bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of proteinase during experimental infection of Ostrea edulis L. larvae with Vibrio alginolyticus NCMB 1339 and the antigenic relationship between proteinases produced by marine vibrios pathogenic for fish and shellfish
Authors: NOTTAGE A. S. , BIRKBECK T. H.
Published: April 2006

Abstract. Seven marine Vibrio strains pathogenic for fish or shellfish (including strains of Vibrio alginolyticus, V. anguillarum, V. tubiashi and V. ordalii) were categorized into three groups on the basis of their extracellular proteinases. Antiserum raised against purified Vibrio alginolyticus NCMB 1339 proteinase neutralized the enzymes produced by all seven Vibrio strains and, on immunodiffusion, the V. alginolyticus proteinase gave a reaction of partial antigenic identity with the other Vibrio strains. In experimental infections of Ostrea edulis larvae with V. alginolyticus, the production of proteinase was demonstrated by immunofluorescence with fluorescein‐labelled anti‐serum. The toxicity of purified proteinase to larval O. edulis was significantly reduced by preincubation with antiserum but, when larvae were challenged with V. alginolyticus culture supernate containing a similar proteinase concentration, preincubation with antiserum had no protective effect.
A study of delayed capture mortality syndrome in skipjack tuna, Katsuwonus pelamis (1).
Authors: BOURKE R. E. , BROCK J. , NAKAMURA R. M.
Published: April 2006

Abstract. This study was initiated to determine the cause(s) of delayed mortality in newly captured skipjack tuna, Katsuwonus pelamis (L.), being held at the National Marine Fisheries Service Kewalo Research Facility. Sixty‐four per cent of 244 skipjack tuna delivered to the facility died, usually on the second or third day after capture. The capture history, morphological data, serum chemistry (21 standard parameters), haematology, and histological samples of major organs, were obtained from 30 fish sampled at sea immediately after capture, or after approximately 4, 9, 24, 48 or 500+ h in captivity. The cause(s) of death in these fish could not be attributed to anoxia, disseminated intravascular coagulation, lactic acidosis, capture myopathy or infection. Post‐capture haemodilution is hypothesized as a major factor of delayed capture mortality syndrome in skipjack tuna.
Epizootic haematopoietic necrosis, a new viral disease in redfin perch, Perca fluviatilis L., in Australia
Authors: LANGDON J. S. , HUMPHREY J. D.
Published: April 2006

Abstract. An epizootic disease in redfin perch, Perca fluviatilis L., in north‐east Victoria, Australia, was found to be caused by a recently described iridovirus. The acute disease is characterized by necrosis of the renal haematopoietic tissue, liver and spleen, with variable involvement of the pancreas. Transmission studies confirmed that the iridovirus is the causative agent of the disease. High mortalities occurred in 0+ juveniles in early summer and appear to be a recurrent seasonal event, whereas more sporadic outbreaks occurred in older age classes. Carrier fish were detected at low prevalence. The disease is described as epizootic haematopoietic necrosis (EHN) and is the only viral disease of fish known to occur in Australia.
Aphanomyces astaci pathogenicity under laboratory and field conditions
Authors: ALDERMAN D. J. , POLGLASE JANE L. , FRAYLING M.
Published: April 2006

Abstract. The high pathogenicity of Aphanomyces astaci to susceptible crayfish has often been mentioned but not well investigated in publications on crayfish plague. This paper presents a study of that pathogenicity and considers the relationships between size of zoospore challenge and challenge temperature, which results in the extremely complex series of pathologies which comprise crayfish plague.
The disease status of Australian salmonids: bacteria and bacterial diseases
Authors: HUMPHREY J. D. , LANCASTER C. E. , GUDKOVS N. , COPLAND J. W.
Published: April 2006

Abstract. Eleven freshwater salmonid hatcheries in southern Australia were surveyed for bacterial pathogens and diseases between 1981 and 1985, Twenty‐five populations of fish were examined in the study, representing a total of 2755 fish, from which kidney, liver, spleen, and in some cases peritoneum, blood and faeces were cultured. Bacteria of pathogenic significance isolated included Aeromonas hvdrophila, Streptococcus sp., Lactobacillus piscicola, Yersinia ruckeri, Mycobacterium fortuitum, M. chelonei and a filamentous acid‐fast organism of uncertain taxonomic position. Lacto‐bacillus piscicola and Streptococcus sp. were associated with clinical and subclinical peritonitis. Mycobacterium chelonei was isolated from visceral granulomas in an externally normal fish. Aeromonas salmonicida, Renibacterium salmoninarum and Edwardsiella tarda were not isolated, indicating that the diseases furunculosis, bacterial kidney disease and edwardsiellosis are exotic to Australian salmonids. Similarly, while Y. ruckeri was isolated, enteric redmouth disease had not been recorded and is considered an exotic disease.
The influence of haemocyte number on the resistance of the freshwater crayfish, Pacifastacus leniusculus Dana, to the parasitic fungus Aphanomyces astaci
Authors: PERSSON M. , CERENIUS L. , SÖDERHÄLL K.
Published: April 2006

Abstract. The number of circulating haemocytes in crayfish, Pacifastacus leniusculus Dana, was reduced after injection of yeast cell walls (Zymosan) into the animals. Crayfish harbouring the parasitic fungus A. astaci as a ‘latent’ infection in melanized areas in the cuticle died due to unrestricted growth of unmelanized hyphae when they were injected with Zymosan. The β–1,3–gIucan laminaran, introduced into the haemocoel of P. leniusculus harbouring A. astaci hyphae in the cuticle, also caused a decrease in the total haemocyte counts (THC), but these animals survived the treatment and no unmelanized hyphae of A, astaci were found. The recovery of THC was found to be more rapid after laminaran injection than after Zymosan injection, which could explain why laminaran treated crayfish retained their resistance and could combat the A. astaci hyphae in the cuticle. The importance of the number of haemocytes in defence and well‐being of crayfish is discussed.
Duration of protective immunity and antibody titres measured by ELISA after vaccination of rainbow trout, Salmo gairdneri Richardson, against vibriosis
Authors: THUVANDER ANN , HONGSLO T. , JANSSON EVA , SUNDQUIST BO
Published: April 2006

Abstract. The level of protective immunity in rainbow trout, Salmo gairdneri Richardson, following vaccination by intraperitoneal (i.p.) injection or by direct immersion with Vibrio anguillarum was studied over a period of 46 weeks. Antibody titres to V. anguillarum O‐antigen were determined with ELISA at the time of each experimental infection to study the relation between specific antibody production and protective immunity. Both vaccination by i.p. injection and vaccination by direct immersion induced a high degree of protective immunity against vibriosis which lasted for at least 46 weeks. At each experimental infection, the proportions of seropositive fish were lower than the proportions of fish with protective immunity. However, seropositive individuals were found in both experimental groups throughout the study.
Systemic amoebiasis in cultured European catfish, Silurus glanis L.
Authors: NASH G. , NASH M. , SCHLOTFELDT H.‐J.
Published: April 2006

Abstract. Parasitic cells resembling amoeba trophozoites were found histologically and ultrastructurally to be associated with severe proliferate gill disease and systemic infection often leading to extensive granulomatous tissue changes in the European catfish, Silurus glanis L. Infections with the normally free‐living amoeba leading to mortalities of up to 30% were considered to result from suboptimal water quality with heavy bacterial loading in a heated partial recirculation system.
Effects of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) or Aroclor 1254 on the resistance of rainbow trout, Salmo gairdneri Richardson, to infectious haematopoietic necrosis virus
Authors: SPITSBERGEN J. M. , SCHAT K. A. , KLEEMAN J. M. , PETERSON R. E.
Published: April 2006

Abstract. Sublethal exposure of rainbow trout fry, Salmo gairdneri Richardson, to polychlorinated biphenyls (PCBs) or 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) did not significantly affect mortality or mean time to death following challenge with infectious haematopoietic necrosis virus (IHNV). Rainbow trout fry were fed experimental diets containing 0, 5. 50 or 500 μg/g of the technical polychlorinated biphenyl mixture, Aroclor 1254, for 30 days or were injected intraperitoneally with graded single doses of TCDD. Fish from each treatment group were challenged by immersion exposure to IHNV. At early time points following virus challenge, histopathologic lesions due to virus disease were more severe and occurred more frequently in virus‐challenged fish which received either toxicant than in virus‐challenged control fish. Taken together, these findings suggest that rainbow trout are less sensitive than mammalian species to the sublethal effects of these structurally related toxicants on resistance to viral disease. However, a subtle effect of these chemicals on the pathogenesis of the virus disease is suggested by the histopathologic data.
A method of experimental infection of kuruma shrimp larvae, Penaeus japonicus Bate, with baculoviral mid‐gut gland necrosis (BMN) virus
Authors: MOMOYAMA K. , SANO T.
Published: April 2006

Abstract. Infectivity experiments were undertaken by water‐borne inoculation of kuruma shrimp, Penaeus japonicus Bate, larvae with BMN virus. Mysis stage larvae were inoculated with the virus by exposure for 2h in sea water containing a homogenized and filtered preparation (450nm) of naturally BMN virus‐infected shrimp stored for about 7 weeks at −80°C. Inoculated shrimp stocked in rearing jars were examined to determine whether nuclear hypertrophy of the mid‐gut gland epithelial cells characteristic for BMN virus infection could be observed in fresh squash preparations under dark field illumination equipped with a wet‐type condenser. Four days post‐inoculation at 25–30°C incubation temperature were considered to be satisfactory for the experimental trial.
Evaluation of profiles of Aeromonas salmonicida as epidemiological markers of furunculosis infections in fish
Authors: BAST L. , DALY J. G. , DEGRANDIS S. A. , STEVENSON R. M. W.
Published: April 2006

Abstract. Strains of Aeromonas salmonicida subsp. salmonicida, the agent of furunculosis disease of salmonid fish, have fairly uniform plasmid patterns. Of 35 strains examined by agarose gel electrophoresis, 28 had a pattern consisting of four small plasmids (4.2, 3.6, 3.5, 3.3 Mda) and a larger plasmid. The larger plasmid was most often 50–56 Mda, but it was larger in some strains. In the remaining seven strains, the same general profile was seen, but one of the small plasmids was missing. An additional plasmid was present in six strains. The pattern seen in 30 strains collected from Ontario fish over an 8‐year period did not differ significantly from five reference isolates from other locations. Plasmid profiles of A. salmonicida strains appear too uniform to provide a useful epidemiological tool. The non‐pigmented. atypical strains of A. salmonicida subsp. achromogenes and A. salmonicida subsp. masoucida, A. media, and brown‐pigmented strains of A. hydrophila had different plasmid DNA profiles, which were distinct from those of typical isolates of A. salmonicida subsp. salmonicida. Antibiotic susceptibility patterns, determined by the agar dilution method, were uniform for most typical strains. A non‐transferable resistance to tetracyclmes was found in two Ontario isolates, but antibiotic resistance was relatively uncommon among the Ontario isolates.
Enzyme‐linked immunosorbent assay (ELISA) detection of infectious pancreatic necrosis virus (IPNV) in culture fluids and tissue homogenates of the rainbow trout, Salmo gairdneri Richardson
Authors: RODÁK L. , POSPÍŠIL Z. , TOMÁNEK J. , VESELÝ T. , OBR T. , VALÍČEK L.
Published: April 2006

Abstract. A double antibody enzyme‐linked immunosorbent assay (ELISA) for the detection of infectious pancreatic necrosis virus (IPNV) is described. The sensitivity of the assay reached 102 TCID50 per 0·1 ml of culture fluid. The specificity of anti‐IPNV sera and of the assay was confirmed by agar‐gel immunodiffusion, by the direct immunoperoxidase technique for the deletion of IPNV in tissue cultures and by the ELISA inhibition test. High values of specific inhibition (over 90% at serum dilutions 1:40–1:2560) and low values of non‐specific inhibition (8·4% at serum dilution 1:160) demonstrated the quality of the rabbit anti‐IPNV serum. The results of ELISA agreed well with those of virological examinations. The potential of ELISA for investigations of a large series of field samples is discussed.
Pleistophora mirandellae Vaney & Conte, 1901, a microsporidian parasite in cyprinid fish of rivers in Herault: taxonomy and histopathology
Authors: MAURAND J. , LOUBES C. , GASC C. , PELLETIER J. , BARRAL J.
Published: April 2006

Abstract. Cyprinid fish from the Lergue and Lez rivers in Herault, southern France, were found to be parasitized by the microsporidian Pleistophora mirandellae Vaney & Conte, 1901. The parasite was found only in the gonads, forming cysts in the connective tissue between the seminiferous tubules of testes or occurring in the oocytes of the ovaries. Two types of uninuclear spores are produced. The synonomy of microsporidia parasitizing the gonads of cyprinid fish is discussed.
The susceptibility of salmonid fish to an atypical strain ofAeromonas salmonicidathat infects goldfish,Carassius auratus(L.), in Australia
Authors: WHITTINGTON R. J. , CULLIS B.
Published: April 2006

Abstract.An enzootic, Australian, atypical strain ofAeromonas salmonicidaisolated from diseased goldfish,Carassius auratus(L.), was inoculated into Atlantic salmon,Salmo salarL., brown trout,S. truttaL., rainbow trout,S. gairdneriRichardson, and brook trout,Salvelinus fontinalis(Mitchill), fingerlings by intraperitoneal injection (i.p.) and by bath challenge, the latter with and without prior abrasion of skin. The 10‐day LD50(i.p.) was estimated to be 7·4 × 10‐3colony forming units (cfu) for Atlantic salmon, 3·0 × 10‐2cfu for brown trout, 3·7 × 102cfu for brook trout and 6·4 × 103cfu for rainbow trout. Brown, rainbow and brook trout succumbed to bath challenges with between 105–106cfu/ml, developing ulcers of the skin and septicaemia. The organism was trasmitted from inoculated fish to five of 195 within‐tank control fish via water and established a carrier state in one of 14 Atlantic salmon. It was concluded that the organism poses a significant threat to the salmonid farming industry and wild salmonid fisheries in Australia.
Presporogonic development of Sphaerospora renicola Dyková & Lorn, 1982, in the swimbladder of the common carp, Cyprinus carpio L.
Authors: MOLNÁR K.
Published: April 2006

Abstract. The prcsporogonic developmental stages of Sphaerospora renicola, the causative agent of swimbladder inflammation (SBI), develop in the swimbladder of common carp by multiple internal cleavage. The earliest development stage is the secondary cell enclosed by the primary cell. The secondary cells undergo multiple amitotic division within the mother cell and the dividing forms are connected by narrow cytoplasmic bridges. As a result of further internal cleavage, two tertiary cells appear in each secondary cell. The triple formation enclosing a secondary and two tertiary cells is identical with the pansporoblast containing two sporoblasts which occurs in the renal tubules.
The pathology caused by Pomphorhynchus laevis Müller in the alimentary tract of the stone loach, Noemacheilus barbatulus (L.)
Authors: WANSTALL S. T. , THOMAS J. S. , ROBOTHAM P. W. J.
Published: April 2006

Abstract. Changes induced in intestinal and rectal structure of the stone loach, Noemacheilus barbatulus (L.) by Pomphorhynchus laevis Müller infection are described. Within the gut, the main effect of the infection is the abrasion and flattening of the mucosa by the parasite. Where the praesoma penetrates the gut wall, there is a marked inflammatory response. This inflammatory response tissue is well vascularized and displays esterase activity. Granulocytes and phagocytic cells, which are found both within the inflammation tissue and within capillaries, are probably host leucocytes. The integument of P. laevis appears undamaged by granulocytes in its proximity and it is unlikely that the host's inflammatory response is capable of rejecting the parasite.
Effects of temperature on chemiluminescence of phagocytes from sea bass, Dicentrarchus labrax L.
Authors: ANGELIDIS P. , BAUDIN‐LAURENCIN F. , YOUINOU P.
Published: April 2006

Abstract Sea bass head kidney cells were incubated at several temperatures with or without opsonized zymosan, Luminol was added to amplify light emission. When stimulated by zymosan cells emitted higher chemiluminescence (CL) at low temperatures (5–20°C) than at high temperatures (25–40°C). CL reached its peak earlier at high temperatures than at low temperatures. Unstimulated cells showed a low level CL response which rose with increasing temperature. Sodium azide inhibited CL by 97%.
Infection of tilapia, Oreochromis mossambicus (Trewavas), by a marine monogenean, Neobenedenia melleni (MacCallum, 1927) Yamaguti, 1963 in Kaneohe Bay, Hawaii, USA, and its treatment
Authors: II J. J. KANEKO , YAMADA R. , BROCK J. A. , NAKAMURA R. M.
Published: April 2006

Abstract A disease of saltwater, cage‐cultured tilapia, Oreochromis mossambicus (Trewavas), caused by the marine monogenean, Neobenedenia melleni (MacCallum, 1927) Yamaguti, 1963, is described. Up to 400 parasites were found attached to the body surface of individual fish. Heavily infected fish showed hyperirritability, heavy mucus secretion and discoloration. Pathology was most marked on the eye, with corneal opacity initially, followed by buphthalmos, corneal ulceration and rupture of the eye with subsequent degeneration of internal structure. The infection was successfully treated using 2 min freshwater dips.
Lack of relationship between virulence of Aeromonas salmonicida and the putative virulence factors: A‐layer, extracellular proteases and extracellular haemolysins
Authors: ELLIS A. E. , BURROWS A. S. , STAPLETON K. J.
Published: April 2006

Abstract The role of A‐layer (A), protease (P) and haemolysin (H) as virulence factors of Aeromonas salmonicida, the aetiological agent of fish furunculosis, was a investigated using three strains of the bacterium. Strain MT004 lacked the A‐Iayer (A−) and produced extracellular caseinase and gelatinase (P+) and haemolysin (T‐lysin; H+). Strain MT028 was A−, P− and H−, and strain MT048 was A+, P+ and H−. The pathology and LD50 produced in rainbow trout by cells or extracellular products (ECP) of each strain were determined. The ECP was produced by two different methods where the protease and haemolytic activities differed in relative levels, or when the protease of MT004 ECP was inhibited by the serine protease inhibitor PMSF. The results indicate that the presence of A‐layer is not essential, at least for a moderate degree of virulence; that in vitro production of extracellular proteases is not a requisite of virulent strains; that presence of protease and haemolysin in ECP can be correlated with the development of certain lesions and a rapid time to death but cannot be correlated with the lethal toxicity of the ECP. The authors conclude that an as‐yet unrecognized component of ECP is responsible for killing fish.
Chlamydiosis: a newly reported serious disease of larval and postmetamorphic bay scallops, Argopecten irradians (Lamarck)
Authors: LEIBOVITZ L.
Published: April 2006

Abstract. Diseases of bivalve molluscs characterized by the presence of prokaryotic intra‐cytoplasmic inclusion bodies in epithelial cells are reviewed. The paper reports the history, clinical and pathological findings during hatchery epizootics of chlamydiosis in larval and postmetamorphic bay scallops, Argopecten irradians (Lamarck), and enzootic infection in wild, captive and cultured adult and juvenile bay scallops during a 15‐year period (1972–1987) of surveillance for scallop diseases in the northeastern Atlantic coastal region of the United States. The disease was found in 44·4% of adult bay scallop laboratory accessions as an endemic disease without overt clinical signs or mortalities, and as a highly fatal epizootic disease with a rapid course in 20% of hatchery‐reared larval and postmetamorphic bay scallop accessions. The pathogenesis and development of the chlamydial agent during hatchery epizootics are described. The importance of the congenital ‘childhood’ diseases of larval bay scallops and other species of bivalve molluscs is discussed.
Visceral necrosis of goldfish, Carassius auratus (L.): a new bacterial disease
Authors: FERGUSON H. W. , OSTLAND V. E. , DALY J. G. , STEVENSON R. M.
Published: April 2006

Abstract. Recent shipments of goldfish into Canada have suffered major mortality within a short time of arrival. The pathology and bacteriology of several of these diseased fish are described. Lesions were either acute and necrotizing with haemorrhage, or they were granulomatous. In either case, the spleen was a prime target, although in severely affected animals other organs were similarly involved; these included anterior and posterior kidney (plus endocrine elements), liver, intestine, mesentery and brain. Associated with these lesions were intracellular bacteria, which were often arranged in a Chinese letters‐like configuration, and which are presumed to be the cause of the disease. The Gram‐negative bacterium was isolated from all fish, but its characteristics were such that it was not easily classified and its taxonomy therefore remains uncertain.
Tolerance of lake trout, Salvelinus namaycush (Walbaum), sac fry to dissolved gas supersaturation
Authors: KRISE W. F. , HERMAN R. L.
Published: April 2006

Abstract. The tolerance of sac fry of lake trout, Salvelinus namaycush (Walbaum), to the acute effects of gas supersaturation, from hatching to swim‐up, was tested using six gas levels, ranging from ΔP 8 to 148. Although many fish were moribund by the time the yolk was nearly absorbed, mortality during the 40‐day study was negligible; survival to swim‐up was 96–99%, including 99% survival at ΔP 148. Of fish examined at ΔP 42, 40% showed bubble formation around the rim of the eye. Signs of trauma were greatest at ΔP 119 and 148, and included intestinal bubbles, a distended abdomen, and bubbles around the eye, in the mouth and in jaw tissues.
Bacteriology and parasitology of red spot disease in sea mullet, Mugil cephalus L., from eastern Australia
Authors: CALLINAN R. B. , KEEP J. A.
Published: April 2006

Abstract. Bacteria and cutaneous ectoparasites associated with red spot disease (RSD) in sea mullet, Mugil cephalus L., from the Clarence and Richmond Rivers in north‐east New South Wales were identified. Various bacteria, including Aeromonas spp., Alcaligenes spp., Pseudomonas spp. and Vibrio spp. were recovered from lesions designated erythematous dermatitis, necrotizing dermatitis and dermal ulcer, but no genus was consistently dominant in cultures from any of the lesion types. Vibrio anguillarum, previously proposed as the cause of RSD, was recovered from four of 37 lesions of erythematous dermatitis, none of 46 lesions of necrotizing dermatitis and eight of 36 dermal ulcers. Bacteria were recovered only rarely from liver and posterior kidney of diseased fish. These results suggest that none of the bacteria isolated is the primary cause of RSD. There was no evidence that cutaneous ectoparasites, including the digencan Prototransversotrema steeri, are significant in the pathogenesis of RSD in sea mullet. None were found on eight normal fish collected in the month preceding a major RSD outbreak. In the first 2 months of the outbreak, none were found on 18 fish with erythematous dermatitis, eight with dermal ulcers or 11 of 12 normal fish. A single digenean, morphologically consistent with P. steeri, was recovered from a normal fish collected during this latter period.
Comparative sensitivity of carp, Cyprinus carpio L. and rainbow trout, Salmo gairdneri Richardson, to Renibacterium salmoninarum
Authors: SAKAI M. , OGASAWARA K. , ATSUTA S. , KOBAYASHI M.
Published: April 2006

Abstract. The pathogenicity of Renibacterium salmoninarum to carp, Cyprinus carpio L., and rainbow trout, Salmo gairdneri Richardson, was investigated. All carp injected with 4·8 × 108 cells/fish, or 4·8 × 107 cells/fish survived for 38 days. R. salmoninarum was isolated from all moribund fish, but not from the kidney of surviving fish, although R. salmoninarum antigen was detected in several of these fish by the dot blot assay. On the other hand, mortality in rainbow trout was 95% in the fish injected with 4·8 × 108 cells/fish, and 15% in those which received 4·8 × 107 cells/fish. R. salmoninarum antigen was detected by the dot blot assay in all surviving rainbow trout. The number of R. salmoninarum cells was immediately decreased by carp or rainbow trout serum, and the serum bactericidal activity of carp was higher than that of rainbow trout. Carp blood leucocytes had higher phagocytic activity than those of rainbow trout.
Histopathology of gonadal neoplasms in cyprinid fish from the lower Great Lakes of North America
Authors: DOWN N. E. , LEATHERLAND J. F.
Published: April 2006

Abstract. The hybrids of carp, Cyprinus carpio L., and goldfish, Carassius auratus (L.), collected from the lower Great Lakes between 1978 and 1981 exhibited epizootics of gonadal neoplasms which were rare in the parental species. The gonadal histology of male and female carp captured for this study was typical of a successfully reproducing population but the hybrids appeared to be sterile. In male hybrids meiosis was often completed, but spermatids usually degenerated in early spermiogenesis. In female hybrids, vitellogenesis was frequently completed but there was no evidence of final maturation or ovulation. Proliferations of undifferentiated germ cells and stromal cells were evident in the tumour nodules of both the male and female hybrids and were considered to represent neoplastic transformations. Proliferations of Sertoli cells were common in males and in the male portion of intersex gonads, which were present in some hybrids. The Sertoli cells of these individuals were well differentiated, formed tubules and accumulated large stores of lipid. Extensive degeneration of germinal cells was often apparent in areas of Sertoli cell proliferation as were numerous, large, melano‐macrophage centres. Gonadal stromal cell tumours did not form tubules or accumulate lipid. The spindle cells of these neoplasms could be found in homogeneous sheets or intermixed to varying degrees with the early stages of germ cells and/or connective tissue elements.
Association of Aeromonas sobria with mortalities of adult gizzard shad, Dorosoma cepedianum Lesueur
Authors: TORANZO A. E. , BAYA A. M. , ROMALDE J. L. , HETRICK F. M.
Published: April 2006

Abstract. This report describes an epizootic in a natural population of spawning females of gizzard shad, Dorosoma cepedianum Lesueur, which occurred in the Potomac River (Maryland, USA). Microbiological analysis of moribund shad revealed the presence in pure culture in all the organs examined of one bacterium which was identified as Aeromonas sobria by conventional tube and plate tests. The different API‐systems used to attempt for a rapid diagnosis of the disease yielded false negative and positive reactions in important differential tests such as ornithine decarboxylase, arabinose fermentation, gelatinase, urease, indole and production of H2S which gave an erroneous identification of the shad isolate. The virulence assays in rainbow trout revealed that A. sobria was pathogenic with a mean LD50 of 2 × 105. Bacterial extracellular products also displayed fish lethality and were cytotoxic for poikilothermic and homeothermic cell‐lines. Although the source of shad infection is unknown, the physico‐chemical conditions of the river, together with the stress associated with the spawning could have been contributing factors in the proliferation of A. sobria inducing this epizootic.
The infectivity by different routes of exposure and shedding rates of Aeromonas salmonicida subsp. salmonicida in Atlantic salmon, Salmo salar L., held in sea water
Authors: ROSE A. S. , ELLIS A. E. , MUNRO A. L. S.
Published: April 2006

Abstract. The infectivity of the bacterial fish pathogen Aeromonas salmonicida subsp. salmonicida to Atlantic salmon, Salmo salar L., in sea water was investigated and found to be similar to that reported for fresh water. The minimal infective dose in short duration bath exposures (1–3 days) was 104 colony‐forming units (cfu) per ml, while prolonged exposure for three weeks, but not for 1 week, produced infection with 102 cfu/ml. Intragastric intubation of A. salmonicida established infection with doses of >105 cfu. Release of bacteria from dead or morbid infected fish was monitored and found to be in the order of 105–108 cfu/fish/h. These results emphasize the importance of removing dead fish from farm sites.
Oral immunization of rainbow trout, Salmo gairdneri Richardson, against vibriosis with vaccines protected against digestive degradation
Authors: LILLEHAUG A.
Published: April 2006

Abstract. In order to reduce digestive degradation of vaccines against vibriosis when administered orally to fish, two methods of protecting the antigens were tested. Lyophilized vaccine was either incorporated into a slow‐release pellet or coated by an acid‐resistant film. These vaccines were compared to both oral vaccination by an unprotected vaccine as well as to standard vaccination methods of immersion and injection. However, mortalities after an artificial challenge showed that the efficacy of the protected vaccines was lower than that of the unprotected vaccine given orally and the standard vaccination procedures. The reason for this is probably that the important antigens of vibriosis vaccines are lipopolysaccharides which are little affected by gastric digestion, and the coating of the vaccine or incorporation into slow‐release pellets resulted only in reduced absorption of the antigens.
The specificity of the major (70 kDa) protease secreted by Aeromonas salmonicida
Authors: PRICE N. C. , BANKS R. MARGARET , CAMPBELL CAROLE M. , DUNCAN DORIS , STEVENS L.
Published: April 2006

Abstract. The specificity of the major protease secreted by Aeromonas salmonicida has been explored using a number of proteins and p‐nitroanilides as substrates. The 70kDa protease was found to hydrolyse two p‐nitroanilides which have been reported to be specific substrates for thrombin. Kinetic parameters (kcat, and Km) were compared for the 70kDa protease and for thrombin as were the effects of a number of inhibitors. The 70kDa protease is able to degrade proteins which have a relatively open structure, for example, caseins or denatured bovine scrum albumin, to small fragments mostly of Mr<2500. However, proteins with a more compact structure are more resistant to the protease. It was concluded that the 70kDa protease shows some of the specificity features of thrombin, although it is less discriminating in its choice of both low and high Mr substrates than thrombin. In preliminary experiments, the 70 kDa protease was found, like thrombin, to decrease the clotting time of rainbow trout blood. The possible physiological significance of these results is discussed.
Viral nervous necrosis in hatchery‐reared larvae and juveniles of Japanese parrotfish, Oplegnathus fasciatus (Temminck & Schlegel)
Authors: YOSHIKOSHI K. , INOUE K.
Published: April 2006

Abstract. Mass mortalities of hatchery‐reared Japanese parrotfish larvae and juveniles, Oplegnathus fasciatus (Temminck & Schlegel), have occurred in Nagasaki Prefecture. Light and electron microscopic examinations showed that the only consistent histopathological feature was extensive nervous necrosis in the spinal cord, spinal ganglia and brain. Numerous non‐enveloped virus particles, icosahedral in morphology and measuring about 34 nm in diameter, were found in the cytoplasm of affected neurones and glial cells. Such nervous necrosis is believed to be the major cause of the mass mortalities of hatchery‐reared Japanese parrotfish larvae and juveniles.
Specific immunoglobulins in serum from Atlantic salmon, Salmo salar L., immunized with Vibrio salmonicida and infectious pancreatic necrosis virus
Authors: HÅVARSTEIN L. S. , ENDRESEN C. , HJELTNES B. , CHRISTIE K. E. , GLETTE J.
Published: April 2006

Abstract. Atlantic salmon, Salmo salar L., responded to intraperitoneal injection of formalin killed Vibrio salmonicida or live infectious pancreatic necrosis virus (ipnv) by producing specific antibodies. The antibody titre varied significantly within the group tested. Western blot analysis demonstrated that high‐titre antisera recognized two major bacterial antigens with molecular weights of 12–15 kD and 22–27 kD. In addition, a few narrow bands with higher molecular weights were observed. An antiserum raised against IPNV recognised two major antigens corresponding to the structural proteins of the virus. Elisa and Western blot analysis showed that the immune serum raised against Vibrio salmonicida reacted slightly with Vibrio anguillarum, whereas no reaction to Yersinia ruckeri or Aeromonas salmonicida was detected. Indirect elisa and an elisa competition assay revealed that the immune serum raised against the N1 serotype was specific for this serotype of ipnv. The results demonstrate that Atlantic salmon has a humoral immune system capable of producing antibodies which discriminate between related bacterial antigens and between different serotypes of a virus.
Some haematological observations on carp, Cyprinus carpio L., experimentally infected with Trypanoplasma borreli Laveran & Mesnil, 1901 (Protozoa: Kinetoplastida)
Authors: STEINHAGEN D. , KRUSE P. , KÖRTING W.
Published: April 2006

Abstract. Common carp, Cyprinus carpio L., were experimentally infected with cloned Trypanoplasma borreli and some haematological data were determined. The haematocrit and total erythrocyte counts were reduced and were lowest at day 29 post‐inoculation during the peak of infection. Differential erythrocyte number showed a reduction in mature erythrocytes and an increase in immature erythrocytes. The total leucocyte number was markedly increased and peaked at day 44 post‐inoculation. Differential blood cell counts showed an increased abundance of leucocytes, especially granuloblasts and granulocytes.
Ultrastructure and development of Pleistophora senegalensis sp. nov. (Protozoa, Microspora) from the gilt‐head sea bream, Sparus aurata L. (Teleost, Sparidae) from the coast of Senegal
Authors: FAYE N. , TOGUEBAYE B. S. , BOUIX G.
Published: April 2006

Abstract. The microsporidian Pleistophora senegalensis sp. nov. parasitizes the gilt‐head sea bream, Sparus aurata L, The parasite is found in the intestinal wall where it forms small xenomas in the muscularis. The development cycle of this species is described by light and electron microscopy. Meronts are rounded plasmodia dividing by plasmotomy and bounded by an amorphous and very regular wall. At the onset of sporogony, sporophorous vesicles are formed by separation of the plasma membrane from the external wall which then becomes a characteristic mesh. Mature spores (4.45 × 2.37μm) are ovoid and slightly pyriform with a large posterior vacuole.
Goussia auxidis (Dogiel, 1948) (Apicomplexa: Calyptosporidae) from tuna (Pisces: Scombridae) in the South Pacific
Authors: JONES J. B.
Published: April 2006

Abstract. A coccidian identified as Goussia auxidis (Dogiel, 1948) is recorded for the first time from the liver and spleen of albacore, Thunnus alalunga; the liver of slender tuna, Allothunnus fallai, skipjack tuna, Katsuwonus pelamis and yellowfin tuna, T. albacares: and in the spleen of Scomber australasicus. All host fish were caught in the western and central South Pacific Ocean. Coccidian spores were not found in the liver of southern bluefin tuna, T. maccoyii, or butterfly tuna, Gasterochisma melampus.
Protection of rainbow trout, Oncorhynchus mykiss (Richardson), against Diplostomum spathaceum (Digenea): the role of specific antibody and activated macrophages
Authors: WHYTE S. K. , CHAPPELL L. H. , SECOMBES C. J.
Published: April 2006

Abstract. The degree of protection in immunized rainbow trout against the infective larval stages of Diplostomum spathaceum was investigated. Immunized rainbow trout demonstrated a 70–80% reduction in the number of metacercariae establishing in their eye‐lenses following challenge with live cercariae compared with unimmunized fish. Both normal trout serum and anti–diplostomule serum weTC cytotoxic to diplostomules in vitro. However, there was no correlation between the degree of protection and the level of serum antibody within individual fish. Reduced establishment of migrating diplostomules, indicative of in vivo killing, occurred in fish possessing activated macrophages and challenged with cercariae opsonized with specific antibody. An antibody–dependent cell–mediated cytotoxic (ADCC) mechanism is proposed, conferring protection in immunized fish. This is supported by the finding that cercarial and diplostomule antigens are capable of activating macrophages in immunized rainbow trout. The role of macrophage activation and specific antibody in conferring protection in immunized fish is discussed.
Electrophoretic and immunochemical analysis of surface antigens of the fish pathogens Vibrio salmonicida and Vibrio anguillarum
Authors: BØGWALD J. , STENSVÅG K. , HOFFMAN J. , ESPELID S. , HOLM K. O. , JØRGENSEN T.
Published: April 2006

Abstract. Outer membranes and lipopolysaccharides of the marine fish pathogens Vibrio salmonicida and Vibrio anguillarum were isolated. SDS‐PAGE profiles of purified LPS preparations from V. salmonicida revealed a broad low molecular weight band, whereas V. anguillarum LPS profiles demonstrated both a low‐molecular band and several weaker high‐molecular weight bands. Hydrolysis of V, salmonicida and V. anguillarum LPS separating the polysaccharide chain from the lipid A part and subsequent gel‐chromatography suggests a polysaccharide molecular weight of ca. 1000 (‘rough type’ LPS) and ca. 6000 ('smooth type’ LPS), respectively. Western blot of V. salmonicida outer membrane preparations and purified lipopolysaccharides and subsequent immunostaining with mouse monoclonal antibodies was performed. Eleven out of 15 monoclonal antibodies made against V. salmonicida cells reacted with one broad antigen‐band in the low molecular weight region of both outer membrane and LPS profiles, corresponding to the LPS region. The previously reported outer surface antigen, VS‐P1 from V. salmonicida, was observed to carry LPS epitopes as revealed by binding of monoclonal antibodies to VS‐P1 as well as purified LPS preparations. These results strongly suggest that the VS‐P1 antigen is a complex of both protein and LPS molecules.
The histopathology associated with the juvenile stages of Lepeophtheirus salmonis on the Atlantic salmon, Salmo salar L.
Authors: JONES M. W. , SOMMERVILLE C. , BRON J.
Published: April 2006

Abstract. Atlantic salmon infected with juvenile stages of Lepeophtheirus salmonis were obtained from sea loch cage sites on the West coast of Scotland. Attached parasites on the skin were studied using light and electron microscopy. Behavioural activity was observed in attached stages maintained on skin in vitro. Pathological changes were associated with four main areas of interaction between the parasite and the host, namely second antennal attachment, filament attachment, maxilliped activity and feeding activity. The skin changes involved were initial mechanical disruption followed by epidermal hyperplasia. The filament material was secreted into the epidermis and spread laterally without breaching the basement membrane. Surprisingly little reaction to the filament occurred, but chalimus activity resulted in chronic changes which were more marked as the later chalimus stages were reached. Fibroplasia was a feature of lesions induced by redundant filaments resulting in small nodular lesions. After erosion of these nodules, all that remained were the melanized rings characteristic of old chalimus sites.
Effect of lytic peptides on selected fish bacterial pathogens*
Authors: KELLY D. , WOLTERS W. R. , JAYNES J.M.
Published: April 2006

Abstract. Two synthetic lytic peptides, derivatives of the naturally occurring lytic peptide cecropin B, were tested for their effect on eight pathogenic fish bacteria. All bacteria were grown on tryptic soy agar at 30°C. Four levels (dilutions) of lytic peptides were incubated with viable cells in the log phase for 1 h. Standard plate counts were made after 24±2h with control plates (no toxin) representing 100% survival. Significant differences (P<0.05) in the toxicity of the two peptides were found for six out of eight bacterial pathogens. Peptide concentration or dilution level also caused significant difference (P<0.01) in bacterial counts. Peptide type by dilution level interactions were significant (P<0.01) for only two bacterial pathogens. The LD50. in molar concentrations of the lytic peptides on the bacterial pathogens, ranged from approximately 10−6 to 10−9. The possible role of utilizing these peptides to enhance disease resistance in aquaculture is discussed.
Evidence for enhanced salinity tolerance of a suspected fungal pathogen of Atlantic menhaden, Brevoortia tyrannus Latrobe
Authors: SHAFER T. H. , PADGETT D. E. , CELIO D. A.
Published: April 2006

Abstract. Two saprolegniaceous fungi, one recovered from Atlantic menhaden, Brevoortia tyrannus Latrobe, and the other from fresh water, were compared for their abilities to withstand salinity stress. Results of stress protein analyses indicated that vegetative mycelium of the isolate from menhaden was better adapted to mesohaline salinities than the freshwater isolate. Experiments testing the propagative ability of both fungi during salt exposure further suggested that the fungus recovered from menhaden was more salt tolerant and possibly survives in estuaries because of nutrients present in susceptible fish. Implications of the findings relative to the pathogenic potential of fish pathogenic saprolegniaceous fungi in estuarinc water columns are discussed.
Enhancement of non‐specific disease resistance in Atlantic salmon, Salmo salar L., by a glucan from Saccharomyces cerevisiae cell walls
Authors: ROBERTSEN B. , RΘRSTAD G. , ENGSTAD R. , RAA J.
Published: April 2006

Abstract. An insoluble polysaccharide from the cell wall of Saccharomyces cerevisiae, called M‐Glucan, has been shown to enhance the non‐specific disease resistance of Atlantic salmon, Salmo salar L., when injected intraperitoneally. M‐Glucan consists only of glucose units which presumably are linked through β‐1,3 and β‐1,6 linkages. Enhanced resistance was demonstrated against Yersinia ruckeri, the causal agent of enteric redmouth disease, against Vibrio anguillarum, the causal agent of classical vibriosis and against Vibrio salmonicida, which causes cold water vibriosis or ‘Hitra‐disease’ in salmon. At a dose of 2mg M‐Glucan per fish (20g mean weight), maximal resistance developed in the fish 3 weeks after injection. Injection of different glucan doses and challenge one week later with Vibrio anguillarum, showed that 50‐200μg glucan per fish resulted in the highest level of resistance. The level of resistance in Atlantic salmon obtained with M‐Glucan was strikingly higher than that obtained with another glucan which was prepared from Saccharomyces cerevisiae by a different procedure.
Infectivity experiments with Cyprinus carpio iridovirus (CCIV), a virus unassociated with carp gill necrosis
Authors: SHCHELKUNOV I. S. , SHCHELKUNOVA T. I.
Published: April 2006

Abstract. Experiments to determine Cyprinus carpio iridovirus (CC1V) virulence to fish of different ages and species were performed; viz. carp, Cyprinus carpio L., goldfish, Carassius auratus (L.), and rainbow trout, Oncorhynchus mykiss (Walbaum). Neither signs of disease nor mortality occurred in any of the fish species tested. Five passages of the virus in carp resulted in its loss and, not surprisingly, there was no enhancement of virulence. In carp inoculated intraperitoncally, the virus persisted for more than 6 weeks at 18‐20°C, more than 12 weeks at a water temperature increasing from 10 to 20°C and more than 27 weeks at 6 5‐8°C. The fish cleared itself of the virus after more than 6 weeks maintenance at 18‐20°C. The viral infectivity via water is very low. It was impossible to infect the fish with the cell culture grown virus either by water immersion or by prolonged cohabitation with experimentally infected fish. From infectivity data, the authors conclude that the investigated iridovirus is not the aetiological agent of carp gill necrosis.
Toxicity and immunogenicity of Aeromonas salmonicida extracellular products to salmonids
Authors: KAWAHARA E. , OSHIMA S. , NOMURA S.
Published: April 2006

Abstract. Aeromonas salmonicida extracellular products (ECP) were fractionated by gel filtration chromatography. Three protein fractions were found. The first and second fractions showed low and high haemolytic activity, respectively, whereas the third fraction showed protcolytic activity. By intramuscular injection into juvenile rainbow trout, the median lethal doses of the first, second and third fractions were calculated at >669, 152 and <1514μg/g body weight, respectively. Cytopathic effects of the fractionated ECP to coho salmon lymphocytes were observed in vitro. The first and second fractions caused cell deformation, nuclear granulation and cytoplasmic streaming after 3h. No cytologic effects with the third fraction were observed. A mixture of the first and third fractions, a mixture of the second and third fractions, and non‐fractionated ECP caused nuclear granulation and cytoplasmic streaming after 3Qmin. Using immunodiffusion analysis, the first and second fractions formed a single precipitating line each against white‐spotted char anti‐ECP sera, but the third fraction did not formed a precipitating line against the antisera.
Pathology of bacterial gill disease: ultrastructure of branchial lesions
Authors: SPEARE D. J. , FERGUSON H. W. , BEAMISH F. W. M. , YAGER J. A. , YAMASHIRO S.
Published: April 2006

Abstract. The range of branchial lesions associated with bacterial gill disease (BGD) in rainbow trout, Oncorhynchus mykiss (Richardson), was investigated through the ultrastructural examination of 23 separate outbreaks of the disease condition within commercially reared stocks. Diseased branchial tissues had a large and diffusely distributed monomorphic population of filamentous bacteria which were strictly epicellular. Although bacterial colonization was restricted to the branchial cavity, it was neither site nor cell specific: epithelial and chloride cells of the lamellae, filaments and lining tissues of the branchial cavity were all uniformly affected. The bacteria possessed an extensive glycocalyx which appeared to facilitate adhesion to the apices of the microridged sub‐unit modifications of the cell surface. Sites of colonization were accompanied by a diffuse pattern of cellular degeneration and necrosis that was generally restricted to the outer layers of epithelium. The polarity and nature of these changes suggest that the mechanism of interaction between the bacteria and host cells includes progressive hydropic change as a sequel to primary membrane damage and consequent increased cell permeability. These cellular changes were accompanied by the range of stereotypical responses of the gill to damage frequently reported for BGD including lamellar fusion, epithelial hyperplasia, and squamous and mucous cell metaplasia, in addition to lamellar spongiosis.