Antibody response against plasmid-encoded toxin (Pet) and the protein involved in intestinal colonization (Pic) in children with diarrhea produced by enteroaggregative Escherichia coli

Enteroaggregative Escherichia eoli (EAEC) is an emerging cause of pediatric and adult travellers diarrhea. the mechanism by which EAEC induce diarrhea is not completely known. Two serine protease autotransporter proteins, named Pet and Pic have been identified in EAEC strains. Pet has enterotoxic and cytotoxic activities, while the role of Pic in pathogenesis may lie on its mucinolytic activity. Little is known about Pet and Pic biological activities in vivo. in this study the antibody responses against these autotransporter proteins in convalescent children is investigated. Fifteen (83%) children showed specific antibodies against Pet or Pic in their sera. IgG and IgM antibodies were the main isotype found. Specific antibodies against Pic, but not against Pet, were detected in sera from age-matched control group. These data show that specific anti-Pet and anti-Pic antibodies are produced during the course of a natural EAEC infection in children. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.Univ São Paulo, Dept Microbiol, Inst Ciencias Biomed, São Paulo, BrazilInst Butantan, Lab Especial Microbiol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilUniv São Paulo, Fac Ciencias Farmaceut, Dept Anal Clin & Toxicol, BR-05508900 São Paulo, BrazilCINVESTAV, IPN, Dept Cell Biol, Mexico City 14000, DF, MexicoUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilWeb of Scienc

AAF/II fimbriae biogenesis in enteroaggregative Escherichia coli

Escherichia coli enteroagregativa (EAEC) e um patogeno emergente, associado a doenca diarreica, que apresenta como caracteristica o padrao de adesao agregativa em celulas HEp-2. Varios fatores de virulencia ja foram descritos em amostras de EAEC, utilizando como modelo a amostra 042, comprovadamente virulenta para humanos. Dentre esses fatores estao as enterotoxinas PET e EAST1, alem da fimbria denominada AAF/II. Todos esses fatores sao codificados pelo plasmidios de 65 MDa (pAA2). Embora seu papel na virulencia tenha sido demonstrado, os determinantes geneticos da biogenese de AAF/II nao eram conhecidos. Para tanto, no presente trabalho foram realizados experimentos para caracterizacao da regiao de pAA2 relacionada a biogenese de AAF/II. Atraves da analise das sequencias de nucleotideos de uma regiao de 25 kb do plasmidio pAA2, foi demonstrado que a mesma alberga os, genes das enterotoxinas (pet e astA), flanqueados por duas regioes relacionadas com a biogenese de AAF/II (regiao l e 2), alem do ativador de transcricao (aggm relacionado a sua expressao. A organizacao genetica da biogenese de AAF/II identificada na amostra 042 e unica, uma vez que na familia Dr de adesinas, da qual AAF/II e membro, esses genes estao organizados em um operon. Nessa organizacao exclusiva, a regiao l apresenta o cluster chaperonina-pilina-ativador de transcricao (aafD-aafA-aggR, enquanto a regiao 2, distante em 12 kb, apresenta o cluster chaperonina nao funcional-usher-invasina. As duas regioes sao flanqueadas por Sequencias de Insercao sugerindo que essa regiao seja um local em pAA2 de alta taxa de recombinacao. A analise de homologias a nivel de aminoacidos indicaram que a regiao l deriva do operon da fimbria AAF/I, enquanto a regiao 2 deriva do operon das adesinas AfaE de E. coli uropatogenicas. Os dados de ativacao da transcricao atraves da regulacao por aggR tambem corroboram com essa hipotese, pois apenas os genes da regiao l sao fortemente regulados pelo mesmo, como ocorre em AAF/I. Atraves da mutagenese nao-polar, foi demonstrado que os genes essenciais para a expressao de AAF/II sao: aafA, aafC, aafD e aggR, os quais correspondem a pilina, usher, chaperonina e ativador de transcricao, respectivamente. Esse locus descrito em pAA2 deve um representar um importante set de determinantes de virulencia em outras amostras de EAEC, uma vez que apresenta os potenciais fatores e ate entao descritos na amostra 042. Alem de AAF/II, a fimbria AAF/I esta...(au)BV UNIFESP: Teses e dissertaçõe

Aeromonas: prevalencia, avaliacao do fenomeno suicida e dos marcadores de virulencia em especies isoladas de criancas com gastroenterite aguda e controles

BV UNIFESP: Teses e dissertaçõe

A sensitive and specific molecular tool for detection of both typical and atypical enteroaggregative Escherichia coli

A multiplex PCR has been standardized and evaluated for the identification of both typical and atypical enteroaggregative Escherichia coli (EAEC). the assay detecting aaiA, aaiG, aggR and aatA presented 94.8% of sensitivity, 94.3% of specificity and was able to efficiently detect both groups of EAEC among E. coli isolated from stool cultures. (C) 2014 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Inst Butantan, Bacteriol Lab, BR-05503900 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilFAPESP: 2010/19515-2Web of Scienc

Culture supernatant of Shiga toxin-producing Escherichia coli strains provoke fluid accumulation in rabbit ileal loops

Production of Shiga toxin (Stx) in Escherichia coli strains belonging to serogroups O26, O111, and O157 was evaluated in the rabbit ileal loop assay and results were compared to those using tissue culture assays and DNA hybridization with specific probes for Stx1 and Stx2. All 14 Shiga toxin-producing E. coli strains tested provoked fluid accumulation in the rabbit intestinal loop. Eleven strains hybridized with Stx1 probe, one strain with Stx2 and two strains with both probes. Filtered culture supernatants of all E. coli strains presented cytotoxic effects in both HeLa and Vero cells, in this study, we found a strong association between the production of Stx and its effect in an animal model. This is the first description of high-level Stx-producing E. coli O111ac isolated in Brazil. (C) 1998 Published by Elsevier Science B.V. All rights reserved.Universidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, BR-04023062 São Paulo, BrazilUniv São Paulo, Fac Med Vet & Zootecn, Dept Patol, São Paulo, BrazilUniv Estadual Londrina, Dept Patol Geral, Londrina, BrazilUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, BR-04023062 São Paulo, BrazilWeb of Scienc