Comparison of Cryptosporidium parvum Viability and Infectivity Assays following Ozone Treatment of Oocysts

Author:

Bukhari Z.1,Marshall M. M.2,Korich D. G.2,Fricker C. R.3,Smith H. V.4,Rosen J.5,Clancy J. L.1

Affiliation:

1. Clancy Environmental Consultants, Inc., St. Albans, Vermont1;

2. University of Arizona, Tucson, Arizona2;

3. Thames Water Utilities, Reading,3 and

4. Scottish Parasite Diagnostic Laboratory, Glasgow,4 United Kingdom; and

5. Technology Planning and Management Corporation, Scituate, Massachusetts5

Abstract

ABSTRACT Several in vitro surrogates have been developed as convenient, user-friendly alternatives to mouse infectivity assays for determining the viability of Cryptosporidium parvum oocysts. Such viability assays have been used increasingly to determine oocyst inactivation following treatment with chemical, physical, or environmental stresses. Defining the relationship between in vitro viability assays and oocyst infectivity in susceptible hosts is critical for determining the significance of existing oocyst inactivation data for these in vitro assays and their suitability in future studies. In this study, four viability assays were compared with mouse infectivity assays, using neonatal CD-1 mice. Studies were conducted in the United States and United Kingdom using fresh (<1 month) or environmentally aged (3 months at 4°C) oocysts, which were partially inactivated by ozonation before viability and/or infectivity analyses. High levels of variability were noted within and between the viability and infectivity assays in the U.S. and United Kingdom studies despite rigorous control over oocyst conditions and disinfection experiments. Based on the viability analysis of oocyst subsamples from each ozonation experiment, SYTO-59 assays demonstrated minimal change in oocyst viability, whereas 4′,6′-diamidino-2-phenylindole–propidium iodide assays, in vitro excystation, and SYTO-9 assays showed a marginal reduction in oocyst viability. In contrast, the neonatal mouse infectivity assay demonstrated significantly higher levels of oocyst inactivation in the U.S. and United Kingdom experiments. These comparisons illustrate that four in vitro viability assays cannot be used to reliably predict oocyst inactivation following treatment with low levels of ozone. Neonatal mouse infectivity assays should continue to be regarded as a “gold standard” until suitable alternative viability surrogates are identified for disinfection studies.

Publisher

American Society for Microbiology

Subject

Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology

Reference27 articles.

1. Armstrong D. C. Casemore D. P. Couper A. M. Martin A. D. Naylor P. J. (1995) Disinfection of Cryptosporidium parvum with ozone at high concentrations. in Protozoan parasites and water. eds BettsW. B.CasemoreD. P.FrickerC. R.SmithH. V.WatkinsJ. (The Royal Society of Chemistry Cambridge England) pp 226–229.

2. Improved purification methods for calf derived Cryptosporidium parvum oocysts using discontinuous sucrose and cesium chloride gradients;Arrowood M. J.;J. Eukaryot. Microbiol.,1996

3. Belosevic M. Taghi-Kilani R. Guy R. A. Neumann N. F. Finch G. R. Gyürek L. L. Liyanage L. R. J. (1997) Vital dye staining of Giardia and Cryptosporidium. (American Water Works Association Denver Colo).

4. Comparison of assays for Cryptosporidium parvum oocysts viability after chemical disinfection;Black E. K.;FEMS Microbiol. Lett.,1996

5. Effect of three concentration techniques on viability of Cryptosporidium parvum oocysts recovered from bovine feces

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3