RESUMO
Certain strains of Staphylococcus aureus usually belonging to phage group II produce epidermolytic toxins (ETA and ETB) which cause intraepidermal splitting in mice, neonates and occasionally adults. Amino acid sequences of ETA and ETB have been reported but the mechanism of epidermolysis remains unknown. A search of the NBRF-PIR computer database showed the toxins to have significant sequence similarity with staphylococcal V8 protease and that the catalytic triad of V8 protease is present in ETA and ETB. Comparison of ETA, ETB and V8 protease with other members of the trypsin-like serine protease family revealed little homology save for the immediate vicinity of the residues constituting the catalytic triad. The toxins, therefore, exhibit a distant relationship to mammalian serine proteases. A potential Ca2(+)-binding loop was identified in ETA (but not ETB) on the basis of sequence similarity with the second calcium-binding loop of rat intestinal calcium-binding protein. Epidermolysis produced by ETA in the mouse bioassay was shown to be inhibited by the presence of EDTA consistent with a Ca2(+)-dependent mechanism.
Assuntos
Toxinas Bacterianas/metabolismo , Exfoliatinas/metabolismo , Serina Endopeptidases/metabolismo , Síndrome da Pele Escaldada Estafilocócica/fisiopatologia , Infecções Cutâneas Estafilocócicas/fisiopatologia , Sequência de Aminoácidos , Animais , Sítios de Ligação , Bioensaio , Cálcio/metabolismo , Exfoliatinas/antagonistas & inibidores , Exfoliatinas/genética , Camundongos , Dados de Sequência Molecular , Inibidores de Proteases/farmacologia , Serina Endopeptidases/genéticaRESUMO
We describe here an inhibitor of Staphylococcus aureus exfoliative toxin. The toxin was extracted from an S. aureus strain isolated from a case of staphylococcus scalded skin syndrome. The activity of the toxin was compared in tryptic soy broth and brain heart infusion broth. Both supported growth of S. aureus but the culture filtrate of brain heart infusion broth lacked exfoliative toxin activity. Furthermore it appeared to contain a substance that neutralized the action of exfoliative toxin. This suggests the possibility of a treatment for staphylococcal scalded skin syndrome and bullous impetigo.
Assuntos
Antitoxinas/farmacologia , Técnicas Bacteriológicas/métodos , Meios de Cultura/análise , Exfoliatinas/antagonistas & inibidores , Impetigo/tratamento farmacológico , Impetigo/microbiologia , Fosfatidilcolinas/farmacologia , Síndrome da Pele Escaldada Estafilocócica/tratamento farmacológico , Síndrome da Pele Escaldada Estafilocócica/microbiologia , Staphylococcus aureus , Animais , Tipagem de Bacteriófagos , Bioensaio , Caseínas , Avaliação Pré-Clínica de Medicamentos , Humanos , Camundongos , Hidrolisados de Proteína , Staphylococcus aureus/classificação , Staphylococcus aureus/crescimento & desenvolvimentoRESUMO
Staphylococcus sciuri (S. sciuri) is a rare pathogen in humans, but it can cause a wide array of human infections. Recently a S. sciuri isolate (HBXX06) was reported to cause fatal exudative epidermitis (EE) in piglets and thus considered as a potential zoonotic agent. To investigate the pathogenicity of this bacterium, we cloned exfoliative toxin C (ExhC), a major toxin of the S. sciuri isolate and performed functional analysis of the recombinant ExhC-his (rExhC) protein using in vitro cell cultures and newborn mice as models. We found that rExhC could induce necrosis in multiple cell lines and peritoneal macrophages as well as skin lesions in newborn mice, and that the rExhC-induced necrosis in cells or skin lesions in newborn mice could be completely abolished if amino acids 79-128 of rExhC were deleted or blocked with a monoclonal antibody (3E4), indicating aa 79-128 portion as an essential necrosis-inducing domain. This information contributes to further understandings of the mechanisms underlying S. sciuri infection.
Assuntos
Anticorpos Monoclonais Murinos/imunologia , Dermotoxinas/metabolismo , Exfoliatinas/metabolismo , Macrófagos Peritoneais/patologia , Proteínas Recombinantes/metabolismo , Dermatopatias/patologia , Animais , Animais Recém-Nascidos , Western Blotting , Caspases/metabolismo , Células Cultivadas , Clonagem Molecular , Dermotoxinas/genética , Exfoliatinas/antagonistas & inibidores , Exfoliatinas/genética , Feminino , Citometria de Fluxo , Humanos , Macrófagos Peritoneais/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Necrose , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Dermatopatias/metabolismoRESUMO
The potential value of human serum globulin for treatment of patients with the staphylococcal scalded-skin syndrome was determined by measuring the exfoliatin antitoxin content of globulin pools. Of 16 lots tested, only four had detectable antitoxin activity, and in these the levels were minimal. These findings suggest that pooled serum globulin is not a practical source of exfoliatin antitoxin.