Evaluation of two Immune-Enzimatic Assays (ELISAs) for detecting Anti-Map anti-bodies in domestic ruminants

The objective of the work was to evaluate two ELISA’s for the detection of anti-Map antibodies. 460 serum and fecal samples of bovines (n=267), ovines (n=140), and goats (n=53) were evaluated. Serums were used for detecting anti-Map antibodies using two different ELISAs, one in-house ELISA made with low-molecular weight proteins (<100 kD) from the antigen ultra-filtrate of Map strain 3065, and a commercial ELISA for paratuberculosis diagnostics. DNA was extracted from faeces to carry out PCR-N IS900. Sensitivity (Se), specificity (E) and Kappa (K) were calculated to estimate concordance between tests. The in-house ELISA made from low-weight map proteins showed a Se of 87%, E of 96% and K of 0.85, while the commercial ELISA showed Se=55%, E=97% and K=0.576, when compared to the PCR-N IS900 test. When comparing both ELISAs, Se was 50%, E was 97%, and K= 0.393. The in-house ELISA made from <100 kD proteins had a better Se and E than the commercial ELISA; concordance between them was low. Low-weight proteins (<100 kD) obtained from the antigen ultra-filtrate of Map strain 3065 are a good candidate for using as antigen in ELISA for the diagnosis of Johne’s disease