gary, it truly has to do with nothing more than the issue of exposure time
and time needed for the virus to be neutralized by the body: both the ELISSA
and IFA test for antigens, NOT antibodies. test with ifa at same time as
ELISSA, and you'll get the same result. test two weeks later, and you'll
still probably get a positive result, because you haven't given kitty's
system time to have processed the virus out. a positive IFA after 4 months
however, is a totally different story--probably high, high 90s chance of
being a true positive in that case. but there's a big difference between a
retest at two weeks and four months, and that's what we have to emphasize.

some research says that you can reliably retest after 30 days, but most says
90 to 120 days. many sanctuaries, and individual FeLV parents, who didn't
know that retesting was necessary, have found that their positive cats
actually aren't, often upon routine testing years later while trying to rule
out something else. you can't trust a single ELISSA, and an IFA run too
early is just as inaccurate in that it'll produce the same result.

i don't know/understand the science enough to explain why there isn't a test
that uses antibodies to confirm or refute positivity with FeLV--in europe,
the western blot, which does test for antibodies, is used for FeLV as well
as for FIV. anyone know why we don't use that here??? i'm sure there are
some specific drawbacks, but if we could test for antibodies to FeLV, we
could at least get a definite yes or no....


On Wed, Apr 8, 2009 at 7:28 PM, gary <> wrote:

> I know there are some who say they have cats that were IFA positive and are
> now negative, I would say it is a rare thing.
> The FeLV vaccine has no effect on the ELISA or the IFA test.  It is the FIV
> vaccine that will make a cat test positive for FIV.
> Gary
> -----Original Message-----
> From:
> [] On Behalf Of James Rauscher
> Sent: Wednesday, April 08, 2009 4:28 PM
> To:
> Subject: Re: [Felvtalk] Interferon and Vetri-DMG - do these things help?
> Thank you for the info, MC! Onyx's IFA test came up positive - do you know
> if cats who are positive on that test ever revert to negative? Also, some
> vets say that vaccinated cats always show up positive on later tests
> (because of the vax), but two of them said that vaccinated cats do not show
> up positive on the IFA test unless they actually have the virus. Can anyone
> clarify that for me?
> Avia
> _______________________________________________
> Felvtalk mailing list

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