title: Development and validation of an enzyme-linked immunosorbent assay for the diagnosis of porcine proliferative enteropathy.
abstract: The objective of this study was to develop an indirect enzyme-linked immunosorbent assay (ELISA) using a sonicated pure culture of Lawsonia intracellularis as the antigen (So-ELISA). A total of 332 serum samples, consisting of 232 experimentally infected animals and 100 animals naturally infected with L. intracellularis, were used to assess the diagnostic sensitivity. Three hundred and fifty-five sera from uninfected animals were used to determine the diagnostic specificity. The receiver operating characteristic and mean +3 standard deviation of optical density (OD) values from uninfected animals were used for selecting cut-off points. The diagnostic accuracy of So-ELISA was considered to be high as the area under the curve index was 0.991 with 0.0029 standard error. The optimal cut-off for So-ELISA was set at 0.45 OD with 89.8% sensitivity and 99.4% specificity based on a combination of good sensitivity and high specificity. No cross-reactivity was found in sera from pigs exposed to Brachyspira pilosicoli, B. hyodysenteriae, Campylobacter mucosalis, C. jejuni, or C. coli. Inter- and intracoefficient of variation of all control sera tested with So-ELISA was less than 10%. The observed agreements between So-ELISA and the immunoperoxidase monolayer assay tested with experimental challenge animals and field samples were 95.08% with 0.88 kappa and 90.65% with 0.74 kappa value, respectively. So-ELISA was able to detect the seroconversion of infected animals at 2 to 4 weeks after exposure to L. intracellularis. Based on the validation results, So-ELISA could be used as an alternative serology for proliferative enteropathy diagnosis.
authors.affiliation: College of Veterinary Medicine, Department of Veterinary and Biomedical Sciences, 1971 Commonwealth Avenue, St. Paul, MN 55108, USA. watta004@umn.edu
authors.forename: Suphot
authors.initials: S
authors.lastname: Wattanaphansak
authors.forename: Tanong
authors.initials: T
authors.lastname: Asawakarn
authors.forename: Connie J
authors.initials: CJ
authors.lastname: Gebhart
authors.forename: John
authors.initials: J
authors.lastname: Deen
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D019540:Area Under Curve; D045824:Desulfovibrionaceae Infections / Q000097:blood / Q000382:microbiology / Q000662:veterinary*; D004751:Enteritis / Q000097:blood / Q000382:microbiology / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary*; D007124:Immunoenzyme Techniques / Q000662:veterinary; D020639:Lawsonia Bacteria / Q000302:isolation & purification*; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013010:Sonication; D013552:Swine; D013553:Swine Diseases / Q000097:blood / Q000382:microbiology*
chemical_list: D000907:Antibodies, Bacterial