**The title, authors, and abstract for this completion report are provided below. For a copy of the completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**
Development of improved diagnostic methods for the herpesvirus associated with epizootic
epitheliotropic disease (EED) in lake trout Salvelinus namaycush.
Ronald P. Hedrick2, Tomofumi Kurobe2, Susan Marcquenski3
2 Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, CA 95616
3 Wisconsin Department of Natural Resources, Box 7921 Madison WI 53707
Epizootic epitheliotropic disease virus (EEDV) has caused catastrophic losses among hatchery-reared juvenile lake trout (Salvelinus namaycush) since the early 1980’s and remains as a major impediment to lake trout restoration in the Great Lakes basin of the United States. Although EEDV has been tentatively designated as a herpesvirus based upon morphological criteria, further characterization of the virus and development of improved detection methods has been hampered by the inability to propagate the virus in cell culture. Recently obtained sequence data for a region of the putative terminase gene from EEDV as well as the related Salmonid herpesvirus 1 and 2 has permitted the development of a polymerase chain reaction (PCR) assay for specific detection of EEDV. The new EEDV PCR demonstrated both an excellent analytic sensitivity and specificity and detected viral DNA as present in the skin of lake trout during periods of active viral outbreaks. In addition, EEDV DNA was detected among healthy appearing juveniles and in the ovarian fluids of spawning adults. A comparison of the new assay with electron microscopy, the current “gold standard” method for virus detection, demonstrated a greater analytical sensitivity for the PCR. An initial assessment of virus prevalence among populations of lake trout indicates a potentially broad geographic salmonid host range than previously recognized. In this study we describe the development and initial validation steps of the EEDV PCR as a replacement for current diagnostic methods which require virus extraction from the skin, partial purification by isopycnic centrifugation and visualization of negatively-stained virions by electron microscopy.