Estudo molecular dos genes de virulência em amostras clássicas de escherichia coli enteropatogênica
Enteropathogenic Escherichia coli (EPEC) is classified into typical and atypical strains based on the presence of the plasmid E. coli adherence factor (EAF). This study characterized 51 aEPEC strains belonged to EPEC serogroups O26, O55, O111, O114, O119, O126, O127, O128 e O142, previously classifi...
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| Tipo de recurso: | tesis de maestría |
| Estado: | Versión publicada |
| Fecha de publicación: | 2014 |
| País: | Brasil |
| Institución: | Universidade Federal de São Paulo (UNIFESP) |
| Repositorio: | Repositório Institucional da UNIFESP |
| Idioma: | portugués |
| OAI Identifier: | oai:repositorio.unifesp.br:11600/46745 |
| Acceso en línea: | https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=1476755 http://repositorio.unifesp.br/handle/11600/46745 |
| Access Level: | acceso abierto |
| Palabra clave: | enteropathogenic escherichia coli (epec) escherichia coli enteropatogênica (epec) |
| Sumario: | Enteropathogenic Escherichia coli (EPEC) is classified into typical and atypical strains based on the presence of the plasmid E. coli adherence factor (EAF). This study characterized 51 aEPEC strains belonged to EPEC serogroups O26, O55, O111, O114, O119, O126, O127, O128 e O142, previously classified by the eae+ EAF-negative stx- genotype, isolated from children with and without diarrhea in Brazil. The strains were examined for the presence of the locus of enterocyte effacement (LEE) encoded genes, and EAF plasmid markers, i.e., the bundle-forming pilus (bfp) operon and the plasmid-encoded regulator (per). In addition, the strains were characterized for the allele type of eae (intimin), bfpA and perA genes by PCR-RFLP to determine whether relationships exist between aEPEC and tEPEC strains belonged to serogroups O55, O111, O119, and O127. All 51 strains hybridized with the LEEA-D probes; in the PCR analysis, ler (LEEA), escC and escN (LEEB), and eae (LEEC) genes were found in all of the strains, whereas espA, espD e espB (LEED) genes were found in 58% of the strains. None of the strains, with exception of strains of serogroup O119, hybridized with the bfpA probe, and 36 (70%) strains of serogroups O26, O55, O111, O114, O119, O126, O127 and O142 reacted with the perABC probe; Southern blots of plasmid DNA of these strains revealed that perABC sequences were present on large and small plasmids. In the PCR analysis, the perA gene was found in 20 strains of serogroups O26, O128, and O142, and the perA, perB and perC were found in O119 strains; Southern blot analysis indicated that bfpA and perABC genes were located on a single plasmid of similar size of EAF plasmid in most of the O119 strains. Moreover, the bfpA and perABC genes were amplified and sequenced in two representative O119 strains. Sequence analysis of the PCR products showed that both strains had intact bfpA and perA genes similar to that of the prototype EPEC E2348/69 strain. PCR-RFLP analysis showed allelic variability of eae e perA genes among typical and atypical EPEC of serogroups O55, O111, O119, and O127. The beta-intimin and beta-perA were the most common subtypes found in typical strains; the beta2-intimin and delta-perA were the most common subtypes found atypical strains. Furthermore, O119 strains showed different types of bfpA alleles, alpha3 in typical and beta2 in atypical EPEC strains. In conclusion, our data suggest that at least some classic aEPEC strains have evolved from tEPEC, in particular the O119 bfpA and perA positive strains. However, further studies are needed to investigate the genetic relationships between typical and atypical O119 strains. |
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