Dear Hideyo: Since the ELISA is very sensitive in detecting the antigen from replicating virus (100 times moreso than the IFA) it is highly unlikely to get a truely false negative, which would mean the test failed to detect antigen that was actually present. A falsely negative result on an ELISA would most likely be due to error on the part of the person doing the test and since the test has been done three times since January, that doesn't seem very likely, unless whoever is doing the test is the same person and very inept.
It would be possible for Uh-oh-oh to test negative on the ELISA and have a latent infection, one which is dormant and so the virus is not replicating. The only reliable way to detect a latent infection would be to do a bone marrow biopsy and the test most typically used is called a bone marrow reactivation test as I understand it. Given what your vet said about the anomalous values for the MCHC, I would suspect perhaps some type of lab error. I don't suppose they would agree to retest that without charging you? From the values for HCT and PCV there seems to be some sort of anemia, but that would probably not be due to a latent FeLV infection because if the virus is not replicating and the infection is not an active one, it is not logical that he would be showing symptoms if illness. Does your vet have an opinion about that? Sally in San Jose
