Université Montpellier I, Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé (CPBS), F-34095, Montpellier, France.
J Infect Dis. 2011 Apr 15;203(8):1129-35. doi: 10.1093/infdis/jiq163.
In murine infections, Brucella microti exhibits an atypical and highly pathogenic behavior resulting in a mortality of 82%. In this study, the possible involvement of the virB type IV secretion system, a key virulence factor of Brucella sp., in this lethal phenotype was investigated. As previously described for B. suis, expression of the virB operon of B. microti was induced in acid minimal medium, partially mimicking intracellular environment. Early neutralization of cellular compartments abolished intracellular replication of B. microti, showing that acidity of the Brucella-containing vacuole is an essential trigger. A ΔvirB mutant of B. microti exhibited strong attenuation in murine and human macrophages in vitro. Interestingly, infection with this mutant was not lethal in Balb/c mice and lacked the typical intrasplenic peak at 3 days post-infection, hence demonstrating that lethality of B. microti in murine infection absolutely requires a functional virB operon.
在鼠类感染中，微小布鲁氏菌表现出一种非典型且高致病性的行为，导致 82%的死亡率。在这项研究中，研究了 virB 型 IV 型分泌系统（布鲁氏菌属的关键毒力因子）在这种致死表型中的可能参与。如先前对猪布鲁氏菌的描述，微小布鲁氏菌的 virB 操纵子在酸性最小培养基中的表达被诱导，部分模拟了细胞内环境。早期中和细胞区室可消除微小布鲁氏菌的细胞内复制，表明布鲁氏菌包含的空泡的酸性是一个必要的触发因素。微小布鲁氏菌的ΔvirB 突变体在体外的鼠和人巨噬细胞中表现出强烈的衰减。有趣的是，这种突变体感染在 Balb/c 小鼠中并不致命，并且在感染后 3 天缺乏典型的脾内峰值，因此证明微小布鲁氏菌在鼠类感染中的致死性绝对需要功能性 virB 操纵子。
