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Infection and Immunity, February 2001, p. 937-948, Vol. 69, No. 2
Unité de Pathogénie
Bactérienne des Muqueuses, Institut Pasteur, 75724 Paris Cedex
15, France
Received 8 August 2000/Returned for modification 21 September
2000/Accepted 14 November 2000
We recently described a new afimbrial adhesin, AfaE-VIII, produced
by animal strains associated with diarrhea and septicemia and by human
isolates associated with extraintestinal infections. Here, we report
that the afa-8 operon, encoding AfaE-VIII adhesin, from the
human blood isolate Escherichia coli AL862 is carried by a
61-kb genomic region with characteristics typical of a pathogenicity island (PAI), including a size larger than 10 kb, the presence of an
integrase-encoding gene, the insertion into a tRNA locus (pheR), and the presence of a small direct repeat at each
extremity. Moreover, the G+C content of the afa-8 operon
(46.4%) is lower than that of the E. coli K-12/MG1655
chromosome (50.8%). Within this PAI, designated PAI
IAL862, we identified open reading frames able to code for
products similar to proteins involved in sugar utilization. Four probes
spanning these sequences hybridized with 74.3% of pathogenic
afa-8-positive E. coli strains isolated from humans and animals, 25% of human pathogenic afa-8-negative
E. coli strains, and only 8% of fecal strains
(P = 0.05), indicating that these sequences are
strongly associated with the afa-8 operon and that this
genetic association may define a PAI widely distributed among human and
animal afa-8-positive strains. One of the distinctive features of this study is that E. coli AL862 also carries
another afa-8-containing PAI (PAI IIAL862),
which appeared to be similar in size and genetic organization to PAI
IAL862 and was inserted into the pheV gene. We
investigated the insertion sites of afa-8-containing PAI in
human and bovine pathogenic E. coli strains and found that this PAI preferentially inserted into the pheV gene.
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.2.937-948.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
afa-8 Gene Cluster Is Carried by a
Pathogenicity Island Inserted into the tRNAPhe of Human and
Bovine Pathogenic Escherichia coli Isolates
*
Corresponding author. Mailing address: Pathogénie
Bactérienne des Muqueuses, Institut Pasteur, 28 Rue du Dr Roux,
75724 Paris Cedex 15, France. Phone: 33 1 40613280. Fax: 33 1 40613640. E-mail: clb{at}pasteur.fr.
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