鼠伤寒沙门菌greA/B基因缺失株的构建及生物学特性

Construction and biological characterization of greA/B-deleted Salmonella Typhimurium strains

摘要:

沙门菌作为一种常见的人畜共患病原体，可导致多种食源性疾病，其中鼠伤寒沙门菌(Salmonella Typhimurium, STM)是关键血清型之一，其研究与防控对公共卫生具有重要意义。目的 探究greA和greB基因对鼠伤寒沙门菌生物学特性和致病性的影响。方法 运用Red同源重组技术构建greA和greB基因缺失株及其回补株，并对其生长特性、生物被膜形成能力、对Caco-2细胞的黏附及侵袭能力进行检测；利用小鼠模型评估了greA和greB基因缺失对STM致病性的影响。结果 成功构建了突变株STM LT2ΔgreA和STM LT2ΔgreB；与野生株相比，greA和greB基因的缺失均不影响其生长速度，但导致STM的生物被膜形成能力、黏附力、侵袭力均有所下降；greA和greB缺失降低了STM对小鼠肝、脾的定殖力，并使得STM的LD₅₀分别上升了39.81倍和2.5倍。结论 greA和greB基因的缺失均可降低鼠伤寒沙门菌的致病性，本研究结果为进一步揭示沙门菌的致病机理提供了理论基础。

Abstract:

Salmonella as common zoonotic pathogens can cause a variety of foodborne diseases. Salmonella Typhimurium (STM) is one of the key serotypes, and the research, prevention, and control of STM are of great significance to public health.Objective To investigate the effects of greA and greB on the biological characteristics and pathogenicity of STM.Methods Red homologous recombination was employed to construct the greA- and greB-deleted STM strains well as the complemented strains. The strains were then characterized in terms of growth characteristics, biofilm formation, and adhesion and invasion in Caco-2 cells. Mouse models were used to evaluate the effects of greA and greB deletion on STM pathogenicity.Results The mutant strains STM LT2ΔgreA and STM LT2ΔgreB were successfully constructed. Compared with the wild-type strain, the deletion of greA and greB did not affect the cell growth rate, while inhibiting the biofilm formation, adhesion, and invasion of STM. In addition, the deletion of greA and greB decreased the colonization of STM in the liver and spleen of mice, increasing the LD₅₀ of STM by 39.81 times and 2.5 times, respectively.Conclusion The deletion of greA and greB could reduce the pathogenicity of STM. This finding provides a theoretical basis for further revealing the pathogenicity of Salmonella.