4b型单核细胞增生李斯特菌内化素基因NTSN_0462的功能初探

目的单核细胞增生性李斯特菌(Listeria monocytogenes,Lm)对宿主的粘附、侵袭作用与其多种内化素蛋白密切相关。本研究以4b型菌株LmNTSN的內化素基因NTSN_0462为研究对象,初步探究其致病作用。方法利用同源重组技术构建该基因缺失的突变株,研究0462基因对NTSN在生长、细胞侵袭和体内定植中的作用。人结肠腺癌细胞Caco-2、人肝癌细胞HepG2的侵袭率,以及BALB/c小鼠体内肝、脾脏中定植能力的差异。结果缺失株的生长曲线结果显示,NTSN_0462基因对Lm在BHI培养基中的生长及代谢未造成明显影响。以人结肠腺癌细胞Caco-2、人肝癌细胞HepG2进行的体外试验表明,缺失株的侵袭能力低于野生株(P0.001)。以BALB/c小鼠进行的体内试验显示,缺失株在肝脏中定殖的能力显著低于野生株(P0.001),在脾脏中无统计学差异。结论 NTSN_0462基因在LmNTSN入侵肝脏和定植中发挥重要作用,是侵袭相关的重要毒力因子。

Function of an internalin gene NTSN_0462 in Listeria monocytognes serotype 4b

Internalins play a key role in the adhesion and invasion of L.monocytogenes into host cells.In this study,the function of internalin gene NTSN_0462 in serotype 4b Lm NTSN was probed into.Firstly,NTSN_0462 was knocked out by homology recombination,then the pathogenic characterization of mutant strain LmNTSNΔ0462 was investigated in vivo and in vitro.The growth curve showed that the deletion of NTSN_0462 gene didn't affect growth and metabolism of Lm in BHI medium.The invasion of the mutant strain into human intestinal epithelial cell line Caco-2 and human hepatocyte cell line HepG2 significantly reduced comparing with the WT strains (P＜0.001).Furthermore,the infection ability to BALB/c mouse was analyzed in vivo,compared with the WT strains,the colonization of LmNTSNΔ0462 in liver decreased significantly (P＜0.001),wheareas there was no significant difference in the spleen,indicating that NTSN_0462 plays an important role in the invasion and multiplication in host livers,heretofore it is an invasion-related virulent factor of L.monocytogenes.