嘉峪关市食源性单核细胞增生李斯特菌的基因组特征与系统发育分析

Genome characteristics and phylogenetic analysis of foodborne Listeria monocytogenes in Jiayuguan City

中文关键词:  单核细胞增生李斯特菌  全基因组测序  毒力基因  嘉峪关市

英文关键词:Listeria monocytogenes  whole-genome sequencing  virulence genes  Jiayuguan City

中文摘要:

      目的 评估甘肃省嘉峪关市食源性单核细胞增生李斯特菌的分子流行特征与潜在风险。方法 本研究从基因组层面解析本地菌株的种群结构、毒力因子谱及其遗传进化关系。对分离自嘉峪关市食品的4株单核细胞增生李斯特菌进行全基因组测序。采用生物信息学方法进行分子分型与血清型预测, 系统筛查毒力与耐药基因, 并通过平均核苷酸一致性(average nucleotide identity, ANI)分析及核心基因组系统发育树构建, 分析菌株间的遗传相似性与进化定位。结果 4株菌分属ST8、ST121、ST91和ST9 4个序列型。所有菌株均携带完整的核心毒力基因簇与侵袭素基因inlA。ST121型菌株表现出actA基因缺失及LIPI-1毒力岛不完整的特征。平均核苷酸一致性与系统发育分析显示, ST9型菌株与特定参考株构成紧密克隆群; ST8型菌株与一株临床来源菌株高度同源[ANI为99.78%], 且在系统发育树上紧密聚类。结论 本研究证实, 嘉峪关市食源性单核细胞增生李斯特菌存在遗传多样性, 并携带完整的核心毒力基因簇。其中, ST8型克隆与临床菌株高度同源, 提示存在明确的食品-人类跨界面传播风险。研究结果为该地区构建基于基因组学的食品安全风险前瞻性预警体系提供了关键数据支撑。

英文摘要:

      Objective To evaluate the molecular epidemiological characteristics and potential risks of foodborne Listeria monocytogenes in Jiayuguan City, Gansu Province. Methods This study analyzed the population structure, virulence factor profiles, and genetic evolutionary relationships of local strains at the genomic level. Whole-genome sequencing was performed on 4 strains of Listeria monocytogenes isolated from food in Jiayuguan City. Bioinformatics methods were used for molecular typing and serotype prediction, systematic screening of virulence and resistance genes, and through average nucleotide identity (ANI) analysis and the construction of core genomic phylogenetic trees, the genetic similarity and evolutionary localization among strains were analyzed. Results The 4 strains belonged to 4 sequence types: ST8, ST121, ST91 and ST9. All strains carried complete core virulence gene clusters and the invasion gene inlA. The ST121 strain exhibited deletion of the actA gene and an incomplete LIPI-1 virulence island. Average nucleotide identity and phylogenetic analysis showed that the ST9 strain formed a tight clonal group with specific reference strains; the ST8 strain was highly homologous to a clinical strain (ANI: 99.78%) and clustered closely on the phylogenetic tree. Conclusion This study confirmes the genetic diversity of foodborne Listeria monocytogenes in Jiayuguan City and their possession of complete core virulence gene clusters. Among them, the ST8 clone showes high homology with clinical strains, indicating a clear risk of food-to-human transmission. The findings provide critical data support for establishing a genomics-based prospective early warning system for food safety risks in the region.