Exploring the genetic background of the botulism neurotoxin BoNT/B2 in Spain

ABSTRACT To determine whether the neurotoxin BoNT/B2 causing botulism in Spain is clonal, the genetic diversity and phylogenetic relationships of Clostridium botulinum from food-borne episodes and infant cases of the condition were explored. The botulinum toxin gene (bont) subtype, the variable regi...

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Main Authors: Sylvia Valdezate, Gema Carrasco, María J. Medina, Noelia Garrido, Silvia del Pino, Monica Valiente, María P. Pallarés, Pilar Villalon
Format: Article
Language:English
Published: American Society for Microbiology 2023-10-01
Series:Microbiology Spectrum
Subjects:
Online Access:https://journals.asm.org/doi/10.1128/spectrum.02380-23
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author Sylvia Valdezate
Gema Carrasco
María J. Medina
Noelia Garrido
Silvia del Pino
Monica Valiente
María P. Pallarés
Pilar Villalon
author_facet Sylvia Valdezate
Gema Carrasco
María J. Medina
Noelia Garrido
Silvia del Pino
Monica Valiente
María P. Pallarés
Pilar Villalon
author_sort Sylvia Valdezate
collection DOAJ
description ABSTRACT To determine whether the neurotoxin BoNT/B2 causing botulism in Spain is clonal, the genetic diversity and phylogenetic relationships of Clostridium botulinum from food-borne episodes and infant cases of the condition were explored. The botulinum toxin gene (bont) subtype, the variable region of the flagellin gene (flaVR), and a seven-gene multi-locus sequence type were examined by sequencing 37 BoNT-positive cultures obtained over the period 2010 to 2022. Out of 37 botulism events, 16 food-borne episodes and 16 infant cases were associated with bont/b2. Eight bont/b2 alleles were detected [nucleotide distance range 0.0259–0.415%, Hunter and Gaston discrimination index (HGDI) 0.71]. The most common bont/b2 allele corresponded to that of strain Prevot 25 NCASE and its single and double locus variations (87.5%). Four known flaVR types were identified (HGDI 0.79), along with one previously unknown (flaVR-15). Sixteen sequence types (STs) (HGDI 0.89) were recorded including seven new STs (ST164–ST170; 10 new alleles) and five new STs (ST171–ST175; with new allele combinations) were also noted. Correlations among some STs and flaVR types were seen. Overall, the present results show that the combined analysis of bont/b2-flaVR-ST at the nucleotide level could be used to track botulism events in Spain. The neurotoxin BoNT/B2 has largely been responsible for human botulism in Spain. The polymorphism analysis of bont/b2, flaVR typing, and sequence type determinations, revealed a wide variety of clones to be responsible for human botulism, ruling out a common source of acquisition. IMPORTANCE Botulism, a potentially fatal disease, is classically characterized by a symmetrical descending flaccid paralysis, which if left untreated can lead to respiratory failure and death. Botulinum neurotoxin (BoNT), produced by certain species of Clostridium, is the most potent biological toxin known, and the direct cause of botulism. This study characterizes the acquisition in Spain of two forms of botulism, i.e., food-borne and infant botulism, which are largely caused by the main neurotoxin BoNT/B2. Polymorphism analysis of the bont/b2 gene, typing of the flagellin variable region sequence (flaVR), and multilocus sequence typing, were used to explore the genetic background of Clostridium botulinum group I. To our knowledge, this is the first phylogenetic and typing study of botulism undertaken in Spain.
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spelling doaj.art-839f9445710640a8acbde0b799364b4c2023-10-17T13:04:36ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972023-10-0111510.1128/spectrum.02380-23Exploring the genetic background of the botulism neurotoxin BoNT/B2 in SpainSylvia Valdezate0Gema Carrasco1María J. Medina2Noelia Garrido3Silvia del Pino4Monica Valiente5María P. Pallarés6Pilar Villalon7Reference and Research Laboratory for Taxonomy, National Centre of Microbiology, Instituto de Salud Carlos III, Majadahonda , Madrid, SpainReference and Research Laboratory for Taxonomy, National Centre of Microbiology, Instituto de Salud Carlos III, Majadahonda , Madrid, SpainReference and Research Laboratory for Taxonomy, National Centre of Microbiology, Instituto de Salud Carlos III, Majadahonda , Madrid, SpainReference and Research Laboratory for Taxonomy, National Centre of Microbiology, Instituto de Salud Carlos III, Majadahonda , Madrid, SpainReference and Research Laboratory for Taxonomy, National Centre of Microbiology, Instituto de Salud Carlos III, Majadahonda , Madrid, SpainReference and Research Laboratory for Taxonomy, National Centre of Microbiology, Instituto de Salud Carlos III, Majadahonda , Madrid, SpainVeterinary Unit, Animal Department, Instituto de Salud Carlos III, Majadahonda , Madrid, SpainReference and Research Laboratory for Taxonomy, National Centre of Microbiology, Instituto de Salud Carlos III, Majadahonda , Madrid, SpainABSTRACT To determine whether the neurotoxin BoNT/B2 causing botulism in Spain is clonal, the genetic diversity and phylogenetic relationships of Clostridium botulinum from food-borne episodes and infant cases of the condition were explored. The botulinum toxin gene (bont) subtype, the variable region of the flagellin gene (flaVR), and a seven-gene multi-locus sequence type were examined by sequencing 37 BoNT-positive cultures obtained over the period 2010 to 2022. Out of 37 botulism events, 16 food-borne episodes and 16 infant cases were associated with bont/b2. Eight bont/b2 alleles were detected [nucleotide distance range 0.0259–0.415%, Hunter and Gaston discrimination index (HGDI) 0.71]. The most common bont/b2 allele corresponded to that of strain Prevot 25 NCASE and its single and double locus variations (87.5%). Four known flaVR types were identified (HGDI 0.79), along with one previously unknown (flaVR-15). Sixteen sequence types (STs) (HGDI 0.89) were recorded including seven new STs (ST164–ST170; 10 new alleles) and five new STs (ST171–ST175; with new allele combinations) were also noted. Correlations among some STs and flaVR types were seen. Overall, the present results show that the combined analysis of bont/b2-flaVR-ST at the nucleotide level could be used to track botulism events in Spain. The neurotoxin BoNT/B2 has largely been responsible for human botulism in Spain. The polymorphism analysis of bont/b2, flaVR typing, and sequence type determinations, revealed a wide variety of clones to be responsible for human botulism, ruling out a common source of acquisition. IMPORTANCE Botulism, a potentially fatal disease, is classically characterized by a symmetrical descending flaccid paralysis, which if left untreated can lead to respiratory failure and death. Botulinum neurotoxin (BoNT), produced by certain species of Clostridium, is the most potent biological toxin known, and the direct cause of botulism. This study characterizes the acquisition in Spain of two forms of botulism, i.e., food-borne and infant botulism, which are largely caused by the main neurotoxin BoNT/B2. Polymorphism analysis of the bont/b2 gene, typing of the flagellin variable region sequence (flaVR), and multilocus sequence typing, were used to explore the genetic background of Clostridium botulinum group I. To our knowledge, this is the first phylogenetic and typing study of botulism undertaken in Spain.https://journals.asm.org/doi/10.1128/spectrum.02380-23Clostridium botulinumbotulismfood-borneinfantneurotoxinBoNT
spellingShingle Sylvia Valdezate
Gema Carrasco
María J. Medina
Noelia Garrido
Silvia del Pino
Monica Valiente
María P. Pallarés
Pilar Villalon
Exploring the genetic background of the botulism neurotoxin BoNT/B2 in Spain
Microbiology Spectrum
Clostridium botulinum
botulism
food-borne
infant
neurotoxin
BoNT
title Exploring the genetic background of the botulism neurotoxin BoNT/B2 in Spain
title_full Exploring the genetic background of the botulism neurotoxin BoNT/B2 in Spain
title_fullStr Exploring the genetic background of the botulism neurotoxin BoNT/B2 in Spain
title_full_unstemmed Exploring the genetic background of the botulism neurotoxin BoNT/B2 in Spain
title_short Exploring the genetic background of the botulism neurotoxin BoNT/B2 in Spain
title_sort exploring the genetic background of the botulism neurotoxin bont b2 in spain
topic Clostridium botulinum
botulism
food-borne
infant
neurotoxin
BoNT
url https://journals.asm.org/doi/10.1128/spectrum.02380-23
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