EFFICACY OF VACCINATION FOR MYCOBACTERIUM-AVIUM WITH WHOLE-CELL AND SUBUNIT VACCINES IN EXPERIMENTALLY INFECTED SWINE

Mycobacterium avium infections are a common problem in large swine pro ducing states and cause substantial financial losses at slaughter insp ection due to carcass condemnation. once the infection is established in a swine herd it is difficult to effectively prevent or eliminate th e disease. Previous mouse studies in our laboratory suggested that Mac rophage Inhibitory Factor-A3 (MIF-A3) is a virulence factor of M. aviu m and potential antigen for vaccine development. In this study we eval uated the efficacy of a killed 'whole cell' M. avium serovar 2 bacteri n and conjugated MIF-A3 subunit vaccine in preventing infection and di sease in swine challenged with virulent M. avium serovar 2. Gross and microscopic pathology, acid-fast staining, culture and polymerase chai n reaction (PCR) for the M. avium specific insertion sequence IS902 we re utilized in evaluation. Results indicated that neither vaccine prev ented infection in challenged animals; however, a 47% reduction in sev erity of disease was found in swine vaccinated with the 'whole cell' M , avium serovar 2 bacterin. Reduction in severity of disease was not d etected in animals vaccinated with the subunit MIF-A3 vaccine. (C) 199 8 Elsevier Science B.V. All rights reserved.