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首页> 外文期刊>Applied Microbiology >Examination of Food Chain-Derived Listeria monocytogenes Strains of Different Serotypes Reveals Considerable Diversity in inlA Genotypes, Mutability, and Adaptation to Cold Temperatures
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Examination of Food Chain-Derived Listeria monocytogenes Strains of Different Serotypes Reveals Considerable Diversity in inlA Genotypes, Mutability, and Adaptation to Cold Temperatures

机译：食物链衍生的单核细胞增生李斯特菌菌株的检查显示inlA基因型，变异性和适应寒冷温度的多样性

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Listeria monocytogenes strains belonging to serotypes 1/2a and 4b are frequently linked to listeriosis. While inlA mutations leading to premature stop codons (PMSCs) and attenuated virulence are common in 1/2a, they are rare in serotype 4b. We observed PMSCs in 35% of L. monocytogenes isolates ( n = 54) recovered from the British Columbia food supply, including serotypes 1/2a (30%), 1/2c (100%), and 3a (100%), and a 3-codon deletion (amino acid positions 738 to 740) seen in 57% of 4b isolates from fish-processing facilities. Caco-2 invasion assays showed that two isolates with the deletion were significantly more invasive than EGD-SmR ( P < 0.0001) and were either as (FF19-1) or more (FE13-1) invasive than a clinical control strain (08-5578) ( P = 0.006). To examine whether serotype 1/2a was more likely to acquire mutations than other serotypes, strains were plated on agar with rifampin, revealing 4b isolates to be significantly more mutable than 1/2a, 1/2c, and 3a serotypes ( P = 0.0002). We also examined the ability of 33 strains to adapt to cold temperature following a downshift from 37°C to 4°C. Overall, three distinct cold-adapting groups (CAG) were observed: 46% were fast ( 200 h) adaptors. Intermediate CAG strains (70%) more frequently possessed inlA PMSCs than did fast (20%) and slow (10%) CAGs; in contrast, 87% of fast adaptors lacked inlA PMSCs. In conclusion, we report food chain-derived 1/2a and 4b serotypes with a 3-codon deletion possessing invasive behavior and the novel association of inlA genotypes encoding a full-length InlA with fast cold-adaptation phenotypes.
机译：属于血清型1 / 2a和4b的单核细胞增生李斯特菌菌株经常与李斯特菌病有关。虽然导致过早终止密码子（PMSC）和毒力减弱的inlA突变在1 / 2a中很常见，但在血清型4b中很少见。我们观察到从不列颠哥伦比亚省食物供应中回收的35％单核细胞增生李斯特菌分离株（n = 54）中的PMSC，包括血清型1 / 2a（30％），1 / 2c（100％）和3a（100％），以及在鱼类加工设施的4b分离株中，有57％出现3位密码子缺失（氨基酸位置738至740）。 Caco-2侵袭试验显示，两个缺失的菌株比EGD-SmR更具侵袭性（P <0.0001），侵袭性（FF19-1）或侵染性（FE13-1）高于临床对照菌株（08- 5578）（P = 0.006）。为了检查1 / 2a血清型是否比其他血清型更容易获得突变，将菌株用利福平接种在琼脂上，发现4b分离株比1 / 2a，1 / 2c和3a血清型更易变（P = 0.0002） 。我们还研究了33种菌株从37°C降到4°C后适应寒冷温度的能力。总体而言，观察到三个不同的冷适应组（CAG）：46％是快速（200小时）适配器。与快速（20％）和慢速（10％）CAG相比，中级CAG菌株（70％）拥有inlA PMSC的频率更高。相反，87％的快速适配器缺少inlA PMSC。总之，我们报告了具有3个密码子缺失的食物链衍生的1 / 2a和4b血清型，具有侵袭行为，并且编码了全长InlA的inlA基因型与快速的冷适应表型具有新型关联。

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