title: Immunoglobulin G1 enzyme-linked immunosorbent assay for diagnosis of Johne's Disease in red deer (Cervus elaphus).
abstract: This study was designed to develop a customized enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of Johne's disease (JD) in farmed deer. Two antigens were selected on the basis of their superior diagnostic readouts: denatured purified protein derivative (PPDj) and undenatured protoplasmic antigen (PpAg). ELISA development was based on the antigen reactivity of the immunoglobulin G1 (IgG1) isotype, which is a highly specific marker for mycobacterial disease seroreactivity in deer. Sensitivity estimates and test parameters were established using 102 Mycobacterium paratuberculosis-infected animals from more than 10 deer herds, and specificity estimates were determined using 508 uninfected animals from 5 known disease-free herds. A receiver-operated characteristic analysis determined that at a cut point of 50 ELISA units, there was a specificity of 99.5% and sensitivities of 84.0% with PPDj antigen, 88.0% with PpAg, and 91.0% when the antigens were used serially in a composite test. Estimated sensitivity was further improved using recombinant protein antigens unique for M. paratuberculosis, which identified infected animals that were unreactive to PPDj or PpAg. While 80% of animals that were seropositive in the IgG1 ELISA had detectable histopathology, the assay could also detect animals with subclinical disease. The test was significantly less sensitive (75%) for animals that were culture positive for M. paratuberculosis but with no detectable pathology than for those with pathological evidence of JD (>90%). When the IgG1 ELISA was used annually over a 4-year period in a deer herd with high levels of clinical JD, it eliminated clinical disease, increased production levels, and reduced JD-related mortality.
authors.affiliation: Disease Research Laboratory, Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin, New Zealand. frank.griffin@stonebow.otago.ac.nz
authors.forename: J Frank T
authors.initials: JF
authors.lastname: Griffin
authors.forename: Evelyn
authors.initials: E
authors.lastname: Spittle
authors.forename: Christie R
authors.initials: CR
authors.lastname: Rodgers
authors.forename: Simon
authors.initials: S
authors.lastname: Liggett
authors.forename: Marc
authors.initials: M
authors.lastname: Cooper
authors.forename: Douwe
authors.initials: D
authors.lastname: Bakker
authors.forename: John P
authors.initials: JP
authors.lastname: Bannantine
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001431:Bacteriological Techniques / Q000379:methods; D003670:Deer; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D007074:Immunoglobulin G / Q000302:isolation & purification*; D016927:Mycobacterium avium subsp. paratuberculosis / Q000276:immunology*; D010283:Paratuberculosis / Q000175:diagnosis* / Q000276:immunology; D011237:Predictive Value of Tests; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012698:Serologic Tests; D014373:Tuberculin
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D014373:Tuberculin