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https://hdl.handle.net/2440/11582
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Type: | Journal article |
Title: | Comparative toxicity and virulence of Escherichia coli clones expressing variant and chimeric Shiga-like toxin type II operons |
Author: | Paton, A. Bourne, A. Manning, P. Paton, J. |
Citation: | Infection and Immunity, 1995; 63(7):2450-2458 |
Publisher: | American Society for Microbiology |
Issue Date: | 1995 |
ISSN: | 0019-9567 1098-5522 |
Abstract: | Shiga-like toxin (SLT)-producing strains of Escherichia coli are known to cause diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome in humans. The SLTs, particularly those related to type II (SLT-II), are a diverse family of toxins which may have differing in vitro or in vivo properties. To examine the impact of naturally occurring SLT-II sequence variation on the capacity of a given E. coli strain to cause disease, operons encoding four different SLT-II-related toxins, designated SLT-II/O111, SLT-II/OX3a, SLT-II/OX3b, and SLTII/ O48, were cloned in the same orientation in pBluescript. French pressure cell lysates of E. coli DH5a derivatives carrying these plasmids differed markedly in cytotoxicity for Vero cells, with 50% cytotoxic doses ranging from 20 to 328,000/ml. The strains also differed in oral virulence for streptomycin-treated mice, as judged by survival rate and/or median survival time, but virulence did not necessarily correlate with in vitro cytotoxicity. The SLT-II type associated with the lowest oral virulence was SLT-II/O111. Both the overall survival rate and the median survival time of mice challenged with clones producing this toxin were significantly greater than that for mice challenged with a clone producing the closely related SLT-II/OX3a. Experiments with clones carrying chimeric O111/OX3a SLT-II operons indicated that the reduced virulence was associated with an Arg-1763Gly substitution in the mature A subunit. Clones producing SLT-II/O48 and SLT-II/OX3b had similarly high cytotoxicities for Vero cells, but the latter was more virulent when fed to streptomycin-treated mice, as judged by median survival time. Experiments with clones carrying chimeric O48/OX3b SLT-II operons indicated that the increased virulence was a function of the A subunit of SLT-II/ OX3b, which differs from the A subunit of SLT-II/O48 by only two amino acids (Met-43Thr and Gly-1023Asp, respectively). These findings raise the possibility that naturally occurring SLT-II sequence variations may impact directly on the capacity of a given SLT-producing E. coli strain to cause disease. |
Keywords: | Kidney Hela Cells Vero Cells Animals Mice, Inbred BALB C Humans Mice Escherichia coli Recombinant Fusion Proteins Oligonucleotide Probes Bacterial Toxins Enterotoxins Mutagenesis, Site-Directed Sequence Alignment Amino Acid Sequence Base Sequence Sequence Homology, Amino Acid Structure-Activity Relationship Genes, Bacterial Operon Molecular Sequence Data Male Shiga Toxin 2 Chlorocebus aethiops |
Rights: | © 1995, American Society for Microbiology |
DOI: | 10.1128/iai.63.7.2450-2458.1995 |
Published version: | http://iai.asm.org/content/63/7/2450 |
Appears in Collections: | Aurora harvest 7 Microbiology and Immunology publications |
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