Gene Cloning and Expression of A Bacteroides Gingivalis-Specific Protein Antigen in Escherichia Coli

¹ Department of Biochemistry, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakaecho-Nishi, Matsudo, Chiba 271, Japan

Gene banks of chromosomal DNA from Bacteroides gingivalis 381 were constructed utilizing the bacteriophage replacement vector Charon4A. A clone encoding a protein antigen from ,B. gingivalis was identified by Western-blot screening, with use of antiserum induced to extracts of B. gingivalis cells. DNA fragments from the phage clone were subcloned into the plasmid vector pACYC184 to yield an immunoreactiveclone. Cell extracts from the subclone reacted with antiserum against B. gingivalis, but did not react with antisera to B. asaccharolyticus, B. intermedius, or B. melaninogenicus. The antiserum against the purified clone products reacted with N-lauryl sarcosine extracts from B. gingivalis cells, but did not react with those of other Bacteroides cells. In addition, human serum from periodontitis patients reacted with the clone product by Western electrophoretic transfer and immunoblotting analysis. These data suggest that the gene coding for a B. gingivalisspecific protein antigen was successfully cloned and functionally expressed in Escherichia coli. This clone product may prove useful for further studies of B. gingivalis as a periodontal pathogen.