A single, engineered protein therapeutic agent neutralizes exotoxins from both Staphylococcus aureus and Streptococcus pyogenes.
CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010;
17:1781-9. [PMID:
20861327 DOI:
10.1128/cvi.00277-10]
[Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Staphylococcus aureus and Streptococcus pyogenes secrete exotoxins that act as superantigens, proteins that cause hyperimmune reactions by binding the variable domain of the T-cell receptor beta chain (Vβ), leading to stimulation of a large fraction of the T-cell repertoire. To develop potential neutralizing agents, we engineered Vβ mutants with high affinity for the superantigens staphylococcal enterotoxin B (SEB), SEC3, and streptococcal pyrogenic exotoxin A (SpeA). Unexpectedly, the high-affinity Vβ mutants generated against SEB cross-reacted with SpeA to a greater extent than they did with SEC3, despite greater sequence similarity between SEB and SEC3. Likewise, the Vβ mutants generated against SpeA cross-reacted with SEB to a greater extent than with SEC3. The structural basis of the high affinity and cross-reactivity was examined by single-site mutational analyses. The cross-reactivity seems to involve only one or two toxin residues. Soluble forms of the cross-reactive Vβ regions neutralized both SEB and SpeA in vivo, suggesting structure-based strategies for generating high-affinity neutralizing agents that can cross-react with multiple exotoxins.
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