Navegando por Palavras-chave "heat-labile toxin"
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- ItemAcesso aberto (Open Access)Different Assay Conditions for Detecting the Production and Release of Heat-Labile and Heat-Stable Toxins in Enterotoxigenic Escherichia coli Isolates(Mdpi Ag, 2013-12-01) Rocha, Leticia B.; Ozaki, Christiane Y.; Horton, Denise S. P. Q.; Menezes, Caroline A.; Silva, Anderson; Fernandes, Irene; Magnoli, Fabio C.; Vaz, Tania M. I.; Guth, Beatriz Ernestina Cabilio [UNIFESP]; Piazza, Roxane M. F.; Butantan Inst; São Paulo Trop Med Inst; Fleury Med & Hlth; Adolfo Lutz Inst; Universidade Federal de São Paulo (UNIFESP)Enterotoxigenic Escherichia coli (ETEC) produce heat-labile (LT) and/or heat-stable enterotoxins (ST). Despite that, the mechanism of action of both toxins are well known, there is great controversy in the literature concerning the in vitro production and release of LT and, for ST, no major concerns have been discussed. Furthermore, the majority of published papers describe the use of only one or a few ETEC isolates to define the production and release of these toxins, which hinders the detection of ETEC by phenotypic approaches. Thus, the present study was undertaken to obtain a better understanding of ST and LT toxin production and release under laboratory conditions. Accordingly, a collection of 90 LT-, ST-, and ST/LT-producing ETEC isolates was used to determine a protocol for toxin production and release aimed at ETEC detection. for this, we used previously raised anti-LT antibodies and the anti-ST monoclonal and polyclonal antibodies described herein. the presence of bile salts and the use of certain antibiotics improved ETEC toxin production/release. Triton X-100, as chemical treatment, proved to be an alternative method for toxin release. Consequently, a common protocol that can increase the production and release of LT and ST toxins could facilitate and enhance the sensitivity of diagnostic tests for ETEC using the raised and described antibodies in the present work.
- ItemSomente MetadadadosProduction and release of heat-labile toxin by wild-type human-derived enterotoxigenic Escherichia coli(Blackwell Publishing, 2006-10-01) Simoes Lasaro, Melissa Ang; Rodrigues, Juliana Falcao; Mathias-Santos, Camila; Guth, Beatriz Ernestina Cabilio [UNIFESP]; Regua-Mangia, Adriana; Piantino Ferreira, Antonio Jose; Takagi, Mickie; Cabrera-Crespo, Joaquin; Sbrogio-Almeida, Maria Elisabete; Souza Ferreira, Luis Carlos de; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP); Fdn Oswaldo Cruz; Inst ButantanProduction and release of heat-labile toxin (LT) by wild-type enterotoxigenic Escherichia coli (ETEC) strains, isolated from diarrheic and asymptomatic Brazilian children, was studied under in vitro and in vivo conditions. Based on a set of 26 genetically diverse LT+ enterotoxigenic E. coli strains, cell-bound LT concentrations varied from 49.8 to 2415 ng mL(-1). the amounts of toxin released in culture supernatants ranged from 0% to 50% of the total synthesized toxin. the amount of LT associated with secreted membrane vesicles represented < 5% of the total toxin detected in culture supernatants. ETEC strains secreting higher amounts of LT, but not those producing high intracellular levels of cell-bound toxin, elicited enhanced fluid accumulation in tied rabbit ileal loops, suggesting that the strain-specific differences in production and secretion of LT correlates with symptoms induced in vivo. However, no clear correlation was established between the ability to produce and secrete LT and the clinical symptoms of the infected individuals. the present results indicate that production and release of LT by wild-type human-derived ETEC strains are heterogeneous traits under both in vitro and in vivo growth conditions and may impact the clinical outcomes of infected individuals.
- ItemAcesso aberto (Open Access)Production, characterization, and application of antibodies against heat-labile type-I toxin for detection of enterotoxigenic Escherichia coli(Instituto Oswaldo Cruz, Ministério da Saúde, 2006-12-01) Menezes, Caroline A; Imamura, Sergio Y; Trabulsi, Luiz Rachid; Fernandes-Filho, Antônio; Martinez, Marina B; Guth, Beatriz Ernestina Cabilio [UNIFESP]; Girão, Dennys M; Piazza, Roxane Mf; Instituto Butantan Laboratório de Bacteriologia; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP); Universidade Federal do Rio de Janeiro Instituto Prof. Paulo de Góes Departamento de Microbiologia MédicaStrains of enterotoxigenic Escherichia coli (ETEC) are responsible for significant rates of morbidity and mortality among children, particularly in developing countries. The majority of clinical and public health laboratories are capable of isolating and identifying Salmonella, Shigella, Campylobacter, and Escherichia coli O157:H7 from stool samples, but ETEC cannot be identified by routine methods. The method most often used to identify ETEC is polymerase chain reaction for heat-stable and heat-labile enterotoxin genes, and subsequent serotyping, but most clinical and public health laboratories do not have the capacity or resources to perform these tests. In this study, polyclonal rabbit and monoclonal mouse IgG2b antibodies against ETEC heat-labile toxin-I (LT) were characterized and the potential applicability of a capture assay was analyzed. IgG-enriched fractions from rabbit polyclonal and the IgG2b monoclonal antibodies recognized LT in a conformational shape and they were excellent tools for detection of LT-producing strains. These findings indicate that the capture immunoassay could be used as a diagnostic assay of ETEC LT-producing strains in routine diagnosis and in epidemiological studies of diarrhea in developing countries as enzyme linked immunosorbent assay techniques remain as effective and economical choice for the detection of specific pathogen antigens in cultures.