Navegando por Palavras-chave "EAST1"

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    Variants of astA gene among extra-intestinal Escherichia coli of human and avian origin
    (Oxford Univ Press, 2017) Maluta, Renato Pariz; Leite, Janaina Luisa; Galvao Rojas, Thais Cabrera; Affonso Scaletsky, Isabel Cristina [UNIFESP]; Lopes Guastalli, Elisabete Aparecida; Ramos, Marcelo de Carvalho; da Silveira, Wanderley Dias
    Many Escherichia coli strains harbour astA, which is the gene encoding the enteroaggregative E. coli heat-stable enterotoxin (EAST1). This gene is embedded in a putative transposase (ORF1) and presents polymorphism in diarrheagenic strains. Although astA and orf1 are detected in extraintestinal strains, little is known about polymorphism and differential gene transcription in this pathotype. In the present work, extraintestinal E. coli from humans (ExPEC - Extraintestinal Pathogenic E. coli) and poultry (APEC - Avian Pathogenic E. coli) were assayed to verify the presence of astA/orf1 and possible polymorphisms in these genes. Three astA/orf1 patterns were detected via Sanger sequencing. Pattern 1 was novel and represented an astA pseudogene. Pattern 2 and pattern 3 presented distinct amino acids within the reading frame encoding astA and were identical to the sequences found in EAEC 17-2 and EAEC 042, respectively. Regarding the frame encoding ORF1, all mutations detected in the three patterns were neutral. The transcripts of astA/orf1 in vitro were underregulated in strains possessing the pattern 1 sequence. The results demonstrate that the same astA sequences may be detected in diarrheagenic and extra-intestinal E. coli. However, extraintestinal isolates may also present an astA pseudogene that has not been reported in diarrheagenic E. coli.
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    Virulence properties of Escherichia coli O111:H12 strains
    (Wiley-Blackwell, 1997-01-01) Monteiro-Neto, Valério; Campos, Leila Carvalho; Ferreira, Antonio José Piantino; Gomes, Tania Aparecida Tardelli [UNIFESP]; Trabulsi, Luiz Rachid; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)
    Seventeen Escherichia coli O111:H12 strains isolated from the feces of children with acute diarrhea were studied with regard to their adherence properties and other virulence characteristics. All strains showed an aggregative adherence pattern to HEp-2 cells and agglutinated bovine and sheep red cells in the presence of mannose. These strains did not have gene sequences homologous to the aggregative adherence fimbria I gene and did not react with any of the DNA probes used to detect other virulence genes in enteropathogens. With one exception, the O111:H12 strains did not induce fluid accumulation in the rabbit ileal loop assay, although 16 of the strains had the enteroaggregative E. coli heat-stable enterotoxin 1 (EAST1) gene sequences. A 60-70 MDa plasmid was present in 16 of the strains studied. We conclude that the O111 :H12 serotype, one of the first E. coli identified in infantile diarrhea, belongs to the enteroaggregative E. coli category but the genes encoding its adherence phenotype are distinct from those previously described.