Construction of Enterococcus faecium-mediated ExoU vaccine and its protective effect in mice challenged with Pseudomonas aeruginosa.

BACKGROUND

Pseudomonas aeruginosa (Pa) is an opportunistic pathogen and an important cause of nosocomial infections, and its antimicrobial resistance is a major therapeutic challenge. DNA vaccination is an attractive antigen-specific immunotherapy approach.

METHODS

In this study, we used the most acutely cytotoxic effector exoenzyme U (ExoU) released by Pa as the specific antigen and the safe and reliable Enterococcus faecium (Ef) as the expression vector, to construct the recombinant Ef-ExoU vaccine. The immune protection and humoral and cellular immune responses of the DNA vaccine were evaluated in mice by oral gavage.

RESULTS

We found that the Ef-ExoU vaccine significantly reduced lung bacterial load and lung inflammatory cytokines (IL-6, TNF-α), probably by inducing higher levels of IgG and spleen CD4+ T cell proliferation, indicating the induction of a mixed Th1 and Th2 immune response.

CONCLUSIONS

This study suggests that Ef-ExoU is a promising subunit vaccine candidate and provides a new strategy for the prevention and treatment of Pa infection.