Now showing items 1-4 of 4

    • Article

      The effects of iron compounds on the virulence of Vibrio anguillarum in Japanese eels and ayu 

      T Nakai, T Kanno, ER Cruz & K Muroga - Fish Pathology, 1987 - Japanese Society of Fish Pathology
      When Japanese eels (Anguilla japonica) were injected intramuscularly (IM) with ferric ammonium citrate (FAC) at a sublethal dose of 10 µg/g and followed by IM-injection with various doses of Vibrio anguillarum, FAC injection enhanced greatly the virulence of the pathogen to eels, lowering the LD50 value from 107.9 to 104.2 CFU/100 g. Similar effects were obtained with ferrous sulfate and ferric chloride in eels. However, such a virulence-enhancing effect of FAC was scarcely observed in ayu (Plecoglossus altivelis), which has high susceptibility to the pathogen by nature. It was also found that addition of FAC (10 µg/ml) in fish sera accelerated the bacterial growth in vitro but the effect was much greater in eel serum than in ayu serum. The results of these in vivo and in vitro experiments demonstrated that the availability of free iron in host fish would have a significant influence on the pathogenesis of V. anguillarum infection.
    • Article

      The effects of Vibrio anguillarum extracellular products on Japanese eels 

      MC de la Cruz & K Muroga - Aquaculture, 1989 - Elsevier
      To test the effect of Vibrio anguillarum extracellular products (ECP) on Japanese eels (Anguilla japonica ), test fish were injected intramuscularly with ECP at a dose of 1 mg protein/100 g body weight of fish.At 3,6,12,24 and 36 h post-injection, blood samples were collected for haematocrit, haemoglobin, and serum protein determinations and tissues were fixed in Bouin's solution. Histopathological observations 24 h post-injection revealed that the ECP caused severe damage to muscle tissue, characterized by extensive muscle liquefaction and haemorrhaging. In addition, extensive haemosiderin deposits were observed in the spleen, with lesser deposits occurring in the kidney and liver. Haematocrit, haemoglobin, and serum protein values were lower in ECP-treated fish than in the untreated controls.
    • Article

      Enhancing nonspecific immune response of grouper, Epinephelus coioides using levamizole as immunostimulant 

      SA Pedrajas-Mendoza, JL Torres & E Amar - UPV Journal of Natural Science, 2008 - University of the Philippines in the Visayas
      The use of levamisole as an alternative approach to disease prevention and control has been resorted to in aquaculture. Its immunomodulatory effect in several fish species is well documented but its effect on grouper, Epinephelus coioides requires further investigation. To determine its immunomodulatory effect on grouper, juveniles were injected and fed with levamisole. Intraperitoneal injection (IP) at 0 (control), 0.5, 5, 10, 20 and 50 mg levamisole/kg body weight was administered. Grouper were also fed diets containing 0 (control), 125, 250 and 500 mg levamisole/kg supplemental dry diet for 10 days. Hematocrit levels, total and differential leucocyte counts and bactericidal activity were examined 7 days post IP. Three, 5 and 7 weeks after last administration of supplemented feeds, growth and bactericidal activity werie checked. A significant (P<0.05) increase in the total leucocyte count was noted in the injection-treated fish. Granulocyte (19.39%) and monocyte (27.38%) percentages increased while lymphocyte(53.40%) population decreased in the differential leucocyte count. However, hematocrit levels were not affected by levamisole. Bactericidal activity against Vibrio anguillarum increased in treated (injected and supplemented) fish. A significant (P<0.05) increase in weight of juvenileswas observed 10 days after last feeding with supplemented diet. Groupers injected with 0.5 mg levamisole/kg body weight and those supplemented with 125 mg levamisole/kg dry diet exhibited the most significant (P<0.05) changes in parameters tested indicating immunostimulation. Growth (weight gain) and bactericidal activity peaked 5 weeks post administration of levamisole in the feeding experiment. Results of the present study strongly suggest that levamisole can enhance nonspecific defenses in grouper and opens the possibility of using immunostimulants in grouper culture.
    • Article

      Fate and location of Vibrio anguillarum in tissues of artificially infected ayu (Plecoglossus altivelis) 

      K Muroga & MC de La Cruz - Fish Pathology, 1987 - Japanese Society of Fish Pathology
      Ayu (Plecoglossus altivelis) were infected with Vibrio anguillarum by a water-born method. At 6, 12, 18, 36, 38-45 (moribund stage) and 48 h (dead) after infection, fish were sampled to determine the fate and location of the bacterium in various tissues by viable cell count and the enzyme-labeled antibody technique (ELAT). V. anguillarum was first detected in the skin at 12 h by bacterial isolation. It appeared in the muscle, spleen and liver at 24 h, but was not isolated from the gills or intestine until 36 h or 38-45 h. The same trend in the fate of the pathogen was confirmed by ELAT, and the cells were found in dermal layer of the skin from the early stage (12h) of infection. Based on these observations it was concluded that the first colonization site of V. anguillarum in ayu was the skin.