Cross-Reactive Monoclonal Antibodies Induced by Lps from Periodontopathic Bacteria

¹ Department of Microbiology, Tokyo Dental College, 1-2-2 Masago, Chiba City 260, Japan

Monoclonal antibodies against lipopolysaccharides (LPS) of Fusobacterium nucleatum ATCC 25586 and Eikenella corrodens FDC 1073 were used for the study of antigenic characteristics of periodontopathic bacteria.

LPS was extracted by the hot-phenol/water method. Three monoclonal antibodies (isotype IgM) against F. nucleatum ATCC 25586 were cross-reactive with LPS from E. corrodens FDC 1073. Four hybridomas producing antibody to E. corrodens FDC 1073 LPS were also obtained. Three out of four monoclonal antibodies (isotype IgM) were found to exhibit cross-reactivity with LPS from F. nucleatum ATCC 25586. These six monoclonal antibodies reacted with four out of seven E. corrodens and nine out of 27 F. nucleatum clinical isolates. Western immunoblotting analysis demonstrated that the six antibodies reacted with a similar fast-migrating band of LPS from F. nucleatum ATCC 25586 and E. corrodens FDC 1073. Another monoclonal antibody (isotype IgG3) against E. corrodens FDC 1073 LPS exhibited cross-reactivity with LPS from Fusobacterium necrophorum ATCC 25286 and Capnocytophaga ochracea M-12. This antibody was found to react with slow-migrating bands of E. corrodens FDC 1073 LPS and a fast-migrating band of LPS from F. necrophorum ATCC 25286 and C. ochracea M-12 by Western immunoblotting analysis. Four out of seven clinical isolates of E. corrodens reacted strongly with this antibody.

The present findings indicate that there is a common LPS core epitope between F. nucleatum ATCC 25586 and E. corrodens FDC 1073. They also indicated that the O-side-chain epitope of E. corrodens FDC 1073 might be common to the LPS core epitopes of F. necrophorum ATCC 25286 and C. ochracea M-12.