OATAO - Open Archive Toulouse Archive Ouverte Open Access Week

Extensive genomic diversity and selective conservation of virulence determinants in enterohemorrhagic Escherichia coli strains of O157 and non O157 serotypes

Ogura, Yoshitoshi and Ooka, Tadasuke and Asadulghani, XX and Terajima, Jun and Nougayrède, Jean-Philippe and Kurokawa, Ken and Tashiro, Kousuke and Tobe, Toru and Nakayama, Keisuke and Kuhara, Satoru and Oswald, Eric and Watanabe, Haruo and Hayashi, Tetsuya Extensive genomic diversity and selective conservation of virulence determinants in enterohemorrhagic Escherichia coli strains of O157 and non O157 serotypes. (2007) Genome Biology, vol. 8 (n° 7). pp. R138. ISSN 1474-7596

[img]
Preview
(Document in English)

PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
1MB

Official URL: http://genomebiology.com/2007/8/7/R138

Abstract

Background: Enterohemorrhagic Escherichia coli (EHEC) O157 causes severe food-borne illness in humans. The chromosome of O157 consists of 4.1 Mb backbone sequences shared by benign E. coli K-12, and 1.4 Mb O157-specific sequences encoding many virulence determinants, such as Shiga toxin genes (stx genes) and the locus of enterocyte effacement (LEE). Non-O157 EHECs belonging to distinct clonal lineages from O157 also cause similar illness in humans. According to the "parallel" evolution model, they have independently acquired the major virulence determinants, the stx genes and LEE. However, the genomic differences between O157 and non-O157 EHECs have not yet been systematically analyzed. Results: Using microarray and whole genome PCR scanning analyses, we performed a whole genome comparison of 20 EHEC strains of O26, O111, and O103 serotypes with O157. In non-O157 EHEC strains, although genome sizes were similar with or rather larger than O157 and the backbone regions were well conserved, O157-specific regions were very poorly conserved. Around only 20% of the O157- specific genes were fully conserved in each non-O157 serotype. However, the non-O157 EHECs contained a significant number of virulence genes that are found on prophages and plasmids in O157, and also multiple prophages similar to, but significantly divergent from, those in O157. Conclusion: Although O157 and non-O157 EHECs have independently acquired a huge amount of serotype- or strain-specific genes by lateral gene transfer, they share an unexpectedly large number of virulence genes. Independent infections of similar but distinct bacteriophages carrying these virulence determinants are deeply involved in the evolution of O157 and non-O157 EHECs.

Item Type:Article
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Institut National de la Recherche Agronomique - INRA
Other partners > Kyushu University (JAPAN)
Other partners > University of Miyazaki (JAPAN)
Université de Toulouse > Ecole Nationale Vétérinaire de Toulouse - ENVT
Other partners > Nara Institute of Science and Technology (JAPAN)
Other partners > Osaka University (JAPAN)
Other partners > National Institute for Infectious Diseases (JAPAN)
Laboratory name:
Statistics:download
Deposited By: Mathieu Andro

Repository Staff Only: item control page