Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China.
PLoS One. 2013 Aug 7;8(8):e67014. doi: 10.1371/journal.pone.0067014. eCollection 2013.
Brucella spp. is a species of facultative intracellular Gram-negative bacteria that induces abortion and causes sterility in domesticated mammals and chronic undulant fever in humans. Important determinants of Brucella's virulence and potential for chronic infection include the ability to circumvent the host cell's internal surveillance system and the capability to proliferate within dedicated and non-dedicated phagocytes. Hence, identifying genes necessary for intracellular survival may hold the key to understanding Brucella infection. In the present study, microarray analysis reveals that 7.82% (244/3334) of all Brucella abortus genes were up-regulated and 5.4% (180/3334) were down-regulated in RAW264.7 cells, compared to free-living cells in TSB. qRT-PCR verification further confirmed a >5-fold up-regulation for fourteen genes. Functional analysis classified araC, ddp, and eryD as to partake in information storage and processing, alp, flgF and virB9 to be involved in cellular processes, hpcd and aldh to play a role in metabolism, mfs and nikC to be involved in both cellular processes and metabolism, and four hypothetical genes (bruAb1_1814, bruAb1_0475, bruAb1_1926, and bruAb1_0292) had unknown functions. Furthermore, we constructed a B. abortus 2308 mutant Δddp where the ddp gene is deleted in order to evaluate the role of ddp in intracellular survival. Infection assay indicated significantly higher adherence and invasion abilities of the Δddp mutant, however it does not survive well in RAW264.7 cells. Brucella may survive in hostile intracellular environment by modulating gene expression.
布鲁氏菌属是一种兼性细胞内革兰氏阴性细菌，可引起家畜流产和不育，并导致人类慢性波浪热。布鲁氏菌的毒力和慢性感染潜力的重要决定因素包括绕过宿主细胞内部监测系统的能力和在专用和非专用吞噬细胞内增殖的能力。因此，确定细胞内生存所必需的基因可能是理解布鲁氏菌感染的关键。在本研究中，微阵列分析显示，与 TSB 中的自由生活细胞相比，3334 个布鲁氏菌流产株基因中有 7.82%（244/3334）上调，5.4%（180/3334）下调。qRT-PCR 验证进一步证实了 14 个基因的 >5 倍上调。功能分析将 araC、ddp 和 eryD 归类为参与信息存储和处理，alp、flgF 和 virB9 参与细胞过程，hpcd 和 aldh 参与代谢，mfs 和 nikC 参与细胞过程和代谢，以及四个假定基因（bruAb1_1814、bruAb1_0475、bruAb1_1926 和 bruAb1_0292）具有未知功能。此外，我们构建了一个 B. abortus 2308Δddp 突变体，其中 ddp 基因缺失，以评估 ddp 在细胞内生存中的作用。感染实验表明，Δddp 突变体的粘附和入侵能力显著提高，但在 RAW264.7 细胞中不能很好地存活。布鲁氏菌可能通过调节基因表达在恶劣的细胞内环境中生存。
