单增李斯特菌内化素基因inlA多态性分析

Genetic polymorphism of inlA in Listeria monocytogenes

目的分析全球不同地区单增李斯特菌内化素A编码基因inlA的多态性,及其与菌株家系、血清群和序列型(sequence types,ST)之间的相关性。方法收集不同国家的4115株单增李斯特菌基因组信息,分析inlA基因的序列多态性,确定其等位基因型,构建基于inlA基因的系统进化树。结果4115株单增李斯特菌基因组中,除3株菌外均携带inlA基因,根据基因序列分为370个inlA等位基因型。编码完整InlA的等位基因型有292种(3164株菌),因点突变出现提前终止密码子(premature stop codon,PMSC)的截短型InlA等位基因型有78种(948株菌),其中84种新的编码完整InlA的等位基因型和16种PMSC类型为首次报道。系统发育分析显示,单增李斯特菌inlA基因与菌株家系、CC克隆群及ST型具有相关性。发生PMSC突变的inlA序列型也呈现多态性,尤其家系II菌株截短的InlA编码基因多样性更高。截短的InlA多见于血清群IIa和IIc菌株中,较少见于临床菌株常见的IVb血清群菌株中。结论inlA基因在单增李斯特菌中普遍存在且序列型呈现多态性,部分inlA的等位基因型与单增李斯特菌ST型具有较强的相关性,可作为特定型别菌株快速筛查的靶标。单增李斯特菌家系I和家系II菌株中截短的InlA编码基因的提前终止位点具有多样性,截短的InlA常见于IIa和IIc血清群菌株中。

This study analyzed the genetic polymorphism of inlA in Listeria monocytogenes strains,and correlated the results with lineage,serogroups,and sequence types(ST)of strains.Genomic information for 4115 strains of L.monocytogenes from different countries was collected.A phylogenetic tree based on the inlA gene sequence was constructed in MEGA 11 software.A total of 99.93%of the L.monocytogenes isolates carried inlA genes,which were divided into 370 inlA genotypes.We identified 78 inlA genotypes(948 strains)with PMSC,among which 16 PMSC types and 84 inlA alleles for intact InlA were firstly reported unreported.The inlA gene was ubiquitous in L.monocytogenes,and the PMSC types of inlA in strains from lineage I and II were diverse.PMSC was more common in inlA of serotype IIa and IIc strains.Specific alleles of inlA can be used as biomarkers for the identification of highly pathogenic strains of L.monocytogenes.