Comparison of tissue culture and animal models for assessment of Cryptospridium parvum infection

Slifko, Theresa R.; Huffman, Debra E.; Dussert, Bertrand W.; Owens, James H.; Jakubowski, Walter; Haas, Charles N.; Rose, Joan B.

doi:10.1016/s0014-4894(02)00100-5

Cited by 34 publications

(26 citation statements)

References 25 publications

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“…The variation in infectivity between C. parvum isolates from different sources, between lots from the same source, with different cell lines, and in different experiments observed in this study has also been described by Slifko et al (26) and Rochelle et al (20). Recently, Di Giovanni and LeChevallier (8) reported different levels of cell culture infection for the isolates that they used to evaluate their quantitative PCR-cell culture assay.…”

Section: Discussionsupporting

confidence: 87%

“…Rochelle et al (20) found that a cell culture assay with HCT-8 cells (including reverse transcription-PCR detection of infection) and a CD-1 mice assay produced equivalent results for predicting oocyst infectivity after ozone or UV treatment. Slikfo et al (26) reported that there were no significant differences between the results obtained by cell culture with HCT-8 cells (microscopic detection of infection) and the results obtained by mouse infectivity assays after UV or chlorine dioxide treatment.…”

Section: Discussionmentioning

confidence: 98%

“…However, our data set for mouse infectivity is limited, and regression analyses showed that there was poor fit of the logit response model to data from two of three experiments. Slifko et al (26) reported that HCT-8 cells were more sensitive to infection with C. parvum oocysts than 4-day-old BALB/c mice or neonatal CD-1 mice. They reported average logit ID 50 s of 8, 64, and 119 for these three assays, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…They are, however, expensive, time-consuming, and not widely applicable, and they may also be considered unethical. Moreover, data generated with mouse infectivity models vary considerably, both in different experiments (20) and between different mouse assays (26), and Cryptosporidium hominis oocysts do not efficiently infect standard mouse infectivity models (17).…”

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confidence: 99%

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Detection of Infectious Cryptosporidium Oocysts by Cell Culture Immunofluorescence Assay: Applicability to Environmental Samples

Schets

Engels

During

et al. 2005

Appl Environ Microbiol

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In the past few years many waterborne outbreaks related to Cryptosporidium have been described. Current methods for detection of Cryptosporidium in water for the most part rely on viability assays which are not informative concerning the infectivity of oocysts. However, for estimation of the risk of infection with Cryptosporidium this information is required. For environmental samples the oocyst counts are often low, and the oocysts have been exposed to unfavorable conditions. Therefore, determination of the infectivity of environmental oocysts requires an assay with a high level of sensitivity. We evaluated the applicability of in vitro cell culture immunofluorescence assays with HCT-8 and Caco-2 cells for determination of oocyst infectivity in naturally contaminated water samples. Cell culture assays were compared with other viability and infectivity assays. Experiments with Cryptosporidium oocysts from different sources revealed that there was considerable variability in infectivity, which was illustrated by variable 50% infective doses, which ranged from 40 to 614 oocysts, and the results indicated that not only relatively large numbers of fresh oocysts but also aged oocysts produced infection in cell cultures. Fifteen Dutch surface water samples were tested, and the cell culture immunofluorescence assays were not capable of determining the infectivity for the low numbers of naturally occurring Cryptosporidium oocysts present in the samples. A comparison with other viability assays, such as the vital dye exclusion assay, demonstrated that surrogate methods overestimate the number of infectious oocysts and therefore the risk of infection with Cryptosporidium. For accurate risk assessment, further improvement of the method for detection of Cryptosporidium in water is needed.Cryptosporidium is one of the important waterborne causative agents of gastrointestinal illness in humans (6, 10). More than 50 outbreaks of cryptosporidiosis associated with either contaminated drinking water or recreational water have been reported worldwide since 1983 (20). In immunocompetent individuals cryptosporidial diarrhea is usually self-limiting, lasting for about 3 weeks, but infected immunocompromised humans may develop severe and potentially fatal illness (5). At present, no consistently effective, approved therapeutic agent with anticryptosporidial activity is available.Cryptosporidium oocysts are ubiquitous in surface water used for recreation or drinking water production (9, 21). They are extremely resistant to chlorination at the concentrations commonly used for drinking water and swimming pool water disinfection (13). The number of oocysts in finished water is usually low but relevant for public health, and the concentrations are below the detection limit of the method used. Therefore, Dutch drinking water legislation requires drinking water companies to perform a quantitative risk assessment for Cryptosporidium, based on the concentration of oocysts in the source water and the efficiency of drinking water treatment proce...

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Detection of Infectious Cryptosporidium Oocysts by Cell Culture Immunofluorescence Assay: Applicability to Environmental Samples

Schets

Engels

During

et al. 2005

Appl Environ Microbiol

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“…However, it is important to point out that during Ascaris egg development to the third-stage larva, the Ascaris egg grows from one cell to about 600 cells (35), which is significantly different from what happens in the life cycle of the single-celled prokaryotic protozoans Giardia and Cryptosporidium. For protozoans exposed to UV, infectivity studies or cell cultures are necessary to measure viability, because the DNA is not fully replicated until the organisms reproduce, after infection (16,18,33,38). In Ascaris, however, the complete DNA of the organism is replicated when the single cell in the egg undergoes the first two cell divisions before it differentiates into the germ and somatic cell lines that form the larva (26).…”

Section: Discussionmentioning

confidence: 99%

Inactivation of Single-Celled Ascaris suum Eggs by Low-Pressure UV Radiation

Brownell

Nelson

2006

Appl Environ Microbiol

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2 ), from 0-to 1.5-log inactivation can be expected, although at typical fluences (less than 1,000 J/m 2 ), the inactivation may be less than 1 log. When the eggs were decorticated (the outer egg shell layers were removed with sodium hypochlorite, leaving only the lipoprotein ascaroside layer) before exposure to UV, 1.80-؎ 0.32-log reduction (98.4%) was achieved with a fluence of 500 J/m 2 , suggesting that the outer eggshell layers protected A. suum eggs from inactivation by UV radiation. This protection may have been due to UV absorption by proteins in the outer layers of the 3-to 4-m-thick eggshell. Stirring alone (without UV exposure) also inactivated some of the Ascaris eggs (ϳ20% after 75 min), which complicated determination of the inactivation caused by UV radiation alone.

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