The virulence of the mycobacteria that cause tuberculosis depends on t
heir ability to multiply in mammalian hosts. Disruption of the bacteri
al erp gene, which encodes the exported repetitive protein, impaired m
ultiplication of M. tuberculosis and M, bovis Bacille Calmette-Guerin
in cultured macrophages and mice. Reintroduction of erp into the mutan
ts restored their ability to multiply. These results indicate that erp
contributes to the virulence of M. tuberculosis.