Molecular Immunology Laboratory, Department of Microbiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción, Chile.
J Clin Microbiol. 2011 Jul;49(7):2461-9. doi: 10.1128/JCM.01176-10. Epub 2011 May 4.
One of the capabilities developed by bacteria is the ability to gain large fragments of DNA from other bacteria or to lose portions of their own genomes. Among these exchangeable fragments are the genomic islands (GIs). Nine GIs have been identified in Brucella, and genomic island 3 (GI-3) is shared by two pathogenic species, B. melitensis and B. abortus. GI-3 encodes mostly unknown proteins. One of the aims of this study was to perform pulsed-field gel electrophoresis (PFGE) on field isolates of B. abortus from Chile to determine whether these isolates are clonally related. Furthermore, we focused on the characterization of GI-3, studying its organization and the genetic conservation of the GI-3 sequence using techniques such as tiling-path PCR (TP-PCR) and restriction fragment length polymorphism-PCR (RFLP-PCR). Our results, after PFGE was performed on 69 field isolates of B. abortus from Chile, showed that the strains were genetically homogeneous. To increase the power of genetic discrimination among these strains, we used multiple locus variable-number tandem-repeat (VNTR) analysis with 16 loci (MLVA-16). The results obtained by MLVA-16 showed that the strains of B. abortus were genetically heterogeneous and that most of them clustered according to their geographic origin. Of the genetic loci studied, panel 2B was the one describing the highest diversity in the analysis, as well as locus Bruce19 in panel 2A. In relation to the study of GI-3, our experimental analysis by TP-PCR identified and confirmed that GI-3 is present in all wild strains of B. abortus, demonstrating the high stability of gene cluster GI-3 in Chilean field strains.
细菌的一种能力是从其他细菌获得大量 DNA 片段，或者失去自身基因组的某些部分。这些可交换片段中有基因组岛 (GI)。在布鲁氏菌中已经鉴定出 9 个 GI，基因组岛 3 (GI-3) 存在于两种病原种，即 B. melitensis 和 B. abortus 中。GI-3 编码大多数未知蛋白。本研究的目的之一是对智利分离的流产布鲁氏菌进行脉冲场凝胶电泳 (PFGE)，以确定这些分离株是否具有克隆相关性。此外，我们专注于 GI-3 的特征描述，使用平铺路径 PCR (TP-PCR) 和限制性片段长度多态性-PCR (RFLP-PCR) 等技术研究其组织和 GI-3 序列的遗传保守性。我们的结果表明，在对来自智利的 69 株流产布鲁氏菌进行 PFGE 后，这些菌株在遗传上是同质的。为了提高这些菌株之间遗传差异的识别能力，我们使用了 16 个基因座的多位点可变数串联重复 (VNTR) 分析 (MLVA-16)。MLVA-16 的结果表明，流产布鲁氏菌的菌株在遗传上是异质的，其中大多数根据其地理起源聚类。在所研究的遗传基因座中，面板 2B 是分析中描述多样性最高的基因座，面板 2A 中的 Bruce19 基因座也是如此。关于 GI-3 的研究，我们通过 TP-PCR 的实验分析确定并证实了 GI-3 存在于所有野生流产布鲁氏菌菌株中，证明了 GI-3 基因簇在智利田间菌株中的高度稳定性。
