Complete Genome Sequence of a Virulent Streptococcus agalactiae Strain, 138P, Isolated from Diseased Nile Tilapia

Pridgeon, Julia W.; Zhang, Dunhua

doi:10.1128/genomea.00295-14

Cited by 9 publications

(10 citation statements)

References 11 publications

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“…Both ST-260 and ST-261 have previously been identified as infecting aquatic animals. ST-260 isolates have been isolated from tilapia in Brazil and Costa Rica and occupy clonal complex 552 (CC552), along with ST-552 and ST-553 strains also isolated from tilapia in Latin America (27), ST-261 has been isolated from tilapia in the United States, China, Ghana, and Israel (9,13,30).…”

Section: Resultsmentioning

confidence: 99%

Microevolution of Streptococcus agalactiae ST-261 from Australia Indicates Dissemination via Imported Tilapia and Ongoing Adaptation to Marine Hosts or Environment

Kawasaki

Delamare-Deboutteville

Bowater³

et al. 2018

Appl Environ Microbiol

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(group B [GBS]) causes disease in a wide range of animals. The serotype Ib lineage is highly adapted to aquatic hosts, exhibiting substantial genome reduction compared with terrestrial conspecifics. Here, we sequence genomes from 40 GBS isolates, including 25 isolates from wild fish and captive stingrays in Australia, six local veterinary or human clinical isolates, and nine isolates from farmed tilapia in Honduras, and compared them with 42 genomes from public databases. Phylogenetic analysis based on nonrecombinant core-genome single nucleotide polymorphisms (SNPs) indicated that aquatic serotype Ib isolates from Queensland were distantly related to local veterinary and human clinical isolates. In contrast, Australian aquatic isolates are most closely related to a tilapia isolate from Israel, differing by only 63 core-genome SNPs. A consensus minimum spanning tree based on core-genome SNPs indicates the dissemination of sequence type 261 (ST-261) from an ancestral tilapia strain, which is congruent with several introductions of tilapia into Australia from Israel during the 1970s and 1980s. Pangenome analysis identified 1,440 genes as core, with the majority being dispensable or strain specific, with non-protein-coding intergenic regions (IGRs) divided among core and strain-specific genes. Aquatic serotype Ib strains have lost many virulence factors during adaptation, but six adhesins were well conserved across the aquatic isolates and might be critical for virulence in fish and for targets in vaccine development. The close relationship among recent ST-261 isolates from Ghana, the United States, and China with the Israeli tilapia isolate from 1988 implicates the global trade in tilapia seed for aquaculture in the widespread dissemination of serotype Ib fish-adapted GBS. (GBS) is a significant pathogen of humans and animals. Some lineages have become adapted to particular hosts, and serotype Ib is highly specialized to fish. Here, we show that this lineage is likely to have been distributed widely by the global trade in tilapia for aquaculture, with probable introduction into Australia in the 1970s and subsequent dissemination in wild fish populations. We report here the variability in the polysaccharide capsule among this lineage but identify a cohort of common surface proteins that may be a focus of future vaccine development to reduce the biosecurity risk in international fish trade.

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Section: Resultsmentioning

confidence: 99%

Microevolution of Streptococcus agalactiae ST-261 from Australia Indicates Dissemination via Imported Tilapia and Ongoing Adaptation to Marine Hosts or Environment

Kawasaki

Delamare-Deboutteville

Bowater³

et al. 2018

Appl Environ Microbiol

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“…; Zhang et al . ; Pridgeon and Zhang ). In Thailand, outbreaks of streptococcosis in tilapia cultures commonly occur between April and September, when the temperature increases and the water quality decreases.…”

Section: Introductionmentioning

confidence: 99%

Molecular serotyping, virulence gene profiling and pathogenicity of Streptococcus agalactiae isolated from tilapia farms in Thailand by multiplex PCR

et al. 2017

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We identified two major serotypes of S. agalactiae isolates associated with the outbreak in tilapia culture in Thailand. We developed multiplex PCR assays for 14 virulence genes, which may be used to predict the pathogenicity of the isolates and track future infections. Multiplex PCR typing of the GBS virulence genes was developed and might be further used to predict the pathogenicity of S. agalactiae.

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“…Molecular serotyping indicated that all Queensland and Honduras aquatic strains belong to serotype Ib but Queensland isolates belong to sequence type (ST)-261 while Honduras strains are ST-260. Both ST-260 and ST-261 have been identified infecting aquatic animals previously with ST-260 isolates found in tilapia from Brazil and Costa Rica and occupying clonal complex (CC) 552 along with ST-552 and ST-553 strains also isolated from tilapia in Latin America (27), whilst ST-261 has been isolated from tilapia in USA, China, Ghana and Israel (9, 13, 30).…”

Section: Resultsmentioning

confidence: 99%

Microevolution of aquaticStreptococcus agalactiaeST-261 from Australia indicates dissemination via imported tilapia and ongoing adaptation to marine hosts or environment

Kawasaki

Delamare-Deboutteville

Bowater³

et al. 2018

Preprint

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Streptococcus agalactiae (GBS) causes disease in a wide range of animals. The serotype 1b lineage is highly adapted to aquatic hosts, exhibiting substantial genome reduction compared with terrestrial con-specifics. Here we sequence genomes from 40 GBS isolates including 25 from wild fish and captive stingrays in Australia, six local veterinary or human clinical isolates, and nine isolates from farmed tilapia in Honduras and compare with 42 genomes from public databases. Phylogenetic analysis based on non-recombinant core genome SNPs indicated that aquatic serotype Ib isolates from Queensland were distantly related to local veterinary and human clinical isolates. In contrast, Australian aquatic isolates are most closely related to a tilapia isolate from Israel, differing by only 63 core-genome SNPs. A consensus minimum spanning tree based on core genome SNPs indicates dissemination of ST-261 from an ancestral tilapia strain, which is congruent with several introductions of tilapia into Australia from Israel during the 1970s and 1980s. Pan-genome analysis identified 1,440 genes as core with the majority being dispensable or strain-specific with non-protein-coding intergenic regions (IGRs) divided amongst core and strain-specific genes. Aquatic serotype Ib strains have lost many virulence factors during adaptation, but six adhesins were well conserved across the aquatic isolates and might be critical for virulence in fish and targets for vaccine development. The close relationship amongst recent ST-261 isolates from Ghana, USA and China with the Israeli tilapia isolate from 1988 implicates the global trade in tilapia seed for aquaculture in the widespread dissemination of serotype Ib fish-adapted GBS.ImportanceStreptococcus agalactiae (GBS) is a significant pathogen of humans and animals. Some lineages have become adapted to particular hosts and serotype Ib is highly specialized to fish. Here we show that this lineage is likely to have been distributed widely by the global trade in tilapia for aquaculture, with probable introduction into Australia in the 1970s and subsequent dissemination in wild fish populations. We report variability in the polysaccharide capsule amongst this lineage, but identify a cohort common surface proteins that may be a focus of future vaccine development to reduce the biosecurity risk in international fish trade.

show abstract

Complete Genome Sequence of a Virulent Streptococcus agalactiae Strain, 138P, Isolated from Diseased Nile Tilapia

Cited by 9 publications

References 11 publications

Microevolution of Streptococcus agalactiae ST-261 from Australia Indicates Dissemination via Imported Tilapia and Ongoing Adaptation to Marine Hosts or Environment

Microevolution of Streptococcus agalactiae ST-261 from Australia Indicates Dissemination via Imported Tilapia and Ongoing Adaptation to Marine Hosts or Environment

Molecular serotyping, virulence gene profiling and pathogenicity of Streptococcus agalactiae isolated from tilapia farms in Thailand by multiplex PCR

Microevolution of aquaticStreptococcus agalactiaeST-261 from Australia indicates dissemination via imported tilapia and ongoing adaptation to marine hosts or environment

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