从鼠粪中分离纯化微小隐孢子虫卵囊方法的研究

Study on Methods for Isolation and Purification of Cryptosporidium parvum Oocysts from Mouse Feces

目的探索一种实用、纯度和回收率高且卵囊活力强的分离纯化微小隐孢子虫卵囊的方法。方法分别采用经典的不连续蔗糖密度梯度离心法、改良饱和盐水漂浮法、氯化铯(CsCl)密度梯度离心法和Percoll密度梯度离心法分离纯化C57BL/6小鼠粪中隐孢子虫卵囊。并将4种方法分离纯化获得的卵囊各105体外感染牛输卵管上皮细胞(BFTE),48h和72h后油镜下观察各分离法卵囊的发育情况,以比较卵囊的纯度和活性。结果经典的不连续蔗糖密度梯度离心法分离获得的卵囊数[(2.86±0.08)×107]与改良饱和盐水漂浮法[(2.88±0.15)×107]无明显差异(P>0.05),但高于Percoll密度梯度离心法[(1.52±0.08)×107](P<0.01)和CsCl密度梯度离心法[(2.46±0.13)×107](P<0.05)。4种方法分离纯化的卵囊体外感染BFTE48h和72h后隐孢子虫数无明显差异(P>0.05)。但CsCl密度梯度离心法纯化的隐孢子虫卵囊纯度明显高于不连续蔗糖密度梯度离心法。结论改良饱和盐水漂浮法较经典的不连续蔗糖密度梯度离心法操作简单、快速;CsCl密度梯度离心法分离的隐孢子虫卵囊纯度较高。

Objective To explore an applicable method for isolation and purification of Cryptosporidium parvum oocysts with high purity, recovery and vigor from mouse feces. Methods Four techniques were used for isolating and purifying C.parvum oocysts from mouse feces： modified saturated saline flotation, percoll gradient centrifugation, CsCl gradient centrifugation and the classical discontinuous sucrose gradient centrifugation. Oocysts received from the methods were used respectively to infect in vitro bovine fallopian tube epithelial cells （BFTE） and the development of the oocysts was examined under microscope after 48 h and 72 h cultivation. Results The number of oocysts received by the classical discontinuous sucrose gradient centrifugation [（2.86±0.08）×10^7] was significantly higher than that of percoll gradient centrifugation [（1.52±0.08）×10^7] （P〈0.01） and CsCl gradient centrifugation [（2.46±0.13）×10^7] （P〈0.05）, but similar to that of the modified saturated saline flotation [（2.88±0.15）×10^7]. No significant difference was found on the number of oocysts by BFTE cultivation at 48 and 72 hours post-inoculation（P〉0.05）. Oocysts received from CsCl gradient centrifugation showed higher purity than those by discontinuous sucrose gradient centrifugation. Conclusion In comparison to the classical discontinuous sucrose gradient centrifugation, operation of the modified saturated saline flotation is easier and faster, and the purity of oocysts isolated by CsCl gradient centrifugation is higher.