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目的 :本研究旨在分析牙龈卟啉菌基因型和其重要毒力因子胶原酶基因 (collagenasegene ,PrtC)的遗传异质性 ,了解细菌遗传变异与其对牙周致病性的相关性。方法 :采用随机引物聚合酶链反应 (AP -PCR)的方法 ,对从 2 4例牙周炎患者口腔中分离的 79株牙龈卟啉菌和参考菌株ATCC332 77进行DNA指纹分析。并随机选择 2 4株临床菌株 ,进一步检测是否存在特异性的胶原酶基因片段。对照菌株为伴放线放线杆菌Y4和中间普氏菌ATCC2 5 6 11,通过酶切鉴定和DNA序列分析 ,了解PrtC基因遗传多样性的变化。结果 :80株牙龈卟啉菌共获得 7种基因型 (I—VII) ,以VII所占比例最高 (2 5 .8%)。 2 4株临床菌株和ATCC332 77中均扩增出特异性的胶原酶基因片段 (5 48bp)。将 4株细菌的序列分析结果与国外的报道相比较 ,发现一些基因序列存在差异 ,其中有 6个核苷酸碱基缺失。结论 :临床分离的牙龈卟啉菌中可检测到多种基因型 ,存在明显的个体差异 ,这些菌株具有合成胶原酶的能力 ,不同菌株胶原酶基因之间存在遗传异质性的变化。
OBJECTIVE: This study aimed to analyze the genetic heterogeneity of genotypes of Porphyromonas gingivalis and its important virulence factor collagenase gene (PrtC) and to understand the relationship between bacterial genetic variation and pathogenicity of periodontal ligament. Methods: DNA fingerprinting of 79 strains of P. gingivalis and reference strain ATCC33277 isolated from the oral cavity of 24 patients with periodontitis were performed by random primer polymerase chain reaction (AP-PCR). A total of 24 clinical isolates were randomly selected to further detect the existence of specific collagenase gene fragments. The control strains were Actinobacillus actinomycetemcomitans Y4 and Prevotella intermedia ATCC2 5 6 11, and the changes of genetic diversity of PrtC gene were analyzed by restriction enzyme digestion and DNA sequence analysis. Results: Seven genotypes (I-VII) were obtained from 80 strains of P. gingivalis, with the highest proportion of VII (25.8%). 24 strains of clinical isolates and ATCC33277 were amplified specific collagenase gene fragment (5 48bp). The sequence analysis results of 4 strains of bacteria were compared with those reported abroad, and some of the gene sequences were found to be different, of which 6 nucleotide bases were deleted. CONCLUSION: A variety of genotypes can be detected in clinically isolated Porphyromonas gingivalis, with significant individual differences. These strains have the ability to synthesize collagenase, and there are genetic heterogeneity among different strains of collagenase genes.