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In the present study, Pseudocohnilembus persalinus was first reported as a species causing scuticociliatosis in olive flounder Paralichthys olivaceus. Based on the stained specimens, P. persalinus was clearly differentiated from Uronema marinum, which has been shown to be a cause of scuticociliatosis in farmed olive flounder in Korea from its characteristic oral infraciliature structure. The 1754 bp small subunit ribosomal RNA (SS rRNA) gene sequence of P. persalinus showed 95% homology with the partial sequence of P. hargisi SS rRNA. Moreover, multiplex PCR based on the species-specific amplification of the SS rRNA gene sequence enabled us to distinguish P. persalinus from U. marinum in a simple and rapid manner. P. persalinus was clearly differentiated from U. marinum even when the host was infected simultaneously with both species. These data suggest that the multiplex PCR procedure would make it possible to avoid the cumbersome and time-consuming procedures of morphological analysis for the definitive identification of ciliates.

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In immunization of fish with polyinosinic-polycytidylic acid (poly[I:C], a synthetic double-stranded RNA), injection of Poly(I:C) followed by challenge with a live virus induces a transient, non-specific antiviral state by interferon activity. When exposed to a virus while in this antiviral state, the fish acquire a specific and protective immunity against the corresponding viral disease and survive. In the present study, the effiacy of Poly(I:C) immunization was investigated in japanese flounder Paralichthys olivaceus using viral hemorrhagic septicemia virus (VHSV) as a model; the minimum dose of Poly(I:C) required for inducing protection and the duration of the antiviral state were determined, and a potentially curative effect of Poly(I:C) administration was assessed. The antiviral state was induced by administration of Poly(I:C) doses ranging from 12.5 to 200 µg fish(-1). Minimum dose to induce the antiviral state (relative percentage survival, RPS: 90%) was 12.5 µg fish(-1). No curative effect of Poly(I:C) was observed in fish pre-infected with VHSV. Fish injected with 200 µg Poly(I:C) fish(-1) were highly protected (RPS: 100%) from an artificial challenge with VHSV, and specific antibodies against VHSV were detected. The corresponding high level of antiviral state against VHSV was attained 1 d post Poly(I:C) injection, lasted for 6 d and susequently decreased. Moreover, the surviving fish were highly protected from re-challenge with VHSV (RPS: 100%). Thus, it was considered that an immunity against viral hemorrhagic septicemia was induced in the Japanese flounder by injecting live VHSV following Poly(I:C) administration

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The effect of cimetidine on the treatment efficacy of praziquantel against Microcotyle sebastis infestation in cultured rockfish Sebastes schlegeli was investigated. Juvenile rockfish were divided into 7 groups, and orally administered praziquantel alone (50, 100 and 200 mg kg -1 body wt, BW) or in combination with cimetidine at a dose of 200 mg kg -1 BW for each praziquantel dose. The fish in the control group were administered only saline. The results clearly showed that coadministration of cimetidine with praziquantel led to a significantly increased treatment efficacy of the latter drug, and consequently would lead to a lowering of the total dose of praziquantel, and a reduction in the administration times and costs for the treatment of M. sebastis infestation in cultured rockfish. KEY WORDS: Praziquantel · Cimetidine · Microcotyle sebastis · Sebastes schlegeli · Treatment efficacy Resale or republication not permitted without written consent of the publisherDis Aquat Org 44: [133][134][135][136] 2001 scribed an increase in praziquantel levels in plasma of mammals when cimetidine is simultaneously administered (Dachman et al. 1994, Ebeid et al. 1994, Metwally et al. 1995, Jung et al. 1997.In the present study, we investigated the treatment efficacy of praziquantel against Microcotyle sebastis infestation in cultured rockfish when administered simultaneously with cimetidine. MATERIALS AND METHODSFish. Netpen-reared juvenile rockfish Sebastes schlegeli (body length: 13 to 16 cm) were obtained from a local rockfish farm in Tongyoung, Korea. The presence of Microcotyle sebastis on the gills was confirmed by examination of 10 fish. After 1 wk acclimation, a total of 70 fish was randomly divided into 7 groups of 10 fish in each group. The volume of each experimental aquarium was 50 l, the water temperature was 20 ± 1°C, and salinity was 33 ‰. Fish were not fed throughout the experiment.Treatment regime. Fish were anaesthetized with MS222 (Sigma) and were intubated directly onto the stomach with varying concentrations of praziquantel and cimetidine. The first group was given 200 mg praziquantel (Shinpoong Pharm. Co. Ltd.) kg -1 BW, the second group 100 mg praziquantel kg -1 BW, and the third group 50 mg praziquantel kg -1 BW. The fourth group was coadministered 200 mg praziquantel and 200 mg cimetidine kg -1 BW, the fifth group 100 mg praziquantel and 200 mg cimetidine kg -1 BW, and the sixth group 50 mg praziquantel and 200 mg cimetidine kg -1 BW. The fish in the seventh group (control group) were given 0.7% saline. At 84 h post-treatment, the gills of all fish in each group were examined to confirm the effectiveness of each treatment. Abundance and prevalence were determined according to the methods given in Margolis et al. (1982).Statistical analysis. All data were analyzed using Mann-Whitney's U-test (SPSS for Windows, SPSS Inc.). RESULTSPrevalence and intensity of Microcotyle sebastis in the fish sampled randomly before the start of the treatments were 100% and 21.9 ± 16.8 (mean ± SD), respective...