First Report and Pathogenicity Analysis of <i>Photobacterium damselae</i> subsp. <i>piscicida</i> in Cage-Cultured Black Rockfish (<i>Sebastes schlegelii</i>) Associated with Skin Ulcers

<i>Photobacterium damselae</i> subsp. <i>Piscicida</i> (PDP), a marine bacterium, has been reported to infect a variety of economically important marine species worldwide. Understanding the occurrence and pathogenicity of PDP is crucial for effective disease control and ensur...

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Main Authors: Dandan Zhou, Binzhe Zhang, Yulie Qiu, Xuepeng Li, Jian Zhang
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Microorganisms
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Online Access:https://www.mdpi.com/2076-2607/13/2/441
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author Dandan Zhou
Binzhe Zhang
Yulie Qiu
Xuepeng Li
Jian Zhang
author_facet Dandan Zhou
Binzhe Zhang
Yulie Qiu
Xuepeng Li
Jian Zhang
author_sort Dandan Zhou
collection DOAJ
description <i>Photobacterium damselae</i> subsp. <i>Piscicida</i> (PDP), a marine bacterium, has been reported to infect a variety of economically important marine species worldwide. Understanding the occurrence and pathogenicity of PDP is crucial for effective disease control and ensuring the success of aquaculture operations. In late August 2023, an epidemic outbreak of <i>P. damselae</i> subsp. <i>piscicida</i> DQ-SS1, accompanied by significant mortality, was recorded in cage-cultured black rockfish <i>(Sebastes schlegelii</i>) located on Daqin Island for the first time. Genomic analysis revealed that DQ-SS1 possesses 2 chromosomes, with a total size of 4,510,445 bp and 3923 predicted CDSs. Pathogenic genes analysis identified 573 and 314 genes related to pathogen–host interactions and virulence, respectively. Additionally, DQ-SS1 displayed susceptibility to 15 antimicrobials, was resistant to 11 antimicrobials, and was intermediately sensitive to four antibiotics. Meanwhile, the in vitro assay revealed that the extracellular products (ECP) of DQ-SS1 were lethal to macrophages and exhibited hemolysin, lipase, and amylase activities. Moreover, DQ-SS1 also demonstrated the ability to survive in fish serum and resist complement-mediated killing. The in vivo assay showed that the infected fish exhibited severe histopathological alterations, such as the infiltration of inflammatory cells, cellular degeneration and necrosis, and loose cell aggregation. Lastly, the in vivo infection assays revealed the LD<sub>50</sub> of DQ-SS1 was 1.7 × 10<sup>3</sup> CFU/g. This is the first study to elucidate the pathogenicity and genomic characteristics of multidrug-resistant PDP in cage-cultured <i>S. schlegelii</i>, which contributes to the advancement of diagnostic and preventative strategies for this disease in marine-cultured fishes and provides information for an in-depth study of the pathogenic mechanism of PDP.
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spelling doaj-art-4e81e2a36d3c4283bf56cd50c54d8f712025-08-20T03:11:22ZengMDPI AGMicroorganisms2076-26072025-02-0113244110.3390/microorganisms13020441First Report and Pathogenicity Analysis of <i>Photobacterium damselae</i> subsp. <i>piscicida</i> in Cage-Cultured Black Rockfish (<i>Sebastes schlegelii</i>) Associated with Skin UlcersDandan Zhou0Binzhe Zhang1Yulie Qiu2Xuepeng Li3Jian Zhang4School of Ocean, Yantai University, Yantai 264005, ChinaSchool of Ocean, Yantai University, Yantai 264005, ChinaSchool of Ocean, Yantai University, Yantai 264005, ChinaSchool of Ocean, Yantai University, Yantai 264005, ChinaSchool of Ocean, Yantai University, Yantai 264005, China<i>Photobacterium damselae</i> subsp. <i>Piscicida</i> (PDP), a marine bacterium, has been reported to infect a variety of economically important marine species worldwide. Understanding the occurrence and pathogenicity of PDP is crucial for effective disease control and ensuring the success of aquaculture operations. In late August 2023, an epidemic outbreak of <i>P. damselae</i> subsp. <i>piscicida</i> DQ-SS1, accompanied by significant mortality, was recorded in cage-cultured black rockfish <i>(Sebastes schlegelii</i>) located on Daqin Island for the first time. Genomic analysis revealed that DQ-SS1 possesses 2 chromosomes, with a total size of 4,510,445 bp and 3923 predicted CDSs. Pathogenic genes analysis identified 573 and 314 genes related to pathogen–host interactions and virulence, respectively. Additionally, DQ-SS1 displayed susceptibility to 15 antimicrobials, was resistant to 11 antimicrobials, and was intermediately sensitive to four antibiotics. Meanwhile, the in vitro assay revealed that the extracellular products (ECP) of DQ-SS1 were lethal to macrophages and exhibited hemolysin, lipase, and amylase activities. Moreover, DQ-SS1 also demonstrated the ability to survive in fish serum and resist complement-mediated killing. The in vivo assay showed that the infected fish exhibited severe histopathological alterations, such as the infiltration of inflammatory cells, cellular degeneration and necrosis, and loose cell aggregation. Lastly, the in vivo infection assays revealed the LD<sub>50</sub> of DQ-SS1 was 1.7 × 10<sup>3</sup> CFU/g. This is the first study to elucidate the pathogenicity and genomic characteristics of multidrug-resistant PDP in cage-cultured <i>S. schlegelii</i>, which contributes to the advancement of diagnostic and preventative strategies for this disease in marine-cultured fishes and provides information for an in-depth study of the pathogenic mechanism of PDP.https://www.mdpi.com/2076-2607/13/2/441<i>Sebastes schlegelii</i><i>Photobacterium damselae</i> subsp. <i>piscicida</i>antimicrobial-resistantextracellular productspathogenicity
spellingShingle Dandan Zhou
Binzhe Zhang
Yulie Qiu
Xuepeng Li
Jian Zhang
First Report and Pathogenicity Analysis of <i>Photobacterium damselae</i> subsp. <i>piscicida</i> in Cage-Cultured Black Rockfish (<i>Sebastes schlegelii</i>) Associated with Skin Ulcers
Microorganisms
<i>Sebastes schlegelii</i>
<i>Photobacterium damselae</i> subsp. <i>piscicida</i>
antimicrobial-resistant
extracellular products
pathogenicity
title First Report and Pathogenicity Analysis of <i>Photobacterium damselae</i> subsp. <i>piscicida</i> in Cage-Cultured Black Rockfish (<i>Sebastes schlegelii</i>) Associated with Skin Ulcers
title_full First Report and Pathogenicity Analysis of <i>Photobacterium damselae</i> subsp. <i>piscicida</i> in Cage-Cultured Black Rockfish (<i>Sebastes schlegelii</i>) Associated with Skin Ulcers
title_fullStr First Report and Pathogenicity Analysis of <i>Photobacterium damselae</i> subsp. <i>piscicida</i> in Cage-Cultured Black Rockfish (<i>Sebastes schlegelii</i>) Associated with Skin Ulcers
title_full_unstemmed First Report and Pathogenicity Analysis of <i>Photobacterium damselae</i> subsp. <i>piscicida</i> in Cage-Cultured Black Rockfish (<i>Sebastes schlegelii</i>) Associated with Skin Ulcers
title_short First Report and Pathogenicity Analysis of <i>Photobacterium damselae</i> subsp. <i>piscicida</i> in Cage-Cultured Black Rockfish (<i>Sebastes schlegelii</i>) Associated with Skin Ulcers
title_sort first report and pathogenicity analysis of i photobacterium damselae i subsp i piscicida i in cage cultured black rockfish i sebastes schlegelii i associated with skin ulcers
topic <i>Sebastes schlegelii</i>
<i>Photobacterium damselae</i> subsp. <i>piscicida</i>
antimicrobial-resistant
extracellular products
pathogenicity
url https://www.mdpi.com/2076-2607/13/2/441
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