Disruption of the mycobacterial cell entry gene of Mycobacterium bovis BCGresults in a mutant that exhibits a reduced invasiveness for epithelial cells

Mycobacteria belonging to the Mycobacterium tuberculosis complex have the a bility to invade and replicate in nonphagocytic cells, an event that requir es the presence of bacterial surface components capable of triggering a cel l response and the subsequent internalization of the microorganism. In this study, we report the sequencing of the mycobacterial cell entry gene (mce) of Mycobacterium bovis bacillus Calmette-Guerin (BCG) and the generation a nd characterization of a mutant BCG strain with an inactivated mce gene, by homologous recombination with double cross-over. This mutant strain does n ot express the mycobacterial cell entry protein (Mce) and exhibits a reduce d ability to invade the non-phagocytic epithelial cell line HeLa as compare d to wild-type BCG. (C) 1999 Federation of European Microbiological Societi es. Published by Elsevier Science B.V. All rights reserved.