关键词: 莱姆病螺旋体, 质粒

Abstract: A simple procedure for extraction of plasmid-enriched DNA from borreliae was used in a plasmid analysis of 23 strains（contain 21 Chinese isolates）of the Lyme disease agent,Borrelia burgdorferi.The extracted DNA was subjected to low-percentage agarose gel electrophoresis and examined either directly by ethidium bromide staining or after southern hybridization of the plasmids with labeled plasmid-enriched DNA of B.burgdorferi isolates B31.The heterogeneity in plasmid contents were observed among these strains.Chinese isolates were allowed to divideinto three groups according to the results above.4 of 21 Chinese strains had the same plasmid profile as B31 had;7 of 21 Chinese strains had very similar plasmid profil;Additional 7 Chinese iso1ates had the same plasmid profile;Its were defined as group I,Ⅱ,Ⅲ,respectively.The result of southern blot of the plasmids showed stronger homology between Group Ⅰ strains and B31,less homology between the rest Chinese isolates and the American strain B31.These result suggested that most of Chinese strains had the features of European strains.Mearwhile,this study suggested that plasmid analysis may be a sensitve tool for identifying B.burgdorferi strains.