Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
PLoS One. 2012;7(3):e31747. doi: 10.1371/journal.pone.0031747. Epub 2012 Mar 5.
Brucella spp. cause chronic zoonotic disease often affecting individuals and animals in impoverished economic or public health conditions; however, these bacteria do not have obvious virulence factors. Restriction of iron availability to pathogens is an effective strategy of host defense. For brucellae, virulence depends on the ability to survive and replicate within the host cell where iron is an essential nutrient for the growth and survival of both mammalian and bacterial cells. Iron is a particularly scarce nutrient for bacteria with an intracellular lifestyle. Brucella melitensis and Brucella canis share ~99% of their genomes but differ in intracellular lifestyles. To identify differences, gene transcription of these two pathogens was examined during infection of murine macrophages and compared to broth grown bacteria. Transcriptome analysis of B. melitensis and B. canis revealed differences of genes involved in iron transport. Gene transcription of the TonB, enterobactin, and ferric anguibactin transport systems was increased in B. canis but not B. melitensis during infection of macrophages. The data suggest differences in iron requirements that may contribute to differences observed in the lifestyles of these closely related pathogens. The initial importance of iron for B. canis but not for B. melitensis helps elucidate differing intracellular survival strategies for two closely related bacteria and provides insight for controlling these pathogens.
布鲁氏菌属引起慢性人畜共患疾病，常影响经济贫困或公共卫生条件差的个体和动物；然而，这些细菌没有明显的毒力因子。限制病原体获得铁是宿主防御的有效策略。对于布鲁氏菌，其毒力取决于在宿主细胞内生存和复制的能力，而铁是哺乳动物和细菌细胞生长和存活所必需的营养物质。铁是一种特别稀缺的营养物质，对于具有细胞内生活方式的细菌来说。布氏杆菌和犬布鲁氏菌共享约 99%的基因组，但在细胞内生活方式上有所不同。为了确定差异，在感染鼠巨噬细胞时检查了这两种病原体的基因转录，并与在肉汤中生长的细菌进行了比较。B. melitensis 和 B. canis 的转录组分析显示了与铁转运相关的基因差异。在感染巨噬细胞时，TonB、肠杆菌素和铁螯合蓝素转运系统的基因转录在犬布鲁氏菌中增加，但在布氏杆菌中没有增加。数据表明，铁需求的差异可能导致这两种密切相关的病原体生活方式的差异。铁对犬布鲁氏菌的初始重要性而不是对布氏杆菌的重要性有助于阐明两种密切相关细菌的不同细胞内生存策略，并为控制这些病原体提供了线索。
