The population structure of Clostridium tetani deduced from its pan-genome

Diana Chapetón-Montes (1) , Lucile Plourde (2) , Christiane Bouchier (3) , Laurence Ma (3) , Laure Diancourt (4) , Alexis Criscuolo (5) , Michel Robert Popoff (1) , Holger Brüggemann (6)

1 Toxines bactériennes - Bacterial Toxins
2 Sanofi Pasteur [Marcy-l'Étoile, France]
3 Génomique (Plate-Forme) - Genomics Platform
4 CNR - Centre National de Référence des Bactéries Anaérobies et Botulisme - National Reference Center Anaerobic Bacteria and Botulism
5 Hub Bioinformatique et Biostatistique - Bioinformatics and Biostatistics HUB
6 Aarhus University [Aarhus]

Clostridium tetani produces a potent neurotoxin, the tetanus neurotoxin (TeNT) that is responsible for the worldwide neurological disease tetanus, but which can be efficiently prevented by vaccination with tetanus toxoid. Until now only one type of TeNT has been characterized and very little information exists about the heterogeneity among C. tetani strains. We report here the genome sequences of 26 C. tetani strains, isolated between 1949 and 2017 and obtained from different locations. Genome analyses revealed that the C. tetani population is distributed in two phylogenetic clades, a major and a minor one, with no evidence for clade separation based on geographical origin or time of isolation. The chromosome of C. tetani is highly conserved; in contrast, the TeNT-encoding plasmid shows substantial heterogeneity. TeNT itself is highly conserved among all strains; the most relevant difference is an insertion of four amino acids in the C-terminal receptor-binding domain in four strains that might impact on receptor-binding properties. Other putative virulence factors, including tetanolysin and collagenase, are encoded in all genomes. This study highlights the population structure of C. tetani and suggests that tetanus-causing strains did not undergo extensive evolutionary diversification, as judged from the high conservation of its main virulence factors.

Keywords: Bacteriology; Genetics

Domains: Life Sciences [q-bio]; Life Sciences [q-bio]; Microbiology and Parasitology; Life Sciences [q-bio]; Microbiology and Parasitology; Bacteriology; Life Sciences [q-bio]; Cellular Biology; Life Sciences [q-bio]; Cellular Biology; Subcellular Processes [q-bio.SC]; Life Sciences [q-bio]; Cellular Biology; Cell Behavior [q-bio.CB]

Diana Chapetón-Montes, Lucile Plourde, Christiane Bouchier, Laurence Ma, Laure Diancourt, et al.. The population structure of Clostridium tetani deduced from its pan-genome. Scientific Reports, 2019, 9 (1), ⟨10.1038/s41598-019-47551-4⟩. ⟨pasteur-02448683⟩