Rapid differentiation of bovine and human tubercle bacilli based on a characteristic mutation in the bovine pyrazinamidase gene

Angelo Scorpio, Desmond Collins, Diana Whipple, Donald Cave, Joseph Bates, Ying Zhang

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish (US)
Pages (from-to)106-110
Number of pages5
JournalJournal of clinical microbiology
Volume35
Issue number1
DOIs
StatePublished - Jan 1997
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology (medical)

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