A single, engineered protein therapeutic agent neutralizes exotoxins from both Staphylococcus aureus and Streptococcus pyogenes.
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.
Wang
Ningyan
N
Department of Biochemistry, University of Illinois, 600 S. Mathews Ave., Urbana, IL 61801, USA.
Mattis
Daiva M
DM
Sundberg
Eric J
EJ
Schlievert
Patrick M
PM
Kranz
David M
DM
D000818:Animals; D000992:Antitoxins / Q000009:adverse effects / Q000235:genetics / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000633:toxicity; D003429:Cross Reactions; D004768:Enterotoxins / Q000037:antagonists & inhibitors* / Q000633:toxicity; D005098:Exotoxins / Q000037:antagonists & inhibitors* / Q000633:toxicity; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000633:toxicity; D011485:Protein Binding; D011817:Rabbits; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000009:adverse effects / Q000235:genetics / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000472:pathogenicity*; D013297:Streptococcus pyogenes / Q000472:pathogenicity*; D018089:Superantigens / Q000378:metabolism*; D016019:Survival Analysis; D037521:Virulence Factors / Q000037:antagonists & inhibitors
D000992:Antitoxins; D001426:Bacterial Proteins; D004768:Enterotoxins; D005098:Exotoxins; D008565:Membrane Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011994:Recombinant Proteins; C117980:SpeA protein, Streptococcus pyogenes; D018089:Superantigens; D037521:Virulence Factors; C031818:enterotoxin B, staphylococcal