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Diagnosis of FIV is made by demonstrating the presence of antibodies against the virus. ELISA tests are available for in-house use, with some kits detecting antibody to the core protein p24 and others detect antibody to the envelope protein gp4l<sup>2</sup>. Non-haemolysed plasma or serum is used for performing the in-house ELISA. Results must be interpreted with caution.  
 
Diagnosis of FIV is made by demonstrating the presence of antibodies against the virus. ELISA tests are available for in-house use, with some kits detecting antibody to the core protein p24 and others detect antibody to the envelope protein gp4l<sup>2</sup>. Non-haemolysed plasma or serum is used for performing the in-house ELISA. Results must be interpreted with caution.  
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Once a cat acquires FIV infection, the antibodies created persist for life. This means that an ELISA test at any stage after infection should give a positive result. However, the test has a sensitivity of 98%, and so false positives do occur. Because of this, animals that test positive to an in-house ELISA, should be re-tested using a different test. Laboratories offer an immunoblot (Western blot) to confirm the diagnosis in cats that test ELISA-positive. The problem of using a test that detects anitbodies becomes apparent when it is neccessart to test kittens that are born to an FIV-positive queen. Antibodies against FIV are passively acquired via the milk, and can be detected wi
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Once a cat acquires FIV infection, the antibodies created persist for life. This means that an ELISA test at any stage after infection should give a positive result. However, the test has a sensitivity of 98%, and so false positives do occur. Because of this, animals that test positive to an in-house ELISA, should be re-tested using a different test. Laboratories offer an immunoblot (Western blot) to confirm the diagnosis in cats that test ELISA-positive. The problem of using a test that detects anitbodies becomes apparent when it is neccessart to test kittens that are born to an FIV-positive queen. Antibodies against FIV are passively acquired via the milk, and can be detected when an ELISA test is used. This makes it imposible to distinguish animals that have been transplacentally infected with virus and are producing their own antibodies from those which have merely acquired pre-formed anitbodies from their mother. Maternally derived anitbodies can persist for up to 6 months<sup>2</sup>, and so animals testing positive before this age should be restested at 8-12 months old<sup>5</sup>.
Passive
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transfer of antibodies occurs via the milk, with the
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result that maternally derived antibodies may be
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detected when kittens are blood tested for FIV antibodies.
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Although all of the kittens born to a queen infected
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with FIV may be antibody positive, the virus itself is
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usually only passed on to a maximum of one-third of the
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kittens in a litter. Maternally derived antibodies may persist
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for up to four months and it may be a further two
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months before infected kittens seroconvert. It is therefore
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recommended that kittens born to FIV-infected
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queens are not antibody tested until they are at least six
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months old.
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* FALSE POSITIVE RESULT.
       
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