Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada.
Front Cell Infect Microbiol. 2011 Dec 9;1:15. doi: 10.3389/fcimb.2011.00015. eCollection 2011.
Members of the Burkholderia cepacia complex (Bcc) are important in medical, biotechnological, and agricultural disciplines. These bacteria naturally occur in soil and water environments and have adapted to survive in association with plants and animals including humans. All Bcc species are opportunistic pathogens including Burkholderia cenocepacia that causes infections in cystic fibrosis and chronic granulomatous disease patients. The adaptation of B. cenocepacia to the host environment was assessed in a rat chronic respiratory infection model and compared to that of high cell-density in vitro grown cultures using transcriptomics. The distribution of genes differentially expressed on chromosomes 1, 2, and 3 was relatively proportional to the size of each genomic element, whereas the proportion of plasmid-encoded genes differentially expressed was much higher relative to its size and most genes were induced in vivo. The majority of genes encoding known virulence factors, components of types II and III secretion systems and chromosome 2-encoded type IV secretion system were similarly expressed between in vitro and in vivo environments. Lower expression in vivo was detected for genes encoding N-acyl-homoserine lactone synthase CepI, orphan LuxR homolog CepR2, zinc metalloproteases ZmpA and ZmpB, LysR-type transcriptional regulator ShvR, nematocidal protein AidA, and genes associated with flagellar motility, Flp type pilus formation, and type VI secretion. Plasmid-encoded type IV secretion genes were markedly induced in vivo. Additional genes induced in vivo included genes predicted to be involved in osmotic stress adaptation or intracellular survival, metal ion, and nutrient transport, as well as those encoding outer membrane proteins. Genes identified in this study are potentially important for virulence during host-pathogen interactions and may be associated with survival and adaptation to the host environment during chronic lung infections.
伯克霍尔德氏菌复合群（Bcc）成员在医学、生物技术和农业领域都很重要。这些细菌自然存在于土壤和水等环境中，并已适应与包括人类在内的动植物共生。所有 Bcc 物种都是机会性病原体，包括引起囊性纤维化和慢性肉芽肿病患者感染的洋葱伯克霍尔德菌。本研究使用转录组学评估了 B. cenocepacia 适应宿主环境的能力，并与高细胞密度体外培养物进行了比较。染色体 1、2 和 3 上差异表达基因的分布与每个基因组元件的大小相对成比例，而差异表达的质粒编码基因的比例与其大小相比要高得多，并且大多数基因在体内诱导表达。大多数编码已知毒力因子、II 型和 III 型分泌系统组件以及染色体 2 编码的 IV 型分泌系统的基因在体外和体内环境中表达相似。体内检测到的基因编码 N-酰基高丝氨酸内酯合酶 CepI、孤儿 LuxR 同源物 CepR2、锌金属蛋白酶 ZmpA 和 ZmpB、LysR 型转录调节因子 ShvR、线虫杀伤蛋白 AidA 以及与鞭毛运动、Flp 型菌毛形成和 VI 型分泌相关的基因表达水平较低。体内显著诱导了质粒编码的 IV 型分泌基因。体内诱导的其他基因包括预测与渗透胁迫适应或细胞内存活、金属离子和营养物质转运以及编码外膜蛋白相关的基因。本研究鉴定的基因可能在宿主-病原体相互作用过程中对毒力很重要，并且可能与慢性肺部感染期间的存活和适应宿主环境有关。
