单核细胞增生性李斯特菌prfA基因缺失株的构建及其生物学特性

Construction and characterization of Listeria monocytogenes ΔprfA mutant strains

摘要:

摘要:【目的】单核细胞增生性李斯特菌(Lm)是人兽共患李斯特菌病的病原菌，其致病性与调控因子PrfA蛋白作用下毒力基因的表达有着密切关系，本文初步探讨了PrfA 蛋白对细菌毒力因子的调控作用。【方法】利用同源重组技术对血清型分别为1/2a和4b的LM4、F4636 进行prfA 基因的敲除，并构建其回复突变株，对获得的突变株LM4ΔprfA、F4636ΔprfA 进行生物学特性研究。【结果】实验结果表明:两株缺失株的溶血活性丧失、回复突变株的溶血活性得到恢复，突变株还丧失磷脂酶活性，黏附和侵袭特性显著下降

关键词:关键词: 单核细胞增生性李斯特菌，突变株，prfA 基因，同源重组，生物学特性

Abstract:

Abstract:［Objective］ Listeria monocytogenes (Lm) is an important pathogen that can cause serious listeriosis in humans and animals． The pathogenicity of Lm has a close relationship with the PrfA protein regulating the expression of virulence genes． Therefore，we studied the regulation functions of PrfA and its role on Lm's virulence．［Methods］ The prfA genes of LM4，serotype 1/2a，and F4636，serotype 4b，were deleted by homologous recombination technology， and the biological characteristics of the mutants were further studied．［Results］ The prfA gene deleted strains LM4ΔprfA and F4636ΔprfA and their back mutation strains were successfully constructed． The results show that the hemolysis activity was lost in prfA deleted strains and was recovered in the reverse mutant strains． The prfA deleted strains lost phospholipase activity; their adhesion and invasion ability significantly decreased． Furthermore，their 50% lethal doses (LD50) were 5 logs higher comparing with wild type strains．［Conclusion］ PrfA regulates hly，plcB and inl gene family and affects significantly Lm's virulence．

Key words:Keywords: Listeria monocytogenes，mutant，prfA，homologous recombination，biological characteristics