Potent Neutralization of Staphylococcal Enterotoxin B In Vivo by Antibodies that Block Binding to the T-Cell Receptor. Issue 21 (4th October 2019)

• Record Type: Journal Article
• Authors: Chen, Gang; Karauzum, Hatice; Long, Hua; Carranza, Danielle; Holtsberg, Frederick W.; Howell, Katie A.; Abaandou, Laura; Zhang, Bojie; Jarvik, Nick; Ye, Wei; Liao, Grant C.; Gross, Michael L.; Leung, Daisy W.; Amarasinghe, Gaya K.; Aman, M. Javad; Sidhu, Sachdev S.
• Is Part Of: Journal of molecular biology. Volume 431:Issue 21(2019)
• Page Start: 4354
• Page End: 4367
• Publication Date: 2019-10-04
• Subjects: Ab antibody -- BLI bio-layer interferometry -- bsAb bispecific antibody -- CDR complementarity-determining region -- ELISA enzyme-linked immunosorbent assay -- Fab antigen-binding fragment -- HDX-MS hydrogen–deuterium exchange coupled to mass spectrometry -- INFγ interferon-gamma -- LPS lipopolysaccharide -- MHC-II class II major histocompatibility complex -- MS mass spectrometry -- PBMC peripheral blood mononuclear cell -- PBS phosphate-buffered saline -- SAg staphylococcal superantigen -- scFv single-chain variable fragment -- SEB staphylococcal enterotoxin B -- SEs staphylococcal enterotoxins -- TCR T-cell receptor -- TNA toxin neutralization assay -- TNFα tumor necrosis factor alpha -- TSS toxic shock syndrome -- TSST-1 toxic shock syndrome toxin 1 -- wt wild-type; synthetic antibody -- phage display -- SEB toxin -- protein engineering -- hydrogen–deuterium exchange coupled to mass spectrometry; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2019.03.017
• Languages: English
• ISSNs: 0022-2836

Abstract

Abstract: To develop an antibody (Ab) therapeutic against staphylococcal enterotoxin B (SEB), a potential incapacitating bioterrorism agent and a major cause of food poisoning, we developed a "class T" anti-SEB neutralizing Ab (GC132) targeting an epitope on SEB distinct from that of previously developed "class M" Abs. A systematic engineering approach was applied to affinity-mature Ab GC132 to yield an optimized therapeutic candidate (GC132a) with sub-nanomolar binding affinity. Mapping of the binding interface by hydrogen–deuterium exchange coupled to mass spectrometry revealed that the class T epitope on SEB overlapped with the T-cell receptor binding site, whereas other evidence suggested that the class M epitope overlapped with the binding site for the major histocompatibility complex. In the IgG format, GC132a showed ∼ 50-fold more potent toxin-neutralizing efficacy than the best class M Ab in vitro, and fully protected mice from lethal challenge in a toxic shock post-exposure model. We also engineered bispecific Abs (bsAbs) that bound tetravalently by utilizing two class M binding sites and two class T binding sites. The bsAbs displayed enhanced toxin neutralization efficacy compared with the respective monospecific Ab subunits as well as a mixture of the two, indicating that enhanced efficacy was due to heterotypic tetravalent binding to two non-overlapping epitopes on SEB. Together, these results suggest that class T anti-SEB Ab GC132a is an excellent candidate for clinical development and for bsAb engineering. Graphical Abstract: Unlabelled Image Highlights: SEB is a potent incapacitating agent and a major cause of food poisoning. SEB neutralizing antibodies were identified from a synthetic antibody phage library. An antibody with picomolar binding affinity was generated by antibody engineering. The best antibody demonstrated superior in vitro and in vitro anti-toxin efficacy. An excellent lead for further development of anti-SEB therapeutics was reported.