DETECTION OF ACTINOBACILLUS-PLEUROPNEUMONIAE SEROTYPE-2 ANTIBODIES INPIG SERA BY AN INHIBITION ENZYME IMMUNE ASSAY (EIA)

An inhibition Enzyme Immune Assay (EIA) for detection of antibodies ag ainst A, pleuropneumoniae serotype 2 (App-2) in pig sera, based on the inhibition of the binding of an App-2 specific monoclonal antibody wa s established The monoclonal antibody (mAb 102-G02) was found to be di rected against an epitope on the O-chain of App-2 LPS. Some App-2 isol ates did not react with the mAb 102-G02. These isolates are referred t o as App-2X. In the inhibition EIA highly purified App-2 LPS was used to coat microtiter plates. Serial dilutions of pig sera were added to the plates prior to the mAb 102-G02. The degree of binding of App-2 an tibodies from pig sera was determined as the percentage inhibition of the mAb 102-G02. Pig sera from specific pathogen free (SPF) herds, fro m experimentally infected animals, and from conventionel herds were te sted. A serum dilution of 1/200 was found to be optimal, when using 50 % inhibition as the discriminating inhibition percentage. Serum from A pp-2X infected herds showed a lower reactivity as compared to serum fr om App-2 infected herds. No crossreactivity was observed with serum fr om pigs infected with other App serotypes. The sensitivity and specifi city were 100% and 98.9%, respectively.