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Reactivity of convalescent-phase hemolytic-uremic syndrome patient sera with the megaplasmid-encoded TagA protein of Shiga toxigenic Escherichia coli O157.

ABSTRACT: A cosmid library of Shiga toxigenic Escherichia coli (STEC) O157:H7 strain EDL933 DNA was screened for clones capable of reacting with convalescent-phase serum from a patient with hemolytic-uremic syndrome (HUS), in an attempt to identify candidate virulence genes. One of the immunoreactive clones contained a portion of the large plasmid pO157, and the immunoreactive gene product was identified as TagA. The function of this 898-amino-acid protein is unknown, but it exhibits 42% amino acid sequence identity and 63% similarity to a 312-amino-acid region of a ToxR-regulated lipoprotein of Vibrio cholerae. Antibodies to E. coli O157 TagA were detected in sera from other HUS patients with O157 STEC infection but not in those from patients whose illnesses were caused by other STEC types or in healthy controls. These data demonstrate that TagA is expressed in vivo and provide circumstantial evidence for a role in the pathogenesis of the disease. The tagA gene is present only in STEC strains belonging to serogroup O157, and so antibodies to TagA are a potentially useful serological marker for infections due to such strains.

SUBMITTER: Paton AW

PROVIDER: S-EPMC140373 | biostudies-literature | 2002 Apr

REPOSITORIES: biostudies-literature

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Reactivity of convalescent-phase hemolytic-uremic syndrome patient sera with the megaplasmid-encoded TagA protein of Shiga toxigenic Escherichia coli O157.

Paton Adrienne W AW Paton James C JC

Journal of clinical microbiology 20020401 4

A cosmid library of Shiga toxigenic Escherichia coli (STEC) O157:H7 strain EDL933 DNA was screened for clones capable of reacting with convalescent-phase serum from a patient with hemolytic-uremic syndrome (HUS), in an attempt to identify candidate virulence genes. One of the immunoreactive clones contained a portion of the large plasmid pO157, and the immunoreactive gene product was identified as TagA. The function of this 898-amino-acid protein is unknown, but it exhibits 42% amino acid sequen ...[more]

PMID: 11923363

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Project description:Western blot analysis was used to assess the reactivity of convalescent-phase sera from patients who were associated with an outbreak of hemolytic-uremic syndrome (HUS) caused by fermented sausage contaminated with Shiga toxin-producing Escherichia coli (STEC). The predominant STEC isolated from HUS patients belonged to serotype O111:H-, and reactivity to O111:H- whole-cell lysates, treated or untreated with proteinase K, was examined. As expected, all five serum samples demonstrated a marked anti-lipopolysaccharide response, but several protein bands were also immunoreactive, particularly one with an apparent size of 94 kDa. One convalescent-phase serum sample was subsequently used to screen an O111:H- cosmid bank and 2 of 900 cosmid clones were found to be positive, both of which contained a similar DNA insert. Western blot analysis of one of these clones identified three major immunoreactive protein bands of approximately 94, 70, and 50 kDa. An immune response to the three proteins was detectable with all five convalescent-phase serum samples but not with healthy human serum. Immunoreactive 94- and 50-kDa species were produced by a deletion derivative of the cosmid containing a 7-kb STEC DNA insert. Sequence analysis of this region indicated that it is part of the locus for enterocyte effacement, including the eaeA gene which encodes intimin. The deduced amino acid sequence of the O111:H- intimin was 88.6% identical to intimin from O157:H7 STEC, and the most divergent region was the 200 residues at the carboxyl terminus, which were only 75% identical. Such variation may be antigenically significant as serum from a HUS patient infected only with the O111:H- STEC reacted with intimin from an enteropathogenic E. coli O111 strain, as well as several other eaeA-positive STEC isolates, but not with an eaeA-positive STEC belonging to serotype O157:H-. Sera from two of the other HUS patients also failed to react with intimin from this latter strain. However, intimin from O157:H- STEC did react with serum from a patient infected with both O111:H- and O157:H- STEC.

Dataset Information

Reactivity of convalescent-phase hemolytic-uremic syndrome patient sera with the megaplasmid-encoded TagA protein of Shiga toxigenic Escherichia coli O157.

Publications

Reactivity of convalescent-phase hemolytic-uremic syndrome patient sera with the megaplasmid-encoded TagA protein of Shiga toxigenic Escherichia coli O157.

Similar Datasets

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