Inactivation of Cryptosporidium using ultraviolet and radioactive reys

实验研究了不同温度和强度的放射线照射对小弧菌卵囊灭活效果的影响。随着辐射剂量的增加，传染性呈指数级下降。导致2 log_<10>的γ射线和β射线剂量分别为94 Gy和92 Gy。温度和照射强度对降低卵囊传染性的效果无显著影响。用体外培养法评估，2 log_<10>的存活率降低所需的伽马射线和β射线剂量分别为13000 Gy和12000 Gy。因此，放射性射线治疗导致卵囊能够脱落但不感染。研究了辐照卵囊通过光活化和暗修复恢复感染性的潜力。荧光灯照射或黑暗保存后，感染性没有恢复。在人素与卵囊均匀混合的卵囊悬浮液中，单位剂量U…More V照射的效果几乎与在纯水中卵囊悬浮液中的效果一样高。这表明，即使紫外线光束通过浑浊流体，单位剂量紫外线照射的有效性仍然保持不变。我们的研究结果还表明，人蛋白与卵囊壁的粘附没有明显的屏蔽作用。对于不粘附在卵囊壁上的高岭土，紫外线照射对含高岭土水中的小虫卵囊悬浮液的作用略大于对纯水中的卵囊悬浮液的作用。然而，由于效力的增加可以忽略不计，我们没有研究这种增加是否是由于高岭土粒子对紫外线光束的散射。我们注意到一个趋势，高岭土与卵囊壁的粘连导致失活的减少，人类蛋白的粘连也是如此。然而，无论是通过体外清除法还是小鼠感染性法，高岭土黏附过程中log_<10>的失活程度仅比纯水低10%左右。少

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