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A few reports indicate the beneficial effects of organic acids and their salts on anti-infective immunity in fish species. In the role of immunostimulants, inorganic acids may prove to be a much cheaper alternative to their organic equivalents. However, no report has described the effect of using inorganic acid as a feed additive on fish immunity. This study is the first attempt to evaluate the effect of hydrochloric acid (HCl) as a fish feed supplement on cellular immunity in the stomachless fish, cypriniform vimba bream, Vimba vimba (L.). Two groups, three replicates each, of juvenile vimba were fed a commercial dry fish diet or its variant containing a 1.5% additive of HCl for 55 days. The experiment was conducted in a recirculating aquaculture system at 25°C. Mortality, growth, condition factor, feed conversion ratio, respiratory burst activity (RBA), potential killing activity (PKA), and the proliferative response of head kidney lymphocytes were determined for both groups at the end of the experiment and compared. The PKA was higher in the group fed the diet with HCl. For all other parameters studied, there were no significant differences between the experimental groups. The results of the current study prove that the dietary additive of inorganic hydrochloric acid can substantially improve immune response to bacterial infections in juvenile vimba bream.

Since 2007 in Poland, skin lesions have been observed in salmon (Salmo salar L.) and sea trout (Salmo trutta L.) entering Pomeranian rivers to spawn. The clinical picture of affected fish resembled ulcerative dermal necrosis (UDN), a disease of unknown etiology affecting mainly the scalps of wild salmonids. The aim of the 2009-2012 study was to determine with microbiological tests the etiological agent of the skin lesions observed in salmonids entering the Pomeranian rivers. During the study, a total of 13 species of Gram-negative bacteria belonging mainly to the Yersiniaceae, Enterobacteriaceae, and Pseudomonadaceae families were isolated and identified from the skin and kidneys of diseased fish. The Gram-positive bacteria isolated were aerobic, hemolytic granules of the genus Streptococcus. Mycological examinations on damaged fish body surfaces revealed yeasts of the genus Rhodotorula and fungi of the family Saprolegniaceae. The results of our study did not permit us to identify unequivocally the direct cause of the fish diseases analyzed since all the bacteria isolated during the study are normally found in aquatic environments. Some of the isolated bacteria identified were assumed to be potentially pathogenic to fish. The fungal infections observed were probably secondary and only exacerbated ongoing disease processes.

The experiment was set to determine the effects of long-term (55-day) use of three commercial prebiotics including Saccharomyces cerevisiae–derived β-glucans and one including inulin on juvenile vimba (Vimba vimba) reared intensively under controlled conditions.

Introduction: Immune-potentiating functions of Lactobacillus plantarum strains in the common carp were evaluated.

The presence of lactic acid bacteria (LAB) favors the stabilization of intestinal flora, facilitates digestion, improves the assimilability of fodder, and has an immunomodulatory effect on the immune system. According to current research, the application of LAB following antibiotic treatment prevents the development of opportunistic bacteria inhabiting the digestive tract. In the study the potential probiotic properties of Lactobacillus plantarum strains, which can be administered as an alternative to antibiotic treatment in aquaculture, were investigated under in vitro conditions. The strains of L. plantarum were characterized for important properties such as the ability to grow in the presence of 10% fish bile, a tolerance of low pH, and antagonism to pathogens dangerous for fish such as Aeromonas salmonicida and Pseudomonas fluorescens; therefore, they meeting the criteria for strains with probiotic properties. In view of currently increasing resistance to antibiotics and a decrease of their efficiency, probiotic bacteria can serve to support immunity to infections in the future.

Background: Betulin, a natural pentacyclic triterpene with the lupane structure that is present in significant amounts in the outer bark of birch, is known for its broad array of biological and pharmacological properties. Betulin has attracted attention as a potential, natural-origin antimicrobial substance. The literature describes it as selectively toxic to neoplastic cells but safe for normal cells. The research aim was to evaluate the basal cytotoxicity of betulin towards fish (BF-2) and murine (NIH/3T3) fibroblasts. We used four colorimetric tests that provide a preliminary evaluation of possible mechanisms of the cytotoxicity of a compound to assess the degree of the toxicity of betulin after 24, 48 and 72 h of incubation with cells: the MTT assay (mitochondrial activity assessment), the NRU assay (lysosomal membrane integrity assessment), the LDH assay (cellular membrane integrity assessment) and the SRB assay (total cellular protein content determination)., Results: The results revealed an exceptionally high sensitivity of mitochondria to the effect of betulin, with the other endpoints being less sensitive. Although murine fibroblasts were more vulnerable to the toxic effect of betulin than fish fibroblasts, the betulin CC 50 values for both cell lines were comparable with analogous IC 50 values determined by other researchers in studies involving cancerous cells., Conclusions: The results indicate the need to verify the claim about the selective toxicity of betulin towards malignant cells and to conduct safety/toxicity tests before any potential therapeutic use of betulin in veterinary medicine.

Bacterial diseases are a significant problem in the controlled rearing of fish. Furunculosis ( Aeromonas sp.), flavobacteriosis ( Flavobacterium sp.), and pseudomonadosis ( Pseudomonas sp.) are currently the most frequently identified diseases in recirculating aquaculture systems of various fish species. Such a situation is also observed in pikeperch rearing. Due to the emerging difficulties of effective prophylaxis using commercial vaccines, interest in the use of autovaccinations is increasing, not only in ichthyopathology but also in other veterinary fields. Our research aimed to assess the effect of the vaccination method on the overall condition of the fish and survival after the experimental infection with Aeromonas salmonicida . Pikeperch were vaccinated by (1) bath, (2) a single i.p. injection, or (3) feed. The fish were measured and weighed on day 0 and after 28 and 56 days of the experiment. Specific growth rate, daily growth rate, condition factor, and feed conversion ratio were calculated. On days 7, 14, 21, and 28 of the experiment, ceruloplasmin and lysozyme levels were rated. In addition, a challenge test was performed. The obtained results showed that the method of vaccination is important and affects the growth of fish, the overall condition of fish, and survival after experimental infection.

Background: The aim of the study has been to compare the effect of dietary supplementation of β-1,3/1,6-glucan, Lactobacillus plantarum bacteria or their mixture on the growth performance, selected parameters of the immune system as well as the liver and intestinal histology of roach. Fish were fed for 14 days with four different diets, each treatment being carried out in triplicate. In control group, fish were fed dry commercial starter feed Aller Performa 2 (Aller Aqua, Denmark). The other experimental fish groups received the same commercial starter feed supplemented with: 1% β-1,3/1,6-glucan (Leiber® Beta-S) in group G; 10 8  cfu L. plantarum g - 1 in group L; 1% β-1,3/1,6-glucan + 10 8  cfu L. plantarum g - 1 in group G + L. The stimulating effect of the tested preparations was evaluated once the feeding with commercial feed exclusively was resumed and 2 weeks afterwards., Results: No effect on the survivability and growth performance of the fish was observed in any of the groups. Supplementation of feed with β-1,3/1,6-glucan improved (P < 0.05) selected parameters of innate humoral immunity and the pinocytotic activity of phagocytes. Increased respiratory burst activity of head kidney phagocytes (RBA) was observed in groups L and G + L (P < 0.05), and the effect persisted for 2 weeks after the commercial feed regime was resumed. An analogous tendency was determined for the killing activity of phagocytes (PKA) of the head kidney with respect to Aeromonas hydrophila, although this effect appeared only during the feed supplementation period. Supplying roach with β-1,3/1,6-glucan, singly or with L. plantarum, had no effect (P > 0.05) on the proliferation of mitogen-activated lymphocytes. However, an increase in the number of CD3-positive cells and goblet cells was noticed in the digestive system of the L group fish (P < 0.05)., Conclusions: The results show that feeding fish with added L. plantarum and β-1,3/1,6-glucan stimulates the non-specific resistance mechanisms and raises the counts of intestinal immune cells. Synbiotic may help to control serious bacterial diseases and offer an alternative to antibiotics commonly used in fish farming, and its prolonged immunostimulatory effect could increase fish surviving after release to the natural environment.

Nutritional support plays an important role in promoting high cellular and humoral innate immunity activity and in preventing outbreaks of disease. The effects of β-glucan Leiber(®)Beta-S dietary supplementation on selected nonspecific immune parameters in juvenile European eel (Anguilla anguilla) in an intensive culture system were studied. The fish were fed commercial pellets containing either 0 (control group) or 200 mg Leiber(®)Beta-S kg-1 of feed (glucan-fed group). After four and eight weeks of feeding, the levels of the following immunological parameters were measured: phagocyte respiratory burst activity, phagocyte potential killing activity, lymphocyte proliferation stimulated by concanavaline A or lipopolysaccharide, serum lysozyme activity, and total immunoglobulin (Ig) serum levels. After four and eight weeks of feeding 200 mg Leiber(®)Beta-S kg feed-1 the levels of all immune parameters were statistically significantly higher (p < 0.05) in the glucan-treated group than in the control group. After eight weeks of feeding the fish 200 mg Leiber(®)Beta-S kg feed-1 and after an additional eight weeks in ponds, the levels of all immune parameters, excluding lymphocyte proliferation stimulated by concanavaline A, were statistically significantly higher (p < 0.05) in the glucan-fed group than in the control group. These data suggest that feeding juvenile eel Leiber(®)Beta-S for four and eight weeks might improve innate immunity.

The aim of this study was to evaluate the in vitro influence of methisoprinol on head kidney phagocyte and lymphocyte activity after suppression induced by VHSV. The VHSV statistically significantly decreased the respiratory burst activity of head kidney phagocytes and the proliferative response of lymphocytes stimulated by ConA. The results of our study showed that methisoprinol at a concentration of 100 microl/ml modulated and restored the phagocyte and lymphocyte activity suppressed by VHSV.

Rhabdoviruses constitute one of the most pathogenic viruses isolated from rainbow trout and carp culture. Several viruses were also isolated from other species of fish. These viruses are mostly associated with epizootics and heavy losses. Spring viraemia of carp virus (SVCV) and pike fry rhabdovirus (PFRV) have been the most extensively studied, due to their significant economic impact. Significant progress has been made towards controlling the major bacterial fish diseases using vaccines, but this approach has not yet been successful in preventing viral diseases in fish culture. However, for an effective therapeutic approach, specific drugs should be developed to selectively inhibit virus replication and/or stimulate antiviral protection. In this investigation we examined the in vitro influence of methisoprinol on the SVCV and virus isolated from catfish (Ictalurus melas) replication by measuring their RNA synthesis. The viruses were propagated in EPC cells and cell cultures containing methisoprinol were followed by infection with SVCV or catfish rhabdovirus suspension containing 10(7) TCID50/ml. Methisoprinol (Polfa, Poland) at concentrations of 0, 100, 200, 300, 400 and 500 microg/ml of medium (Glasgow MEM) was used in this study. The results of this study show the strong inhibition of incorporation (cpm) of [3H]-uridine into SVCV and catfish rhabdovirus RNA in cell culture exposed to methisoprinol at various concentrations. The highest percent of inhibition of viral RNA at 72 h after infection with two rhabdoviruses were observed in doses of 400 and 500 microg/ml of methisoprinol in medium. The results of this in vitro study showed that methisoprinol inhibits the rhabdoviruses isolated from carp and catfish.

The aim of the present study was to investigate possible pleiotropic effects of the genotypes controlling the palomino and albino coloration on blood phagocyte and lymphocyte activity. The results showed that the wild coloured trout has a higher metabolic and potential killing activity of blood phagocytes, compared to albino and palomino coloured trout. The proliferative response of blood lymphocytes stimulated by ConA or LPS indicated a similar pattern. The results showed that lymphocyte proliferation was statistically significantly higher in wild coloured trout, compared to albino and palomino trout.