bassianolide and Protozoan-Infections--Animal

Fish mariculture has dramatically expanded in recent years in Mediterranean countries. In this scenario, several pathological problems have logically arisen and parasitological etiologies are increasingly being reported, either as primary or secondary pathogens. Myxozoa is the most diverse and economically important group of fish parasites, and several species are known to cause or contribute to losses in mariculture. Species of the genus Enteromyxum currently constitute the most serious parasitological threat. Some unusual biological characters, such as wide host spectrum and direct fish-to-fish transmission, together with high virulence for some host species, combine a dangerous cocktail which is emerging in recent years. Closed-system (recirculation) and heated-water locations are especially sensitive to chronic infections by these parasites, which can cause serious mortality and even discourage culture of some fish species at certain locations (i.e, Diplodus puntazzo). The presentation presents an overview of recent advances in research of marine myxozoans, focusing mainly in the most pathogenic, Enteromyxum spp. The incidence of these and other emerging infections, and the design of potential strategies for control will be introduced.

Topics: Animals; Bass; Fish Diseases; Fisheries; Fishes; Glomerulonephritis; Mediterranean Sea; Protozoan Infections, Animal; Sea Bream

Amyloodinium ocellatum, the causative agent of amyloodiniosis (marine velvet, velvet disease), affects marine and brackish fish in various warm and temperate habitats. We recorded disease outbreaks with high morbidity and mortality rates in marine-cultured European seabass Dicentrarchus labrax fry at 2 locations in northwest Egypt. The sudden outbreak, high morbidity and mortality rates, and skin lesions with a velvety appearance in affected fish all indicated A. ocellatum infection. This was further confirmed by microscopic findings of the parasitic stage (trophonts) in skin and gill smears. While ecological factors including water temperature and salinity were all amenable to parasite establishment and propagation, mortality rates differed between the 2 farms, with rates of mortality well correlated with prevalence and intensity of A. ocellatum infections. Characterization by PCR targeting rDNA gene fragments and subsequent DNA sequencing and phylogenetic analysis further confirmed the molecular identity of the A. ocellatum isolate, which was genetically similar to isolates from other geographical locations. Finally, an improved treatment method using dual hyposalination and copper sulfate exposure to increase the efficiency and decrease the toxicity of copper sulfate was tested. The gradual reduction in water salinity coupled with copper sulfate treatment was more efficient at controlling the disease than only applying copper sulfate. To our knowledge, this is the first parasitological and molecular characterization of A. ocellatum in marine cultures in Egypt. The high molecular identity and close phylogenetic relationship further confirmed the monophyletic nature of A. ocellatum isolates.

Topics: Animals; Aquaculture; Bass; Copper Sulfate; Dinoflagellida; Disease Outbreaks; Ectoparasitic Infestations; Fish Diseases; Phylogeny; Protozoan Infections, Animal; Salinity; Water

Topics: Animals; Bass; Dinoflagellida; Fish Diseases; Gene Expression; Gills; Head Kidney; Immunity, Innate; Protozoan Infections, Animal; RNA, Messenger

Sessiline ciliates live as eco commensals (low numbers) and parasites (high numbers) on different hosts, like mollusks copepods, mysids and fish. Riboscyphidia ecto-protozoan is moderately pathogenic but high numbers of it on the gills can physically prevent gas exchange. The present study aimed to describe the epizoic ciliates Riboscyphidia found on the Red Sea cultured Asian sea bass and obtain more information on the Epidemiology of the parasite with special references to control and histopathological examination of naturally infected sea bass.. The occurrence of epizoic ciliates on the adult Asian Sea bass. About 100 Asian sea bass were collected by the fishing net at a private marine fish farm at Ismailia governorate and transferred to the hydrobiology laboratory at National Research Centre. A parasitological and histopathological study of epizoic sessile ciliate species was done. ANOVA test was used for Statistical analysis.. Riboscyphidia sp. was found and isolated after parasitological examination of investigated adult's Asian sea bass. The prevalence of Riboscyphidiosis was 64%. Sessile ciliates were found on gills, skin and fins. The clinical signs of Riboscyphidiosis were respiratory distress, flashing and off food. Histopathological alterations in naturally infested Asian sea bass were investigated.. The treatment of choice of Riboscyphidiosis was prolonged immersion by Copper citrate with a dose of 0.56 mg mL-1 for 7 days.

Topics: Animals; Antiprotozoal Agents; Aquaculture; Bass; Citrates; Fish Diseases; Indian Ocean; Protozoan Infections, Animal

The ectoparasite protozoan

Topics: Animals; Bass; Dinoflagellida; Fish Diseases; Gills; High-Throughput Nucleotide Sequencing; Protozoan Infections, Animal; Protozoan Proteins; Transcriptome; Virulence Factors

In the Mediterranean area, amyloodiniosis represents a major hindrance for marine aquaculture, causing high mortalities in lagoon-type based rearing sites during warm seasons. Amyloodinium ocellatum (AO) is the most common and important dinoflagellate parasitizing fish, and is one of the few fish parasites that can infest several fish species living within its ecological range. In the present study, A. ocellatum was recorded and collected from infected European sea bass (Dicentrarchus labrax) during a summer 2017 outbreak in north east Italy. Histological observation of infected ESB gill samples emphasized the presence of round or pear-shaped trophonts anchored to the oro-pharingeal cavity. Molecular analysis for small subunit (SSU) rDNA of A. ocellatum from gill genomic DNA amplified consistently and yielded 248 bp specific amplicon of A. ocellatum, that was also confirmed using sequencing and NCBI Blast analysis. Histological sections of ESB gill samples were addressed to immunohistochemical procedure for the labelling of ESB igm, inos, tlr2, tlr4, pcna and cytokeratin. Infected gills resulted positive for igm, inos, pcna and cytokeratin but negative to tlr-2 and tlr-4. Furthermore, ESB immune related gene response (innate immunity, adaptive immunity, and stress) in the course of A. ocellatum infection using quantitative polymerase chain reaction (qpcr) for infected gills and head kidney was analysed. Among the twenty three immune related gene molecules tested, cc1, il-8, il-10, hep, cox-2, cla, cat, casp9, and igt were significantly expressed in diseased fish. Altogether, these data on parasite identification and expression of host immune-related genes will allow for a better understanding of immune response in European sea bass against A. ocellatum and could promote the development of effective control measures.

Topics: Animals; Bass; Dinoflagellida; Disease Outbreaks; Fish Diseases; Fish Proteins; Gene Expression; Gills; Head Kidney; Protozoan Infections, Animal

This investigation is aimed to improve the knowledge on the physiological alterations occurring at morphological and molecular level in European sea bass naturally infected by A. ocellatum and reared at different salinities. European sea bass juveniles (Dicentrarchus labrax) weighing 20 ± 0.5 g were divided in three aquaponics systems: CTRL, reared at 20 ppt salinity; AFI, reared in freshwater (0 ppt) and infected with the dinoflagellate Amyloodinium ocellatum; ASI, reared at 20 ppt salinity and infected with A. ocellatum. Beta vulgaris plants were introduced in each of the aquaponic systems. Temperature was increased 1 °C every second day from 18 to 25 °C during the experiment. At the end of the trial, liver, brain, intestine and gills were sampled for molecular and histological analyses. A. ocellatum affected D. labrax growth (insulin-like growth factor I, IGF-I) and appetite (Neuropeptide Y, NPY) signals in ASI. Immune system was activated in ASI by the presence of parasites by producing higher levels of Interleukin-1 (IL-1) and Tumor Necrosis Factor α (TNFα). Peroxisome proliferator-activated receptor α (PPAR α), codifying for a protein involved in lipid metabolism, was upregulated in ASI because of the necessity to produce energy to maintain homeostasis. On the contrary, A. ocellatum did not cause signs of infection in AFI as confirmed by gene expression and histological analysis, that were similar to CTRL. However, in freshwater reared fish, a modification of lipid metabolism was observed through a reduction in PPARα gene expression and hepatic lipid content.

Topics: Animals; Bass; Dinoflagellida; Fish Diseases; Fresh Water; Gene Expression; Protozoan Infections, Animal; Salinity; Seawater

Topics: Animals; Bass; Disease Transmission, Infectious; Eukaryota; Fish Diseases; Host-Parasite Interactions; Intestines; Protozoan Infections, Animal; Sea Bream

Gilt-head sea bream, Sparus aurata L., the Mediterranean's most important mariculture species, has been cultured for the last 30 yr in Eilat (Israeli Red Sea). Kudoa sp. was the first myxosporean parasite reported from this species. In recent years, an increase in prevalence in both land-based and sea-cage facilities in Eilat has been observed. Infections with the same Kudoa species appeared in cultured European sea bass Dicentrarchus labrax (L.) and grey mullet Mugil cephalus in the same farms, as well as in 10 species of wild Red Sea reef fish, indicating that Kudoa sp. is not fastidious with regard to its host. All affected species displayed 1- to 2-mm (up to 5 mm) whitish, spherical, or oval polysporous plasmodia. The parasite established multiple site infections, most commonly in the muscles and intracranial adipose tissue of the brain and eye periphery. Other sites were subcutaneous adipose tissue, nerve axons, mouth, eye, mesenteries, peritoneum, swim bladder, intestinal musculature, heart, pericardium, kidney, and ovary. On the basis of spore morphology, the parasite was identified as Kudoa iwatai Egusa and Shiomitsu, 1983. Ultrastructural features were comparable to those of previously studied Kudoa species. The 18S rDNA from 7 Red Sea isolates was sequenced and compared with the sequence of the same gene from K. iwatai isolated from cultured red sea bream, Pagrus major, in Japan. The phylogenetic position of K. iwatai within the genus was determined using sequence analysis of all related taxa available in GenBank. The 3 isolates of K. iwatai clustered together on a newly formed, highly supported clade. The Red Sea strain of K. iwatai is apparently native to the region. In the absence of records of this Kudoa sp. from the extensive Mediterranean sea bream and sea bass production industries, introduction with its Mediterranean hosts seems unlikely. Therefore, we conclude that K. iwatai is an Indo-Pacific species that, in the Red Sea, has extended its host range to include the allochthonous gilt-head sea bream, European sea bass, and grey mullet.

Topics: Animals; Base Sequence; Bass; DNA, Protozoan; DNA, Ribosomal; Eukaryota; Fish Diseases; Molecular Sequence Data; Phylogeny; Polymerase Chain Reaction; Protozoan Infections, Animal; RNA, Ribosomal, 18S; Sea Bream; Smegmamorpha; Spores, Protozoan

The distribution of Sphaerospora dicentrarchi Sitjà-Bobadilla et Alvarez-Pellitero, 1992 and S. testicularis Sitjà-Bobadilla et Alvarez-Pellitero, 1990, myxozoan parasites of European seabass Dicentrarchus labrax (L.), was investigated in different farming systems in Italy. In total, 1406 fish were examined. High S. dicentrarchi prevalence was observed in all the farming systems involved in this survey (extensive farms: 51.5%; intensive farms: inland 59.6%, inshore floating cages 76.2%, offshore floating cages 41.6%) except for submersible cages (7.4%). S. testicularis was detected only in nine male fish from two intensive farms. The epidemiology and pathological effects of the parasites are discussed.

Topics: Animals; Aquaculture; Bass; Eukaryota; Fish Diseases; Italy; Prevalence; Protozoan Infections, Animal; Species Specificity; Spores, Protozoan

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

The existence and localisation of carbohydrates in four myxosporean parasites was investigated at transmission electron microscope, using lectin histochemistry techniques. The Myxosporea studied showed different lectin binding patterns. N-acetyl-glucosamine or its polymers were predominant in the valves of Leptotheca sp. and were also present in Sphaerospora dicentrarchi and Polysporoplasma sparis ones. Mannose and/or glucose terminals were mainly detected in S. dicentrarchi and P. sparis valves. Polar capsule walls were intensively recognised by Con-A is S. dicentrarchi and with medium intensity in P. sparis and Leptotheca sp. The polar filament was scarcely labelled except in Leptotheca sp. with BS-I. The sporoplasms of the studied parasites were stained with all the lectins tested with each myxosporea, except those of Leptotheca sp. with BS-I. Some structures of the developmental stages of Zschokkella mugilis and Leptotheca sp. were stained with BS-I. The possible role of these carbohydrate terminals found in the studied Myxosporea is discussed.

Topics: Animals; Bass; Carbohydrates; Eukaryota; Fish Diseases; Gills; Lectins; Microscopy, Electron; Protozoan Infections, Animal; Spores

Several in vitro studies were performed to study the cellular reaction of European sea bass (Dicentrarchus labrax L.) against Sphaerospora dicentrarchi. Head kidney phagocytes were obtained from parasitised (P) and non-parasitised (NP) fish. The production of superoxide anion (O2-), tested by the NBT method, was higher in P than in NP fish. The addition of increasing amounts of sea bass serum (SBS) produced a gradual increment of the respiratory burst with SBS from parasitised animals (P-SBS), whereas this increment reached a plateau at lower concentration with SBS from nonparasitised ones (NP-SBS). O2- production was higher when adding NP-SBS than with P-SBS or fetal bovine serum. Heat inactivation of NP-SBS and FBS reduced the respiratory burst significantly, whereas it did not change the effect of P-SBS. The number of NBT-positive cells after particulate stimulation was significantly higher using S. dicentrarchi spores than using SRBC, but lower than with phorbol myristate acetate. Phagocytes primed overnight with spore extracts produced higher amounts of O2- than those LPS-primed or non-primed ones. A similar percentage of phagocytosis was detected using glutaraldehyde fixed spores and SRBC. Most of the phagocytes engulfed three or more SRBC, whereas most of the phagocytes engulfed only one spore. Complement mediated opsonisation by NP-SBS may occur, as the phagocytic index was reduced when the serum was heat inactivated.

Topics: Animals; Bass; Eukaryota; Fish Diseases; Hot Temperature; In Vitro Techniques; Phagocytes; Phagocytosis; Protozoan Infections, Animal; Respiratory Burst; Superoxides

Immunological staining with rabbit antibodies raised against Sphaerospora testicularis and Ceratomyxa labracis was used to characterise their specificity and their reactivity towards other fish parasites. Polar capsules and valves of S. testicularis and C. labracis were labelled with their homologous antibody and cross reaction was observed with all the myxosporean parasites assayed from marine and freshwater fish hosts. All polar capsules were stained with both antibodies, except those of Zschokkella mugilis, which were not labelled with anti-S. testicularis serum. These observations suggest that polar capsules may be very conserved structures in myxosporean parasites from different hosts.

Topics: Animals; Antibodies, Protozoan; Antibody Specificity; Antigens, Helminth; Bass; Cross Reactions; Epitopes; Eukaryota; Fish Diseases; Fishes; Host-Parasite Interactions; Immunohistochemistry; Protozoan Infections, Animal; Rabbits; Seawater

In the present study, the pathogenic effects of Sphaerospora dicentrarchi and S. testicularis, histozoic and coelozoic myxosporean parasites of the Mediterranean sea bass Dicentrarchus labrax L., respectively, are described. The infection caused by the latter, which usually invades the testes and neighboring tissues, is considered to represent parasitic castration. S. dicentrarchi seems to be harmless except in massive infections, which probably result in organic disfunctions. The cellular host reaction generated by S. testicularis depends on the location of the parasite and is more intense than that produced by S. dicentrarchi. In both sphaerosporoses, macrophages, granulocytes, lymphocytes, plasmacytes, and fibroblast-like cells are involved. The role of the different immune cells is discussed.

Topics: Animals; Bass; Fish Diseases; Immunity, Cellular; Intestines; Lymphocyte Activation; Lymphocytes; Macrophages; Male; Microscopy, Electron; Pancreas; Protozoan Infections; Protozoan Infections, Animal; Spermatogenesis; Testis

The population dynamics of Sphaerospora dicentrarchi and S. testicularis, myxosporean parasites of sea bass (Dicentrarchus labrax), was studied in different groups of cultured and wild fish. S. dicentrarchi prevalence was higher for wild fish (100%) than for cultured ones (70.5%). Infection levels increased with host age and there were no significant sex differences in cultured fish. Among parasitized organs, the gall bladder and intestine registered the highest infection levels in wild and cultured fish. A progressive increase in infection levels of S. testicularis was observed in cultured males during the spawning season in four consecutive periods. The evolution of the percentage of the different parasitic stages is pointed out. The infection seems to be related to water temperature and gonadal maturation.

Topics: Animals; Bass; Female; Fish Diseases; Fresh Water; Gallbladder; Host-Parasite Interactions; Intestines; Male; Protozoan Infections; Protozoan Infections, Animal; Seasons; Spain