to 188 of hsp6 5, indicating that the epitope is immunogenic in the PhoE-associated c onformation.