Blocking enzyme-linked immunosorbent assay for detection of antibodies against Actinobacillus pleuropneumoniae serotype 8.

A blocking enzyme-linked immunosorbent assay (ELISA) for detection of antibodies against Actinobacillus pleuropneumoniae serotype 8 is described. The test is based upon a competitive reaction between the serum to be tested and a polyclonal rabbit antiserum prepared against serotype 8 and absorbed with whole cells of serotypes 3 and 6. The blocking ELISA proved able to distinguish animals infected with serotype 8 from those infected with any other serotype of A. pleuropneumoniae including the antigenically closely related serotypes 3 and 6. Positive results were not observed with field sera from serotype 6 infected herds or from herds known to be free from A. pleuropneumoniae infection.