Urease activity does not contribute dramatically to persistence of Mycobacterium bovis bacillus Calmette-Guérin.

Multiplication of BCGure-, an isogenic urease-negative mutant of Mycobacterium bovis BCG constructed by allelic exchange (J. M. Reyrat, F. X. Berthet, and B. Gicquel, Proc. Natl. Acad. Sci. USA 92:8768-8772, 1995), was examined in human macrophages and mice. Although ureolytic activity was not essential to BCGure-growth, a slight decrease in the multiplication and persistence of the mutated strain compared with wild-type BCG was observed in lungs of infected mice.