Deletion and point mutations exist in the haemagglutinins/adhesions domain of prtH gene of Porphyromonas gingivalis clinical isolates
Objective Porphyromonas gingivalis ( P. gingivalis ) is thought to be a major etiologic bacterium associated with the initiation and progression of human periodontitis. The aim of the present study was to investigate the genetic diversity of P. gingivalis prt H gene. Methods Polymerase chain reaction(PCR) was applied to P. gingivalis strains, including reference strain P. gingivalis ATCC33277 and 140 clinical strains isolated from 24 unrelated Chinese periodontitis patients. To illustrate the prt H heterogeneity among P. gingivalis strains, the genomic DNAs were extracted and screened by PCR with two pairs of specific primers, and the PCR products were digested with restriction endonucleases AluⅠ. Using the biotin-labeled prt H sequence as probe, Dot blot hybridization was used to confirm the existence of prt H. To evaluate the sequence heterogeneity of the P. gingivalis prt H genes, sequence analysis of five prt H protease gene regions of clinical isolates was performed. Results Using PCR with two pairs of specific primers, 54.2% (primer A) and 84% (primer B) showed the positive amplified fragment among 140 strains. Dot blot hybridization revealed that 82.4% PCR products were positive. Restriction endonucleases analyses showed that all the PCR products were P. gingivalis prt H patterns. Sequence analysis verified that there were deletion and point mutations in five PCR products, compared with the reference strain P. gingivalis ATCC33277 and W83. Conclusion The results demonstrated genetic diversity existed among these clinical strains isolated from Chinese periodontitis patients.