CaracterizaÃÃo molecular de cepas de Vibrio cholerae O26, isoladas de processos entÃricos humanos no nordeste do Brasil

AUTOR(ES)

Francisco Andrà Marques de Oliveira Cariri

DATA DE PUBLICAÇÃO

2008

RESUMO

The emergence of the Vibrio cholerae O139 serogroup as a second ethiologic agent for cholera served as an alert to the rise of other epidemic strains that may pass unnoticed by traditional methods of diagnosis, usually based on the use of antiserum directed against the traditional O1 serogroup. In previous studies, out of 179 non-O1/ non-O139 V. cholerae strains isolated from clinical cases during the cholera outbreak in Brazil, seven strains classified as V. cholerae O26 and one strain defined as not-typable (17155) were selected which contained virulence genes associated with the development of this disease. Two strains (4756 and 17155) contained the gene rfbN specific to the O1 serogroup, suggesting that genotypically they belonged to this serogroup, and were also able to express the cholera toxin in culture. Here a more detailed genetic analysis of these eight strains was carried out comparing the serological classification with other molecular markers. In this respect the 16S-23S rRNA intergenic spacer regions (ISRs) from the various V. cholerae operons were amplified, cloned and sequenced from each strain. From the analysis of the sequence of five operons (totalizing 210 sequenced clones), three phylogenetic trees were built in which strains 4756 and 17155 always clustered with control O1 strains, whilst the remaining O26 strains clustered separately. Thus, the two strains 4756 and 17155 phylogenetically belong to the O1 serogroup and the difference in the serological results may be a consequence of seroconversion caused by changes in the genes required for the biosynthesis of the antigen O

ASSUNTO(S)

vibrio cholerae non-o1/ non-o139 sistemÃtica molecular genetica 16s/23s rrna intergenic spacer regions serological conversion vibrio cholerae nÃo-o1/ nÃo-o139 regiÃo espaÃadora intergÃnica rrna16s-23s conversÃo sorolÃgica molecular systematic

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