Clostridium botulinum strain Af84 contains three neurotoxin gene clusters: bont/A2, bont/F4 and bont/F5.

Nir Dover,Jason R Barash,Karen K Hill,Karen W Davenport,Stephen S Arnon,Gary Xie,Hazuki Teshima,Michel R Popoff

doi:10.1371/journal.pone.0061205

Nir Dover, Jason R Barash + Show 6 more

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https://doi.org/10.1371/journal.pone.0061205

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Abstract

Sanger and shotgun sequencing of Clostridium botulinum strain Af84 type Af and its botulinum neurotoxin gene (bont) clusters identified the presence of three bont gene clusters rather than the expected two. The three toxin gene clusters consisted of bont subtypes A2, F4 and F5. The bont/A2 and bont/F4 gene clusters were located within the chromosome (the latter in a novel location), while the bont/F5 toxin gene cluster was located within a large 246 kb plasmid. These findings are the first identification of a C. botulinum strain that contains three botulinum neurotoxin gene clusters.

Highlights

Botulinum neurotoxin (BoNT), the most poisonous substance known, exists as seven toxin types A-G that are distinguished by the inability of polyclonal antibodies specific for one toxin type to neutralize any of the other six toxin types [1]
The assembled sequences showed the presence of the three bonts, the possibility that the original culture might have contained a mixture of C. botulinum A2f4 and A2f5 bacteria [3] needed to be examined
All 10 PCR amplification reactions confirmed the presence of bont/A2, bont/F4 and bont/F5 in each of the 10 single colonies of strain Af84

Summary

Introduction

Botulinum neurotoxin (BoNT), the most poisonous substance known, exists as seven toxin types A-G that are distinguished by the inability of polyclonal antibodies specific for one toxin type to neutralize any of the other six toxin types [1]. The genomic location of the bont gene cluster may be either within the chromosome, a phage or a plasmid [15,16,17]. In bivalent strains with two bont gene clusters, the bont gene clusters have both been located either within the chromosome or both located within a plasmid [15,18]. The locations of the bont gene clusters appear to be conserved; for instance, in C. botulinum proteolytic (Group I) strains the bont gene cluster is found at specific locations in the chromosome or within a plasmid [18]

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