Vibrio mimicus carrying the Type III Secretion System 2 (T3SS2) and TDH toxin of Vibrio parahaemolyticus in an integrative conjugative element context
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Objectives
Identify possible virulence factors in the genomes of Vibrio mimicus that may be determinants of diarrheal cases/outbreaks.
Methods
All V. mimicus genomes from Genbank were retrieved and the virulome was searched with Abricate using the VFDB database. Genomic islands (GIs) and integrative conjugative elements (ICEs) were identified using IslandViewer and ICEberg, respectively.
Results
Five ctx-negative V. mimicus genomes carrying the Type III Secretion System 2 (T3SS2) and the TDH/TRH toxin from Vibrio parahaemolyticus were identified. The T3SS-positive genomes presented the phylotypes T3SS2α and T3SS2β and formed two clusters and one singleton throughout the V. mimicus phylogeny. Genomes carrying T3SS2α and T3SS2β were associated with the tdh and trh genes, respectively. Furthermore, genomic analyses characterized an integrative conjugative element (ICE) with a size of ∼150 kb carrying both V. parahaemolyticus virulence determinants.
Conclusions
In addition to looking for cholera toxin genes in V. mimicus cases/outbreaks, it is important to consider V. parahaemolyticus toxins such as TDH and TRH. Furthermore, an ICE was identified and characterized in V. mimicus , being associated with T3SS2 and the TDH toxin, which is worrying, as it can disseminate these virulence factors among Vibrio spp.
