The potential protective immune responses to synthetic peptides containing conserved epitopes of Porphyromonas gingivalis fimbrial protein.

The immunodominant and T-cell epitopes within the fimbrial subunit protein (fimbrilin) of Porphyromonas gingivalis strain 381 were analysed by multi-pin peptide synthesis technology. Six regions with immunodominant epitopes within a sequence of 337 amino acids that reacted with the serum of patients with adult periodontitis were detected. T cells from mice immunised with P. gingivalis fimbriae exhibited proliferative responses to P. gingivalis fimbriae or to six 10-mer synthetic peptides from the amino-acid sequence of the fimbrillin. Three synthetic peptides that contained the regions responsible for the immunodominant epitopes as well as those which coincided with a T-cell epitope of P. gingivalis fimbrial molecules--FP38 (142-161), FP381(202-221) and FP381(216-243)--were selected and synthesised. When guinea-pigs were immunised with fimbriae or one of the three synthetic peptide segments and an adjuvant in Freund's incomplete adjuvant, enhanced production of the antigen-specific IgG antibodies was induced in the serum of the animals. Furthermore, of the three synthetic peptides tested, FP381(202-221) produced the greatest protective immune response in guinea-pigs infected with P. gingivalis and this was more effective than the native fimbrial protein.