OriginalProduction of antibody against a synthetic peptide of Porphyromonas gingivalis 40-kDa outer membrane protein Abstract: Porphyromonas gingivalis has been implicated as a major pathogen in periodontal diseases. We previously cloned a 40-kDa outer membrane protein (OMP) gene from P. gingivalis 381 and succeeded in producing sufficient quantities of the recombinant protein for experimental use. Since antibodies against the recombinant (r) 40-kDa OMP have potent ability to kill P gingivalis cells by complement activation and opsonization, r40-kDa OMP has been the subject of considerable interest as a possible vaccine candidate. In this study, in order to develop a component vaccine, the immunodominant domain in 40-kDa OMP was identified. Peptides corresponding to portions of the Nterminal regions of 40-kDa OMP were synthesized chemically and their immunoreactivities with antibody against r40-kDa OMP were tested. The 16-mer peptide, LDDEYKERVFQTFVHY, was found to react strongly with the antibody. Furthermore, a rabbit antibody was prepared by immunization with the 16-mer peptide, cross-linked with dehydrofolate reductase, and its immunoreactivity was then examined. In a BIAcore experiment the antibody clearly reacted with r40-kDa OMP as well as P gingivalis strains. These findings suggest that the 16-mer synthetic peptide may be useful for development of a component vaccine against P. gingivalis. (J. Oral Sci. 45, 111-116, 2003)