Genotypes of Kgp (Lys-gingipain) in subgingival plaque from puberty gingivitis

Objectives: Kgp proteinase (Lys-gingipain) appears to play an important role in the pathogenesis of Porphyromonas gingivalis on periodontal disease. The aim of this study was to assess the prevalence of specific kgp genotypes in puberty gingivitis as well as to reveal their possible association with disease severity. Methods: 92 pubertal children aged from 14 to 17 years were enrolled in the study, which were divided into two groups, gingivitis group and healthy (control) group. Prior to the collection of subgingival plaque, clinical parameters were evaluated. subgingival plaque samples were obtained. The bacterial chromosomal DNA was prepared and part of kgp gene was amplified by use of PCR. The PCR products were digested with restriction enzymes. Results: The kgp-A type was digested in fragments of 102bp, 288bp and 402 bp, and kgp-B type was unrestricted with 792 bp. The virulent strain W83 showed kgp-A genotype, while the avirulent strain ATCC33277 showed kgp-B genotype. All P. gingivalis positive subjects were subgingivally colonized by only one kgp genotype. 78.95 percent of subjects in puberty gingivitis group were colonized by kgp-A type, while 22.22 percent of subjects in gingival healthy group were colonized by kgp-B type. Fisher's exact test demonstrated that the distribution differences of kgp-A and kgp-B between the two groups were statistically different. There was no statistically significant difference in the PD, PLI, GI, and SBI in pubertal subjects harboring P. gingivalis of kgp-A type compared to that of kgp-B type. Conclusions: kgp-A genotype might be better adapted to environmental challenges. Subjects with puberty gingivitis may mostly be colonized by virulent strain of P. gingivalis. Further studies are needed to monitor the change of kgp genotype and its correlation with disease progression. This study was supported by the National Foundation of China(No.30371542).