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>. | 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>. |