Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Hemmat Highway, Tehran, Iran.
Cellular and Molecular Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran.
Curr Microbiol. 2023 Oct 25;80(12):388. doi: 10.1007/s00284-023-03508-5.
CRISPR arrays, which are organized to fight against non-self DNA elements, have shown sequence diversity that could be useful in evolution and typing studies. In this study, 55 samples of L. monocytogenes isolated from different sources were evaluated for CRISPR sequence polymorphism. The CRISPR loci were identified using CRISPR databases. A single PCR assay was designed to amplify the target CRISPRs using an appropriate universal primer. Sequencing results were analyzed using CRISPR databases and BLASTn, and the CRISPR locus was present in all the strains. Three hundred repeats including 55 terminal repeats were identified. Four types of consensuses direct repeat (DR) with different lengths and sequences were characterized. Sixty repeat variants were observed which possessed different polymorphisms. Two hundred and fifty spacers were identified from which 35 consensus sequences were determined, indicating the high polymorphism of the CRISPR spacers. The identified spacers showed similarities to listeria phage sequences, other bacterial phage sequences, plasmid sequences and bacterial sequences. In order to control the bacterial outbreaks, a robust and precise system of subtyping is required. High levels of polymorphism in the CRISPR loci in this study might be related to the origin and time of the samples' isolation. However, it is essential to assess, on a case-by-case basis, the characteristics of any given CRISPR locus before its use as an epidemiological marker. In conclusion, the results of this study showed that the use of sequence content of CRISPR area could provide new and valuable information on the evolution and typing of the L. monocytogenes bacterium.
CRISPR 阵列是为了对抗非自身 DNA 元件而组织起来的，它们表现出的序列多样性在进化和分型研究中可能很有用。在这项研究中，评估了来自不同来源的 55 株单核细胞增生李斯特菌的 CRISPR 序列多态性。使用 CRISPR 数据库鉴定了 CRISPR 基因座。设计了一个单一的 PCR 检测来扩增目标 CRISPR，使用适当的通用引物。使用 CRISPR 数据库和 BLASTn 对测序结果进行分析，结果表明所有菌株均存在 CRISPR 基因座。鉴定出的 300 个重复序列包括 55 个末端重复序列。确定了具有不同长度和序列的四种类型的一致重复（DR）。观察到 60 个重复变体，它们具有不同的多态性。从 250 个间隔子中确定了 35 个共识序列，表明 CRISPR 间隔子的高度多态性。鉴定出的间隔子与李斯特菌噬菌体序列、其他细菌噬菌体序列、质粒序列和细菌序列具有相似性。为了控制细菌爆发，需要一个强大而精确的分型系统。本研究中 CRISPR 基因座的高水平多态性可能与样本的起源和时间有关。然而，在将任何给定的 CRISPR 基因座用作流行病学标记之前，有必要逐个评估其特征。总之，本研究结果表明，CRISPR 区域的序列内容的使用可以为单核细胞增生李斯特菌的进化和分型提供新的有价值的信息。
