To evaluate the virulence roles of vjbR, the mutant and complementary strains of vjbR were constructed, and their survival capabilities in macrophage and mice were assayed. By using homologous recombination, the vjbR (BMEII1116) was replaced by kanamycin gene, resulting the deletion mutant 16MΔvjbR. The ORF was PCR amplified and cloned into pMD-18T, which was transformed into mutant strain to generate the complementary strain 16MΔvjbR-C. The three strains, 16M, 16MΔvjbR and 16MΔvjbR-C, were used to infect macrophage and mice, and their survival capability were assayed and compared. The vjbR mutant strain16MΔvjbR showed reduced survival in macrophage and mice, indicating that vjbR is a virulence gene of Brucella, and is essential for establishment of choronic infection.