• Journal of Life Science
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• v.17 no.1 s.81
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• pp.162-165
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• 2007

Brown Ring Disease (BRD) is a bacterial disease caused by Vibrio tapetis which affects cultured clam Ruditapes philippinarum and causes heavy economic losses on Atlantic coasts of france, Spain and England. In this study, to evaluate the effective detection of the pathogen, specific primer set based on 16S ribosomal RNA (rRNA) sequences designed for rapid detection of V. tapetis. Polymerase chain reaction (PCR) with this primer set produced the specific band for each V. tapetis. The length of PCR product using designed primer set of Vbts-F and Vbts-R was about 400 bp. Therefore, these primers will be provided with a basic tool for rapid detection of V. tapetis in the various cases such as examination of imported aquatic products, diagnosis of aquatic organisms, and etc.

• Journal of fish pathology
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• v.18 no.1
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• pp.39-48
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• 2005

Pathogenicity of Vibrio tapetis, the causative bacterium of 'brown ring disease (BRD)' was evaluated in Manila clams (Ruditapes philippinarumi by artificially 0.1 $m\ell$ infection of $1.0\times10^5$cells and $1.0\times10^8$ cells at 20 $^{\circ}C$. A PCR assay based on 16S rRNA to detect the bacteria in clam tissues was established. Accumulative mortality of clams infected with $1.0\times10^7$cells and $1.0\times10^4$ cells per an individual of the bacteria was 67.5% and 7.5%, respectively. However, the deposit of brown pigment in the inner shells by accumulation of chonchiolin was not found. The bacteria were not be able to re-isolate from the infected clams by the conventional agar plate method but were easily detected by PCR assay established in this experiment. In clams artificially infected with 10 species of Vibrio, a 414bp for V. tapetis was detected in PCR assay. The specific band in the clams infected with $1.0\times10^4$cells per an individual of V. tapetis was detected only in gills one day after the infection but never be found in any tissues including gills three days after the infection. In the case of clams infected with $1.0\times10^8$cells per an individual of V. tapetis the specific band was detected in gills and intestine one day after the infection, in all tissues three days after the infection, and then in gills and adductor muscle nine days after the infection. The PCR assay was applied to detect V. tapetis in manila clam, surf clam (Mactra veneriformis), oyster (Crassostrea gigas) and Thomas' rapa whelk (Rapana venosa) taken from Taean and Gochang from April to July 2004. The infection rates were detected to 23.1% and 9.4% in the oyster and surf clam, while manila clam and Thomas' rapa whelk were not found.

• The Korean Journal of Malacology
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• v.29 no.2
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• pp.155-161
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• 2013

Cathepsins are lysosomal/cysteine proteases belong to papain family (C1 family) that is involved in intracellular protein degradation, antigen processing, hormone maturation, and immune responses. In this study, member of cathepsin family was identified from Manila clam (Mc-Cathepsin D) and investigated the immune response against brown ring disease (BRD) causing Vibrio tapetis challenge. The identified Mc-Cathepsin D gene encodes characteristic features typical for the cathepsin family including eukaryotic and viral aspartyl protease signature domain and two highly conserved active sites ($^{84}VVFDTGSSNLWV^{95}$ and $^{270}IADTGTSLLAG^{281}$). Moreover, MC-Cathepsin D shows higher identity values (-50-70%) and conserved amino acids with known cathepsin D members. Transcriptional results (by quantitative real-time RT-PCR) showed that Mc-Cathepsin D was expressed at higher levels in gills and hemocytes than mantle, adductor muscle, foot, and siphon. After the V. tapetis challenge under laboratory conditions, Mc-Cathepsin D mRNA was up-regulated in gills and hemocytes. Present study indicates that Mc-Cathepsin D is constitutively expressed in different tissues and potentially inducible when infecting BRD by V. tapetis. It is further suggesting that Mc-Cathepsin D may be involved in multiple role including immune response reactions against BRD.

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.431-432
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• 2006

• Proceedings of the Malacological Society of Korea Conference
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• 2005.07a
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• pp.16-16
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• 2005

• The Korean Journal of Malacology
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• v.31 no.2
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• pp.123-127
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• 2015

${\beta}$-Glucan is a polysaccharide that is widely used as an adductive in fish feed to facilitate immune stimulation. This study aimed to investigate the effect of ${\beta}$-glucan on immune responses in the Manila clam Ruditapes philippinarum. For this purpose, three groups of R. philippinarum were exposed to 0%, 0.1%, or 1% ${\beta}$-glucan in sea water for 1 hr/day for 2 weeks using an immersion method. Thereafter, two immune parameters-phagocytic rate and antibacterial activity-were measured. R. philippinarum exposed to 1% ${\beta}$-glucan showed an approximate 30% significant increase in phagocytic rate. In addition, ${\beta}$-glucan significantly limited the growth of the pathogenic bacteria Vibrio tapetis, V. parahaemolyticus, and V. ordalii. Moreover, the mortality rates of ${\beta}$-glucan-treated clams decreased during a 17-day experiment. Our study suggests that treatment with ${\beta}$-glucan significantly increases the immune responses in R. philippinarum, and that immersion is a simple and effective method for immune stimulation in this species.