bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of environmental conditions on the infectivity of Flexibacter columnaris to fish
Authors: WAKABAYASHI H.
Published: April 2006

Abstract. Columnaris disease, Flexibacter columnaris infection, was first described in North America. Recent publications indicate that its distribution is worldwide. Both warmwater and coldwater fish are infected with F. columnaris. All freshwater fish are probably susceptible to the disease under environmental conditions favourable to the bacterium and stressful to the fish. Flexibacter columnaris cannot tolerate sea water. Generally, outbreaks occur when the average water temperatures reach 15°C. The bacterium apparently enters the fish through the skin and gills. The swarms of bacteria involved give the lesions a characteristic yellow pigmentation. The external lesions destroy the skin, muscle and gill tissues. It is relatively easy to isolate the bacteria from the internal organs of the diseased fish, but there is no evidence of internal tissue damage. In this short review, emphasis is placed on several factors relative to water environment which play a role in the development of outbreaks of columnaris disease:

The optimum temperature for an outbreak of F. columnaris infection is thought to be between 20 and 30°C. Mortalities seldom occur at temperatures below 15°C, although highly virulent strains can kill fish at lower temperatures.

Flexibacter columnaris can survive longer in water of normal to high hardness, as well as in water containing small amounts of sodium, potassium, calcium or magnesium salts, but it cannot live in sea water.

Flexibacter columnaris grows well on paniculate fish feeds so that such deposits in the water may act as reservoirs of infection.

An important source of infection is feral fish. In the Columbia River or the Fraser River, resident coarse fish such as suckers, Catostomus spp., are thought to transmit the infection to returning adult salmon.

Flexibacter columnaris fails to invade fish in the presence of competitive bacteria like Citrobacter freundii when its initial numbers are approximately one in a 100 less than those of the competitors.

Crowding seems to be not only a stressor for fish, but also a factor that increases the chance of adhesion of F. columnaris to the external tissues of fish.
Biochemical and physiological characteristics and plasmid profiles of Aeromonas hydrophila strains, isolated from freshwater fish and from fresh water
Authors: NOTERDAEME L. , BIGAWA S. , WILLEMS K. A. , OLLEVIER F.
Published: April 2006

Abstract. Twenty‐five Aeromonas hydrophila strains, isolated from freshwater fish and from freshwater samples were identified, using API 20NE and CH50. They were screened for the one plasmid (20 kb), and a third group (four strains) contained two or three plasmids. A 20 kb plasmid was common to all plasmid‐positive strains. Although their plasmid profile differs, all groups are very similar with regard to their biochemical and physiological characterization. However, the differences observed using clustering can be explained by characteristics, some of which have been reported as virulence associated. No relationship between these factors and the presence of plasmids is found. The possibility of differentiating A. hydrophila strains on the basis of biochemical characteristics using a cluster analysis is considered.
Aeromonas salmonicida in Finland: pathological problems associated with atypical and typical strains
Authors: RINTAMÄKI P. , VALTONEN E. T.
Published: April 2006

Abstract. Aeromonas salmonicida was studied at fish farms producing salmonid smolts in northern and central Finland from 1982 onwards. Aeromonas salmonicida subsp. salmonicida has been causing epizootics in salmon, Salmo salar L., and trout, S. trutta L., at two coastal farms in northern Finland sinee 1986, involving 1–29% mortality in the fish‐rearing units affceted. The disease causes more serious losses of sea trout yearlings and brood fish than of salmon. The achromogenic atypical A. salmonicida proved to be the most common bacterial disease in brown and sea trout at one farm in northern Finland throughout the period, causing constant heavy losses, mainly of fingerlings, especially in 1982–1986. It was found only occasionally in central Finland. Pigment‐producing atypical A‐ salmonicida caused mortality among brown trout at one farm in northern Finland and one in central Finland.
The use of API 20E for the identification of Vibrio anguillarum and V. ordalii
Authors: GRISEZ L. , CEUSTERS R. , OLLEVIER F.
Published: April 2006

Abstract. Sixty‐eight strains of Vibrio anguillarum, five of V. ordalii and the type strains of V. alginolyticus, V. carchariae, V. damsela and V. parahaemolyticus were compared using the API 20E gallery. Within the V. anguillarum strains, distinct groups could be separated mainly on the basis of their reaction on indole production and the fermentation of amygdalin and arabinose. Vibrio ordalii, the former V. anguillarum biotype 2, could easily be separated from V. anguillarum and from the other fish pathogenic Vibrio spp.
Analysis of protective mechanisms in cultured ayu, Plecoglossus altivelis Temminck and Schlegel, administered Vibrio vaccine by the immersion method
Authors: KITAO T. , ESHIMA T. , YOSHIDA T.
Published: April 2006

Abstract. The protective effect of Vibrio angnillarum immunization administered by the direct immersion technique in ayu, Plecoglossus altivelis Temminck and Schlegel, was investigated. The activities of phagoeytic cells were suppressed at the time of vaccination by previous bath exposures to a cyclophosphamide solution containing a concentration of 500 mg/kg/ml on days 2 and 3 before vaccination. An artificial challenge was carried out 3 weeks after vaccination by bath exposure. The survival rate of the vaccine group pretreated with cyclophosphamide was 96%. In the group given traditional vaccine only, 73% survived; and in the non‐vaccine control group, 10% survived. These results suggest that protective immunity of ayu vaccinated by the direct immersion technique may not implicate the early activities of phagoeytic cells.
Vibrio bacteria isolated from black tiger shrimp, Penaeus monodon Fabricius
Authors: RUANGPAN L. , KITAO T.
Published: April 2006

Abstract. Two hundred and five isolates of Vibrio bacteria were obtained from diseased black tiger shrimp, Penaeus monodon Fabricius, cultured in Thailand during the period from February 1988 to January 1990. Ninety‐six isolates of the bacteria were identified as Vibrio parahaemolyticus. The others included 74 isolates of V. vulnificus, 18 isolates of V. alginolyticus, six isolates of V. fluvialis and 11 isolates of Vibrio spp. Comparisons of some characteristics of the bacteria studied are given.
Do extracellular products of Aeromonas salmonicida induce thrombosis by entering the fish coagulation system at factor X?
Authors: SALTE R. , NORBERG K. , ØDEGAARD O. R.
Published: April 2006

Abstract. Thrombosis of minute vessels is a common feature of acute furunculosis in Atlantic salmon. Crude extracellular products (F.CP) of Aeromans, salmonicida injected into the dorsal aorta of cannulated fish elicited an activation of the coagulations systems of the fish When screened with a number of chromogenic substrates, the ECP protease revealed a factor‐X like activity. Thus, it may he hypothesized that the ECP induces thrombosis by entering the fish coagulation systems at factor X. and that thrombus formation is a way of creating a site of infection.
Protection of turbot, Scophthalmus maximus (L.), and rainbow trout, Oncorhynchus mykiss (Richardson), against vibriosis using two different vaccines
Authors: SANTOS Y. , BANDIN I. , NUÑEZ S. , GRAVNINGEN K. , TORANZO A. E.
Published: April 2006

Abstact. The potency of a whole‐cell bacterin (WCB) and a toxoid enriched whole‐cell vaccine (WCEB) administered intraperitoncally into rainbow trout, Oncorhynchus mykiss (Richardson), were compared. The most effective vaccine was further evaluated by bathing turbot, Scophthalmus maximus (L.). These vaccines were composed of three strains of V. anguillarun, of the serotypes 01 and 02. Both vaccines conferred the highest protection against strains of serotype 01 within 4 weeks. With the toxoid enriched vaccine giving the best results (77 RPS). When trout were revaccinated after 7 weeks with this vaccine, good protection was achieved against strains of serotypes 01 and 02. Interestingly, when the WCEB was administered by bath to turbot, acceptable levels of protection against strains of both serotypes were obtained after 4 weeks of immunization.
Identification of cultured Aeromonas salmonicida by an indirect dot blot immunoassay
Authors: BERNOTH E.‐M.
Published: April 2006

Abstract. A method is described which improves both the specificity and paracticability of immune identification of Aeromonas salmonicida. The modified assay employs antisera raised against outer membrane proteins (OMP) of A. salmonicida cells and is carried out as a dot blot test on nitrocellulose membranes. Performance of the test with 55 non‐A. salmonicida bacterial isolates from fish and water revealed weak cross reactivity in five cases. However, these cross reactive only occur at very high antigen concentrations and can be overcome by adequate dilution.
Towards strategic use of fungicides against Saprolegnia parasitica in salmonid fish hatcheries
Authors: WILLOUGHBY L. G. , ROBERTS R. J.
Published: April 2006

Abstract. The life‐cycle of Saprolegnia parasitica was considered in relation to the use of protective fungicides against it in salmonid fish hatcheries. Malachite green oxalate was the example fungicide, and all experiments were at 10°C. If the fungicide is to be used as a continuous addition to the water, as a protectant, then target stages of the fungus are identified as zoospores and secondary zoospore cysts: the latter, although physically sedimentary, have a remarkably high degree of buoyancy in the water and hence pose a constant threat to the fish. Continuous addition to the water, to give 0·25 mgl−1 malachite green oxalate, would be expected to kill zoospores and zoospore cysts, but 0·05 mgl−1, while allowing zoospore cyst germination, was a strong inhibitor to fungal growth and, aided by natural defences of the fish, might well succeed in disease prevention. If the fungicide is to be used as an intermittent addition to the water (every 24 h), then target stages of the fungus are small mycelia on the fish in addition to zoospores and zoospore cysts in the water. An experimental model was made to consider the vulnerability of these small mycelia, growing on the fish over the preceding 24 h, to malachite green oxalate. If mycelia are of narrow diameter, as expected, then 0·25 mgl−1 malachite green oxalate, applied for 15 min, should control their growth and protect the fish.
Serratia marcescens: a potential pathogen for fish
Authors: BAYA A. M. , TORANZO A. E. , LUPIANI B. , SANTOS Y. , HETRICK F. M.
Published: April 2006

Abstract. Characterization of a red pigmented enterobacterium isolated from natural population of white perch, Morone americanus (Gmelin), during the course of a bacteriological survey in the Back River (Baltimore, Maryland, USA) indicated that the bacterium belonged to the species Serratia marcescents. The virulence properties of this isolate (RB 469), studied in comparison with the reference strain of S. marcescens ATCC 1800 and S. plymuthica K1R, revealed that all the strains were highly pathogenic for fish with LD50s raging from 5 × 103 to 1 × 105. Similarly, te extracellular products (ECP) from the three isolates were lethal for fish (LD50 ranging from 0·22 to 4·8 μg protein g‐1 fish). However, only ECP from strains with strong proteolytic activity (the white perch isolate and S. plymuthica) were cytotoxic for both in fish and homoiothermic cell cultures and both activities were completely destroyed by heating at 100°C for 10min. In contrast, only the two S. marcescens strains which possessed phospholipase active were pathogenic for mice and produced enterotoxins. None of the Serratia strains displayed dermonecrotic factor in rabbits. All these lindings indicate that a direct relationship between eytotoxicity and virulence cannot be established.
Siderophores produced by Vibrio anguillarum in vitro and in infected rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: MACKIE C. , BIRKBECK T. H.
Published: April 2006

Abstract. Ten strains of Vibrio anguillarum produced three different types of iron‐binding compounds when cultured under different conditions. These were (1) a common phenolate siderophore produced by all strains. (2) a hydroxamate siderophore produced by three strains and (3) a second phenolate siderophore, tentatively identified as anguibactin, produced by V. anguillarum strain 775 and two other strains, all of which contained a plasmid of 45–50 Md. The relative affinities of these siderophores, determined by competition for 55Fe was: anguibactin < hydroxamate siderophore < common phenolate siderophore. However, under these conditions, none removed iron from purified aerobactin. Experimental infection of rainbow trout. Oncorhynchus mykiss (Walbaum), showed that only the common phenolate siderophore was detected in the kidney and spleen of fish infected with strains 91079 and NCIMB6. The hydroxamate siderophore produced in vitro by strain NCIMB6 was not detected in vivo. However, in the kidney of fish infected with strain 775, both the common phenolate siderophore and anguibactin were detected, showing that a second uptake system is required by strain 775 in vivo and that the iron‐uptake system based on the common phenolate siderophore is defective.
Study on the pathogenicity of Nocardia asteroides to the Formosa snakehead, Channa maculata (Lacepède), and largemouth bass, Micropterus salmoides (Lacepède)
Authors: CHEN S.‐C.
Published: April 2006

Abstract. The Formosa snakehead, Channa maculata (Lacepède), and the largemouth bass, Micropterus salmoides (Lacepède), were given an intraperitoneal (i.p.) and/or intramuscular (i.m.) inoculation of Nocardia asteroides isolated from cultured Formosa snakehead, Typical granulomatous lesions induced by the experimental fish were similar to the naturally infected cases. The Formosa snakehead showed 100% and 93% mortality at 14 and 35 days after i.m. inoculation with 8 mg and 0·8 mg of bacterial suspension, respectively. The largemouth bass was slightly resistant to N. asteroides but still had 95% mortality at 35 days after inoculation (i.m.) with 8 mg bacterial suspension. The bacteria were easily reisolated from spleen and kidney of the experimental fish. Many typical multifocal granulomata were found at the sites of injection and the internal organs such as liver, spleen, kidneys, pancreas, intestine, gills, eyes and brain. The result indicated that the N. asteroides isolated from the field ease was pathogenic to Formosa snakehead and largemouth bass.
Development of monoclonal antibodies for the rapid identification of epizootic Vibrio species
Authors: HANNA P. J. , ALTMANN K. , CHEN D. , SMITH A. , COSIC S. , MOON P. , HAMMOND L. S.
Published: April 2006

Abstract. A library of monoclonal antibodies has been developed for use in rapid diagnosis of Vibrio infecftions. It covers the Vibrio Species that are regarded as the major fish and shellfish pathogens, many of which are also human pathogens. Blind tests confirm the accurary of the monoclonals as a diagnostic test. Conjugation of enzyme lable onto the monoclonals is providing rapid identification of Vibrio species by use of direct, rather than indirect, immunological testing.
The A‐layer protein of Aeromonas salmonicida: further characterization and a new isolation procedure
Authors: BJØRNSDOTTIR R. , EGGSET G. , NILSEN R. , JØRGENSEN T. Ø
Published: April 2006

Abstract. The predominant cell surface protein (A‐protein) of Aeromonas salmonicida has been purified by a method utilizing a glycine/hydrochloridc extraction from whole cells and HPLC/ion exchanger (DEAE) columns. This procedure yielded two LPS‐frec molecules (a 40‐ and a 50‐kDa form) both shown to contain A‐protein determinants. The former appears to be a digest product of the latter, as a serine protease produced by A. salmonicida was shown to process the 50‐kDa form into a 40‐kDa molecule in vitro. The A‐layer protein was shown to contain one isoform, although multiple isoelectric forms appeared as preparative artifacts, probably due to deamidation. The A‐layer protein and LPS arc the most significant surface antigens recognized by the Atlantic salmon B‐lymphocytes or antibodies. Immunological studies of LPS‐free and LPS‐containing A‐protein preparations were undertaken to test whether the two components behave like antigenie competitors or whether the LPS moiety could adjuvant the antibody response against the A‐protein. The latter was shown to be the case.
Occurrence and pathogenicity of Yersinia ruckeri at fish farms in northern and central Finland
Authors: VALTONEN E. TELLERVO , RINTAMÄKI P. , KOSKIVAARA M.
Published: April 2006

Abstract. Salmonid fish at fish farms in northern and central Finland and perch, Perca fluviatilis L., roach, Rutilus rutilus (L.), and whitefish, Coregonus sp., from four lakes in central Finland were studied between 1985 and 1990 for the occurrence of Yersinia ruckeri. The bacteria were found in fish from both areas, but in most cases, only single diseased salmon, Salmo salar L., brown trout, S. trutta L., rainbow trout, Oncorhynchus mykiss (Walbaum), whitefish and perch were encountered and were always connected with stress conditions. One clinical outbreak occured in salmon fingerlings in northern Finland, and the fish were successfully treated with trimethoprim‐sulpha. Monthly monitoring of lake fish revealed two symptomless carrier perch in two lakes. Outwith the main study a moribund perch with yersiniosis was found in a polluted lake, and for the first time in Finland, a rainbow trout was also found to have contracted yersiniosis in a small private pond. Sorbitol‐positive and negative isolates have been found to occur in both moribund and carrier farmed fish, indicating that the sorbitol test is not essential when evaluating the pathogenicity of Y. ruckeri.
Aphanomyces species associated with red spot disease: an ulcerative disease of estuarine fish from eastern Australia
Authors: FRASER G. C. , CALLINAN R. B. , CALDER L. M.
Published: April 2006

Abstract. Broad, non‐septate, fungal hyphae are a constant finding in the necrotising dermatitis lesions and dermal ulcers characteristic of red spot disease. During a one‐year period, fungi with hyphae morphologically consistent with those seen in histological sections of lesions were recovered from 27 out of 28 lesions on sea mullet, Mugil cephalus L., yellowfin bream, Acanthopagrus australis (Owen), and sand whiting, Sillago ciliata Cuvier, collected from three widely separated river systems in eastern Australia. Cultural and morphological characteristics, including spore formation, of 24 of these isolates were examined. In addition, tolerances to different salinities, growth on different media and growth at different temperatures were studied for three representative isolates, one from each species of fish. These studies suggest that all isolates belonged to a single species within the genus Aphanomyces. Their role in the pathogenesis of red spot disease, and their relationship with other Aphanomyces spp. affecting fish, is discussed.
Cytotoxin elaboration by Aeromonas hydrophila isolated from fish with epizootic ulcerative syndrome
Authors: YADAV M. , INDIRA G. , ANSARY A.
Published: April 2006

Abstract. Twenty‐eight strains of A. Hydeophila, 18 from fish with epizootic ulcerative syndrome (EUS) and 10 from apparently normal fish, were examined for their ability to produce cylotoxins and haemolysins. Bacterial culture supernantants were tested for cytotoxin elaborated using the visual cell damage technique and a novel clorimetric method. Two types of target cells were used and the WEHI cells were reproducibly more sensitive than Vero cells in both the cytotoxin assays. Cytotoxin‐producer strains were more frequently associated with EUS‐infected fish compared to normal fish. Haemolysin‐producing strains were equally present in healthy and EUS‐positive fish, and the haemolysin was not correlated with cytotoxin production. It appears that the progression of pathogenicity of EUS may be linked with the presence of cytotoxic strains of A. hydrophila in the EUS lesions.
Reduced sensitivity of the salmon louse, Lepeophtheirus salmonis, to the organophosphate dichlorvos
Authors: JONES M. W. , SOMMERVILLE C. , WOOTTEN R.
Published: April 2006

Abstract. Anecdotal reports from the Scottish fish farming industry suggested a reduction in the sensitivity of salmon lice, Lepeophtheirus salmonis, to the organophosphate dichlorvos. In this study, pro‐adult and adult lice were collected from marine salmon sites showing a variety of ‘sensitivities’ to dichlorvos and subjected to dichlorvos exposure at a range of doses for a 48‐h period in vitro. From the lice mortalities, 24 and 48 h LC50 values were calculated, and using a ‘sensitive’ source of lice as a reference, resistance ratios calculated. The data generated suggests that L. salmonis from different geographic areas shows differences in sensitivity to dichlorvos. The implications for the salmon farming industry are discussed.
Comparative in vitro studies on virulent and avirulent strains of Cryptobia salmositica (Sarcomastigophora: Kinetoplastida)
Authors: WOO P. T. K. , THOMAS P. T.
Published: April 2006

Abstract. The optimum temperature for in vitro multiplication of Cryptobia salmositica was 10°C. The avirulent strain multiplied more rapidly than the virulent strain. The haemolytic components, lytic component (LC) and immune complex‐forming component (ICC), were secreted by the two strains into the culture medium and were detectable from one week post‐inoculation. The haemolytic activity in the supernatant increased with increasing parasite numbers in both strains. Although cultures of the avirulent strain had higher parasite numbers than those of the virulent strain, the haemolytic activity was significantly lower than that of the virulent strain. Antiserum against ICC was produced in rabbit by immunization with ICC‐coated rainbow trout red blood cells.
Virulence of infectious pancreatic necrosis virus is associated with the larger RNA segment (RNA segment A)
Authors: SANO M. , OKAMOTO N. , FUKUDA H. , SANEYOSHI M. , SANO T.
Published: April 2006

Abstract. Infectious pancreatic necrosis virus (IPNV) contains two segments of double‐ stranded RNA (the larger RNA segment, A; and a smaller RNA segment, B). The IPNV‐ Buhl isolate belongs to the VR299 serotype, and eel virus European (EVE) is serologically the same as the Ab serotype. IPNV‐Buhl is virulent to rainbow trout fry, Oncorhynchus mykiss (Walbaum), whereas EVE is avirulent. To determine the genetic basis for the difference of the virulence, intertypic reassortants were made between IPNV‐Buhl and EVE. The reassortants with the genotypes of P/E (segment A of IPNV‐Buhl and segment B of EVE) and E/P (segment A of EVE and segment B of IPNV‐Buhl) were studied for their pathogenicity to rainbow trout fry. The P/E reassortant was highly virulent, similar to the IPNV‐Buhl parent (P/P), while the E/P reassortant was avirulent, as was the EVE parent (E/E). A high level of viral replication was observed in almost all organs of the fry infected with the P/E reassortant and the IPNV‐Buhl parent. In contrast, viral replication was restricted to the epidermal cells of the fry infected with the E/P reassortant and the EVE parent. The results demonstrate that the larger RNA segment (RNA segment A) of IPNV is related to cell tropism in vivo and is responsible for virulence in rainbow trout fry.
Glucan administration potentiates immune defence mechanisms of channel catfish, Ictalurus punctatus Rafinesque
Authors: CHEN D. , AINSWORTH A. J.
Published: April 2006

Abstract. Intraperitoncal injection of β‐l,3 glucan in channel catfish, Ictalurus punctatus Rafinesque, greatly reduces mortality from experimental infection with Edwardsiella ictaluri. Anterior kidney phagocytes from fish receiving glucan had enhanced phagocytic and bactericidal ability. The elevated bactericidal ability of phagocytes was not accompanied by increased production of hydrogen peroxide. Fish injected with glucan responded to subsequent E. ictaluri immunizations with higher serum antibody titres relative to the control catfish. The timing of glucan administration and antigen immunization was also important. These results indicate that β‐1,3 glucan potentially could be utilized prophylactically as an immunomodulator in channel catfish.
Experimental transmission per os of microsporidiosis due to Vavraia parastacida in the marron, Cherax tenuimanus (Smith), and yabby, Cherax albidus Clark
Authors: LANGDON J. S. , THORNE T.
Published: April 2006

Abstract. The possibility of oral transmission of the pleistophorid microsporidian parasite Vavraia parastacida Langdon from marron, Cherax tenuimanus (Smith), was investigated by feeding infected marron and yabby, Cherax albidus Clark, muscle to juvenile marron and yabbies. Infections were established in a proportion of marron and yabbies with tissue from both crayfish, and both mounted a vigorous haemocytic response which failed to arrest progress of the disease. The disease appeared to progress more rapidly in the yabbies, in which no natural cases have been found. It would appear inadvisable to mix marron and yabbies on crayfish farms unless the marron are first demonstrated to be free of the parasite. As an intermediate host is not essential to transmission, which can occur through cannibalism, the exclusion of possible vectors will not control vavraiasis on crayfish farms, It remains possible that an alternate life cycle involving intermediate or transport hosts also takes place.
Attachment of Vibrio pathogens to cells of rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: CHEN D. , HANNA P. J.
Published: April 2006

Abstract. The attachment of Vibrio pathogens to cells of rainbow trout, Oncorhynchus mykiss (Walbaum), was studied by use of species‐specific monoclonal antibodies and indirect FITC‐ immunofluorescence microscopy. Vibrio anguillarum, V. ordalii and V. parahaemolyticus attached to cultured cells of rainbow trout gonads, various tissues of cryostat sections of whole fish, and smears of gills, intestine, buccal mucosa and skin. The attachment was inhibited by prior incubation of bacteria with monoclonal antibodies at titres of 1:32, or less. Other Vibrio pathogens used in this study did not attach to any trout cells. The research provides approaches to study the mechanisms of bacterial attachment in the onset of Vibrio infections.
Development of monoclonal antibodies to PK‘X’, the causative agent of proliferative kidney disease
Authors: ADAMS A. , RICHARDS R. H. , DE MATEO M. MARIN
Published: April 2006

Abstract. Two monoclonal antibody probes were produced against PK'X’ cells. The parasites were partially purified by filtration and centrifugation of kidney tissue from rainbow trout with proliferative kidney disease and used as antigen for immunization of mice. The resulting monoclonal antibodies reacted with PK'X’ cell antigens in enzyme‐linked immunosorbent assay and immunohistochemistry tests. One antibody (Mab 12) appeared to be specific for PK'X’in kidney tissue, while the other (Mab 18) cross‐reacted with host cell antigens in the kidney tubules. These probes are invaluable tools for the investigation of parasite surface antigens and life cycle studies.
The histopathology associated with the pre‐adult and adult stages of Lepeophtheirus salmonis on the Atlantic salmon, Salmo salar L.
Authors: JÓNSDÓTTIR H. , BRON J. E. , WOOTTEN R. , TURNBULL J. F.
Published: April 2006

Abstract. Atlantic salmon, Salmo salar L., infected with the pre‐adult and adult stages of Lepeophtheirus salmonis were obtained from sea loch cage sites on the west coast of Scotland, and infection experiments were carried out in the laboratory. The motile parasites were retained at the point of attachment by prefixation with cooled alcohol. They were studied using light and scanning electron microscopy. Lepeophtheirus salmonis were found to leave an oval‘imprint’ corresponding to the margin of the parasite cephalothorax on the host skin and/or to wedge under its scales. General pathological changes including oedema, hyperplasia, sloughing of cells and cellular inflammation were observed in the host at and around the point of feeding and attachment. In gross lesions, serious damage occurred to the host epidermis with scale loss and haemorrhage a common feature. The most obvious changes were associated with the louse mouthtube, marginal membrane, second antenna, maxilliped and sternal furca.
Environmental factors influencing the prevalence of a cutaneous ulcerative disease (red spot) in the sea mullet, Mugil cephalus L., in the Clarence River, New South Wales, Australia
Authors: VIRGONA J. L.
Published: April 2006

Abstract A cutaneous ulcerative disease (red spot) in sea mullet, Mugil cephalus L., from the Clarence River, New South Wales, Australia, was first reported in 1972. In this study, reports of disease outbreaks have been compared with rainfall and river flow records for the period from 1972 to 1988. Detailed disease prevalence, rainfall, river flow and water quality data were compared for the period from 1985 to 1988. Significant correlations between weekly rainfall in the lower catchment and the prevalence of early stage lesions have been found. Progression to later stages of the disease occurred after rainfall and high river flows, which also caused rapid changes in various water‐quality characteristics such as salinity, temperature, dissolved oxygen, pH and turbidity. Organochlorine insecticide residues were not found to be associated with the disease in this area. The rainfall record since 1902 does not explain the absence of earlier reports of the disease. It is postulated that extensive structural developments for flood mitigation purposes and the increase in agricultural cultivation in the lower Clarence catchment during the last 20 years may be factors associated with the onset of the early stage of red spot disease. Fish in this early stage of the disease may then develop dermal ulcers under the stressful river conditions typically present during the autumn (high rainfall) season.
The significance of myxosporean infections in roach, Rutilus rutilus L., in different habitats
Authors: ATHANASSOPOULOU F. , SOMMERVILLE C.
Published: April 2006

Abstract. Two Myxobolus species, M. pseudodispar and M. ellipsoides, and two Myxidium species, M. rhodei and M. pfeifferi, were found in roach, Rutilus rutilus L., from three different locations in northern Greece, northern England and Scotland. Their prevalence, distribution in the host and pathology were studied. In the ease of M. rhodei, the pathological changes were quantitatively evaluated by computer‐based image analysis, and the results expressed in terms of area and volume of organs affected. The pathology of M. pfeifferi was associated with trophozoites in the bile duets and the infection ranged from mild to severe. In the severe eases, degeneration of duetal mucosa sometimes progressed to focal hepatitis. Myxidium rhodei was found in the kidneys as large cysts containing mature and immature spores (Type A cysts), and less often, in the form of small concentric cysts (Type B) which contained no obvious spores but which were characterized by a marked host response giving the appearance of focal granulomas. Type A cysts were also found in liver and spleen, and Type B cysts in the heart. Trophozoites of M. rhodei were observed in only a few eases and occurred in enlarged renal corpuscles in which the capillary tuft was atrophied and compressed. The pathology of M. rhodei was significant due to the enlargement of glomeruli from four to seven times their normal size and with an estimated increase in volume of 54 to 78 times. In addition to the functional damage to the glomeruli, there was also damage of the surrounding interstitial tissue and tubules as a result of the pressure from these enlarged glomeruli. The two myxobolid species were considered to be mainly specific to the kidney with no serious pathology in this organ, but caused significant pathology in the muscles (M. pseudodispar) and gills (M. ellipsoides).
Monoclonal antibodies against the structural proteins of viral haemorrhagic septicaemia virus isolates
Authors: SANZ F. , BASURCO B. , BABIN M. , DOMINGUEZ J. , COLL J. M.
Published: April 2006

Abstract. Five VHSV isolates from different host species and Spanish geographical locations and three viral haemorrhagic septicaemia virus (VHSV) international reference serotypes (F1, F2 and 23˙75) were studied by several characterized monoclonal antibodies (MAbs) including a neutralizing MAb to four structural proteins of VHSV. We report here the lack of reaction between anti‐M1 and some of the isolates of VHSV and the homogeneity of most of the isolates with respect to the MAbs tested. The reagents obtained will improve diagnostic tests which currently use polyclonal antibodies.
Vaccination of channel catfish, Ictalurus punctatus (Rafinesque), by immersion and oral booster against Edwardsiella ictaluri
Authors: PLUMB J. A. , VINITNANTHARAT S.
Published: April 2006

Abstract. A commercially prepared vaccine against Edwardsiella ictaluri was used to vaccinate 12‐day‐old channel catfish fry by immersion, or by immersion plus an oral booster 2 months later. One month after the fish were fed the booster vaccine, they were challenged by waterborne exposure to 2·1 × 106 cells ml−1 of E. ictaluri. Immersion only vaccinated fish suffered 6·7% mortality and immersion plus oral‐boosted fish had a 3·3% mortality. Mortality among non‐vaccinated controls was 96·7% and was significantly (P < 0·01) above the vaccinated mortality. The relative per cent survival for the immersion‐only fish was 93·1, while it was 96·6 for the immersion plus oral‐boosted fish. Agglutinating antibody titres of the vaccinated fish were significantly (P < 0·05) higher than the control fish. When the ponds were drained 6 months after stocking, 42·7% of non‐vaccinated, 56·3% of immersion‐only and 70·8% of immersion plus oral‐boosted fish were harvested. Survival of immersion plus orally‐boosted fish was significantly (P < 0·05) higher than the controls of immersion‐only fish. Duplicate populations of immersion plus oral‐booster‐vaccinated fish grew 34% and 56% faster, respectively, on an average daily gain than the control fish, while immersion‐only fish in one pond grew 20% less per day and fish in the second pond grew 48% faster.
Glycerophospholipid:cholesterol acyltransferase complexed with lipopolysaccharide (GCAT‐LPS) of Aeromonas salmonicida produces lysophospholipids in salmonid red cell membranes: a probable haemolytic mechanism
Authors: RØSJØ C. , SALTE R. , THOMASSEN M. S. , EGGSET G.
Published: April 2006

Abstract. The enzymic activity of GCAT‐LPS was studied using whole blood (in vivo), citrated blood or washed red blood cells as substrate. Results demonstrated in vitro and in vivo haemolysis of Atlantic salmon, Salmo salar L., red blood cells, and in vitro haemolysis of rainbow trout, Oncorhynchus mykiss (Walbaum), red blood cells, by purified GCAT‐LPS. Haemolysis coincided with 10% or more lysophospholipids, as a per cent of total phospholipids, in the red cell membranes. Addition of soybean lysophosphatidylcholine to citrated whole blood from salmon caused haemolysis. This suggests that it is the observed accumulation of lysophospholipids, caused by the enzymic activity of GCAT‐LPS, which leads to lysis of salmonid red blood cells. When membranes were used as substrate, GCAT‐LPS seemed to express acyltransferase and possibly some phospholipase activity, while accumulation of lysophospholipids suggests that the lysophospholipase activity is inhibited or severely suppressed. Deacylation of both phosphatidylcholine and phosphatidylethanolamine was observed, indicating that both phospholipids are substrates for the enzyme.
Enzyme‐linked immunosorbent assay (ELISA) for the detection of spring viraemia of carp virus (SVCV) in tissue homogenates of the carp, Cyprinus carpio L.
Authors: RODÁK L. , POSPÍŠIL Z. , TOMÁNEK J. , VESELÝ T. , OBR T. , VALÍČEK L.
Published: April 2006

Abstract. An enzyme‐linked immunosorbent assay (ELISA) for the demonstration of the virus of spring viraemia of carp (SVCV) in liver, kidney and spleen homogenates, and in infected cell cultures is described. The sensitivity of the method is 102·8–103·5 TCID50 0·lml−1 of the examined fluid. The specificity has been confirmed by the ELISA inhibition test and by results of virological examinations. Contamination with bacteria or fungi of samples taken from dead fish had no effect on the results of ELISA. Specific anti‐SVCV sera were used successfully for the production of conjugates for the direct immunoperoxidase and immunofluorescence detection of SVCV in infected cell cultures.
Protective properties of egg yolk IgY containing anti‐Edwardsiella tarda antibody against paracolo disease in the Japanese eel, Anguilla japonica Temminck & Schlegel
Authors: GUTIERREZ M. A. , MIYAZAKI T. , HATTA H. , KIM M.
Published: April 2006

Abstract. Immunized hens are known to contain a high level of immunoglobulin Y (IgY) in their egg yolk. In this study, the present authors obtained anti‐Edwardsiella tarda IgY (containing 20% specific IgY, agglutination titre, 1:128) from hens vaccinated by injection with formalin‐killed bacterin. The IgY was stable against eel digestive factors, and therefore, was orally administered with viable E. tarda to the Japanese eels and the efficacy of protection against E. tarda infection was evaluated. Orally administered IgY at a dose of 400mg fish‐1 cleared E. tarda inoculated simultaneously at 105–6 CFU fish‐1 from the intestine within 24h. Moreover, orally administered IgY at doses of 200 and 400mg fish‐1 inhibited the penetration of E. tarda inoculated simultaneously at 104–6 CFU fish‐1 into the liver and kidney via the damaged intestine. The fish orally administered with IgY showed reduced mortality. These results suggest that egg yolk containing anti‐E. tarda IgY is effective in preventing edwardsiellosis.
Demonstration of infectious pancreatic necrosis virus strain VR‐299 in Japanese eel, Anguilla japonica Temminck & Schlegel
Authors: HSU Y.‐L. , CHEN B.‐S. , WU J.‐L.
Published: April 2006

Abstract. Six isolates of infectious pancreatic necrosis virus (IPNV) were obtained from trout or eel farms in Taiwan in 1987. By using the electrophoretic analysis of 35S‐methionine‐labelled early viral polypeptide patterns and silver‐stained ds RNA gel patterns, a comparison of these isolates with the three archetypal IPNV serotypes (AB, SP and VR‐299) was made. They were all identical with VR‐299, both in the RNA and early viral polypeptide patterns. From the results obtained, it was apparent that the VR‐299 serotype of IPNV was just as widespread in eel as in trout in Taiwan. This is the first case of VR‐299 isolation from eel.
Role of free radicals in swimbladder inflammation of carp
Authors: NEMCSÓK J. , VIG É. , BASKA F. , KUFCSÁK O.
Published: April 2006

Abstract. Several diseases are known, including a number of inflammatory origin, in which the role of free radicals has been proved. In the elimination of reactive oxygen intermediates, SOD, catalase and GPase have a significant role. A study of the activities of these enzymes and of the lipid peroxidation in carp with swimbladder inflammation showed that the formation of free radicals plays a direct or indirect role in the development and/or progress of this inflammation.
Histopathological changes in the livers of dab, Limanda limanda (L.)
Authors: BUCKE D. , FEIST S. W.
Published: April 2006

Abstract. The dab, Limanda limanda (L.), is a common species of flatfish found in the shallow waters of the North Sea, particularly in inshore regions. Because of its distribution and habits, it is a useful species for investigations into the biological effects of marine pollution; it is also susceptible to certain, easily‐detectable, gross diseases, including a variety of hepatic lesions, some of which are putative neoplasias. Investigations over the past 10 years on the histopathology of dab livers, have revealed that many lesions are associated with parasitic infections or trauma, and others include the presence of basophilic foci and putative adenoma as well as cell storage changes. The significance of these lesions is discussed in relation to other biological and physical data, and the necessity for histological evaluation is emphasized.
Peritoneal and head kidney cell response to intraperitoneally injected yeast glucan in Atlantic salmon, Salmo salar L.
Authors: JØRGENSEN J. B. , LUNDE H. , ROBERTSEN B.
Published: April 2006

Abstract. Previous studies have shown that intraperitoneal (i.p.) injection of a yeast cell wall glucan into Atlantic slamon, Salmo salar L., resulted in increased resistance to bacterial pathogens and that the glucan enhanced the protective effect of an i.p.‐administered furunculosis vaccine in salmon. In the present work, the peritoneal cell responses to yeast glucan, glycogen, Freund's incomplete adjuvant (FIA) and saline were compared. Whereas saline gave no detectable peritoneal cell response, injection of the three other agents resulted in accumulation of macrophages, neutrophils and thrombocytes in the peritoneal cavity 2–22 days later. Glucan and glycogen gave maximum leucocyte responses 2 days after injection, whereas the number of leucocytes after FIA injection showed a continuous increase during the 22‐day experimental period. Two days after injection, macrophages dominated in the leucocyte response to yeast glucan, whereas neutrophils dominated in response to glycogen and FIA. At 8 and 22 days post‐injection of yeast glucan and FIA, thrombocytes represented the largest fraction of peritoneal cells. Except for an elevated number of neutrophils 3 weeks after injection, i.p. administration of yeast glucan gave no significant change in leucocyte numbers from the head kidney. On the other hand, head kidney macrophages from glucan‐treated fish showed an increased ability to kill a virulent strain of Aeromonas salmonicida.
Leucocytes from Atlantic salmon, Salmo salar L., experimentally infected with infectious salmon anaemia (ISA) exhibit an impaired response to mitogens
Authors: DANNEVIG B. H. , FALK K. , KROGSRUD J.
Published: April 2006

Abstract. The proliferative response to mitogens of head kidney leucocytes from Atlantic salmon, Salmo salar L., experimentally infected with infectious salmon anaemia (ISA) was examined. The mean haematocrits of ISA‐inoculated fish were significantly lower than the mean haematocrits of control‐inoculated fish at day 14. Mortality in ISA‐inoculated fish appeared at day 16 after inoculation. Seven days after inoculation, leucocytes from ISA‐inoculated fish showed an increased response to phytohaemagglutinin (PHA) compared to control‐inoculated fish, while no change in the response to lipopolysaccharide from Escherichia coli (LPS) could be observed. At days 14 and 22 after inoculation, the responses to both LPS and PHA of leucocytes from ISA‐inoculated fish were severely impaired. These suppressions of the immune response of leucocytes from ISA‐inoculated fish were found in fish with low haematocrits (< 15) as well as in fish with haematocrits higher than 30, suggesting that suppression of the immune system and the development of anaemia are independent events in the pathogenesis of ISA.
Observation of a rickettsia‐like organism in Atlantic salmon, Salmo salar L., in Ireland
Authors: RODGER H. D. , DRINAN E. M.
Published: April 2006

Abstract. A rickettsia‐like organism was observed in tissues of farmed Atlantic salmon, Salmo salar L., experiencing mortalities in the West of Ireland. Gross pathology of affected fish included haemorrhages in the skeletal muscle, splenomegaly, congestion of pyloric caeca and yellow mottling of livers, which appeared in ring formations in some cases. Histopathology was most obvious in the spleens, livers, kidneys and hearts, with widespread tissue necrosis and numerous basophilic granules present in the cytoplasm and cytoplasmic vacuoles of a variety of cells. Transmission electron microscopy revealed micro‐organisms within membrane‐bound cytoplasmic vacuoles similar in appearance to rickettsia.
Characteristics of an Enterococcus‐like bacterium from Australia and South Africa, pathogenic for rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: CARSON J. , GUDKOVS N. , AUSTIN B.
Published: April 2006

Abstract. Severe mortalities of up to 60% have occurred in Australian and South African farmed rainbow trout, Oncorhynchus mykiss (Walbaum), infected with Gram‐positive cocci. Infected fish develop septicaemia and characteristic exophthalmos. Strains collected from outbreaks of disease appear to have attributes of the genus Enterococcus although no Lancefield group D antigen could be detected. All strains grew at 10°C but not at 45°C, grew in 6·5% NaCI, were bile‐aesculin positive and hydrolysed L‐pyrrolidonyl‐β‐naphthylamide. Isolates from both countries have similar phenetic characteristics and whole cell protein profiles.
Mycobacterium infection in pejerrey, Odonthestes bonariensis Cuvier & Valenciennes
Authors: HATAI K. , LAWHAVINIT O. , TODA K. , SUGOU Y.
Published: April 2006

Abstract. Mycobacterium infection was found in pejerrey, Odonthestes bonariensis Cuvier & Valenciennes, with and without saprolegniasis, in Japan. Many typical focal mycobacterial granulomas were found in the kidney, spleen, liver and pancreas, but they were not found in lateral musculature at sites of fungal infection, or in the intestine, ovary, heart and gills of infected fish. The isolated bacterium was photochromogenic and was identified as a rapidly growing species of the genus Mycobacterium.
Ichthyophthirius multifiliis: axenic isolation and short‐term maintenance in selected monophasic media
Authors: EKLESS L. M. , MATTHEWS R. A.
Published: April 2006

Abstract. All stages in the life cycle of Ichthyophthirius multifiliis were successfully isolated axenically, without loss of viability, by use of 1% penicillin:streptomycin solution (100IUcm−3:100μg cm−3). Survival and development of each stage was investigated in selected monophasic media at 20°C. Parasite survival was extended over that observed in water controls, suggesting that both parasitic and free‐living stages are capable of some degree of nutrient uptake. The tomite survived within the cyst for a maximum of 22 days when incubated in EMEM without added serum (EMEM‐S) and diluted 50:50 with distilled water. Viable theronts survived for up to 5 days within EMEM, 3 days longer than controls, and mature trophonts survived, with no further development, for up to 16 days within Glasgow modification of EMEM with added 10% serum. Successful encystment and excystment was dependent on water and occurred only in diluted media. Delayed encystment was achieved by incubation in concentrated media, the production of sterile, viable theronts being delayed for up to 96h within EMEM‐S, 72h later than normally observed in the aquatic environment. The significance of the results are discussed with regard to the routine maintenance of the parasite and future prospects for in vitro culture.