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NO51 - 1

Vibrio harveyi Infection in Farmed Greater Amberjack Seriola dumerili

Takayuki Minami1*, Kazuo Iwata1, Yoshiko Shimahara2 and Kei Yuasa2

1Miyazaki Prefectural Fisheries Research Institute, Miyazaki 889-2162, Japan
2Diagnosis and Training Center for Fish Disease, National Research Institute of Aquaculture, Fisheries Research Agency, Mie 516-0193, Japan

ABSTRACT―Mortalities accompanied with symptoms similar to vibriosis were observed in farmed greater amberjack Seriola dumerili immunized with a commercial Vibrio anguillarum vaccine (serotype J-O-3). The symptoms of infection included exfoliation of the head epithelium, ragged caudal fin, accumulated ascites, and ophthalmitis. Bacteria isolated from infected fish were positive in species-specific PCR assays for V. harveyi. A phylogenic analysis based on topA (DNA topoisomerase I) and mreB (rod shape-determining protein mreB) concatenated gene sequence provided further confirmation of the isolated bacteria as V. harveyi. Experimental infection revealed that the isolate was pathogenic to greater amberjack. In a vaccine trial, mortality of fish immunized with formalin-killed cells (FKC) of the isolate was significantly lower than that of control fish, suggesting that FKC of the isolate prevents greater amberjack from V. harveyi infection.

Key words: Seriola dumerili, amberjack, Vibrio harveyi, vibriosis, vaccine

Histopathological Features of Cysts in Wild Medaka Fish

Toshiyuki Nishimaki1, Takafumi Katsumura1, Shoji Oda2*,
Atsunori Oga3, Motoyuki Ogawa1 and Hiroki Oota1

1Department of Anatomy, Kitasato University School of Medicine, Kanagawa 252-0374, Japan
2Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8562, Japan
3Department of Pathology, Yamaguchi University Graduate School of Medicine, Yamaguchi 755-8505, Japan

ABSTRACT―Pathogenic studies using model animals for diseases that are found in similar diagnosis as in humans are widespreading and medaka fish Oryzias latipes is one of such animal models, however, histological studies on their diseases are still limited. In this study, we applied whole body serial tissue sectioning to adult medaka; it is similar to whole body computed tomography (CT) scanning to decide the lesion (s) location, furthermore, it can give us more precisely microscopic histological information. When adult medaka collected from a wild population were examined, we found cystic lesion (s) in their testis with a diameter of about 500 μm, filled with serous material. Because each of cysts was covered with epithelium, the lesion was found to be a true cyst. Cysts with the same histological appearance were also found adjacent to ovary and liver, and some of the medaka showed polycystic condition. This condition was seen at a high frequency in wild medaka, but it had not been found in laboratory-reared medaka. Although number of observations is small for giving conclusion, these results suggest that cysts could be a common lesion in wild medaka and whole body sectioning can be a powerful methodology for pathological examination of model animal like medaka.

Key words: Cyst, medaka, whole body serial tissue section, polycystic kidney disease

Generation and Application of Monoclonal Antibodies Specific for the Envelope Protein pORF132 of Cyprinid Herpesvirus 3

Zhenxing Liu*, Le Hao, Yanping Ma, Zhiling Liang, Jiangyao Ma and Hao Ke*

Institute of Animal Heath, Guangdong Academy of Agricultural Sciences, Guangdong Open Laboratory of Veterinary Public Health, Guangdong Provincial Key Laboratory of Livestock Disease Prevention, Guangzhou 510640, China

ABSTRACT―Cyprinid herpesvirus 3 (CyHV-3), also named koi herpesvirus (KHV), is a lethal pathogen of koi and common carp Cyprinus carpio. In the present study, we described a procedure to generate monoclonal antibodies (mAbs) against the envelope protein pORF132 of CyHV-3 and application of the mAb. Three recombinant plasmids targeting the expression of one complete pORF132 and two truncated pORF132 were constructed, respectively. After induction, a truncated pORF132 was successfully expressed in a soluble form and the purified recombinant protein was used in the preparation of mAbs. Two hybridoma cell clones, 4E11 and 4B11, were obtained and mAb 4E11 reacted to CyHV-3 infected cells and not to CyHV-2 (goldfish hematopoietic necrosis virus) and IcHV-1 (channel catfish virus) infected cells. An antigen-capture ELISA based on the pair of mAb 4E11 and anti-CyHV-3 IgY was primarily constructed. This antigen-capture ELISA could distinguish between the CyHV-3 infected and uninfected fish samples.

Key words: cyprinid herpesvirus 3, KHV, monoclonal antibody, ORF132, ELISA, prokaryotic expression

Efficacy of Sand Filtration and Ultraviolet Irradiation as Seawater Treatment to Prevent Kudoa septempunctata (Myxozoa: Multivalvulida) Infection in Olive Flounder Paralichthys olivaceus

Toyohiro Nishioka1, Jun Satoh1, Tohru Mekata1, Koh-ichiro Mori2, Kengo Ohta3, Taizo Morioka4, Meibi Lu5, Hiroshi Yokoyama5* and Tomoyoshi Yoshinaga5

1Kamiura Laboratory, National Research Institute of Aquaculture, Oita 879-2602, Japan
2National Research Institute of Aquaculture, Mie 516-0193, Japan
3Hakatajima Laboratory, National Research Institute of Fisheries and Environment of Inland Sea, Ehime 794-2305, Japan
4Amami Laboratory, Research Center for Tuna Aquaculture, Seikai National Fisheries Research Institute, Kagoshima 894-2414, Japan
5Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan

ABSTRACTKudoa septempunctata infecting the muscle of the olive flounder Paralichthys olivaceus has been recently demonstrated to cause food poisoning in humans who eat the raw flesh of flounder. In the present study, we assessed the effective treatments of a water supply to prevent K. septempunctata infection in a flounder hatchery where the parasite was enzootic. The prevalence of infection in a positive control fish group exposed to unfiltered seawater was 33% at 3 months post-exposure, whereas no infection was observed in the treated fish groups exposed to sand-filtered seawater, sand- and cartridge (5 μm)-filtered seawater or sand-filtered seawater followed by ultraviolet (UV) irradiation at a dose of 46 mJ/cm2. Additionally, treatment with UV irradiation alone was effective for the prevention of K. septempunctata infection. To ensure complete protection from K. septempunctata infection, we recommend double treatments of a water supply with sand filtration and UV irradiation in olive flounder hatcheries.

Key words: Kudoa septempunctata, Paralichthys olivaceus, olive flounder, food poisoning, ultraviolet irradiation, sand filtration

First Detection of Cyprinid Herpesvirus 3 in Cultured Common Carp in Vietnam

Richard Mayrhofer1, Johannes Pucher2, Mona Saleh1, Simon Menanteau-Ledouble1, Sven Bergmann3, Ulfert Focken4 and Mansour El-Matbouli1*

1Clinical Division of Fish Medicine, University of Veterinary Medicine, 1210 Vienna, Austria
2Life Science Centre, University of Hohenheim, 70599 Stuttgart, Germany
3Friedrich-Loeffler-Institute, 17493 Greifswald-Insel Riems, Germany
4Thünen-Institute of Fisheries Ecology, 22926 Ahrensburg, Germany

ABSTRACT―Cyprinid herpesvirus 3 (CyHV-3) is the causative agent of koi herpesvirus disease and poses a significant threat to common and koi carp. Since its first description, the virus has spread worldwide. In 2010 and 2011, mass mortality of common carp was reported in a hatchery and several ponds in northern Vietnam. CyHV-3 was detected in infected tissues by PCR, confirmed by sequencing of the thymidine kinase gene. Duplex PCR demonstrated that the virus belonged to the genetic lineage (I++/II--) previously described in Indonesia. This suggests CyHV-3 as the causative agent of the disease outbreak and constitute the first report of CyHV-3 in Vietnam.

Key words: Cyprinid herpesvirus 3, outbreak, Vietnam, first detection, genetic lineage

Passive Immunization against Red Sea Bream Iridoviral Disease in Five Marine Fish Species

Tomomasa Matsuyama1*, Takayuki Minami2, Yutaka Fukuda3, Natsumi Sano1, Takamitsu Sakai1, Tomokazu Takano1 and Chihaya Nakayasu1

1National Research Institute of Aquaculture, Fisheries Research Agency, Mie 516-0193, Japan
2Miyazaki Prefectural Fisheries Research Institute, Miyazaki 889-2162, Japan
3Fisheries Research Division, Oita Prefectural Agriculture, Forestry and Fisheries Research Center, Oita 879-2602, Japan

ABSTRACT―Passive immunization was performed to determine whether serum antibodies were involved in protection for red sea bream iridoviral disease (RSIVD) in Pagrus major, Seriola quinqueradiata, S. lalandi, S. dumerili and Oplegnathus fasciatus. When fish were experimentally challenged, significantly lower mortality was noted in the fish received the convalescent serum than control fish, except for O. fasciatus. The administration of serum from fish immunized with a commercial vaccine, significantly suppressed mortality of the recipient, except for S. lalandi and O. fasciatus. The results suggest that serum antibodies play a primary role in the protection against RSIVD in red sea bream and the genus Seriola.

Key words: red sea bream iridovirus, passive immunization, antibody