Flagella overexpression attenuates Salmonella pathogenesis.

Area of Science:

• Bacteriology
• Immunology
• Microbial Pathogenesis

Background:

• Bacterial flagella are crucial for motility, biofilm formation, and chemotaxis.
• Flagella can also act as potent immunogens, stimulating host immune responses.
• Attenuating gene expression (AGE) via appendage overexpression can weaken bacteria, as previously shown.

Purpose of the Study:

• To investigate if flagella overexpression can attenuate Salmonella Typhimurium virulence.
• To determine the mechanisms behind flagellum-mediated attenuation.
• To assess the immunogenicity and protective potential of flagellum-attenuated Salmonella.

Main Methods:

• Overexpression of flagellar filament subunit FliC and master regulator FlhDC in Salmonella Typhimurium.
• Assessment of bacterial replication within macrophages and lethality in mice.
• Evaluation of susceptibility to hydrogen peroxide and bile.
• Analysis of immune responses and protection against wild-type Salmonella challenge.

Main Results:

• Overexpression of FliC or FlhDC, individually or together, significantly attenuated Salmonella Typhimurium.
• Flagellated, attenuated bacteria could not replicate in macrophages and were non-lethal to mice.
• Flagellum-mediated AGE resulted from disruptive effects on the bacterial membrane, increasing susceptibility to oxidative stress and bile.
• Attenuated Salmonella elicited enhanced immune responses and provided protection against wild-type Salmonella challenge.

Conclusions:

• Flagella overexpression is a viable strategy for attenuating Salmonella Typhimurium.
• Flagellum-attenuated Salmonella exhibits reduced virulence and enhanced immunogenicity.
• This approach holds potential for developing novel Salmonella vaccines or therapeutics.