GENOMIC ANALYSIS OF MYCOBACTERIUM-BOVIS AND OTHER MEMBERS OF THE MYCOBACTERIUM-TUBERCULOSIS COMPLEX BY ISOENZYME ANALYSIS AND PULSED-FIELD GEL-ELECTROPHORESIS

Initially, multilocus enzyme electrophoresis was used to examine genet ic relationships among 63 isolates of Mycobacterium bovis and 13 other members of the M. tuberculosis complex. The isolates were divided int o five electrophoretic types, with a mean genetic diversity of 0.1. Th e strains were genetically homogenous, indicating that members of the complex were closely related. This supported the suggestion that they should be considered as subspecies of a single species. Pulsed-field g el electrophoresis (PFGE) was then used to differentiate these isolate s, as well as 59 additional isolates of M. bovis from different parts of the world, PFGE differentiated these strains into 63 patterns (53 p atterns for M. bovis). Isolates of M. bovis from Western Australia (n = 46) were more homogenous than isolates from other regions. Eight str ains were identified in that state, and one predominantly bovine strai n was isolated from two human beings and a feral pig. Although M. bovi s isolates from different parts of the world had distinct DNA patterns , some were very similar. PFGE is a highly discriminatory technique fo r epidemiological studies of bovine tuberculosis. For example, it allo wed differentiation between isolates of M. bovis cultured from animals in separate outbreaks of tuberculosis, it suggested the transmission of infection between certain properties, and it demonstrated the exist ence of multiple infections with different strains at certain farms.