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Date: July 21, 2003
Posted by: Yvette Girard <yagirard@utmb.edu>

Date: Wed, 16 Jul 2003
From: "Girard, Yvette A" <yagirard@utmb.edu>
Subject: [WNV-L] Cautions on the use of the VecTest for West Nile 
Virus Detection in Bird Brain Suspensions

We have had problems similar to those described by Ward Stone (NYS 
Dept. of Environmental Conservation) with both false positive and 
false negative results in trying to use the VecTest West Nile Virus 
Antigen Assay to test bird brain homogenates for the presence of 
virus.  Our lab compared the sensitivity of the VecTest to both PCR 
and cell culture on brains from dead birds collected in Harris 
County, TX, and found that out of 199 birds
tested, 61 (31%) were positive by VecTest, while only 4 of these were 
positive by cell culture.  Ninety-eight of the 199  bird brain 
samples were chosen for WNV detection by PCR and three were positive 
by this technique.
Of the three PCR-positive birds, two were VecTest-positive (one Blue 
Jay andone American Crow); the third was  VecTest negative but cell 
culture positive (Carolina Chickadee).  These results call into 
question the usefulness of
the VecTest for field applications beyond mosquito samples.

Yvette Girard, MPH
Graduate Student, Department of Pathology
University of Texas Medical Branch, Galveston, TX
yagirard@utmb.edu


Dr. Robert B. Tesh
Professor, Department of Pathology
University of Texas Medical Branch, Galveston, TX

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