Evaluation of the efficacy of Mycoplasma hyopneumoniae bacterin following immunization of young pigs in the presence of varying levels of maternal antibodies

Mycoplasma hyopneumoniae causes enzootic pneumonia that primarily affects growing pigs. Although the disease is nonfatal, it causes substantial losses attributable to reduced growth performance, increased susceptibility to secondary bacterial pneumonia, and potentiation of PRRSV-induced pneumonia (1, 2). Both cell-mediated and humoral immune responses appear to be important in providing protection against infection (3). The Tween 20 ELISA and monoclonal antibody blocking ELISA (Commercial DAKO test) have been used for determining antibody response to M. hyopneumoniae (4, 5). Schering-Plough Animal Health Corp. (SPAH) has also developed a competitive ELISA (CE) using rabbit polyclonal serum to measure the M. hyopneumoniae antibody response following vaccination of pigs. A previous study in our laboratory indicated that 4and 6-week-old antibody positive pigs born to vaccinated sows were significantly protected against lung consolidation following experimental M. hyopneumoniae challenge (6). In that study, conducted in pigs raised in a commercial setting, secondary pathogens contributed to the lesions observed. The purpose of this current study was to expand upon the previous study and to evaluate the relationship between the level of maternally derived antibodies and potential interference with active immunization of young pigs. An additional objective of this study was to compare the antibody response as measured by the DAKO test, the Tween 20 ELISA and SPAH’s competitive ELISA (SPAH-CE).