A Short Peptide of Autotransporter Ata Is a Promising Protective Antigen for Vaccination Against Acinetobacter baumannii

Abstract

With the emergence of multidrug-resistant strains, Acinetobacter baumannii infection is becoming a thorny health problem in hospitals. However, there are no licensed vaccines against A. baumannii. Acinetobacter trimeric autotransporter (Ata) is an important known virulence factor located on the outer membrane of bacteria. Herein, we carried out a series of experiments to test the immunogenicity of a short C-terminal extracellular region of Ata (Ataα, only containing 39 amino acids) in a murine model. The short peptide Ataα was fused with the cholera toxin B subunit (CTB), which has been reported to have immunoadjuvant activity. The fusion protein showed no inflammation and organ damages, and have the ability to elicit both Th1 and Th2 immune responses in mice. The bactericidal activities against A. baumannii and prophylactic effects of the fusion protein were further evidenced by a significant reduction in the bacterial load in the organs and blood. In addition, the candidate vaccine could provide broad protection against lethal challenges with a variety of A. baumannii strains. Moreover, when CpG was added on the basis of aluminum adjuvant, the immune response, especially cellular immunity, could be further strengthened. Overall, these results revealed that the Ataα is a promising vaccine target against A. baumannii infection.

Subunit vaccines for Acinetobacter baumannii

“…Subcutaneous and intraperitoneal immunization of mice with the fusion protein elicited T1 and T2 immune responses in vivo . When challenged with A. baumannii , the survival rate of mice immunized subcutaneously was 60% to 90% and that of mice immunized intraperitoneally was 100% ( 35 ).…”

Vaccine development for bacterial pathogens: Advances, challenges and prospects

“…In the vaccine design, the peptide Ata α was fused with CTB (cholera toxin B subunit), an immunoadjuvant. In the preclinical investigation, the vaccine constructs induced Th1 and Th2 immunological responses in mice and significantly reduced bacteria load [71].…”