Construction of Salmonella typhimurium sptP mutant and evaluation of its characterization and immunoprotective effect

Abstract

Salmonella typhimurium is a pathogen that poses a severe health risk to humans and animals. We discussed the feasibility of the Salmonella typhimurium ΔsptP mutant as a live attenuated vaccine, constructed a Salmonella typhimurium ΔsptP mutant by homologous recombination, and evaluated its biological functions, such as growth characteristics, immunogenicity, and protective properties. We found that the ΔsptP gene mutant of Salmonella typhimurium is a safe and effective live attenuated vaccine. The mutation of the sptP gene does not affect the growth and character of bacteria and has genetic stability. Compared with wild-type Salmonella typhimurium, the colonization ability of the mutant in RAW264.7 mouse macrophages and mice was significantly weakened. The median lethal dose (LD50) of the ΔsptP mutant was 39.92 times that of the wild-type strain, indicating that the virulence of the ΔsptP mutant was significantly weakened. After inoculation with 2×104 CFU ΔsptP mutant and one booster immunization, the mice were able to resist 87.5% of the virulent strains compared to the PBS control group, and the level of IgG antibodies produced by the mutant was similar to that of the wild-type strain. These results show that ΔsptP mutants of Salmonella typhimurium are significantly less virulent to mice than wild-type strains. The sptP mutant is immunogenic and protective in mice, and ΔsptP can be used as a live attenuated vaccine for Salmonella typhimurium disease.