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Inactivation of Cryptosporidium using ultraviolet and radioactive reys

使用紫外线和放射性射线灭活隐孢子虫

基本信息

批准号：
13450217
负责人：
HIRATA Tsuyoshi
金额：
$ 9.54万
依托单位：
Azabu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Experimental studies on radioactive rays irradiation were conducted to determine the efficacy of inactivating C. parvum oocysts at various temperatures and intensities. The infectivity decreased exponentially as radiation doses increased. The gamma ray and beta ray doses resulting in a 2 log_<10> reduction in infectivity were 94 Gy and 92 Gy, respectively. Temperature and intensity did not significantly affect the efficacy of radioactive rays irradiation in reducing the infectivity of oocysts. Gamma ray and beta ray doses required for 2 log_<10> reduction in viability as evaluated using in vitro excystation were 13,000 Gy and 12,000 Gy, respectively. Thus, radioactive ray treatment resulted in oocysts that were able to excyst but not infect.The potential of irradiated oocysts to recover infectivity by photoreactivation and dark repair was investigated. There was no recovery in infectivity following treatment by fluorescent-light irradiation or storage in darkness.The effectiveness of U … More V irradiation per unit dose towards an oocyst suspension where humin was mixed homogeneously with the oocysts, was nearly as high as that towards an oocyst suspension in pure water. This indicates that even though the UV beam passed through a turbid fluid, the effectiveness of UV irradiation per unit dose remained unaltered. Our results also suggest that the adhesion of humin to the oocyst wall has no marked shielding effect. As to kaoline which does not adhere to the oocyst wall, UV irradiation was slightly more potent towards C. parvum oocyst suspensions in water containing kaoline than towards oocyst suspensions in pure water. Because the increase in potency was negligible, however we did not study whether the increase resulted from scattering of the UV beam by kaoline particles. A trend was noted that adhesion of kaoline to the oocyst wall resulted in a decrease in inactivation as did adhesion of humin. However, the magnitude of log_<10> inactivation during adhesion of kaoline was only about 10% less than that in pure water irrespective of whether assessment was made by excystation assay or by mouse infectivity assay. Less

采用放射线照射的方法，研究了灭活C.在不同的温度和强度的卵囊。随着辐射剂量的增加，传染性呈指数级下降。导致感染性降低2 log_的γ射线和β射线剂量<10>分别为94戈伊和92戈伊。温度和强度对放射线照射降低卵囊感染性的效果无显著影响。如<10>使用体外脱囊所评估的，存活率降低2 log所需的γ射线和β射线剂量分别为13，000戈伊和12，000戈伊。因此，放射性射线处理导致卵囊能够脱囊，但不infective.Potential的照射卵囊恢复感染性的光复活和黑暗修复进行了研究。用荧光灯照射或避光保存处理后，感染性没有恢复。 ...更多信息 V照射每单位剂量对卵囊悬浮液胡敏素均匀混合的卵囊，是几乎一样高，对卵囊悬浮液在纯水中。这表明，即使UV光束穿过混浊的流体，每单位剂量的UV照射的有效性保持不变。我们的研究结果还表明，胡敏素对卵囊壁的粘附没有明显的屏蔽作用。对于不粘附卵囊壁的高岭土，紫外线照射对C.卵囊悬浮液中含有高岭土比对卵囊悬浮液在纯水中。由于效力的增加可以忽略不计，但是我们没有研究这种增加是否是由于高岭土颗粒对UV光束的散射造成的。一个趋势是注意到，高岭土的粘附卵囊壁导致减少灭活胡敏素的粘附。然而，无论是<10>脱囊试验还是小鼠感染性试验，高岭土粘附过程中的log_失活量仅比纯水中的log_失活量小约10%。少