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Journal of Clinical Microbiology, Jan 1997, 106-110, Vol 35, No. 1
A Scorpio, D Collins, D Whipple, D Cave, J Bates and Y Zhang
Bovine tuberculosis (TB) caused by Mycobacterium bovis is an important
veterinary disease that can also afflict humans. Although M. bovis shares
an almost identical genome with M. tuberculosis, subtle differences in host
specificity and several biochemical parameters can be used to distinguish
the two closely related species. The current method for distinguishing M.
bovis from M. tuberculosis relies on tedious testing of biochemical
parameters, including natural resistance to pyrazinamide and defective
pyrazinamidase (PZase) activity of M. bovis strains. In this study, we
report the development of a rapid PCR- single-strand conformation
polymorphism (SSCP) assay to differentiate M. bovis from M. tuberculosis
strains, based on the detection of a single characteristic point mutation
in the PZase gene (pncA) of M. bovis. Eighty-seven of 89 M. bovis strains
could be distinguished from M. tuberculosis strains. Surprisingly, two
animal isolates which were initially identified as M. bovis were shown to
be M. africanum because they had a wild-type pncA sequence with positive
PZase. These two M. africanum strains contain multiple (three and six)
copies of insertion sequence IS6110, a feature they have in common with M.
tuberculosis. The implication of this finding for the taxonomy of M.
tuberculosis complex is discussed in relation to host preference and
epidemiology. The development of a rapid PCR-SSCP test for distinguishing
M. bovis from M. tuberculosis will be useful for monitoring the spread of
bovine TB to humans in areas where bovine TB is endemic and for directing
the treatment of human TB caused by M. bovis.
Copyright © 1997 by the American Society for Microbiology. All rights reserved.
Rapid differentiation of bovine and human tubercle bacilli based on a characteristic mutation in the bovine pyrazinamidase gene
Department of Molecular Microbiology and Immunology, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.
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