Evaluation of five diagnostic methods for the detection and quantification of Myxobolus cerebralis

Garry O. Kelley, Francisco J. Zagmutt-Vergara, Christian M. Leutenegger, Karin A. Myklebust, Mark A. Adkison, Terry S. McDowell, Gary D. Marty, Alex L. Kahler, Arla L. Bush, Ian Gardner, Ronald Hedrick

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57 Scopus citations


Diagnostic methods were used to identify and quantify Myxobolus cerebralis, a myxozoan parasite of salmonid fish. In this study, 7-week-old, pathogen-free rainbow trout (Oncorhynchus mykiss) were experimentally infected with M. cerebralis and at 7 months postinfection were evaluated with 5 diagnostic assays: 1) pepsin-trypsin digest (PTD) to detect and enumerate spores found in cranial cartilage, 2) 2 different histopathology grading scales that provide a numerical score for severity of microscopic lesions in the head, 3) a conventional single-round polymerase chain reaction (PCR), 4) a nested PCR assay, and 5) a newly developed quantitative real-time TaqMan PCR. There were no significant differences (P > 0.05) among the 5 diagnostic assays in distinguishing between experimentally infected and uninfected control fish. The 2 histopathology grading scales were highly correlated (P < 0.001) for assessment of microscopic lesion severity. Quantification of parasite levels in cranial tissues using PTD and real-time TaqMan PCR was significantly correlated r = 0.540 (P < 0.001). Lastly, 104 copies of the 18S rDNA gene are present in the M. cerebralis genome, a feature that makes this gene an excellent target for PCR-based diagnostic assays. Also, 2 copies of the insulin growth factor-I gene are found in the rainbow trout genome, whose detection can serve both as an internal quality control for amplifiable DNA and as a basis to quantify pathogen genome equivalents present in quantitative PCR assays.

Original languageEnglish (US)
Pages (from-to)202-211
Number of pages10
JournalJournal of Veterinary Diagnostic Investigation
Issue number3
StatePublished - Jan 1 2004

ASJC Scopus subject areas

  • veterinary(all)


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