muramidase and Protozoan-Infections--Animal

The innate and adaptive immune responses against Enteromyxum scophthalmi was studied in turbot (Scopthalmus maximus (L.)) experimentally exposed to the parasite by cohabitation. Haematological, histopathological, cellular and humoral factors were determined in samples taken from control (CTRL) and recipient (RCPT, naïve fish cohabited with donor infected fish) animals at 0, 20, 29, 40 and 43 days post exposure (p.e). Infection was first detected at day 20 p.e. and prevalence reached 100% at 40 days p.e, when first mortalities occurred. A significant reduction in weight and condition factor was found in RCPT, though no significant differences in haematocrit or serum protein levels were detected between CTRL and RCPT. Some immune effectors were clearly activated in RCPT: the percentage of circulating granulocytes was significantly increased, as well as the number of blood cells positive in the respiratory burst assay; leucocyte infiltration in intestine was found mainly on days 20 and 29 p.e.; total serum antiproteases and alpha-2-macroglobulin levels were higher in most of the samplings, with significant differences on the last sampling. Other effectors were clearly down regulated in RCPT: haematopoietic depletion appeared in head kidney from day 29 p.e. onwards, and the number of apoptotic cells and MMC increased in head kidney and spleen; the percentage of lymphocytes decreased progressively and significantly; a clear, but not statistically significant, drop in serum complement was registered at 40 days p.e.; also, a significant decrease occurred in serum lysozyme at 29 days p.e. No specific antibodies against the parasite were detected in any sampling.

Topics: alpha-Macroglobulins; Animals; Blood Cells; Complement Pathway, Alternative; Eukaryota; Fish Diseases; Flatfishes; Granulocytes; Immunity, Active; Immunity, Innate; Kidney; Muramidase; Protease Inhibitors; Protozoan Infections, Animal; Spleen; Time Factors

The hemocytes of invertebrates play key roles in both cellular and humoral immune reactions by phagocytosis or delivering immune factors such as lectin and anti-microbial peptides. Bacterial infection causes changes in components such as lectins, anti-bacterial peptides, and lysosomal enzymes of plasma or hemolymph in molluscs. Previously, we found that infection with the protozoan parasite, Perkinsus, increases lectin synthesis in hemocytes. In order to investigate the patterns of genes expressed in Manila clams (Ruditapes philippinarum) infected with the protozoan parasite Perkinsus olseni, we constructed a cDNA library and sequenced 1850 clones (expressed sequence tags). A total of 79 ESTs, were related to 29 functional immune genes such as C-type lectin, lysozyme, and cystatin B, in Manila clams. Lectins were the largest group of immune-function ESTs found in our Manila clams library. Among 7 lectin clones, two full length cDNAs of lectins were cloned. MCL-3, which is a simple C-type lectin composed of 151 amino acids, has a relatively short signal sequence of 17aa and single carbohydrate-recognition domain (CRD) of approximately 130 residues. It is highly homologous to eel C-type lectin. The sequence of mc-sialic acid-binding lectin consists of 168 amino acid residues with molecular weight of 19.2 and shows high homology to sialic acid-binding lectin from the snail, Cepaea hortensis. The expression of 7 different lectins in hemocytes was analyzed by RT-PCR using gene-specific primers. Hemocytes from Perkinsus-infected clam expressed different sets of lectins than with Vibrio infection. These results demonstrate that several lectins are involved in Manila clam innate immunity and different challenges induce expression of different lectins.

Topics: Amino Acid Sequence; Animals; Base Sequence; Bivalvia; Cystatin B; Cystatins; Expressed Sequence Tags; Gene Library; Hemocytes; Lectins, C-Type; Molecular Sequence Data; Muramidase; Phylogeny; Protozoan Infections, Animal; Reverse Transcriptase Polymerase Chain Reaction; Sequence Alignment

An experiment was conducted to determine the effect of Neoparamoeba sp. infection on the innate immune responses of Atlantic salmon. Atlantic salmon were experimentally infected with Neoparamoeba sp. and serially sampled 0, 1, 4, 6, 8 and 11 days post-exposure (dpe). Histological analysis of infected fish gill arches identified the presence of characteristic amoebic gill disease lesions as early as 1 dpe with a steady increase in the number of affected gill filaments over time. Immune parameters investigated were anterior kidney phagocyte function (respiratory burst, chemotaxis and phagocytosis) and total plasma protein and lysozyme. In comparison with non-exposed control fish basal respiratory burst responses were suppressed at 8 and 11 dpe, while phorbol myristate acetate-stimulated activity was significantly suppressed at 11 dpe. Variable differences in phagocytic activity and phagocytic rate following infection were identified. There was an increase in the chemotactic response of anterior kidney macrophages isolated from exposed fish relative to control fish at 8 dpe. Total protein and lysozyme levels were not affected by Neoparamoeba sp. exposure.

Topics: Animals; Aquaculture; Blood Proteins; Chemotaxis; Fish Diseases; Gills; Histological Techniques; Immunity, Innate; Lobosea; Muramidase; Phagocytosis; Protozoan Infections; Protozoan Infections, Animal; Respiratory Burst; Salmo salar; Time Factors

The potential antiparasitic and immunomodulatory effect of three treatments against myxosporean parasites on the innate immune system of sharpsnout sea bream (Diplodus puntazzo) was investigated. Fish naturally infected with Myxobolus sp. (Bivalvulida/Platysporina), a histozoic parasite mainly affecting the renal interstitial tissue, were treated by oral administration of a combination of salinomycin with amprolium, Origanum essential oil or fumagillin in a small-scale field trial. Various leucocyte functions influenced by myxosporean infection were examined in order to determine treatment effects on leucocyte immunocompetence of treated fish. One month post treatment all drugs caused a significant decrease in prevalence and intensity of infection in comparison to untreated, infected fish. The effect was most prominent in salinomycin with amprolium treated fish, which 1-month post treatment contained either no cysts at all or a few spores free in melanomacrophage centres revealing almost total elimination of the parasite and the antiparasitic action of the treatment. There was no histopathological evidence of drug toxicity. Antiparasitic action was accompanied by a significant enhancement of phagocytic activity demonstrated by ingestion of large numbers of latex beads and the secretion of high levels of reactive nitrogen intermediates by phagocytes in vitro. Complete restoration of the diminished mitogenic responses and serum lysozyme secretion was also detected in salinomycin with amprolium-treated fish compared to untreated, infected fish. These data suggest that salilomycin with amprolium may be a promising treatment for myxosporean infections in intensively cultured warm-water fish, exhibiting action partially via the enhancement of host, innate immune functions and leading to parasite elimination.

Topics: Amprolium; Animals; Antiprotozoal Agents; Cell Proliferation; Cyclohexanes; Eukaryota; Fatty Acids, Unsaturated; Fish Diseases; Histocytochemistry; Kidney Diseases; Leukocytes; Mediterranean Sea; Muramidase; Oils, Volatile; Phagocytosis; Protozoan Infections, Animal; Pyrans; Reactive Nitrogen Species; Sea Bream; Sesquiterpenes

The immune response of European sea bass after intracaelomic immunization with Sphaerospora dicentrarchi was studied. Fish were injected with S. dicentrarchi spores (DIC), with spores plus adjuvant (DIC + FCA), with adjuvant alone (FCA) or with PBS. Several parameters of the immune response were measured. Serum lysozyme increased significantly in DIC fish 1 week after immunization (p.i.) and it remained significantly higher in DIC + FCA fish 4 weeks p.i., and in DIC fish 8 weeks p.i. than in PBS-injected fish. The number of nitroblue tetrazolium-positive blood cells was significantly higher in DIC + FCA fish 1, 4 and 8 weeks p.i, but the highest values were detected 1 week p.i. The highest stimulation index was detected in phagocytes from DIC + FCA fish. The number of S. dicentrarchi antibody-secreting cells was significantly higher in DIC + FCA fish than in DIC fish. Serum from DIC and DIC + FCA fish, stained the polar capsules and the valves of S. dicentrarchi spores in immunohistochemistry. Serum antibodies could not be detected using immunoblot assay. All these results show that immunization with S. dicentrarchi resulted in the activation of the non-specific immune response, mainly 7 days p.i. A specific humoral response against the parasite was also demonstrated but it had a low magnitude.

Topics: Animals; Antibodies, Protozoan; Antibody-Producing Cells; Bass; Complement Pathway, Alternative; Eukaryota; Fish Diseases; Immunity, Cellular; Immunization; Muramidase; Nitroblue Tetrazolium; Protozoan Infections, Animal; Respiratory Burst