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NO44 - 2

Shrimp White Spot Syndrome ・from Pathology to Pathogenomics

<>Kuan Fu Liu1,2, Wang-Jing Liu1, Guang-Hsiung Kou1 and Chu-Fang Lo1*<>1Institute of Zoology, National Taiwan University, Taipei 106, Taiwan, ROC
2Tungkang Marine Laboratory, Taiwan Fisheries Research Institute, Tungkang, Taiwan, ROC

ABSTRACT友or shrimp with low-level white spot syndrome virus (WSSV, = PRDV) infection, environmental or physiological stresses can trigger replication of the virus and lead to a full-blown outbreak of white spot disease. This review will describe how pathogenomic studies have revealed some of the mechanisms that underlie this aspect of WSSV pathology. In the model that emerges, stressors activate shrimp STAT (signal transducer and activator of transcription), which is then annexed by the virus and used to activate the promoter of the immediate early gene WSSV ie1. This in turn leads to rapid replication of the virus.

Key words: white spot syndrome, penaeid acute viremia, pathogenomics, shrimp STAT, WSSV ie1 gene, WSSV, PRDV

Molecular Epidemiology of Koi Herpesvirus

<>Jun Kurita1*, Kei Yuasa2, Takafumi Ito1, Motohiko Sano2, Ronald P. Hedrick3,Marc Y. Engelsma4, Olga L. M. Haenen4, Agus Sunarto5, Edy Barkat Kholidin6,Hsin-Yiu Chou7, Ming-Chen Tung8, Leobert de la Pe9, Gilda Lio-Po9,Chien Tu10, Keith Way11 and Takaji Iida2<>1Tamaki Station, National Research Institute of Aquaculture, Fisheries Research Agency, Mie 519-0423, Japan
2Nansei Station, National Research Institute of Aquaculture, Fisheries Research Agency, Mie 516-0193, Japan
3Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616, USA
4CIDC-Lelystad, Wageningen UR, Fish and Shellfish Diseases Laboratory, P.O. Box 2004, 8203 AA Lelystad, the Netherlands
5Fish Health Research Laboratory, Agency for Marine and Fisheries Research, Jakarta, Indonesia
6Jambi Freshwater Aquaculture Development Center; Sungai Gelam, Kumpeh Ulu, Muara Jambi, Indonesia
7Department of Aquaculture, National Taiwan Ocean University, Taiwan, Republic of China
8Department of Veterinary Medicine, National Pingtung University of Science & Technology, Taiwan, Republic of China
9Fish Health Section, Southeast Asian Fisheries Development Center Aquaculture Department (SEAFDEC/AQD), Tigbauan, Iloilo 5021, Philippines
10Fish Health Laboratory, Animal Health Research Institute, 376 Chung-Cheng Rd Tanshui, 251, Taiwan, Republic of China
11Centre for Environment Fisheries and Aquaculture Science (Cefas), Weymouth, Dorset DT4 8UB, UK

(Received March 12, 2008)

ABSTRACT裕hree regions of koi herpesvirus (KHV) genomic DNA were compared for 34 samples from Japan, six from Indonesia, two from Taiwan, one from the Philippines, 13 from the Netherlands, one from the UK, one from the USA and one from Israel. The analyzed genomic regions included known PCR-detection targets (SphI-5, 9/5 and the thymidine kinase gene). The KHVs from Asian countries were very homogeneous, although two variants were noted based on a single nucleotide polymorphism. In contrast, seven variants were found in KHVs from outside of Asia, and although closely related to one another, they were clearly distinct from those from Asian. The results suggest that a clear genetic distinction exists between Asian and European (including each single isolate from the USA and Israel) types of KHV, and that unique types of KHV were independently introduced or emerged in the respective geographic locations.

Key words: koi herpesvirus, KHV, Cyprinid herpesvirus-3, CyHV-3, molecular epidemiology, fish herpesvirus, Cyprinus carpio

Field Trials of Febantel against Gill Fluke Disease Caused by the Monogenean Heterobothrium okamotoi in Cultured Tiger Puffer Takifugu rubripes

<>Takeshi Kimura1*, Yoshinori Nomura2, Hidemasa Kawakami3, Tomokazu Itano3 Masahiko Iwasaki4, Jun Morita5 and Jungo Enomoto6<>1Kumamoto Prefectural Fisheries Development Division, Kumamoto 862-8570, Japan
2Kumamoto Prefectural Fisheries Research Center, Kumamoto 869-3603, Japan
3Ehime Prefectural Fish Disease Control Center, Ehime 798-0087, Japan
4Amakusa Fisheries Research Center, Kumamoto 866-0325, Japan
5Animal Health Dept. Research and Development, Agricultural and Veterinary Division, Meiji Seika Kaisha, Ltd., Tokyo 104-8002, Japan
6Animal Health Dept. Agricultural and Veterinary Research, Meiji Seika Kaisha, Ltd., Kanagawa 222-8567, Japan

(Received June 30, 2008)

ABSTRACT邑e conducted six field trials on the efficacy of febantel against the monogenean Heterobothrium okamotoi infecting cultured tiger puffer Takifugu rubripes at four sites in Kumamoto and Ehime, Japan. From 2,500 to 4,500 one-year-old tiger puffers per experiment group were used in these trials, in which tiger puffer were orally administrated febantel at 12.5 or 25 mg/kg fish/day for 5 days. The maximum rate of worm eradication was 80.9%. However, a large difference was observed in the eradication rate between the experiment groups. We observed no adverse effect of febantel such as decreased appetite or increased mortality on the experimental fish.

Key words: febantel, Heterobothrium okamotoi, Takifugu rubripes, tiger puffer, clinical trial

Morphological and Molecular Comparisons of Myxobolus spp. in the Nerve Tissues of Salmonid Fishes with the Description of Myxobolus murakamii n. sp., the Causative Agent of Myxosporean Sleeping Disease

<>Shigehiko Urawa1,2*, Yoshisuke Iida3, Mark A. Freeman4, Tetsuya Yanagida5, Egil Karlsbakk6 and Hiroshi Yokoyama7<>1Research Division, National Salmon Resources Center, Fisheries Research Agency, Hokkaido 062-0922, Japan
2North Pacific Anadromous Fish Commission, 502-889 West Pender Street, Vancouver, BC, V6C 3B2, Canada
3Fisheries and Marine Technology Center, Hiroshima Prefectural Technology Research Institute, Hiroshima 737-1207, Japan
4Institute of Biological Sciences, University of Malaya, Kuala Lumpur 50603, Malaysia
5Department of Parasitology, Asahikawa Medical College, Hokkaido 078-8510, Japan
6Department of Biology, University of Bergen, 5020 Bergen, Norway
7Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan

(Received December 11, 2008)

ABSTRACT柚yxosporean sleeping disease is known to cause severe mortality of masu salmon Oncorhynchus masou masou and amago salmon O. masou ishikawae farmed in Hiroshima, western Japan. Diseased fish become unable to swim, and shortly afterwards die on the bottom of the pond. The causative agent is Myxobolus sp. which infects the peripheral nerves of salmon, but its definitive identity and taxonomic status have been unresolved for years. We investigated interspecific relationships among Myxobolus spp. infecting the nerve tissues of salmonid fishes from Japan, Europe and North America. Our morphological comparisons revealed that myxospores varied in spore shape, and separated into two types: spherical (typically M. neurobius, M. kisutchi and M. neurotropus) or pyriform (typically M. arcticus and M. fryeri). Molecular analysis based on small subunit ribosomal DNA (SSU rDNA) demonstrated that Myxobolus sp. from the lateral line nerve of amago salmon with sleeping disease in Hiroshima was genetically distinct from other myxosporean species, but had 99.5% sequence similarity to Myxobolus sp. from the lateral line nerve of subclinical masu salmon in the Mena River, Hokkaido. Both myxosporeans had similar spherical-type spores. Consequently, Myxobolus sp. from the lateral line nerve of both amago and masu salmon in Hiroshima and Hokkaido are considered to be a new species, and described as M. murakamii n. sp.

Key words: Myxozoa, new species, Myxobolus murakamii, myxosporean sleeping disease, Oncorhynchus masou, peripheral nerve

Pathogenicity of Anamorphic Fungi Plectosporium oratosquillae and Acremonium sp. to Mantis Shrimp Oratosquilla oratoria

<>Pham Minh Duc1,2 and Kishio Hatai1*<>1Laboratory of Fish Diseases, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
2College of Aquaculture and Fisheries, Cantho University, Can Tho City, Viet Nam

(Received December 29, 2008)

ABSTRACT裕his study was carried out to determine pathogenicity of anamorphic fungi Plectosporium oratosquillae NJM 0662 and Acremonium sp. NJM 0672, which were isolated from gills of mantis shrimp Oratosquilla oratoria caught in Yamaguchi and Aichi Prefectures in Japan. Cumulative mortality of the mantis shrimp injected with a high dose (5.0 × 106 conidia/mL) and a low dose (5.0 × 104 conidia/mL) of the isolate NJM 0662 reached 100% and 60% at day 25, respectively. Cumulative mortality of the shrimp injected with the high dose and the low dose of the isolate NJM 0672 reached 100% and 80% at day 25, respectively. The gill lesions in the shrimp experimentally infected with the fungi were similar to those of naturally infected shrimp. Histopathologically, the hyphae and conidia were found in the gill filaments and heart, and the hyphae were encapsulated by hemocytes in the gill filaments and the base of gills. The result confirmed that these two anamorphic fungi were pathogenic to mantis shrimp.

Key words: Acremonium sp., Plectosporium oratosquillae, Oratosquilla oratoria, mantis shrimp, pathogenicity

Persistent Expression of Shrimp-virus Antigens in Two Insect Cell Lines Challenged with Two Shrimp Viruses

<>Anuwat Sriton1,2, Nipaporn Kanthong3, Warachin Gangnonngiw2,4, Siriporn Sriurairatana2, Sukathida Ubol1 and Timothy W. Flegel2,4,5*<>1Dept. Microbiology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
2Centex Shrimp, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
3Dept. Biotechnology, Faculty of Science and Technology, Rajamangala University of Technology Tawan-ok, Sriracha, Chonburi 20210, Thailand
4National Center for Genetic Engineering and Biotechnology (BIOTEC),
National Science and Technology Development Agency
Klong 1, Klong Luang, Pratum Thani 12120, Thailand
5Dept. Biotechnology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand

(Received March 12, 2009)

ABSTRACT勇xperiments with crustacean viruses are hampered by lack of susceptible continuous cell lines. To overcome this problem, immortal mosquito and lepidopteran cell lines were both separately challenged with a shrimp DNA virus (white spot syndrome virus: WSSV, = PRDV) and RNA virus (yellow head virus: YHV) followed by serial, split-passage with immunohistochemical monitoring by confocal laser microscopy using labeled monoclonal antibodies to shrimp viral antigens. Stable, immortal cultures with 100% of the cells expressing shrimp-virus antigens were obtained, although the infected cells appeared grossly normal by phase contrast microscopy. Nor did they show any ultrastructural modifications characteristic of the challenge viruses. These persistently-expressing insect cell cultures were stable and could be continuously passaged, stored and revived as required. Since disparate viruses and insect cells were used, this appears to be a generic process that may be applicable to other shrimp viruses as well.

Key words: shrimp, virus, insect cell line, WSSV, YHV, PRDV

The Expression Analysis of Innate Immune-related Genes in Kuruma Shrimp Penaeus japonicus after DNA Vaccination against Penaeid Rod-shaped DNA Virus

<>Tomoya Kono1, Kohei Sonoda1, Yoichi Kitao1, Tohru Mekata2, Toshiaki Itami1 and Masahiro Sakai1*<>1Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan
2Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki, Miyazaki 889-2192, Japan

(Received July 11, 2008)

ABSTRACT悠n this study, we have developed a DNA vaccine encoding viral envelope protein VP28 of penaeid rod-shaped DNA virus (PRDV, = WSSV). Protective efficacy of the DNA vaccine against PRDV was confirmed at 7 days post vaccination in kuruma shrimp Penaeus japonicus. The VP28 transcript derived from the vaccine was detected in various tissues at 1, 3 and 7 days post vaccination. Moreover, notable up-regulated expression of Rab7, penaeidin, lysozyme and crustin genes was observed upon DNA vaccination. These results suggest that the DNA vaccine significantly increased the protection and innate immune responses in kuruma shrimp against PRDV.

Key words: DNA vaccine, Penaeus japonicus, VP28, PRDV, WSSV, innate immune-related genes