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Thank you very much, Nina. It’s very helpful! -----Original
Message----- Hi Hideyo, Yes, Dr. Susan is correct
that ELISA tests for the antigen of the FeLV virus. If a patient is
positive for a virus, say HIV, then the patient's serum contains antibodies to
HIV and it will bind to the HIV antigens. For simplicity I left this
out. I would like you to see how ELISA works. If you go to www.biology.arizona.edu/immunology/activities/elisa/technique.html,
there is an animation of how ELISA works that is simple to understand.
Dr. Susan also says that she recommends IFA. If you look on the internet
several studies also agree with her, and it appears to be also a good
test. However, she does not support PCR. As I said before, lab
interpretation of PCR may be difficult and purification of feline DNA from
viral DNA, may be difficult, but not impossible and certainly doable. PCR
detects the nucleic acids of the virus. More specific primers may be
needed for PCR of FeLV, but scientifically, if you have these primers and a
patient is positive, a positve PCR means positive infection. I've
attached a whole bunch of web sites for you to look at. Some are
scientific papers, some are FeLV web sites, and some will help you learn more
about the science of testing for FeLV. The best suggestion that I can give
is to learn the science behind these tests. Secondly, I have included web
sites that do not necessarily agree with each other. I can find articles
in Vet journals and in scientific journals that say that PCR is a really great
thing for testing FeLV and is much better than ELISA. I can also find
journals that say PCR doesn't really give that great of results, and to use IFA
if you get a negative test for ELISA. You have to understand that there
will always be debates in science and medicine. Noboby knows the whole
story on any virus, nor how to cure a virus. We use science and
experience to find out what works and how to make treatments better. Both
Dr. Susan and I come with our own opinions. As a vet, she will see what works
in her clinic. Other vets may come to different conclusions.
As a scientist, I have my personal faith in testing such as
PCR. It's a great technique that allows us to take a small amount of
genetic material and amplify it; However, for each specific virus we need to
know the signature sequences of the virus, to make PCR more specific.
Basically, you are only getting opinions from both Dr. Susan and I.
Nobody knows how to cure a virus- any virus- from HIV to the common cold to
FeLV. Period. Animals doctors, human doctors, and scientists
have one particularly irritating trait in common. This is
arrogance. We do know the answers to many things, but what they
don't want the public to know is that, what we do know is actually so very
little in the scheme of things. For instance, the connation of brain
surgeon, conjures up someone who is really smart. Ask a
neurolgist how memory is stored in the brain, and if he or she is honest,
you will get the answer of "I don't know." In other words, even
the most basic question in neurology still can't be answered. Never
forget, there is alot we don't know. The
best thing I can let you know is to 1) keep asking questions, but more
importantly, start learning the science behind these questions. Do first
hand research, grab virology, immunology, and biochemistry textbooks from a
university bookstore (or you can buy them used on the internet). Look
up how antibodies and antigens work. Look up PCR and how it
works. 2) Know that science and medicine are ever changing, and we learn
more everyday (including sometimes, that we can be wrong). 3) We do not
have all the answers, and in fact we actually only know very
little. 4) Keep faith that as more is learned about the virus, better
treatments will come along, as well as better testing. 5) The more
doctors and scientists you ask, the more opinions you will get. Start
learning the science for yourself, and you may find you agree or disagree with
different treatments and proceedures. Try out those treatments that you
believe may work (do your homework first!!!). The more informed you
are, the better for your kitties. <> <>Here is a list of articles and info to check out: www.healthgene.com/scripts/test.asp?code=D341 www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9026077&dopt=Abstract www.vet.ohio-state.edu/docs/vcs724/lectures/sherding/fiv.pdf www.marleyfund.com/testing.html www.vetmed.lsu.edu/oncology/RETRO.html www.laboklin.de/en/VetInfo/LABOKLIN%20aktuell/FeLV_FIV_FIP_questions.htm
(quote from:) FeLV-Diagnosis: http://www.users.waitrose.com/~thecatgroup/fiv.html Testing
for FIV There are several test
systems available for FIV including in-practice test kits. In-practice tests
detect anti-virus antibody, usually directed against a viral core protein
(p24), the transmembrane envelope protein (gp40) or a
combination of both. The most common test systems are based on enzyme-linked immunosorbent assays (ELISA) or immunochromatography
(IC). Combination tests that enable simultaneous testing for FIV and FeLV are widely used. The more specialised tests include immunofluorescence
and western blotting for the detection of antibodies to FIV, and virus
isolation and polymerase chain reaction (PCR) for the detection of the virus
itself. Several laboratories use immunofluorescence
as their first-line test, as this is very sensitive and detects antibody to any
of the viral proteins. Western blotting is a second sensitive test, which
allows the detection of antibodies to individual viral proteins. Virus
isolation is sensitive but is limited by practical considerations (expense,
facilities and time) and it is not suitable for routine use. PCR tests, which
detect the FIV nucleic acids (genetic material) are now more readily available
and are very sensitive. Similar issues of
accuracy and the potential for errors apply to the in-practice test kits for
anti-FIV antibody as for FeLV antigen. Providing the
test has been performed correctly with an appropriate sample, and the
specificity of the test is very high, positive results are generally reliable.
However, it is recommended that a positive result on an in-practice test of a
healthy cat should be confirmed by another type of test, such as immunofluorescence or western blotting. The in-practice
test kits require blood samples and are best performed with serum or plasma,
rather than whole blood. As with all test kits there is a possibility for false
positive and false negative results. In cats with a high suspicion of infection
but which are negative on in-practice test kits, use of another test system to
confirm the negative result is also highly recommended. www.vetscite.org/issue1/tools/txt_leut_0800.htm ***www.biology.arizona.edu/immunology/activities/elisa/technique.html
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