The mtp40 gene is not present in Mycobacterium bovis

The mtp40 gene was initially reported to be lacking in classical Mycobacterium bovis strains, while being specific to classical M. tuberculosis strains. Later two clinical isolates reported to be M. bovis were shown to possess the mtp40 gene (A. Weil, B.B. Plikaytis, W.R. Butler, C.L. Woodley and T.M. Shinnik, J Clin Microbiol 1996; 34: 2309-2311). The two strains were, however, not fully characterized biochemically or genotypically. By PCR amplification of whole cell lysates and subsequent spoligotyping, which classifies isolates within the M. tuberculosis complex, the two strains were found to possess the spacers 40-43 which typically are lacking in classicalM. bovis, but had a spoligotyping pattern compatible with M. africanum. We conclude that the two strains, previously designated M. bovis, should be designated M. africanum. This reinvestigation has implications for the phylogenetic classification of M. bovis.