Abstract: 　Objective To establish a simplified amplification method for obtaining a large number of purified Cryptosporidium parvum oocysts from infected C57BL/6N mice. Methods All mice in the experimental groups were immunosuppressed by given different concentrations of dexamethasone phosphate added in drinking water throughout the experiment. The recovery and purity of the oocysts obtained using different purification methods was compared. The infectivity of the oocysts obtained from the same origin but different animals and different purification methods in a bovine fallopian tube epithelial cell culture system was studied. Results 4.16×10 9 oocysts were obtained in 30 mice in the 3rd group with dexamethasone of 20 μg/ml in drinking water. No significant difference in the oocyst recovery, purity and infectivity was found between methods using saturated saline floatation and sucrose density gradient centrifugation. The infectivity of the oocysts obtained from the same origin but different animals was similar. Conclusion A simplified amplification method for obtaining a large number of purified Cryptosporidium parvum oocysts from the infected mice was established.

Key words: Cryptosporidium parvum oocysts, mouse, saturated saline floatation, sucrose density gradient centrifugation, cell culture