Appl Environ Microbiol. 2010 Jun 11. [Epub ahead of print]
Determining UV Inactivation of Toxoplasma gondii Oocysts Using Cell Culture and a Mouse Bioassay
Ware MW, Augustine SA, Erisman DO, See MJ, Wymer L, Hayes SL, Dubey JP, Villegas EN.
National Exposure Research Laboratory, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, OH 45268; Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, OH 45220; Animal Parasitic Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD, 20705.
The effect of UV exposure on Toxoplasma gondii oocysts has not been completely defined for use in water disinfection. This study evaluated UV irradiated oocysts by three assays: a SCID mouse bioassay, an in vitro T. gondii oocyst plaque assay (TOP-assay), and a quantitative reverse-transcriptase real-time PCR (RT-qPCR) assay. The results from the animal bioassay show that 1 and 3 log10 inactivation is achieved with 4 mJ/cm(2) UV and 10 mJ/cm(2) low pressure UV, respectively. TOP-assay results, but not RT-qPCR results, correlate well with bioassay results. In conclusion, a 3 log10 inactivation of T. gondii oocysts is achieved by a 10 mJ/cm(2) low pressure UV, and the in vitro TOP-assay is a promising alternative to the mouse bioassay.