Porphyromonas gingivalis is a major etiologic agent of periodontitis, a chronic inflammatory disease that ultimately results in the loss of the supporting tissues of the teeth. Previous work has demonstrated the usefulness of avirulent Salmonella enterica serovar Typhimurium strains as antigen delivery systems for protective antigens of pathogens that colonize or cross mucosal surfaces. In this study, we constructed and characterized a recombinant S. enterica serovar Typhimurium avirulent vaccine strain which expresses hemagglutinin A and carries no antibiotic resistance markers. HagA, a major virulence-associated surface protein, is a potentially useful immunogen that contains an antigenic epitope which, in humans, elicits an immune response that is protective against subsequent colonization by P. gingivalis. The hagA gene, including its promoter, was cloned into a balanced-lethal Salmonella vector and transferred to the vaccine strain. Heterologous expression of HagA was demonstrated in both Escherichia coli JM109 and S. enterica serovar Typhimurium vaccine strain 4072. The HagA epitope was present in its native configuration as determined by immunochemistry and immunoelectron microscopy. Purified recombinant HagA was recognized by sera from mice immunized with the S. enterica serovar Typhimurium vaccine strain. The HagA-specific antigen of the vaccine was also found to be recognized by serum from a periodontal patient. This vaccine strain, which expresses the functional hemagglutinin protein, induces a humoral immune response against HagA and may be useful for developing a protective vaccine against periodontal diseases associated with P. gingivalis.

Recently, two new kits, HITAZYME (Hitachi Chemical Co., Ltd.) and SERO IPALISA (Savyon Diagnostics, Ltd.), for the assay of anti-C. trachomatis antibodies by the enzyme immunoassay (EIA) method have been developed and put into clinical application. In the study reported here, the authors investigated the clinical usefulness of these assay kits, together with the IPAzyme and micro-IF test, in the diagnosis of cases of urogenital tract C. trachomatis infections. 1. The positive rates for IgA antibodies, which are considered to be an indicator of active infection, obtained with the HITAZYME and SERO IPALISA kits in the 82 antigen-positive cases were significantly (p < 0.005) higher than the rates obtained with the IPAzyme and micro-IF test. These results showed the usefulness of the HITAZYME and SERO IPALISA kits for detecting C. trachomatis infections. 2. A comparison was made of the assay results obtained with the HITAZYME and SERO IPALISA kits, and it was found that there was a large number of cases (142) that tested negative for IgA antibodies with the HITAZYME but positive with the SERO IPALISA kit. We carried out a confirmatory test on the specimens of cases for which the results obtained with the HITAZYME and SERO IPALISA kits were not in agreement. This test employed the Western blotting method using COMC (the antigen extracted from EB of C. trachomatis strain L2 and used in the HITAZYME kit) and whole EB of C. trachomatis strain L2 (the antigen used in the SERO IPALISA kit). The results showed a significantly higher degree of agreement between the HITAZYME kit data and the Western blotting data than between the SERO IPALISA kit data and the Western blotting data. 3. In addition, with the objective of investigating the existence of cross reactivity with anti-C. pneumoniae antibodies, we performed Western blotting using as the antigen crude whole EB of C. pneumoniae strain TW-183. The results showed that anti-C. pneumoniae antibodies were detected in 25 of 35 (71.4%) cases that were negative with C. trachomatis antigen and the HITAZYME kit and positive with the SERO IPALISA kit. These findings indicate a strong possibility that these cases positive with the SERO IPALISA kit are due to a cross reaction with anti-C. pneumoniae antibodies.(ABSTRACT TRUNCATED AT 400 WORDS)