Subclinical Infection of &lt;i&gt;Renibacterium salmoninarum&lt;/i&gt; in Fry and Juveniles Chum Salmon &lt;i&gt;Oncorhynchus keta&lt;/i&gt; in Hokkaido, Japan

Suzuki, Kazutoshi; Misaka, Naoyuki; Mizuno, Shinya; Sasaki, Yoshitaka

doi:10.3147/jsfp.52.89

Cited by 9 publications

(16 citation statements)

References 41 publications

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“…In addition, R. salmoninarum has been detected in chum salmon (Oncorhynchus keta) in kidney and mucus samples by Suzuki et al in 2017 in Japan. These authors indicated that R. salmoninarum could be identified from asymptomatic fish in sub-clinical stage of disease by using PCR [21]. Similarly, this organism has been identified in sub-clinical stage in the other different regions and species [53,54].…”

Section: Discussionmentioning

confidence: 97%

“…Fish infected with R. salmoninarum can display external and internal clinical signs such as exophthalmia, blebs and blister on the epidermis with white or yellowish haemorrhagic fluid, petechiae and haemorrhages around the fins and lateral line, swelling of the kidney, heart, spleen, and liver alongside creamy-white and greyish granulomatous lesions on the surface of the viscera [18][19][20]. Notably, this organism has been associated with sub-clinical infections in salmonid fish and can establish asymptomatic infections in members of susceptible species [21].…”

Section: Introductionmentioning

confidence: 99%

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Renibacterium salmoninarum and Mycobacterium spp.: two bacterial pathogens present at low levels in wild brown trout (Salmo trutta fario) populations in Austrian rivers

et al. 2020

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Background: Renibacterium salmoninarum and Mycobacterium sp. are important bacterial pathogens of fish. R. salmoninarum is the causative agent of bacterial kidney disease, a Gram-positive bacterium mostly known for causing chronic infections in salmonid fish, while multiple species belonging to the Mycobacterium genus have been associated with mycobacteriosis in fish as well as in human. The objective of this study was to determine the prevalence of these two bacterial pathogens in populations of wild brown trout (Salmo trutta fario) in four rivers (Kamp, Wulka, Traun and Ybbs) in Austria. Results: A total of 457 kidney samples were examined for both bacterial agents using nested and conventional PCR as well as bacterial cultivation on KDM-2, histological examination and immunohistochemistry. Molecular evidence showed an estimated prevalence level of 0.94% for R. salmoninarum in 2017 while the bacterium could not be detected in 2018 and histology showed signs consistent with a low-level chronic inflammation in the kidney of infected fish. Similarly, no fish were found positive for Mycobacterium in 2017 but in 2018, the prevalence was found to be 37.03% in the Kamp river (4.08% across all rivers). The sequencing data confirmed that these fish carried Mycobacterium sp. although the precise species of Mycobacterium could not be ascertained. Conclusions: This survey constitutes the first insight into the prevalence rate of R. salmoninarum and Mycobacterium sp. in wild brown trout (Salmo trutta fario) populations in Austria. Both of these pathogens were only detected in the summer months (June and July), which might suggest that the stress linked to increased water temperature could act as stressor factor and contribute to the outbreak of these diseases. The age of the fish might also play a role, especially in the case of Mycobacterium sp. as all the infected fish were in their first summer (June).

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Renibacterium salmoninarum and Mycobacterium spp.: two bacterial pathogens present at low levels in wild brown trout (Salmo trutta fario) populations in Austrian rivers

et al. 2020

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“…In other recent research, we detected the msa gene DNA and msa mRNA of R. salmoninarum in the kidneys and surface mucus of asymptomatic chum salmon fry and juveniles in a hatchery in Hokkaido (Suzuki et al, 2017). It is well established that R. salmoninarum cells can be transmitted horizontally as well as vertically, from adult females via gametes to offspring (Elliott et al, 1989;Murray et al, 1992;Okuda et al, 2006).…”

Section: Resultsmentioning

confidence: 87%

PCR- Based Detection and Quantification of Renibacterium salmoninarum in Ovarian Fluid of Returning Chum Salmon Oncorhynchus keta and Masu Salmon O. masou in Hokkaido, Japan

et al. 2017

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Renibacterium salmoninarum was detected in ovarian fluid of returning salmonids using nested PCR; chum salmon from seven rivers (925 samples) and masu salmon from three rivers (309 samples) in Hokkaido in 2015 and 2016. Real-time PCR was also performed for the samples in 2016. In chum salmon prevalence of R. salmoninarum genome was 0%-90% in 2015 and 12%-98% in 2016. In masu salmon the prevalence was 0% in 2015 and 50%-84% in 2016. In 2016, the prevalence had risen in the samples in eight of ten rivers. The numbers of R. salmoninarum genome were estimated to be 1.0 × 10 1-8.0 × 10 2 copies/μL of ovarian fluid.

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“…DNA was extracted from samples according to our previous report (Suzuki et al, 2017a). One micro-liter of the DNA solution contained DNA from 1 mg of tissue.…”

Section: Nested Pcr Assay and Quantitative Real-time Pcr Assaymentioning

confidence: 99%

“…One micro-liter of the DNA solution contained DNA from 1 mg of tissue. The nPCR and qPCR assay for the msa gene were conducted as previously reported (Suzuki et al, 2017a). Sensitivity of nPCR was higher than that of qPCR.…”

Section: Nested Pcr Assay and Quantitative Real-time Pcr Assaymentioning

confidence: 99%

Asymptomatic Infection of Renibacterium salmoninarum in Hatchery-reared Juvenile Chum Salmon Oncorhynchus keta Resulted in Mass Mortalities after Long-term Rearing

et al. 2018

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A previous study detected the major soluble antigen (msa) gene and its corresponding mRNA from Renibacterium salmoninarum (R.s.) in the kidney tissue and surface mucus of asymptomatic chum salmon fry and juveniles by nested PCR (nPCR), quantitative realtime PCR (qPCR) and a reverse transcription nested PCR assay (RT-nPCR) (Suzuki et al., 2017a). The chum salmon had been transferred from a hatchery in Hokkaido at the fry-stage (0.5 g) and reared at a wetlaboratory in the Salmon and Freshwater Fisheries Research Institute in a fresh water environment for 10 months (Suzuki et al., 2017a). In January 2017, the same group of asymptomatic chum salmon juveniles and another group of asymptomatic chum salmon juveniles, which were transferred at the fertilized-egg stage from another hatchery in Hokkaido to the wet laboratory and reared until juvenile, began to die. Most of the dead fish showed the clinical signs of bacterial kidney disease (BKD). The purpose of the present study was to examine the outbreaks of BKD in chum salmon juveniles subclinically infected with R.s. Materials and Methods Fish Two groups of asymptomatic chum salmon (hereafter referred to as Group-A and Group-B) were examined. Group-A fish were the progeny of returning chum salmon female adults in 2015 at Site A (Suzuki et al., 2017a, 2017b) and transferred from Site A at the fry-stage weighing 0.5 g in March 25, 2016, and reared until juveniles at the wet laboratory in the Salmon and Freshwater Fisheries Research Institute (Suzuki et al., 2017a). BKD had not previously been reported at this institute. The fish were confirmed by nPCR, qPCR and RT-nPCR for the presence of the msa gene and msa mRNA to indicate subclinical infection with R.s. seven times (Suzuki et al., 2017a). Group-B fish were transferred from another hatchery in Hokkaido at the fertilized-egg stage in October 8, 2015, to the wet laboratory and reared until juvenile. Group-B fish were confirmed by nPCR and qPCR to be subclinically infected with R.s. twice.

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Subclinical Infection of <i>Renibacterium salmoninarum</i> in Fry and Juveniles Chum Salmon <i>Oncorhynchus keta</i> in Hokkaido, Japan

Cited by 9 publications

References 41 publications

Renibacterium salmoninarum and Mycobacterium spp.: two bacterial pathogens present at low levels in wild brown trout (Salmo trutta fario) populations in Austrian rivers

Renibacterium salmoninarum and Mycobacterium spp.: two bacterial pathogens present at low levels in wild brown trout (Salmo trutta fario) populations in Austrian rivers

PCR- Based Detection and Quantification of <i>Renibacterium salmoninarum</i> in Ovarian Fluid of Returning Chum Salmon <i>Oncorhynchus keta</i> and Masu Salmon <i>O. masou</i> in Hokkaido, Japan

Asymptomatic Infection of <i>Renibacterium salmoninarum</i> in Hatchery-reared Juvenile Chum Salmon <i>Oncorhynchus keta</i> Resulted in Mass Mortalities after Long-term Rearing

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