It seemed that there was some specificity between the rodent

species and B.burgdorferi s.l. genospecies. More samples should be included to illuminate whether there are differences in various genospecies among host ranges. Conclusion The study showed the role of two rodent species in maintaining the pathogen of Lyme disease in the environment from Gansu Province. The isolates which isolated from rodents were identified as two different genospecies. Methods Rodents collection During the September and November of 1998, rodents were bait-captured using snap traps in Gannan Tibetan Autonomou Prefecture of Gansu Province which located 420 km south of Lanzhou City (Figure 1). The study area belonged to SAR302503 cell line Diebu forested region, which located on the eastern border of Qinghai-Tibet Plateau, with an elevation of 1 600-4 920 m. The study area mainly are bush grassland and forest grassland with an average elevation of 1600 m (33°40′ N, 103°47′ E). The temperature ranges from -10 to 25°C, with an average of 6.7°C Figure 1 Study area in Gansu Province. The black solid

line is old silk road in Gansu Province; the dotted line is the Yellow River; pentagon is study area. DNA sample preparation After species identification of the captured rodents, a small piece of spleen was triturated in 2 ml of TE buffer for culture and PCR. After centrifugation, the samples Natural Product Library were subjected to DNA extraction second using DNA extraction Kit (Sangon) according instruction. DNA of culture isolates were extracted by boiling method. Briefly, cultures were harvested by centrifugation (10,000 × g; 20 min). The bacterial pellet was washed in phosphate-buffered FRAX597 saline and

resuspended. The DNA was extracted from the centrifugation pellet of cultivated isolates by boiling in water at 100°C for 10 min, and stored at -20°C until use. Culture and identification The samples from spleen were cultured in 4 ml BSKII medium (Sigma, St Louis, MO, USA) supplemented with 6% rabbit serum and 1% antibiotic mixture for Borrelia (Sigma, St Louis, MO, USA) at 32°C. Cultures were subsequently examined for spirochetes by dark-field microscopy for 6 weeks at ×400. Spirochetal isolates were analyzed by IFA with monoclonal antibody. The monoclonal antibody H5332, FITC-labeled goat anti-mouse IgG were friendly provided by Professor Chenxu Ai from Beijing Institute of Microbiology and Epidemiology. The IFA was performed briefly as follow: cultures were harvested by centrifugation and washed three times by suspension in 500 ul of phosphate-buffered saline (PBS) (0.01 M, pH 7.38), recentrifugation at 12,000 × g for 25 s, and removal of the supernatant. After being washed, the pellet was resuspended in PBS to a final concentration of 5 × 107/ml. Ten microliters of this suspension was applied to wells on a glass slide. Slides were air dried, fixed in acetone for 10 min, and stored in airtight containers until use.