My sister and I have a disagreement maybe some of you can shed light on
this.

We have a three year old cat (Candy) that was around others cats, one of
which that tested positive for Feline leukemia virus.  So we isolated Candy
for TWO months and got her tested for FeLV/FIV.  The vet drew blood and sent
it to a lab and it came back negative.  We are planning on giving her away
to a lady who has a cat, but there is some concern about the possibility of
a false negative.  Someone told my sister that for best results, you must
wait THREE months before you test to allow the virus to activate enough to
be accurately tested.  So my sister wants to warn this lady that even though
the test came back negative, that because we didn't wait for three months,
the results may not be as valid as they could be.

I'm wondering if I can get a clear answer on this.  Is there any research
indicating that waiting three months would be significantly better than
waiting two months?  If possible, I'd like to get some kind of
quantification on this.  What is the probability of her being positive for
FeLV if the test comes back negative after a one month isolation?  After a
two month isolation?  After a three month isolation?  Note

I'm asking about the probability of a SINGLE TEST being performed.  In
reality, I'm going to ask the lady to isolate the cat for two weeks and
retest her.  Two negative tests several weeks apart will be a very strong
indication of negative.

Regards,
Louis