Localizing antibody-defined immunoreactivity in Porphyromonas gingivalis HtpG recognized by human serum utilizing selective protein expression.

Earlier studies suggested that specific immunoreactive domains of the prokaryotic homologue of Hsp90, HtpG, might contribute to the virulence of the periodontal pathogen, Porphyromonas gingivalis (Pg) [J. Periodontol. 70 (1999) 1185]. Since serum antibodies to this protein appeared to be associated with oral health, we developed a rapid epitope-mapping system that could be tailored to detect antibodies against specific immunoreactive regions of the Pg HtpG protein. This paper describes the use of Caulobacter crescentus (Cc) and the creation of a Cc RsaA fusion protein library that defined specific regions of the Pg HtpG protein. The fusion protein library was used to identify immunoreactive regions in the Pg HtpG dominant in patient and control sera. The development of methods to rapidly localize dominant immunoreactive regions in protein antigens may prove useful for the development of screening tests, vaccines and therapeutics in periodontal and other infectious diseases.