Evaluation of three serum antibody enzyme-linked immunosorbent assays for Mycoplasma hyopneumoniae

Objective: To compare the performance of three ELISAs in detecting Mycoplasma hyopneumoniae serum antibodies from M hyopneumoniae-naive and experimentally inoculated pigs. Methods: Archived serum samples from experimentally infected and known seronegative swine were tested using three M hyopneumoniae ELISAs, including a Tween-20 ELISA and two commercially available ELISA tests, the HerdChek Mycoplasma hyopneumoniae (Idexx Laboratories, Westbrook, Maine) and the DAKO Mycoplasma hyopneumoniae ELISA (DAKO Corporation, Carpenteria, California). Statistical analyses, including kappa coefficients, receiver operating characteristic curves, and covariance of tests, were used to compare the three assays. Results: The sensitivities of all three assays were lower than previously reported in the literature. The blocking ELISA was the most sensitive of these three assays. All three assays had excellent specificity. Using tests in combination increased sensitivity. Implications: Mycoplasma hyopneumoniae ELISA assays may be less sensitive than previously reported, especially for vaccinated animals and animals less than 21 days postinfection. These assays are inefficient at detecting serum antibodies in the early stages of infection; therefore, care should be exercised when interpreting results. Using a combination of tests to increase sensitivity may be valuable for the diagnosis of M hyopneumoniae infection.