To the FML: I've been involved in a recent discussion concerning possible false positive results by CIEP for ADV Antibody along with Drs. Williams and Bloom. It is my contention that a false positive reading is possible for two reasons (I respond here with some of the same language used prior in this discussion): First, the basis of potential false positive results would not be cross-reactivity with distemper virus, antibodies to distemper or any other virus (including parvovirus) or their antibodies. The basis for this is the production in ferrets of antibodies to cellular debris in vaccines, present as a by-product of their manufacture in cell culture. Similar cellular debris may be present in the whole ADV viral lysate (actually a mixture of several ADV-related proteins, or antigens) used in the test. When antibodies to this debris in the ferret serum encounter the ADV lysate in the test a precipitate line can be formed which is similar to an ADV Antibody positive. Especially in cases where the ferret is tested by this technique within 2-3 months of receiving a vaccine I believe there is some likelihood of a false positive result due to this phenomenon. Even United Vaccines notes the possibility of false positives from recently vaccinated ferrets. Second, and admittedly subjective, is the issue of reading results. As I understand it, the CIEP result is determined by an operator's judgement as to whether a precipitate line is formed in the gel, which is a subjective method itself. In my conversations with Dr. Bloom, he indicated that with any questionable result in his laboratory, the CIEP gel is washed and further treated with a protein dye stain for better visual detection, and the interpretation thus confirmed. I don't wish to contradict Dr. Williams, but I must respectfully add that Dr. Bloom did not say outright there are no false positives associated with CIEP. He points out that there conceivably are false positives, but there is no peer-reviewed evidence to prove it or the contrary. As I mentioned, even United states concerns about testing around the time of vaccinations. While I have not seen data as to the accuracy, sensitivity or specificity of CIEP, I agree that anyone who has a CIEP positive ferret should take appropriate steps to isolate the ferret and not equivocate, because of the nature of the danger involved. As a disclaimer, let me say that my organization is one of the groups mentioned by Dr. Williams as being involved in the development of a new diagnostic tool for ADV Antibody. I do think that the ELISA we've developed is a better diagnostic test for ADV Antibody for several reasons. When we are finished with our clinical/other studies I will demonstrate this with the data in the appropriate forum. I plan on being at the Pennsauken show on December 2, and would be happy to discuss these issues with all present. Sincerely, Robert L. Stephon, Ph.D. Avecon Diagnostics, Inc. [Posted in FML issue 3223]