隐孢子虫感染小鼠动物模型的建立

目的　建立免疫抑制小鼠的隐孢子虫感染模型。　方法　饮水中加地塞米松 ( DEX)抑制 4周龄小鼠免疫功能 ,人工灌喂隐孢子虫卵囊 ( CSO)感染小鼠。通过观察小鼠粪便中 CSO排出情况和小鼠生存情况 ,比较 5个品系小鼠( BAL B/c、C5 7、ICR、NIH、KM)的易感性 ,比较不同 DEX剂量 ( 1mg/L、2 .5 mg/L、5 mg/L、10 mg/L)对小鼠免疫功能的影响 ,比较不同 CSO接种剂量 ( 10 5、10 6 )对小鼠感染的影响 ,从而确定适宜的模型小鼠、DEX剂量和 CSO接种剂量 ,建立小鼠感染模型。　结果　 ( 1) 5个品系小鼠中 KM鼠的 CSO排出量最多 ,而且持续整个实验期 ,小鼠死亡数较少 ( NIH鼠全部死亡 ) ;( 2 ) 10 mg/L、5 mg/L DEX组小鼠 CSO排出量较多 ,2 .5 mg/L、1mg/L 组小鼠死亡数少 ,但卵囊排出量明显低于前两组 ,且不能持续整个实验期 ;( 3) 10 5与 10 6个 CSO接种量的小鼠 CSO排出量没有明显差别 ,但前者的小鼠死亡数较少。　结论　 KM鼠饮水中加 DEX5 mg/L,每只小鼠接种 10 5个 CSO,可以建立稳定的感染模型。

AN ANIMAL MODEL FOR CRYPTOSPORIDIUM PARVUM IN MICE

Objective To establish a Cryptosporidium parvum infective model in immunosuppressed mice. Methods 4-week-old mice immunosuppressed with dexamethasone (DEX) in drinking water, were inoculated intragastrically with C. parvum oocysts (CSO). Oocysts shedding intensity was observed, and the dead mice were counted. Three experiments were designed, each group was allocated 10 mice. (1) BALB/c, C57, ICR, NIH and KM strain mice were immunosuppressed with 10 mg/L DEX, and were inoculated intragastrically with 106 CSO, the strain was selected, which shed the highest oocysts intensity and had fewer dead mouse. (2) The selected strain mice were inoculated immunosuppressed with different DEX dosage(1, 2.5, 5, 10 mg/L), and were intragastrically with 106 CSO too. The suitable DEX dosage was determined as before. (3) The selected strain mice were immunosuppressed with suitable DEX dosage, and were inoculated intragastrically with 105 CSO, then the oocysts shedding intensity was compared with that of 106 CSO inoculation group to determine the suitable CSO inoculation dosage. Results (1) It was KM strain that shed the highest oocysts intensity, which was kept through the DEX-duration. Oocysts intensities which other strains shed were lower than KM stain, and declined before DEX was finished. Five KM, three ICR, six BALB/c and C57 mice were dead, and all NIH mice were dead before DEX was out. (2) As the 10 mg/L DEX group, the 5 mg/L DEX group shed higher oocysts intensity than other groups, which was kept all the 30-day experiment duration. (3) There was no significant difference in oocysts shedding in groups with 106 and 105 CSO inoculation. Conclusion When KM mice were immunosuppressed with 5 mg/L DEX in drinking water, and were inoculated intragastrically with 105 CSO, a mouse model infected C. parvum could be established steadily.