Tannic Acid Inhibits Serovar Typhimurium Infection by Targeting the Type III Secretion System.

serovar Typhimurium ( Typhimurium) is a zoonotic pathogen that can cause food poisoning and diarrhea in both humans and animals worldwide. The pathogenicity island (SPI) genes encoded type III secretion system (T3SS) is important for Typhimurium invasion and replication in host cells. Due to the increasing problem of antibiotic resistance, antibiotic treatment for clinical infection has gradually been limited. Anti-virulence inhibitors are a promising alternative to antibiotics because they do not easily induce bacterial antibiotic resistance. Here, we systematically evaluated the therapeutic effect of tannic acid (TA) on infected mice and elucidated its anti-infection mechanism. TA treatment improved the survival rate of Typhimurium-infected mice and alleviated cecum pathological lesions. In addition, TA inhibited Typhimurium invasion to HeLa cells without affecting their growth. Further studies showed that TA could inhibit the expression of and This inhibition may be implemented by inhibiting the transcription of key regulatory and structural genes of the T3SS. This study provides an alternative anti-virulence strategy for infection treatment.