We learned earlier that the immune system makes antibodies to proteins found on the surface of the virus. The immune system of the goat makes antibodies to components of the envelope protein and to the protein that makes up the capsid. Since the goat is infected with CAEV for life, once the immune system has begun to produce antibodies to the virus they can be detected at any time during the goat's life.
Sensitivity is a measure of the amount of antibody present. A test that is highly sensitive will find low levels of antibody. If the test is not very sensitive then it will miss a low level of antibodies even if the goat is infected. This can result in a false negative.
Specificity is a measure of the type of antibody found. A highly specific test will find only the exact antibodies to the CAE virus. False positives are a measure of specificity.