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NO49 - 2

Rapid and Simple Detection Method of "Candidatus Xenohaliotis californiensis" Using Fecal PCR in Abalone Haliotis discus discus and H. gigantea

Ikunari Kiryu1*, Toyohiro Nishioka1**, Kei Yuasa1, Jun Kurita1, Yoshiko Shimahara1, Mitsuru Ototake1***, Naoya Ikegami2 and Norihisa Oseko1****
1National Research Institute of Aquaculture, Fisheries Research Agency, Mie 516-0193, Japan
2Chiba Prefectural Fisheries Research Center, Chiba 295-0024, Japan

(Received November 1, 2013)

ABSTRACT―We developed a simple PCR-based method using feces to detect "Candidatus Xenohaliotis californiensis" (Rickettsia-like organism, RLO), which is responsible for withering syndrome (WS). Four abalone groups (Haliotis discus discus and H. gigantea) naturally or artificially infected with WS-RLO were prepared. After daily collection of the feces from individual animals over a seven-day period, the posterior esophagus (PE) was excised, and subjected to PCR for WS-RLO. WS-RLO-positive results were obtained from the feces of 30-67% animals, and from the PE of 17-97% animals. For the fecal PCR, more than one animal was positive from each group every day, although the WS-RLO-positive rate daily varied. When the sensitivity of the PCR was compared between DNA extracted from feces by boiling and that by QIAamp® DNA Stool Kit, there was no difference between the two methods. Fecal PCR combined with boiling DNA extraction is rapid and simple for screening abalone groups infected with WS-RLO.
Key words: withering syndrome, Candidatus Xenohaliotis californiensis, abalone, feces, boiling extraction, fecal PCR, screening

Mortality of Wild Three-lips Opsariichthys uncirostris by Infection with Chilodonella hexasticha

Takashi Okamura1*, Kunihiko Kuwamura1 and Kazuo Ogawa2
1Shiga Prefectural Fishery Experiment Station, Shiga 522-0057, Japan
2Meguro Parasitological Museum, Tokyo 153-0064, Japan

(Received January 7, 2014)

ABSTRACT―Mortalities of three-lips Opsariichthys uncirostris occurred in a river in Shiga Prefecture, Japan, during the summer of 2013. The gills of diseased fish were heavily infected with the parasitic ciliate Chilodonella hexasticha. The intensity of parasite was 0.73-1.15 millions in dead fish, and 0.45-0.52 millions in apparently healthy fish. The cause of fish death may be a respiratory dysfunction by congestion due to the heavy infection with C. hexasticha on the gills. This is the first report of C. hexasticha infection of wild fish in Japan.
Key words: Chilodonella hexasticha, Opsariichthys uncirostris, mortality, parasite, ciliate

Outbreak of Viral Nervous Necrosis in Endangered Fish species Epinephelus costae and E. marginatus in Northern Tunisian Coasts

Sondès Haddad-Boubaker1*, Wassim Boughdir2, Soufien Sghaier1, Jamila Ben Souissi2, Aida Megdich1, Raouf Dhaouadi3, Abdelkader Amara3, Valentina Panzarin4 and Emna Fakhfakh1
1Laboratory of Virology, Veterinary Research Institute of Tunisia, 1006 Tunis, Tunisia
2National Agronomic Institute of Tunisia, 1002 Tunis, Tunisia
3Laboratory of Aquaculture, Marine Biology and Fish pathology, National School of Veterinary Medicine, 2020 Sidi Thabet, Tunisia
4Research & Innovation Department, Istituto Zooprofilattico Sperimentale delle Venezie, viale dell'Università 10, 35020 Legnaro (PD), Italy

(Received January 9, 2014)

ABSTRACT―In this study, we report outbreak of viral nervous necrosis (VNN) in wild Epinephelus species, which are of an endangered fish group, in different Tunisian coastal areas in 2012. Seven fish of E. marginatus and E. costae caught at dead or moribund condition were investigated. Betanodavirus was detected in the brain and retinal tissues of all fish by RT-PCR and at high infective titers (106.0-8.8 TCID50/g) in five of seven fish. Sequence and phylogenic analyses of the viral genes revealed that the viruses belonged to RGNNV genotype and were closely related to some previously reported Mediterranean betanodavirus strains, suggesting virus exchanges among different fish populations in the Mediterranean Sea.
Key words: betanodaviruses, disease outbreak, Epinephelus spp., phylogeny, RGNNV

First Report of Enteromyxum leei (Myxozoa) in the Black Sea in a Potential Reservoir Host Chromis chromis

Ahmet Özer*, Türkay Öztürk, Hakan Özkan and Arzu Çam
Sinop University, Faculty of Fisheries and Aquatic Sciences, 57000 Sinop, Turkey

(Received January 25, 2014)

ABSTRACT―Damselfish Chromis chromis collected from the Black Sea coasts of Sinop, Turkey, were examined for myxosporeans in June and July 2013. One of 25 healthy fish and 2 dead fish had infections with Enteromyxum leei. Developing plasmodia and fully developed spores were numerously observed in the intestine and gall bladder of infected fish. This finding suggests that E. leei can develop normally in this fish species. Absence of fish farms close to the sampling site suggests that the parasite was not originated from farmed fish. This is the first report of E. leei in the Black Sea.

Key words: Enteromyxum leei, Chromis chromis, Black Sea, Turkey, reservoir host

Water Temperature Effect on Edwardsiella ictaluri Infection of Ayu Plecoglossus altivelis

akahiro Nagai1* and Toshihiro Nakai2
1Fisheries and Marine Technology Center, Hiroshima Prefectural Technology Research Institute, Hiroshima 737-1207, Japan
2Graduate School of Biosphere Science, Hiroshima University, Hiroshima 739-8528, Japan

(Received March 29, 2014)

ABSTRACT―Experimental infection of ayu Plecoglossus altivelis with Edwardsiella ictaluri PH-0744 was performed under two different water temperatures, 20°C and 28°C. The strain exhibited higher virulence at 28°C than at 20°C in intraperitoneal injection challenge, with the LD50 values being < 6.0 × 10 CFU/fish at 28°C and 7.4 × 103 CFU/fish at 20°C. In immersion challenge at a dose of 2.5 × 107 CFU/mL for 30 min, mortality of fish was 95% at 28°C and 0% at 20°C. This high virulence of E. ictaluri at 28°C may explain frequent occurrence of E. ictaluri infection of ayu at high water temperature in rivers.

Key words: Edwardsiella ictaluri, Plecoglossus altivelis, water temperature, virulence, ayu