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Research Project: Improving Salmonid Health through Breeding, Vaccination and Microbiome Modulation

Location: Cool and Cold Water Aquaculture Research

Title: Comparative and Evolutionary Genomics of Isolates Provide Insight into the Pathoadaptation of Aeromonas

item TALAGRAND-REBOUL, EMILIE - University Of Montpellier
item COLSTON, SOPHIE - University Of Connecticut
item GRAF, JOERG - University Of Connecticut
item LAMY, BRIGITTE - University Of Montpellier
item JUMAS-BILAK, ESTELLE - University Of Montpellier

Submitted to: Genome Biology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2020
Publication Date: 5/20/2020
Citation: Talagrand-Reboul, E., Colston, S.M., Graf, J., Lamy, B., Jumas-Bilak, E. 2020. Comparative and Evolutionary Genomics of Isolates Provide Insight into the Pathoadaptation of Aeromonas. Genome Biology and Evolution. 12(5):535-552.

Interpretive Summary: Aeromonas species can cause serious diseases in fish, humans and other animals. It is not well understood what features these bacteria need to cause disease. It is important to understand how the bacteria gain features that allow them to cause disease. In this study, we used a comparative genomic approach of 66 genomes to characterize 13 genes associated with causing disease. The study found that some genes are found in specific lineages but others follow no discernable pattern. This indicates that the evolution of virulence is very complex in this genus. This can perhaps explain why so many different Aeromonas species can cause disease in fish.

Technical Abstract: Aeromonads are ubiquitous aquatic bacteria that cause opportunistic infections in humans, but their pathogenesis remains poorly understood. A pathogenomic approach was undertaken to provide insights into the emergence and evolution of pathogenic traits in aeromonads. The genomes of 64 Aeromonas strains representative of the whole genus were analyzed to study the distribution, phylogeny, and synteny of the flanking sequences of 13 virulence-associated genes. The reconstructed evolutionary histories varied markedly depending on the gene analyzed and ranged from vertical evolution, which followed the core genome evolution (alt and colAh), to complex evolution, involving gene loss by insertion sequence-driven gene disruption, horizontal gene transfer, and paraphyly with some virulence genes associated with a phylogroup (aer, ser, and type 3 secretion system components) or no phylogroup (type 3 secretion system effectors, Ast, ExoA, and RtxA toxins). The general pathogenomic overview of aeromonads showed great complexity with diverse evolution modes and gene organization and uneven distribution of virulence genes in the genus; the results provided insights into aeromonad pathoadaptation or the ability of members of this group to emerge as pathogens. Finally, these findings suggest that aeromonad virulence-associated genes should be examined at the population level and that studies performed on type or model strains at the species level cannot be generalized to the whole species.