bluuebunny/crossref_metadata_2025 huggingface dataset:
Current practices in the chemotherapeutic control of sea lice infestations in aquaculture: a review
Authors: ROTH M. , RICHARDS R. H. , SOMMERVILLE C.
Published: April 2006

Abstract. This review surveys the available literature on the efficacy and ecotoxicology of chemotherapeutic agents for the control of sea lice (Copepoda: Caligidae) infestations in marine aquaculture. To date, treatment for the disease has relied almost exclusively on the use of the organophosphorus pesticides, trichlorfon and dichlorvos. While use of dichlorvos and trichlorfon appears to have little, if any, environmental impact, protracted use in some areas has led to reduced efficacy. Compounds proposed for sea lice control currently under field evaluation include azamethiphos (organophosphate), ivermectin (avermectin), pyrethrum (pyrethrin) and hydrogen peroxide. Although all of these compounds are effi cacious, at present published information on marine environmental toxicology is scarce and is limited to in vitro toxicity testing. Other compounds that have been considered for sea lice control include formalin, malathion (organophosphate), carbaryl (carbamate), diflubenzuron (insect growth regulator) and natural remedies (i.e. onions and garlic). In general, formaldehyde (aldehyde), malathion and natural compounds show either poor efficacy or unsuitable therapeutic margins. Although carbaryl and diflubenzuron are both efficacious and exhibit suitable therapeutic margins, available data suggests that the compounds, due to undesirable environmental toxicological characteristics, would be unsuitable for sea lice control.
A comparative study of the myxosporeans Myxidium rhodei Léger, 1905 and Myxidium pfeifferi Auerbach, 1908 in roach, Rutilus rutilus L.
Authors: ATHANASSOPOULOU F. , SOMMERVILLE C.
Published: April 2006

Abstract. The morphology and dimensions of Myxidium rhodei and M. pfeifferi were studied in roach originating from two different geographic locations (Greece and UK) using both scanning and light microscopy. The measurements and morphology of both mature spores and immature stages (trophozoites and spores) were studied and compared. No differences were observed in the morphology of mature or immature spores of both species when examined under light and SEM. Furthermore, no differences were found in the dimensions of the mature spores of both species in all fish. However, immature spores of both species were found to be smaller but wider than mature ones in all organs and in both habitats. Size differences between the two species were only seen in immature spores, M. rhodei immature spores being always larger than those of M. pfeifferi. When comparing the dimensions of the spores between the two habitats, these were larger and wider in the Greek fish than those in the British fish. The information in this study suggests that, in roach, M. pfeifferi is undistinguishable from M. rhodei and that similar studies should be carried out on the tench, Tinca tinca L., the type host of M. pfeifferi.
Production of the lethal acetylcholinesterase toxin by different Aeromonas hydrophila strains
Authors: RODRIGUEZ L. A. , FERNANDEZ A. I. G. , NIETO T. P.
Published: April 2006

Abstract. Seven fish pathogenic isolates of Aeromonas hydrophila, one A. sobria and one A. caviae were investigated for production of the fish lethal acetylcholinesterase toxin (AcChE‐toxin). Western blotting was used for screening the ECP of these strains with a rabbit antiserum prepared against the purified toxin of strain B32 and all the isolates (except A. sobria) gave positive results with different patterns of bands. The AcChE‐toxin appears to be secreted as a protein of high molecular weight which is stable at −20°C, and in 90% of the strains tested, it appears to be split into lower molecular weight fragments by the action of other components present in the ECP. The smallest, stable and highly active fragment has a MW of 15kDa.
Immunochemical analyses of Vibrio anguillarum strains isolated from cod, Gadus morhua L., suffering from vibriosis
Authors: KNAPPSKOG D. H. , RØDSETH O. M. , SLINDE E. , ENDRESEN C.
Published: April 2006

Abstract. Vibrio anguillarum isolates were sampled from cod fry showing clinical signs of vibriosis at different cod farms along the western coast of Norway. Except for one isolate, all were shown to cause mortality in laboratory challenge experiments. Using biochemical analysis and specific rabbit antisera (O1–O5), all the pathogenic isolates were classified as typical V. anguillarum serotype O2. SDS‐PAGE and Western blot analysis of both whole bacterial cells and purified lipopolysaccharides (LPS) showed that the LPS structures were heterogeneous. ELISA analyses using adsorbed antisera identified the presence of two different subgroups within serogroup O2, which correspond with O2a/O2α and O2b/O2β described previously.
Cryptocaryon irritans Brown, 1951 (Ichthyophthiriidae): the ultrastructure of the somatic cortex throughout the life cycle
Authors: MATTHEWS B. F. , MATTHEWS R. A. , BURGESS P. J.
Published: April 2006

Abstract. Cryptocaryon irritans was isolated from Grammistes sexlineatus and maintained in aquaria under controlled conditions using the mullet, Chelon labrosus (Risso), as an experimental host. The pellicle and cortical cytoplasm of the trophont, tomont, tomite and theront stages were investigated with the aid of transmission electron microscopy. The general structural organization of the pellicle resembles that of the freshwater holotrich, Ichthyophthirius multifiliis; however, the pellicular alveoli are characterized by the accumulation of electron‐dense material in the trophont, tomite and theront, this material being lost in the newly‐encysted tomont. The outer membranes of the pellicle are infolded into the alveoli of the trophont. Cilia are present at all stages of the life cycle, although at encystment their numbers are greatly reduced by shedding. Mitochondria, mucocysts and Golgi‐like cisternae are distributed throughout the cortical cytoplasm. Mucocysts differ from those of I. multifiliis in size, shape and distribution and are of uniform electron density. The role of the pellicle and cortical cytoplasm is discussed in relation to the invasion of the fish epidermis, possible intertransferance of materials between parasite and host and the process of encystment.
Resistance of Aeromonas salmonicida to amoxicillin
Authors: INGLIS V. , MILLAR S. D. , RICHARDS R. H.
Published: April 2006

Abstract. Isolates of Aeromonas salmonicida were obtained from farmed Atlantic salmon, salmo salar L., with amoxicillin minimum inhibitory concentrations (MICs) of 2·5–10 μg ml‐1 Several antibiotic sensitivity patterns were found among the isolates including resistance to the four UK‐licensed antibacterial drugs. Combination of clavulanic acid with amoxicillin was not effective, but all isolates were sensitive to florfenicol and to a cephalosporin, the latter having very low MICs.
Pathogenicity of the causative agent of viral nervous necrosis disease in striped jack, Pseudocaranx dentex (Bloch & Schneider)
Authors: ARIMOTO M. , MORI K. , NAKAI T. , MUROGA K. , FURUSAWA I.
Published: April 2006

Abstract. The pathogenicity of the agent causing viral nervous necrosis (VNN) of striped jack, Pseudocaranx dentex (Bloch & Schneider), was examined in striped jack and other selected marine fish species. Fish were exposed to purified striped jack nervous necrosis virus (SJNNV) (0·1–100 ng ml−1) or homogenates of diseased striped jack larvae. Striped jack larvae (3·5 and 4·4 mm total length) were susceptible to the virus, but juveniles (78 mm) were not. The viral antigens were detected by indirect ELISA and the characteristic pathological changes, i.e. vacuolation in the retina and brain, were reproduced in the affected larvae. The infection was also established in healthy larvae by cohabitation with the diseased larvae. Larvae of red sea bream, Pagrus major Temminck & Schlegel, yellowtail, Seriola quinqueradiata Temminck & Schlegel, and goldstriped amberjack, Seriola lalandi Valenciennes, were not susceptible to SJNNV.
Plasma protein levels as potential marker traits for resistance to furunculosis
Authors: SALTE R. , GJØEN H. M. , NORBERG K. , GJEDREM T.
Published: April 2006

Abstract. The feasibility of including individual records on correlated traits in a family selection programme which aims to increase resistance to furunculosis in Atlantic salmon was studied; markers were selected because of their potential role in the pathogenesis of the disease. Fibrinogen and α2‐antiplasmin both show genetic variation; both are correlated with survival after challenge with Aeromonas salmonicida, the correlation being 0·44 and 0·37 (P < 0·05), respectively, and it is possible to measure both on a large scale at low costs. Contrary to α2‐antiplasmin, fibrinogen was negatively correlated with survival due to furunculosis within the 10 most resistant families and within the 10 most susceptible families in contrast to an overall positive correlation. This inconsistency could be attributable to the presence of different allelic phases in different families, and of major linked loci influencing survival and fibrinogen levels. Thus, only α2‐antiplasmin fulfils the requirements for a marker trait for resistance to the disease suitable for individual selection at the population level, whereas the use of fibrinogen would be restricted to within family selection. The full statistical model explained 51% of the variation in resistance to furunculosis, and α2‐antiplasmin contributed 15% to this variation when considered as a separate entity. Thus, the additional gain from including individual records on α2‐antiplasmin in a family selection programme could be significant.
Disease resistance of carp, Cyprinus carpio L.: identification of individual genetic differences by bath challenge with atypical Aeromonas salmonicida
Authors: WIEGERTJES G. F. , DALY J. G. , VAN MUISWINKEL W. B.
Published: April 2006

Abstract. The present study was undertaken to identify female breeders, resistant or susceptible to disease, which might be used to obtain gynogenetically cloned carp lines differing in disease resistance. Experimentally induced erythrodermatitis was used as the disease model. Firstly, the effect of age on the resistance to bath challenge with atypical Aeromonas salmonicida was examined. These challenges indicated a shift from subacute to chronic infection with increasing age, as shown by a lower survival at 3 and 5 months (both 15%) compared to 10 months of age (60%). Then, to conserve and characterize breeder females, offspring of two females (nos 21 and 38), including F1, F2 and backcross (B1 and B2) progenies, were bath challenged at the age of 3 months. Comparison of the survival data showed a segregation into two groups of progenies: one resistant with nearly 100% survivors (W, F1 and B2), and one relatively susceptible group with 25% (R8 and F2) or 50% (B1) mortality. Analysis of inheritance indicated dominance of the resistant phenotype. Thus, the results identified two breeder females whose (gynogenetic) progeny might be expected to differ in resistance to bath challenge with atypical A. salmonicida.
Humoral immune response of turbot, Scophthalmus maximus (L.), to antigens from Tetramicra brevifilum Matthews & Matthews, 1980 (Microspora)
Authors: LEIRO J. , ESTÉVEZ J. , SANTAMARINA M. T. , SANMARTÍN M. L. , UBEIRA F. M.
Published: April 2006

Abstract. The humoral immune response of turbot, Scophthalmus maximus (L.), to antigens from the microsporean parasite Tetramicra brevifilum Matthews & Matthews, 1980, was studied. Thirty days after intraperitoneal immunization with whole T. brevifilum spores in Freund's complete adjuvant, double indirect ELISA indicated that initial production of antibodies to parasite surface antigens was considerably higher than production of antibodies to the antigens contained in a crude extract (CE) of spores. Following re‐immunization without adjuvant on day 30, levels of antibodies to surface antigens gradually declined, whilst levels of antibodies to CE antigens increased. The antibody response of intraperitoneally immunized fish was characterized by Western blotting of total soluble antigens obtained by heating and reduction of T. brevifilum spores at 95–100°C in Tris‐HCl buffer containing SDS and dithiothreitol: a series of bands with molecular weights between 20 and 53 kDa was recognized by immunized turbot sera. Four additional bands (with molecular weights between 15 and 18kdA) were recognized by serum from re‐immunized fish. ELISA studies of sera from naturally infected fish revealed a surprisingly low incidence of strong T. brevifilum seropositivity (61% individuals); antibodies to surface antigens predominated in seropositive individuals. The low background response levels and high sensitivity of the ELISA used in this study indicate that the assay is of value for the monitoring of serum antibody levels in turbot. However, given the relatively low seropositivities observed in naturally infected turbot, particularly to CE antigens, the use of anti‐T. brevifilum serum antibody levels for the diagnosis of infection by this parasite may lead to false negative results.
Acquired resistance of the eel, Anguilla anguilla L., to challenge infections with gill monogeneans
Authors: SLOTVED H. C. , BUCHMANN K.
Published: April 2006

Abstract. The European eel, Anguilla anguilla L., is able to respond to infections with ectoparasitic gill monogeneans of the genus Pseudodactylogyrus Gussev, 1965. A primary infection offers the host a relative resistance to challenge infections. The relative protection was detected at both 14 and 33 days after mebendazole termination of the primary infection by a significantly greater parasite reduction in previously infected eels compared to non‐primed eels. No complete immunity was obtained.
Plasmid‐mediated antibiotic resistance in Aeromonas salmonicida isolated from Atlantic salmon, Salmo salar L., in Scotland
Authors: INGLIS V. , YIMER E. , BACON E. J. , FERGUSON S.
Published: April 2006

Abstract. Forty oxytetracycline‐resistant isolates of Aeromonas salmonicida obtained from outbreaks of furunculosis in Atlantic salmon in Scotland were tested for their susceptibility to 12 antibacterial agents. There were 10 resistance patterns with multiple resistance to two to six antibacterial agents. Transferable R‐plasmids encoding oxytetracycline resistance were demonstrated in 11 out of the 40 isolates. The resistance transferred was multiple; to oxytetracycline, streptomycin, sulphamethoxine and trimethoprim, or to oxytetracycline and one or two of these in combination. Oxytetracycline resistance was transferred in a single, large step, >250‐fold increase, and the MICs for individual transconjugants from mating populations were the same.
Detection of Renibacterium salmoninarum in salmonid kidney samples: a comparison of results using double‐sandwich ELISA and isolation on selective medium
Authors: GUDMUNDSDOTTIR S. , BENEDIKTSDOTTIR E. , HELGASON S.
Published: April 2006

Abstract A total of 1239 kidney samples from four species of salmonid fish, Atlantic salmon, Salmo salar L., brown trout, Salmo trutta L., Arctic charr, Salvelinus alpinus (L.), and rainbow trout, Oncorhynchus mykiss (Walbaum), were screened for Renibacterium salmoninarum using double‐sandwich ELISA and bacterial isolation. For bacterial isolation, samples were homogenized, washed, plated onto S‐KDM and incubated for 12 weeks. Samples for ELISA were kept frozen until tested. After thawing, 25% homogenates in PBS were heated at 100°C for 15 min in the presence (2.5% v/v) of HemoDe solvent (terpene and butylated hydroxyanisole) and then centrifuged. The supernatant was tested with polyclonal antibodies against whole bacterium in a double‐sandwich ELISA. In seven out of 12 groups tested, all samples were negative in both tests. Positive ELISA results occurred in five groups. Renibacterium salmoninarum was isolated on SKDM from samples in four out of these five groups. The ELISA test gave significantly higher numbers of positive samples in three out of the four groups showing positive results in both tests.
X‐cell gill disease obliterates the lamellar blood supply in the Antarctic teleost, Pagothenia borchgreviniki (Boulenger 1902)
Authors: FRANKLIN C. E. , McKENZIE J. C. , DAVISON W. , CAREY P. W.
Published: April 2006

Abstract Vascular corrosion casting methods were used to elucidate the pathological effects of X‐cell disease on the blood supply to the gills of the Antarctic teleost, Pagothenia borchgrevinki (Boulenger, 1902). Afferent and efferent branchial arteries were patent in X‐cell diseased fish; however, the blood supply to the lamellae was markedly reduced or obliterated in areas in which there was a predominance of X‐cells. The present authors believe that the tissue hyperplasia associated with X‐cell disease results in the compression of the lamellar vascular bed which leads eventually to the occlusion of vessels.
Haemorrhagic areas in the mouth of farmed turbot, Scophthalmus maximus (L.)
Authors: ANGULO L. , LOPEZ J. E. , VICENTE J. A. , SABORIDO A. M.
Published: April 2006

Abstract. An epizootic in juvenile turbol reared on a farm located in The Ria de Vigo, Galicia, Northwest Spain, is described. The diseased turbot did not display unusual swimming behavior; the external signs of the disease were abdominal distension and haemorrbagic areas in the mouth. Internal examination of the fist showed an accumulation of reddish fluid in the peritoneal cavity. Microbiological analysis of the diseased fish revealed the presence, in pure culture in all the organs and lesions examined, of a bacterium which was characterized biochemically asVibrio splendidus biotype I. The virulence tests showed that theV. splendidus biotype I isolate was pathogenic for rainbow trout (LD50: 2.2 × 104) and also for turbot (LD50: 1.2 × 104). The treatment of the fish using flumequine incorporated into the feed was effective in offsetting the mortality rate.
Vibrio anguillarum serovars associated with vibriosis in fish
Authors: LARSEN J. L. , PEDERSEN K. , DALSGAARD I.
Published: April 2006

Abstract. A total of 517 Vibrio anguillarum strains isolated from discased fish together with 14 V. anguillarum serogroup O2 and V. ordalii type strains were serotyped using the European scrotyping system. Marked species differences were recorded. In isolates from salmonids serovar O1 (70.2%) and O2 (20.2%) were dominantwhilst a minor proportion belonged to other serogroups or were non‐typeable. Figures for turbot were similar to those from salmonids. In 32 isolates from sea bass, sea bream and mullet, most strains belonged to serogroup O1. while one was O2a. one O7, and the rest non‐typeable In cod serovar O2 was dominant while only a minor proportion belonged to other serogroups or were non‐typeable. The ecl isolates belonged equally to serovars O2 and O3. All O2 strain were subtyped with absorbed O2a and O2b antisera. O2a was dominant in all fish species. but in cod. the relative number of O2b isolates was considerably higher than in other fish species. The applicability of the European serotyping system is discussed and compared with other serotyping systems.
Jaundice disease in the farmed catfish hybrid, Clarias macrocephalus (Gunther) ×C. gariepinus (Burchell), in Thailand
Authors: PEARSON M. D. , CHINABUT S. , KARNCHANAKHARN S. , SOMSIRI T.
Published: April 2006

Abstract. In recent years, jaundice disease in farmed hybrid catfish in Thailand has caused high levels of mortalities. Affected fish are lethargic and anorexic and show yellow pigmentation of the skin and gills. Internally, the spleen, kidney and gall bladder are enlarged, and the spleen, kidney, liver and body fat are a pale yellow colour. Most fish contain a yellow ascitic fluid in their abdomen. Histological examination of tissues from diseased fish revealed heavy deposits of haemosiderin and ceroid in the spleen, kidney and liver. Haematological measurements showed that haematocrit values, RBC count, haemoglobin concentration, MCH and MCHC were significantly decreased in affected fish while MCV, total bilirubin and direct reacting bilirubin were significantly increased. The results indicate that the fish are suffering from a haemolytic anaemia associated with lipoid liver degeneration. The disease is thought to be due to the feeding of rancid chicken viscera.
The route of entry and progression of infectious haematopoietic necrosis virus in Oncorhynchus mykiss (Walbaum): a sequential immunohistochemical study
Authors: DROLET B. S. , ROHOVEC J. S. , LEONG J. C.
Published: April 2006

Abstract. Steelhead trout, Oncorhynchus mykiss (Walbaum), fry were experimentally infected with infectious haematopoietic necrosis virus (IHNV) Round Butte 1983 (Type 1). Fry were sampled daily, before and during the epizootic. Fish tissues were tested for infectious virus by tissue culture assay and for IHNV nucleocapsid protein by alkaline phosphatase immunohistochemistry (APIH). The progression of virus through the tissues was followed by APIH until the fourteenth day. Viral infection progressed from two major sites: from the gills into the circulatory system; and from the oral region into the gastrointestinal tract and then into the circulatory system. Once in the blood, virus was disseminated to virtually every organ. Progression of IHNV within and between organs is discussed.
Protective effect of sodium alginates against bacterial infection in common carp, Cyprinus carpio L.
Authors: FUJIKI K. , MATSUYAMA H. , YANO T.
Published: April 2006

Abstract. A hot‐water extract of Undaria pinnatifida was found to contain polysaccharide(s) which showed immunostimulating activity in fish. In order to identify the effective component(s), the hot‐water extract was fractionated and acid‐soluble (Fraction I) and acid‐insoluble (Fraction II) polysaccharides were evaluated for their potential to enhance protection against Edwardsiella tarda infection in common carp. Intraperitoneal injection of Fraction II in carp 6 and 3 days prior to challenge with E. tarda resulted in a significantly greater survival rate than that of control fish at doses of 10–30mgkg‐1. On the other hand, Fraction I was not effective at any dose. Chemical and physicochemical analyses revealed that Fraction II was sodium alginate with a high degree of purity, with a molecular weight of 45000 and an M/G ratio of 0.8. Some commercial alginates were similarly evaluated for their efficacy. Alginates from Macrocystis pyrifera (MW, 146000‐264000; M/G ratio, 0.9–1.0) significantly increased survival rate, but alginates from Lessonia nigrescens (MW, 177000–290000; M/G ratio, 1.3) had little effect. There are indications that the efficacy (protective effect) of alginates has some relationship to their M/G ratios.
Utilization of haem compounds by Aeromonas salmonicida
Authors: HIRST I. D. , HASTINGS T. S. , ELLIS A. E.
Published: April 2006

Abstract. The ability of A‐layer‐positi ve (A+) and A‐layer‐negative (A−) strains of Aeromonas salmonicida to utilize haem sources of iron under conditions of iron‐restriction was evaluated. In a plate bioassay, only A+ strains of A. salmonicida were able to utilize haem from a variety of sources including haem, haemin, myoglobin, haemoglobin, haemoglobin‐ haptoglobin and haem‐albumin complexes. Trypsin‐digestion of whole cells abolished haem‐ binding, indicating that binding was cell‐surface associated, involving a protein binding site or receptor. Competitive binding studies indicated that all haem compounds were bound by a common receptor, which was not iron‐regulated and was associated with the presence of the 49‐kDa A‐layer protein. The ability of both typical A+ (siderophore‐positive) and atypical A+ (siderophore‐negative) strains to utilize haem indicated that the mechanism of haem utilization was not siderophore‐mediated and that A. salmonicida possesses both siderophore‐dependent and siderophore‐independent mechanisms to overcome iron‐restricted conditions encountered in vivo.
Aeromonas salmonicida subsp. salmonicida: correlation of protein patterns, antibiotic resistance, exoprotease activity, haemolysis and pathological lesions produced in vivo
Authors: NIELSEN B. , DALSGAARD I. , BROWN D. J. , LARSEN J. L.
Published: April 2006

Abstract. A collection of 130 strains of the bacterial fish pathogen Aeromonas salmonicida subsp. salmonicida isolated from diseased salmonids in Denmark, Norway, North America and Scotland has been characterized with regard to protein patterns, antibiotic resistance and exoprotease activity. Whole cell and outer membrane protein profiling could distinguish three different profiles in A. salmonicida. Eight outer membrane proteins were demonstrated (49, 40, 38, 37, 33, 31, 30 and 29 kDa). One protein profile was deficient in a 38 kDa outer membrane protein and instead contained an outer membrane protein of 37 kDa which was not detectable among the other protein profiles. Strains with the 37 kDa outer membrane protein showed multiple low‐level antibiotic resistance towards cephalothin, penicillin, chloramp‐henicol, tetracycline and quinolones. In addition, these strains were exoprotease deficient. Strains with the 37 kDa protein were unable to degrade cattle and trout serum proteins and displayed a delayed degradation of casein. Haemolysis on cattle blood agar plates was similarly delayed. In vivo examination of extracellular products from a normal protein profile strain and one with the 37 kDa outer membrane protein demonstrated major differences in pathological effects in rainbow trout. The strain possessing the 37 kDa outer membrane protein produced almost no pathological effects while the normal protein profile strain produced typical furuncles.
An enzyme‐linked immunosorbent assay (ELISA) for the detection of antibodies against the pathogenic haemoflagellate, Cryptobia salmositica Katz, and protection against cryptobiosis in juvenile rainbow trout, Oncorhynchus mykiss (Walbaum), inoculated with a live vaccine
Authors: SITJA‐BOBADILLA A. , WOO P. T. K.
Published: April 2006

Abstract. An enzyme‐linked immunosorbent assay using dried blood on filter paper, was developed for the detection of antibodies against the haemoflagellate Cryptobia salmositica in juvenile rainbow trout, Oncorhynchus mykiss (Walbaum). Each fish (average weight about 5g) in three experimental groups was either inoculated with 20000 attenuated live C. salmositica vaccine, or inoculated with 2000 or 20000 pathogenic parasites per fish. The vaccine was effective in protecting juvenile trout 4 weeks after vaccination and antibody titers were higher in vaccinated and challenged fish than in unvaccinated and infected ones. Specific antibodies were detected one week post‐infection (w.p.i.) with the pathogen and declined to low levels at 6 w.p.i. The high‐dose group (20000 per fish) had antibody titres comparable to those of the vaccinated and challenged fish.
Antigenic analysis of reference strains and Norwegian field strains of aquatic birnaviruses by the use of six monoclonal antibodies produced against the infectious pancreatic necrosis virus N1 strain
Authors: MELBY H. P. , CHRISTIE K. E.
Published: April 2006

Abstract. Six monoclonal antibodies (MAbs) produced against the infectious pancreatic necrosis virus (IPNV) N1 strain were used in a dot‐blot assay to examine reference strains of the nine proposed serotypes and a representative selection of 81 Norwegian aquatic birnavirus isolates. These isolates had earlier been serotyped by use of a panel of 11 MAbs produced against other strains of IPNV. Correlations between the reaction patterns of the two panels of MAbs were found. All reference strains and field isolates shared two epitopes, one on VP2 and one on VP3. Seventy‐seven of the field isolates reacted identically with the N1 strain (positive with all six MAbs). The Sp type strain was positive with five of the MAbs and was different from all the field strains. The other reference strains (WB, VR299, Ab, Ja, Te, He, C1, C2 and C3) were positive with two to four of the MAbs. Together with previously published data, these findings indicate that most Norwegian isolates are closely related to, or identical with, the N1 strain and belong to the Sp serotype. No correlation between the health status of Atlantic salmon and antigenicity of the isolates was found. Testing of the reference strains in ELISA revealed some discrepancies with the dot‐blot results.
Pathology of attachment and vascular damage associated with larval stages of Dissonus manteri Kabata, 1966 (Copepoda: Dissonidae) on the gills of coral trout, Plectropomus leopardus (Lacépède) (Serranidae)
Authors: BENNETT S. M. , BENNETT M. B.
Published: April 2006

Abstract. Tissue responses in Plectropomus leopardus gills infested with Dissonus manteri copepodid and ehalimus larvae were almost entirely proliferative, with little or no cellular infiltration. The pathological changes were related to attachment, feeding and parasite size, and comprised progressive mechanical erosion, epithelial hyperplasia and fibrosis. When present, infiltrating cells were associated with initial attachment by the copepodid and with the frontal filament basal plate. Approximately 2.4% of the respiratory area was lost as a result of direct vascular damage. Disruption of branchial blood flow resulted from the burrowing and feeding activities of the larvae and compression of adjacent vessels as the parasite increased in size. Chalimus stages were attached by a frontal filament which consisted of a stem with a terminal anchor, and a basal plate in contact with the cartilaginous filament ray. Following chalimus release, the branchial tissue appeared to repair rapidly. No frontal filament remains were found.
Prevalence and pathogenicity of infectious pancreatic necrosis virus (IPNV) associated with feral lake trout, Salvelinus namaycush (Walbaum)
Authors: SHANKAR K. M. , YAMAMOTO T.
Published: April 2006

Abstract. A study was undertaken in 1987 to determine the prevalence of infectious panercatic necrosis virus (1PNV) infection in the lake trout population of Cornwall Lake. Alberta, Canada, and its pathogenicity to cultivable salmonid fish. Virological examination indicated that 44.4% of the adult lake trout in the lake, which is situated in a remote northern region of Alberta, were infected with the virus, mainly in the pyloric caeca and intestine. Virus was not detected in kidney, leucocytes, liver or gonads. In experimental immersion infection of brook trout fry, the virus caused a cumulative mortality of up to 74% in 30 days, beginning at 10 days post‐infection. Pyloric caeca, intestine and to some extent gills were found to be early sites of viral replication. The virus was less pathogenic to rainbow trout causing a cumulative mortality of 10% and the survivors were IPNV carriers for at least 3 months. The virus did not cause mortality in young lake trout, the natural host, but the infected fish carried the virus during the experimental period of 30 days.
Epitope analysis of infectious pancreatic necrosis virus (IPNV) isolated from lake trout, Salvelinus namaycush (Walbaum), by monoclonal antibodies
Authors: SHANKAR K. M. , YAM AMOTO T.
Published: April 2006

Abstract. A panel of 15 monoclonal antibodies (MAbs) were raised against infeetious panercretic mecrosis virus (IPNV) associated with lake trout.salvelinus namaycush (Walwaum). (LT‐IPNV) in Cornwall Lake Alberta, for LT‐IPNV epietope analysis and comparison with other Canadian IPNV isolates. All the MAbs reacted with IPNV VP2 polypeptide in western blot and 10 MAbs were neutralizing. Both conformation and sequence dependent epitopes were found to be present on the IPNV VP, protein. The antibodies reeognized different epitopes on VP, protein in reeiproeal bloeking ELISA. Twelve MAbs reeognized common epitopes present on LT‐IPNV and IPNV from Aretic char. Salvelinus alpinus (L.), (AC‐IPNV) in binding and neutralization assays. Three MAbs reacted only with LT‐IPNV indicating that it has distinct epitopes, and thus clerly differentiaing it from AC‐IPNV isolated from the adjacent Northwest Trritories.Only two MAbs bound to Ja and BCI‐IPNV isolate and none of the MAbs neutralized these two IPNV isolates. LT‐IPNV was found to be distinct isolate, more colosly related to AC‐IPNV and Canda ‐2 than to Ja‐IPNV from alberta or other isolates in Canda. Additionally, the panel of MAbs could differnciate all the propsed Canadian IPNV scrotypes, namely C1. C2. C3 and Ja.
Immunohistochemical characterization of malignant lymphoma in northern pike, Esox lucius L., from Estonian Baltic waters
Authors: BOGOVSKI S. , ROSSI L. , BOCCHINI V. , LASTRAIOLI S. , AIELLO C. , SANTI L.
Published: April 2006

Abstract. Twenty malignant lymphomas of northern pike, Esox lucius L., from the Baltic coast of Estonia were investigated immunohistochemically using rabbit anti‐human polyclonal antibodies against lysozyme (LYS), alpha‐1‐antichymotrypsin (ACT) and S‐100 protein. Based on the strongly positive reactions to LYS, ACT and S‐100 found in a great number of histiocytes, two of these tumours were classified as histocytic diffuse malignant lymphomas. Furthermore, the weaker positive reaction to these antibodies detected in some of the histocytes in 10 other cases of diffuse malignant lymphoma indicates their histocytoid‐lymphocytic origin. In addition, the lack of reaction to all antibodies used found in the remaining eight tumours, as well as their general morphological structure, allowed their diagnosis as lymphocytic diffuse malignant lymphomas. Thus, the immunohistochemical reactions to LYS, ACT and S‐100 served as a tool for precisely distinguishing between the different types of lymphomas as well as for better understanding their origin.
Brook charr, Salvelinus fontinalis (Mitchill), and cryptobiosis: a potential salmonid reservoir host for Cryptobia salmositica Katz, 1951
Authors: ARDELLI B. F. , FORWARD G. M. , WOO P. T. K.
Published: April 2006

Abstract. Laboratory‐raised Cryptobia‐susceptible brook charr, Salvelinus fontinalis (Mitchill), and rainbow trout, Oncorhynchus mykiss (Walbaum), were vaccinated intraperitoneally with a live Cryptobia salmositica vaccine (250000 parasites per fish), and 4 weeks later were challenged with the pathogen (250000 parasites per fish). Unvaccinated and infected brook charr had high parasitaemias but no clinical signs of disease, while unvaccinated and infected rainbow trout had anaemia and general oedema. Vaccinated and challenged fish had very low parasitaemias compared to unvaccinated and infected brook charr and rainbow trout. Complement fixing antibodies were detected in vaccinated and challenged fish 2 weeks after challenge. Unvaccinated and infected brook charr had consistently higher litres of complement fixing antibody than unvaccinated and infected rainbow trout. Parasitaemias were lower in all fish in which titres of complement fixing antibody were high. In a second experiment, brook charr inoculated intraperitoneally or intramuscularly with 100000 C. salmositica per fish had high parasitaemias but no anaemia or other clinical signs. The results show that susceptible brook charr do not suffer from cryptobiosis and may serve as reservoir hosts for C. salmositica in areas where the disease is prevalent. Vaccination to reduce the parasitaemia when fish become infected may be a control strategy in these areas.
Development of a cell line from primary cultures of rainbow trout, Oncorhynchus mykiss (Walbaum), gills
Authors: BOLS N. C. , BARLIAN A. , CHIRINO‐TREJO M. , CALDWELL S. J. , GOEGAN P. , LEE L. E. J.
Published: April 2006

Abstract. Collagenase was used to prepare primary cell cultures from rainbow trout, Oncorhynchus mykiss (Walbaum), gills. Although difficult to subcultivate, one primary culture led to the development of a cell line, RTgill‐W1. RTgill‐W1 grew in the basal medium, L‐15, supplemented with foetal bovine serum at between 5 and 10%, but not in L‐15 alone. The cells have been passaged approximately 50 times over a 4‐year period. At confluency, the cell shape was predominantly polygonal or epithelial‐like. RTgill‐Wl cultures were demonstrated by DNA staining with H33258 and by growth on agar to be contaminated with mycoplasma, but this contaminant was eradicated by treatment with mycoplasma removal agent (MRA) and BM cyclin.
Integumental damage caused by Dolops ranarum (Stuhlmann, 1891) (Crustacea: Branchiura) to Clarias gariepinus (Burchell), with reference to normal histology and wound‐inflicting structures
Authors: AVENANT‐OLDEWAGE A.
Published: April 2006

Abstract. The African catfish, C. gariepinus (Burchell), a candidate species for aquaculture in southern Africa, is frequently infested by the branchiuran ectoparasite Dolops ranarum. Normal integument, as well as damage caused by this parasite, is described by means of scanning electron microscopy and histology. Wound healing and the attachment and feeding mechanism of the parasite is described.
Use of cloned cDNA probes for diagnosis of infectious pancreatic necrosis virus infections
Authors: DOPAZO C. P. , HETRICK F. M. , SAMAL S. K.
Published: April 2006

Abstract. A dot‐blot hybridization test has been developed for the detection of infectious pancreatic necrosis virus (IPNV) in infected fish. For this purpose, cloning of the dsRNA of the West Buxton strain of IPNV was carried out. Two cDNA clones (WB and A4) were characterized for use as diagnostic probes and corresponded to IPNV genome segments A and B. respectively. Clone WB1, with an insert of 812 base pairs, showed an 87 and 77% nuclcotidc sequence homology with the corresponding sequences of Jasper and N1 strains, respectively. Clone A4, with an insert size of 596bp, presented a nuclcotidc sequence homology of 90 and 80% with the corresponding sequences of the Jasper and Sp strains, respectively. Both probes were able to detect 15 ng of purified dsRNA, and were highly efficient in detecting the RNA of American IPNV strains. However, the A4 probe was less effective than WB1 in hybridizing to RNA from European and Spanish strains of IPNV. Both probes detected IPNV RNA in cells 4–8h post‐infection with the homologous West Buxton strain, 8–12h post‐infection with other American strains and 24h post‐infection with the European strains of IPNV. The method was less sensitive in detecting IPNV RNA directly in infected fish tissues. However, the present authors obtained a 100% effectiveness to detect viral RNA in cells inoculated with fish tissues confirmed by conventional diagnostic methods as being infected with IPNV. Therefore, the hybridization test is appropriate if combined with conventional diagnostic procedures, e.g. applying the dot blot hybridization test on tissue cultures 12–24 h after inoculation with infected fish tissue homogenates.
Cultivation of Trypanosoma danilewskyi (Laveran & Mesnil, 1904) in serum‐free medium and assessment of the course of infection in goldfish, Carassius auratus (L.)
Authors: WANG R. , BELOSEVIC M.
Published: April 2006

Abstract. Purification and in vitro cultivation techniques were developed for the fish haemoflagellate, Trypanosoma danilewskyi. The parasites were isolated and purified from the peripheral blood of experimentally infected goldfish, using a combination of Ficolt‐paque gradient centrifugation to remove fish red blood cells and in vitro incubation to remove the remaining fish leucocytes. A serum‐free culture medium for T. danilewskyi supported both short‐ and long‐term cultivation of the haemoflagellates. The serum‐free medium is a mixture of reagents available commercially: Leibovitz's L‐15 medium, Dulbecco's Modified Eagle Medium and Hank's balanced salt solution. The doubling time was calculated to be 44.4 × 7.8h. Typically, a two‐ to five‐fold increase in the number of cultured parasites was observed on day 7 after subculture with 1 × 106 and 5 × 105 trypanosomes ml−1, respectively. When administered to fish, the in vitro‐derived parasites caused an infection and pathology whose characteristics were similar to those observed following infection with trypanosomes obtained from infected goldfish. The freshly isolated and in vitro‐grown parasites were successfully cryoprescrvcd in the culture medium containing 10% glycerine at −80°C for at least 3 months. Although the viability of the parasite decreased by 40–50% after thawing, cryoprcserved parasites retained the ability to infect goldfish.

Correspondence: Dr M. Belosevic, Associate Professor, Department of Zoology, CW‐312 Biological Sciences Building, University of Alberta, Edmonton, AB, Canada T6G 2E9.
Protection against carp erythrodermatitis following bath or subcutaneous exposure to sublethal numbers of virulent Aeromonas salmonicida subsp. nova
Authors: DALY J. G. , WIEGERTJES G. F. , VAN MUISWINKEL W. B.
Published: April 2006

Abstract. A bath challenge system was used to infect carp. Cyprinus carpio L., with Aeromonas salmonicida subsp. nova, the causative agent of carp cruthrodermatitis. Bath‐challenged fish became infected with the bacterium exihibitinng typical signs of the disease, Carp that were sublethally bath exposed became infected and exhibited some skin lesions, but after one week, these quickly healed and the animals fully recovered from the infection, Naive fish that had not been previously exposed to the bacterium had mortalities of 100% when infected by the subcutaneous route and 40–60% by the bath route of infection. Carp that received sublethal infections were able to withstand subsequent lethal infection and recover regardless of the route of infection. Sublethally bath‐exposed carp were protected from subsequently lethal challenges of A. salmonicida subsp. nova for at least 5 months.
Antigen retention and enzyme reactivity in the spleen of Atlantic salmon, Salmo salar L., following administration of injectable furunculosis vaccines
Authors: PRESS C. McL. , REITAN L. J. , LANDSVERK T.
Published: April 2006

Abstract. The retention of vaccine components and phenotypes of leucocyte populations were examined in the spleen of Atlantic salmon, Salmo salar L., 12 weeks after intraperitoneal administration of three different furunculosis vaccines. There were marked differences between the vaccine groups as judged by serum antibody response and survival following challenge with Aeromonas salmonicida. Abundant vaccine components were present in the spleen following administration of the two adjuvanted vaccines but not the non‐adjuvanted vaccine. The non‐adjuvanted group showed a disrupted pattern of silver staining in the splenic ellipsoids, suggesting possible toxic changes. Altered levels of enzyme reactivity in the spleens of vaccinated fish suggested activation of macrophages. Computer‐assisted morphometric analysis was used to demonstrate that a significant (P < 0.05) increase in acid phosphatase reactivity associated with the melanomacrophage accumulations only occurred in the group that had shown a good response to challenge (14% mortality when control group = 60%), and a high level of anti‐A. salmonicida antibodies. The findings of the present study suggest that the retention of antigen and the activation of macrophages in melanomacrophage accumulations of Atlantic salmon are of significance in vaccination against furunculosis.
Factors affecting outbreaks of epizootic ulcerative syndrome in farmed fish in Bangladesh*
Authors: AHMED M. , RAB M. A.
Published: April 2006

Abstract. Among 257 Bangladesh fish ponds investigated, 46% were affected by epizootic ulcerative syndrome (EUS) either fully or partially. Thai silver barb, Puntius gonionotus (Bleeker), culture ponds were worst affected (64%) by EUS, while all Nile tilapia, Oreochromis niloticus (L.), monoculture ponds remained unaffected. Stocking of silver barb for culture, use of piscicides as means of moving predators or unwanted species prior to stocking of cultured species, and culture of fish in previously derelict ponds are factors which significantly affected the probability of occurrence of EUS. Choice of species other than silver barb and use of lime during the post‐stocking period significantly affected the probability of pond stocks being less adversely affected by EUS.
Cryptocaryon irritans (Ciliophora): primary infection in thick‐lipped mullet, Chelon labrosus (Risso)
Authors: MATTHEWS R. A. , BURGESS P. J.
Published: April 2006

Abstract. Cryptocaryon irritans (Ciliophora), isolated from the reef fish, Grammistes sexlineatus Thumberg, was established as primary infections in mullet, Chelon labrosus (Risso). Only a small percentage (<22%) of exposed theronts established infection under controlled conditions. This is discussed in relation to the probability of host parasite contact and susceptibility. There was no evidence of density‐dependent or intra‐specific competition in trophont establishment, a strong linear relationship being found between the levels of exposure and infection. Infection intensity was assessed in relation to host survival, indicating a 90% probability of host death following levels of >200 trophonts per gram of host. A close temporal association between host death and trophont exit was found, possibly as a result of epidermal disruption leading to dysfunction of osmoregulatory and respiratory systems.
A comparison of the effect of silicone coated ascorbic acid and ascorbyl phosphate on the course of ichthyophthiriosis in rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: WAHLI T. , FRISCHKNECHT R. , SCHMITT M. , GABAUDAN J. , VERLHAC V. , MEIER W.
Published: April 2006

Abstract. The aim of the present study was to compare the effect of high and low doses of different vitamin C formulations on the course of ichthyophthiriosis (Ichthyophthirius multifiliis infection) in rainbow trout. After a depletion period, trout fingerlings were fed diets deficient in vitamin C(AA 0), or containing different levels of silicone coated ascorbic acid (AA; 50/200 mg kg feed−1) or ascorbyl phosphate (AP; 50/2000 mg AA equivalent kg feed−1). Fish infected with I. multifiliis demonstrated a significant reduction in mortality when fed high levels of AA or AP. A correlation between the parasite burden and the vitamin C content in the diet was not found. Specific immunity—measured as immobilization litre of sera—was not influenced by the level or the formulation of vitamin C in the diet. The most probable mechanism of high level doses of vitamin C is an increase of the general health status expressed as an improved nonspecific resistance and ability to cope with different stressors. In rainbow trout infected with I. multifiliis, the beneficial effect of ascorbyl phosphate is equal to that of silicone coated ascorbic acid, and therefore, the more stable AP may be a valuable alternative for use in fish diets.
Effect of buffers on the gill structure of common carp, Cyprinus carpio L., and rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: KANTHAM K. P. L. , RICHARDS R. H.
Published: April 2006

Abstract. The effects of phosphate and tris buffers on the gill structure of common carp, Cyprinus carpio L, and rainbow trout, Oncorhynchus mykiss (Walbaum), were investigated. Common carp maintained in phosphate‐buffered (a combination of sodium di‐hydrogen phosphate and di‐sodium hydrogen phosphate at a final concentration of 0.01 m) standard dilution water for a period of 8 days developed severe pathological changes in the gill tissues, while carp maintained in tris‐buffered (0.01 m) dilution water and trout subjected to either of these buffers showed no such changes. Histological changes in the gills of carp exposed to phosphate buffered dilution water included an extensive mucous cell proliferation on the lamellar and filarnental epithelium, and an increased infiltration of eosinophilic granular cells into the gill tissues. A moderate epithelial hyperplasia and an increase in the chloride cell densities on the gill epithelia were also noted. The implications of these findings on the widely accepted practice of the use of phosphate salts and various other buffers in pH control of experimental water are highlighted.