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J Biol Chem. 2015 Feb 6;290(6):3576-91. doi: 10.1074/jbc.M114.585281. Epub 2014 Dec 10.

The Bordetella adenylate cyclase repeat-in-toxin (RTX) domain is immunodominant and elicits neutralizing antibodies.

Author information

1
From the Departments of Biochemistry and.
2
Chemical Engineering, University of Texas at Austin, Austin, Texas 78712 maynard@che.utexas.edu.
3
Division of Infectious Diseases and International Health, Deparment of Medicine, University of Virginia, Charlottesville, Virginia, 22908.

Abstract

The adenylate cyclase toxin (ACT) is a multifunctional virulence factor secreted by Bordetella species. Upon interaction of its C-terminal hemolysin moiety with the cell surface receptor αMβ2 integrin, the N-terminal cyclase domain translocates into the host cell cytosol where it rapidly generates supraphysiological cAMP concentrations, which inhibit host cell anti-bacterial activities. Although ACT has been shown to induce protective immunity in mice, it is not included in any current acellular pertussis vaccines due to protein stability issues and a poor understanding of its role as a protective antigen. Here, we aimed to determine whether any single domain could recapitulate the antibody responses induced by the holo-toxin and to characterize the dominant neutralizing antibody response. We first immunized mice with ACT and screened antibody phage display libraries for binding to purified ACT. The vast majority of unique antibodies identified bound the C-terminal repeat-in-toxin (RTX) domain. Representative antibodies binding two nonoverlapping, neutralizing epitopes in the RTX domain prevented ACT association with J774A.1 macrophages and soluble αMβ2 integrin, suggesting that these antibodies inhibit the ACT-receptor interaction. Sera from mice immunized with the RTX domain showed similar neutralizing activity as ACT-immunized mice, indicating that this domain induced an antibody response similar to that induced by ACT. These data demonstrate that RTX can elicit neutralizing antibodies and suggest it may present an alternative to ACT.

KEYWORDS:

Adenylate Cyclase; Antibody Engineering; Antigen; Bacterial Toxin; Bordetella pertussis; CyaA; Immunogen Engineering; Immunogenicity; Protein Engineering; Structural Vaccinology

PMID:
25505186
PMCID:
PMC4319024
DOI:
10.1074/jbc.M114.585281
[Indexed for MEDLINE]
Free PMC Article

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