Several important genes related to virulence, which are closely related to intracellular survival of Brucella (Elzer et al., 1996; Köhler et al., 1996; Edmonds et al., 2002; Haine et al., 2005; Caro-Hernández et al., 2007; Uzureau et al., 2007), including omp25, omp31, dnaK, htrA, gntR, and vjbRwere selected, and their expression in 16M, 16MΔhfq, and 16MΔhfq-C during infection were analyzed. The gene discussed is HTRA1; the disease is infection.