CAUTIONS ON USE OF THE VECTEST FOR WEST NILE VIRUS DETECT ION IN BIRD BRAIN SUSPENSIONS

July 21, 2003

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 and
one 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.

by
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
Received on Mon Jul 21 11:30:55 2003