A DNA vaccine encoding MPB 83 from Mycobacterium bovis reduces M bovis dissemination to the kidneys of mice and is expressed in primary cell cultures of the European badger (Meles meles)

Abstract

Nucleic acid (DNA) vaccination against tuberculosis in the European badger (Meles meles) is one approach to addressing the escalating problem of bovine tuberculosis in Great Britain. The aim of vaccination is to reduce the burden of tuberculosis within the badger population and the shedding of Mycobacterium bovis to levels that would break the transmission of infection to cattle. To this end, the vaccine would be required to limit the amount of disseminated tuberculosis in the badger, especially dissemination to the kidney from where M bovis can be shed in the urine. A promising candidate DNA vaccine encoding a 26kDa major antigen (MPB 83) of M bovis was evaluated in a mouse model of disseminated M bovis infection. Using the DNA vaccine, protection against infection of the kidney was found to be greater than that achieved with the current live vaccine, Bacille Calmette-Guerı́n (BCG). Kidney tissue and skeletal muscle from the badger was used to derive primary cell cultures in which to examine the expression ofMPB 83 following transfection with the DNA vaccine. Kidney cortex gave rise to a monotypic culture of epithelial cells whilst the muscle gave rise to a mixed culture of fibroblasts and myoblasts. During culture the myoblasts differentiated into multinucleated myotubes, verified by immunofluorescent detection of mammalian desmin. Successful expression of MPB 83 by transfected epithelial and myotube cells was confirmed by immunofluorescence using a monoclonal antibody specific to the protein. These observations fulfil the early requirements for the development of a DNA vaccine for badger tuberculosis.