title: Detection of serotype-specific antibodies or capsular antigen of Actinobacillus pleuropneumoniae by a double-label radioimmunoassay.
abstract: Diagnostic tests for Actinobacillus pleuropneumoniae have been problematic because current tests do not use a purified antigen and in most cases measure either antibody or antigen, but not both. We describe a Farr-type double-label radioimmunoassay that utilizes purified, serotype-specific, 3H-capsule to measure antibody to capsule directly or that can measure capsule in a sample indirectly by inhibition of antibody binding. The assay could detect about 1 ng of serotype-specific antibody in serum or at least 100 pg of capsule in a sample. Due to the sensitivity of the assay, false-positive results were common with neat sera (probably due to cross-reacting antibodies to unrelated antigens), but the specificity was improved when the sera were diluted 1:100. The radioimmunoassay should prove to be a useful reference method for research and diagnostic testing and for comparison of new assays for detection of capsule or antibodies to capsule.
authors.affiliation: Department of Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg 24061.
authors.forename: T J
authors.initials: TJ
authors.lastname: Inzana
authors.forename: G F
authors.initials: GF
authors.lastname: Clark
authors.forename: J
authors.initials: J
authors.lastname: Todd
mesh_terms: D000188:Actinobacillus / Q000145:classification / Q000276:immunology* / Q000302:isolation & purification; D000189:Actinobacillus Infections / Q000175:diagnosis / Q000662:veterinary; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis*; D000942:Antigens, Bacterial / Q000032:analysis*; D005069:Evaluation Studies as Topic; D005189:False Positive Reactions; D011135:Polysaccharides, Bacterial / Q000276:immunology; D011863:Radioimmunoassay / Q000379:methods*; D012703:Serotyping; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D011135:Polysaccharides, Bacterial