Inactivation of the Mycobacterium bovis homologue of the polymorphic RD1 gene Rv3879c (Mb3909c) does not affect virulence

The RD1 locus is deleted from all strains of Mycobacterium bovis BCG but present in virulent isolates of M. bovis and Mycobacterium tuberculosis. The RD1 gene Rv3879c encodes a proline- and alanine-rich protein that shows sequence polymorphism across members of the M. tuberculosis complex. The role of this protein in virulence was investigated by deleting the Rv3879c homologue from M. bovis (Mb3909c) and testing the virulence of the mutant in the guinea pig model. The M. bovis DeltaMb3909c mutant was not attenuated in the guinea pig model, showing that this gene does not encode a virulence factor and plays no role in the attenuation caused by loss of RD1. Crown Copyright (C) 2003 Published by Elsevier Ltd. All rights reserved.