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

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.