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The Evolution of a Specialized, Highly Virulent Fish Pathogen through Gene Loss and Acquisition of Host-Specific Survival Mechanisms

Photobacterium damselae comprises two subspecies, P. damselae subsp. damselae and P. damselae subsp. piscicida, that contrast remarkably despite their taxonomic relationship. The former is opportunistic and free-living but can cause disease in compromised individuals from a broad diversity of taxa,...

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Autores principales: Baseggio, Laura, Silayeva, Oleksandra, Engelstädter, Jan, Barnes, Andrew C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Microbiology 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9317898/
https://www.ncbi.nlm.nih.gov/pubmed/35862683
http://dx.doi.org/10.1128/aem.00222-22
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author Baseggio, Laura
Silayeva, Oleksandra
Engelstädter, Jan
Barnes, Andrew C.
author_facet Baseggio, Laura
Silayeva, Oleksandra
Engelstädter, Jan
Barnes, Andrew C.
author_sort Baseggio, Laura
collection PubMed
description Photobacterium damselae comprises two subspecies, P. damselae subsp. damselae and P. damselae subsp. piscicida, that contrast remarkably despite their taxonomic relationship. The former is opportunistic and free-living but can cause disease in compromised individuals from a broad diversity of taxa, while the latter is a highly specialized, primary fish pathogen. Here, we employ new closed curated genome assemblies from Australia to estimate the global phylogenetic structure of the species P. damselae. We identify genes responsible for the shift from an opportunist to a host-adapted fish pathogen, potentially via an arthropod vector as fish-to-fish transmission was not achieved in repeated cohabitation challenges despite high virulence for Seriola lalandi. Acquisition of ShdA adhesin and of thiol peroxidase may have allowed the environmental, generalist ancestor to colonize zooplankton and to occasionally enter in fish host sentinel cells. As dependence on the host has increased, P. damselae has lost nonessential genes, such as those related to nitrite and sulfite reduction, urea degradation, a type 6 secretion system (T6SS) and several toxin-antitoxin (TA) systems. Similar to the evolution of Yersinia pestis, the loss of urease may be the crucial event that allowed the pathogen to stably colonize zooplankton vectors. Acquisition of host-specific genes, such as those required to form a sialic acid capsule, was likely necessary for the emergent P. damselae subsp. piscicida to become a highly specialized, facultative intracellular fish pathogen. Processes that have shaped P. damselae subsp. piscicida from subsp. damselae are similar to those underlying evolution of Yersinia pestis from Y. pseudotuberculosis. IMPORTANCE Photobacterium damselae subsp. damselae is a ubiquitous marine bacterium and opportunistic pathogen of compromised hosts of diverse taxa. In contrast, its sister subspecies P. damselae subsp. piscicida (Pdp) is highly virulent in fish. Pdp has evolved from a single subclade of Pdd through gene loss and acquisition. We show that fish-to-fish transmission does not occur in repeated infection models in the primary host, Seriola lalandi, and present genomic evidence for vector-borne transmission, potentially via zooplankton. The broad genomic changes from generalist Pdd to specialist Pdp parallel those of the environmental opportunist Yersinia pseudotuberculosis to vector-borne plague bacterium Y. pestis and demonstrate that evolutionary processes in bacterial pathogens are universal between the terrestrial and marine biosphere.
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spelling pubmed-93178982022-07-27 The Evolution of a Specialized, Highly Virulent Fish Pathogen through Gene Loss and Acquisition of Host-Specific Survival Mechanisms Baseggio, Laura Silayeva, Oleksandra Engelstädter, Jan Barnes, Andrew C. Appl Environ Microbiol Evolutionary and Genomic Microbiology Photobacterium damselae comprises two subspecies, P. damselae subsp. damselae and P. damselae subsp. piscicida, that contrast remarkably despite their taxonomic relationship. The former is opportunistic and free-living but can cause disease in compromised individuals from a broad diversity of taxa, while the latter is a highly specialized, primary fish pathogen. Here, we employ new closed curated genome assemblies from Australia to estimate the global phylogenetic structure of the species P. damselae. We identify genes responsible for the shift from an opportunist to a host-adapted fish pathogen, potentially via an arthropod vector as fish-to-fish transmission was not achieved in repeated cohabitation challenges despite high virulence for Seriola lalandi. Acquisition of ShdA adhesin and of thiol peroxidase may have allowed the environmental, generalist ancestor to colonize zooplankton and to occasionally enter in fish host sentinel cells. As dependence on the host has increased, P. damselae has lost nonessential genes, such as those related to nitrite and sulfite reduction, urea degradation, a type 6 secretion system (T6SS) and several toxin-antitoxin (TA) systems. Similar to the evolution of Yersinia pestis, the loss of urease may be the crucial event that allowed the pathogen to stably colonize zooplankton vectors. Acquisition of host-specific genes, such as those required to form a sialic acid capsule, was likely necessary for the emergent P. damselae subsp. piscicida to become a highly specialized, facultative intracellular fish pathogen. Processes that have shaped P. damselae subsp. piscicida from subsp. damselae are similar to those underlying evolution of Yersinia pestis from Y. pseudotuberculosis. IMPORTANCE Photobacterium damselae subsp. damselae is a ubiquitous marine bacterium and opportunistic pathogen of compromised hosts of diverse taxa. In contrast, its sister subspecies P. damselae subsp. piscicida (Pdp) is highly virulent in fish. Pdp has evolved from a single subclade of Pdd through gene loss and acquisition. We show that fish-to-fish transmission does not occur in repeated infection models in the primary host, Seriola lalandi, and present genomic evidence for vector-borne transmission, potentially via zooplankton. The broad genomic changes from generalist Pdd to specialist Pdp parallel those of the environmental opportunist Yersinia pseudotuberculosis to vector-borne plague bacterium Y. pestis and demonstrate that evolutionary processes in bacterial pathogens are universal between the terrestrial and marine biosphere. American Society for Microbiology 2022-07-11 /pmc/articles/PMC9317898/ /pubmed/35862683 http://dx.doi.org/10.1128/aem.00222-22 Text en © Crown copyright 2022. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Evolutionary and Genomic Microbiology
Baseggio, Laura
Silayeva, Oleksandra
Engelstädter, Jan
Barnes, Andrew C.
The Evolution of a Specialized, Highly Virulent Fish Pathogen through Gene Loss and Acquisition of Host-Specific Survival Mechanisms
title The Evolution of a Specialized, Highly Virulent Fish Pathogen through Gene Loss and Acquisition of Host-Specific Survival Mechanisms
title_full The Evolution of a Specialized, Highly Virulent Fish Pathogen through Gene Loss and Acquisition of Host-Specific Survival Mechanisms
title_fullStr The Evolution of a Specialized, Highly Virulent Fish Pathogen through Gene Loss and Acquisition of Host-Specific Survival Mechanisms
title_full_unstemmed The Evolution of a Specialized, Highly Virulent Fish Pathogen through Gene Loss and Acquisition of Host-Specific Survival Mechanisms
title_short The Evolution of a Specialized, Highly Virulent Fish Pathogen through Gene Loss and Acquisition of Host-Specific Survival Mechanisms
title_sort evolution of a specialized, highly virulent fish pathogen through gene loss and acquisition of host-specific survival mechanisms
topic Evolutionary and Genomic Microbiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9317898/
https://www.ncbi.nlm.nih.gov/pubmed/35862683
http://dx.doi.org/10.1128/aem.00222-22
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