Infectivity of Cryptosporidium parvum oocysts stored in water at environmental temperatures
Infectivity of Cryptosporidium parvum oocysts stored in water at environmental temperatures
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DOI：
10.2307/3284666
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发表时间：
1998-12-01
影响因子：
1.3
通讯作者：
Jenkins, MC
中科院分区：
文献类型：
--
作者：
Fayer, R;Trout, JM;Jenkins, MC
通过密度梯度离心将从小牛获得的微小隐孢子虫卵囊清除粪便碎片，并将其悬浮在微量离心管中的去离子水中。将试管置于温度为-10、-5、0、5、10、15、20、25、30或35 ℃的循环水浴中，并在1、2、4、8、12、16、20和24周后从每个水浴中取出2个试管。以每只小鼠1.5 × 10（5）个卵囊的比例将1个试管中的卵囊给予2窝新生BALB/c小鼠，当在小鼠肠道组织切片中发现发育阶段和/或获得C.小鼠回肠中的微小DNA。将第二个试管保持在-70 ℃，直到所有时间段的试管都可用，然后测定试管内的卵囊的支链淀粉浓度。保存在-10 ℃下的卵囊在储存1周内是感染性的，保存在-5 ℃下的卵囊在储存8周内是感染性的，这是通过PCR而不是组织学测定的。在0、5、10、15和20 ℃下保存的卵囊在储存24周后仍具有感染性。通过对小鼠组织的显微镜检查，在20 ℃下保存的卵囊在储存24周后仅感染10只小鼠中的1只，并且在储存4周后发育阶段的数量开始下降;在25和30 ℃下保存的卵囊在储存后12周内分别在10只小鼠中的1只中产生感染，并且在储存后4周开始发育阶段的数量减少。这些在35 ℃下保存的小鼠在10只小鼠中的2只中仅在长达1周的储存中产生轻度感染。支链淀粉含量随贮藏时间的延长或温度的升高而降低。这些研究结果提供了一个指南，估计在广泛的环境温度范围内的卵囊感染性的潜在持续时间，并证明支链淀粉浓度和感染性之间的关系。
Oocysts of Cryptosporidium parvum obtained from calves were cleaned of fecal debris by density gradient centrifugation and suspended in deionized water in microcentrifuge tubes. The tubes were placed in circulating water baths at temperatures of -10, -5, 0, 5, 10, 15, 20, 25, 30, or 35 C, and 2 tubes were removed from each water bath 1, 2, 4, 8, 12, 16, 20, and 24 wk later. Oocysts from 1 tube were administered at the rate of 1.5 x 10(5) oocysts per mouse to 2 litters of neonatal BALB/c mice and were considered infective when developmental stages were found in histologic sections of mouse gut and/or a positive polymerase chain reaction (PCR) was obtained for C. parvum DNA in mouse ileum. The second tube was held at -70 C until tubes from all time periods were available, then oocysts within the tubes were assayed for amylopectin concentration. Oocysts held at -10 C were infectious up to 1 wk of storage, and those held at -5 C were infectious up to 8 wk of storage, as determined by PCR but not histology. Oocysts held at 0, 5, 10, 15, and 20 C were still infectious after 24 wk of storage. By microscopic examination of mouse tissue, oocysts held at 20 C infected only 1 of 10 mice after 24 wk of storage, and the number of developmental stages began declining after 4 wk of storage; those held at 25 and 30 C each produced infections up to 12 wk after storage in 1 of 10 mice with reduced numbers of developmental stages beginning 4 wk after storage. These held at 35 C produced light infections in 2 of 10 mice only up to 1 wk of storage. Amylopectin concentration decreased with increasing length of storage time or temperature. These findings provide a guide for estimating the potential duration of oocyst infectivity within a wide range of environmental temperatures and demonstrate the relationship between amylopectin concentration and infectivity.