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Infection and Immunity, January 2000, p. 64-71, Vol. 68, No. 1
Unité INRA-ENVT de Microbiologie
Moléculaire, Ecole Vétérinaire de Toulouse, 31076 Toulouse Cedex, France1; Institut
für Hygiene und Mikrobiologie, University of Wurzburg, Wurzburg
97080, Germany2; and Laboratorio di
Medicina Veterinaria, Istituto Superiore di Sanità, 00161 Rome,
Italy3
Received 26 July 1999/Returned for modification 8 September
1999/Accepted 30 September 1999
Enteropathogenic Escherichia coli (EPEC) and
enterohemorrhagic E. coli (EHEC) produce the characteristic
"attaching and effacing" (A/E) lesion of the brush border. Intimin,
an outer membrane protein encoded by eae, is responsible
for the tight association of both pathogens with the host cell. Several
eae have been cloned from different EPEC and EHEC strains
isolated from humans and animals. These sequences are conserved in the
N-terminal region but highly variable in the last C-terminal 280 amino
acids (aa), where the cell binding activity is localized. Based on
these considerations, we developed a panel of specific primers to
investigate the eae heterogeneity of the variable 3' region
by using PCR amplification. We then investigated the distribution of
the known intimin types in a large collection of EPEC and EHEC strains
isolated from humans and different animal species. The existence of a
yet-unknown family of intimin was suspected because several EHEC
strains, isolated from human and cattle, did not react with any of the
specific primer pairs, although these strains were eae
positive when primers amplifying the conserved 5' end were used. We
then cloned and sequenced the eae present in one of these
strains (EHEC of serotype O103:H2) and subsequently designed a PCR
primer that recognizes in a specific manner the variable 3' region of
this new intimin type. This intimin, referred to as "
0019-9567/0/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Typing of Intimin Genes in Human and Animal Enterohemorrhagic and
Enteropathogenic Escherichia coli: Characterization of a
New Intimin Variant
," was
present in human and bovine EHEC strains of serogroups O8, O11, O45,
O103, O121, and O165. Intimin
is the largest intimin cloned to date
(948 aa) and shares the greatest overall sequence identity with intimin
, although analysis of the last C-terminal 280 aa suggests a greater
similarity with intimins
and
.
*
Corresponding author. Mailing address: Unité
mixte INRA-ENVT de Microbiologie Moléculaire, 23 chemin des
Capelles, 31076 Toulouse Cedex, France. Phone: (33) 561-19-39-91. Fax:
(33) 561-19-39-75. E-mail: e.oswald{at}envt.fr.
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