Identification and characterization of a new variant of Shiga toxin 1 in Escherichia coli ONT:H19 of bovine origin.
A new variant of Shiga toxin 1 (Stx1), designated Stx1d, which deviates considerably more than any other known variant from Stx1 encoded by phage 933J, was identified in an Escherichia coli strain, ONT:H19, isolated from bovine feces. The complete stx(1) gene of this strain was amplified and sequenced. Nucleotide sequence homology with stx(1) from phage 933J was only 91%, resulting in the substitution of 20 amino acids in the A subunit and 7 amino acids in the B subunit of the protein. Cell culture supernatant of this strain, which was negative for stx(2) by PCR testing, was cytotoxic to Vero cells and gave positive results in two commercial enzyme-linked immunosorbent assays for Stx. PCR primers were constructed for the specific detection of the new variant. The findings of this study suggest that Stx1 is not as conserved as thought before and that there might be more variants which cannot be detected by commonly used PCR methods.
Institute for Hygiene and Technology of Food of Animal Origin, Veterinary Faculty, Ludwig-Maximilians-Universität, 80539 Munich, Germany. c.buerk@mh.vetmed.uni-muenchen.de
Christine
C
Bürk
Richard
R
Dietrich
Gabriele
G
Açar
Maximilian
M
Moravek
Michael
M
Bülte
Erwin
E
Märtlbauer
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002522:Chlorocebus aethiops; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D005798:Genes, Bacterial; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012703:Serotyping; D022622:Shiga Toxin 1 / Q000235:genetics*; D013045:Species Specificity; D014709:Vero Cells
D017931:DNA Primers; D004269:DNA, Bacterial; D022622:Shiga Toxin 1