title: Engineering a soluble high-affinity receptor domain that neutralizes staphylococcal enterotoxin C in rabbit models of disease.
abstract: Superantigens (SAgs) are a class of immunostimulatory exotoxins that activate large numbers of T cells, leading to overproduction of cytokines and subsequent inflammatory reactions and systemic toxicity. Staphylococcal enterotoxin C (SEC), a SAg secreted by Staphylococcus aureus, has been implicated in various illnesses including non-menstrual toxic shock syndrome (TSS) and necrotizing pneumonia. SEC has been shown to cause TSS illness in rabbits and the toxin contributes to lethality associated with methicillin-resistant S.aureus (MRSA) in a rabbit model of pneumonia. With the goal of reducing morbidity and mortality associated with SEC, a high-affinity variant of the extracellular variable domain of the T-cell receptor beta-chain for SEC (~14 kDa) was generated by directed evolution using yeast display. This protein was characterized biochemically and shown to cross-react with the homologous (65% identical) SAg staphylococcal enterotoxin B (SEB). The soluble, high-affinity T-cell receptor protein neutralized SEC and SEB in vitro and also significantly reduced the bacterial burden of an SEC-positive strain of MRSA (USA400 MW2) in an infective endocarditis model. The neutralizing agent also prevented lethality due to MW2 in a necrotizing pneumonia rabbit model. These studies characterize a soluble high-affinity neutralizing agent against SEC, which is cross-reactive with SEB, and that has potential to be used intravenously with antibiotics to manage staphylococcal diseases that involve these SAgs.
authors.affiliation: Department of Biochemistry,  University of Illinois, Urbana, IL 61801,  USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Mattis
authors.forename: A R
authors.initials: AR
authors.lastname: Spaulding
authors.forename: O N
authors.initials: ON
authors.lastname: Chuang-Smith
authors.forename: E J
authors.initials: EJ
authors.lastname: Sundberg
authors.forename: P M
authors.initials: PM
authors.lastname: Schlievert
authors.forename: D M
authors.initials: DM
authors.lastname: Kranz
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000096:biosynthesis / Q000737:chemistry; D002460:Cell Line; D061505:Cell Surface Display Techniques; D019020:Directed Molecular Evolution; D004195:Disease Models, Animal; D004697:Endocarditis, Bacterial / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology; D004768:Enterotoxins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D008213:Lymphocyte Activation; D055624:Methicillin-Resistant Staphylococcus aureus / Q000276:immunology / Q000378:metabolism; D011023:Pneumonia, Staphylococcal / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology; D011485:Protein Binding; D015202:Protein Engineering; D011817:Rabbits; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000008:administration & dosage* / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology; D018089:Superantigens / Q000378:metabolism* / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D004768:Enterotoxins; D007376:Interleukin-2; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011994:Recombinant Proteins; D018089:Superantigens; C034959:enterotoxin C, staphylococcal