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Journal of Clinical Microbiology, June 2001, p. 2065-2071, Vol. 39, No. 6
Immunology and Disease Resistance
Laboratory,1 Animal Waste Pathogens
Laboratory,2 and Parasite Biology,
Epidemiology and Systematics Laboratory,3 ANRI,
ARS, U.S. Department of Agriculture, Beltsville, Maryland 20705
Received 21 November 2000/Returned for modification 23 January
2001/Accepted 9 March 2001
A highly sensitive and specific method has been developed to
reproducibly detect and quantitate Toxoplasma gondii burden
in animal tissue samples using T. gondii ITS1-derived
primers and a fluorogenic probe via real-time PCR. Assay specificity
was confirmed against a panel of DNA samples from T. gondii
and other common protozoa as well as host animal tissue. This Toxo
TaqMan assay was able to detect as little as 0.1 pg of T. gondii genomic DNA, which is equivalent to 1 T. gondii bradyzoite, and has a dynamic range of detection of from
100 ng to 100 fg of T. gondii DNA. Tissues from
experimentally infected mice and pigs as well as bradyzoite-spiked pig
muscle samples were used to test and standardize this technique.
Positive signals were obtained with T. gondii parasite
concentrations ranging from 4 to 3.7 × 105 parasites
per g of spiked pig tissue, with excellent linearity (R2 = 0.9776). All T. gondii-infected animals were correctly identified by this
technique. Results indicate that this assay is applicable to swine
carcasses and commercial pig products, is compatible with automation
technology for potential slaughterhouse use, and will enable scientists
to diagnose and quantitate T. gondii in animal tissues.
0095-1137/01/$04.00+0 DOI: 10.1128/JCM.39.6.2065-2071.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Development of a Real-Time PCR Assay for Detection
of Toxoplasma gondii in Pig and Mouse Tissues

*
Corresponding author. Mailing address: Immunology and
Disease Resistance Lab, ANRI, ARS, USDA, Bldg. 1040, Rm. 105, Beltsville, MD 20705. Phone: (301) 504-8201. Fax: (301) 504-5306. E-mail: jlunney{at}anri.barc.usda.gov.
Present address: Virology Area, Faculty of Veterinary Sciences,
University of Buenos Aires, (1427) Buenos Aires, Argentina.
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