Characterization of the immunodominant antigens of Porphyromonas gingivalis 381 in high-responder patients

The immunodominant antigens of Porphyromonas gingivalis 381 whole cells that reacted with sera from high-responder patients were examined in this study. Whole cells, phenol-water extracted lipopolysaccharide, and fimbriae from P. gingivalis 381 were analyzed using sera from 14 patients with adult periodontitis, rapidly progressive periodontitis or juvenile periodontitis as well as from two healthy subjects. Western blot analysis and enzyme-linked immunosorbent assay (ELISA) were performed. On Western blots, among many prominent protein bands, a smear was observed which was removed after adsorption of the sera with P. gingivalis phenol-water extracted lipopolysaccharide. Two major protein bands of 43 kDa and 41 kDa were found to be prominent even at very high dilutions of sera, the latter of which showed the same molecular weight as the fimbrilin band. These two bands were resistant to treatment by papain and trypsin. ELISA titers remained high after adsorption of the sera with P. gingivalis phenol-water extracted lipopolysaccharide. The results of this study suggest that the 43-kDa and the fimbrilin (41 kDa) proteins may play an important role as immunodominant antigens of P. gingivalis 381.