Extracellular virulence factors of Aeromonas hydrophila in fish infections

1981 ◽  
Vol 27 (10) ◽  
pp. 1114-1122 ◽  
Author(s):  
Brenda J. Allan ◽  
Roselynn M. W. Stevenson
Keyword(s):  
Rainbow Trout ◽  
Virulence Factors ◽  
Aeromonas Hydrophila ◽  
Parental Strain ◽  
Salvelinus Fontinalis ◽  
Salmo Gairdneri ◽  
Haemolytic Activity ◽  
Deficient Mutant ◽  
Protease Deficient ◽  
Extracellular Substances

Aeromonas hydrophila NRC 505 produced extracellular substances which were capable of causing pathological effects when injected into trout. Proteolytic activity and haemolytic activity of the extracellular products, and the effect on fish, were lost on heating. The extracellular substances from strain G35, a protease-deficient mutant, were significantly more toxic to both rainbow trout (Salmo gairdneri) and speckled trout (Salvelinus fontinalis) than the analogous preparation from the parental strain NRC 505. The response of speckled trout injected intraperitoneally with dilutions of the extracellular preparations implicates haemolytic activity as a significant lethality factor.

Food Specialization By Individual Trout

1972 ◽  
Vol 29 (11) ◽  
pp. 1615-1624 ◽  
Author(s):  
James E. Bryan ◽  
P. A. Larkin
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Stomach Contents ◽  
Cutthroat Trout ◽  
Salmo Gairdneri ◽  
Potential Prey ◽  
Repeated Observation ◽  
Size Growth ◽  
Salmo Clarki

Analyses of stomach contents showed that the kinds of prey eaten by brook trout (Salvelinus fontinalis), cutthroat trout (Salmo clarki), and rainbow trout (Salmo gairdneri) were seldom distributed at random among the individuals. Repeated observation of food eaten by individuals in a stream and ponds showed that prey types were eaten in proportions which were characteristic for an individual.Specialization occurred on several different kinds of prey. Although the degree of specialization was higher during shorter intervals, the data suggested that some specialization persisted for half a year. There were no striking correlations between degree of specialization and other individual properties such as size, growth rate, weight of food, number of food items, previous specialization, or area of recapture.In addition to the observations on trout in relatively undisturbed habitats, a field experiment was conducted using laboratory-reared rainbow trout held in small ponds. The food of each trout in the experiment was sampled repeatedly. In analysis of variance, interaction among the individuals and kinds of prey eaten showed that food specialization occurred. Both the absolute and relative abundance of potential prey were constant during the experiment.

Aeromonas salmonicida: Relationship between Extracellular Growth Products and Isolate Virulence

1981 ◽  
Vol 38 (11) ◽  
pp. 1322-1326 ◽  
Author(s):  
Rocco C. Cipriano ◽  
Billy R. Griffin ◽  
Burton C. Lidgerding
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Aeromonas Salmonicida ◽  
Salmo Gairdneri ◽  
Lesion Development ◽  
Culture Supernatants ◽  
Crude Material

Extracellular growth products, extracted from culture supernatants of Aeromonas salmonicida by precipitation with ammonium sulfate and ethanol, were resolved into four fractions by ion-exchange chromatography. Although one of these (fraction II) possessed leukocytolytic activity, virulence of the pathogen was not associated with leukocytotoxicity. A positive correlation was established, however, between virulence and the toxicity of extracted material to cultured rainbow trout gonad (RTG-2) cells. The crude material and fractions II and III from virulent isolates were more toxic to RTG-2 cells than were similar preparations from avirulent isolates. Preparations from virulent isolates caused hemorrhaging, lesion development, and mortality when injected intramuscularly into brook trout (Salvelinus fontinalis) and Atlantic salmon (Salmo solar). Rainbow trout (Salmo gairdneri) were more resistant and lesions could be produced only with fraction II. Fraction II also possessed proteolytic activity.Key words: Aeromonas salmonicida, furunculosis, pathogenicity, salmonids, extracellular products, cytotoxicity, leukocytolysis, proteolysis, fishes

Models of Ammonia Excretion for Brook Trout (Salvelinus fontinalis) and Rainbow Trout (Salmo gairdneri)

1980 ◽  
Vol 37 (9) ◽  
pp. 1421-1425 ◽  
Author(s):  
Larry J. Paulson
Keyword(s):  
Body Weight ◽  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Ammonia Excretion ◽  
Salmo Gairdneri ◽  
Feeding Rates ◽  
Data Set ◽  
Nitrogen Consumption ◽  
Good Agreement

Ammonia excretion by brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) was measured in relation to nitrogen consumption, body weight (15–154 g for rainbow trout and 50–360 g for brook trout), and temperature (11.2–21.0 °C) under laboratory conditions. Four natural diets, collected from Castle Lake, California, and a commercial pellet diet were fed to the trout in gelatin capsules at feeding rates from 2.5 to 5% body weight∙d−1. Nitrogen consumption was the most important factor influencing ammonia excretion, followed by body weight and temperature. Testing the models with an independent data set revealed good agreement between measured and predicted rates of excretion. The models seem to estimate adequately ammonia excretion by trout in both natural and artificial aquatic systems.Key words: models, ammonia excretion, nitrogen consumption, body weight, temperature, multiple regression, rainbow trout, brook trout

A Leukocytolytic Factor Isolated from Cultures of Aeromonas salmonicida

1977 ◽  
Vol 34 (8) ◽  
pp. 1118-1125 ◽  
Author(s):  
D. W. Fuller ◽  
K. S. Pilcher ◽  
J. L. Fryer
Keyword(s):  
Rainbow Trout ◽  
Virulence Factors ◽  
Coho Salmon ◽  
Virulent Strain ◽  
Deae Cellulose ◽  
Aeromonas Salmonicida ◽  
Salmo Gairdneri ◽  
Amino Sugars ◽  
Avirulent Strain

A substance characterized as a glycoprotein, isolated from the supernatant fluids of broth cultures of Aeromonas salmonicida by a combination of ammonium sulfate and ethanol precipitations followed by chromatography on DEAE-cellulose, was cytolytic for rainbow trout (Salmo gairdneri) leukocytes, and antigenic when injected into rabbits. The ratio of protein to hexose determined by analysis of the purified fraction was between 0.35 and 0.45, and small amounts of amino sugars were detected. A virulent strain of A. salmonicida produced much more of this factor than an avirulent strain. This factor was cytolytic for leukocytes in vitro and also produced a pronounced leukopenia when injected intravenously in adult rainbow trout. When injected in small coho salmon (Oncorhyncus kisutch) 8–13 cm long together with about one LD50 of live A. salmonicida 36 of 40 fish succumbed to the combination, whereas only 14 of 40 died from an injection of the bacterium alone. Thus, the pathogenicity of the organism was enhanced, presumably by increasing the susceptibility of the host. Hence, this glycoprotein apparently is one of the virulence factors of this bacterium. Key words: leukocytolytic factor, Aeromonas salmonicida, glycoprotein, virulence factor

Myxosoma cerebralis: Inactivation of Spores by Hot Smoking of Infected Trout

1982 ◽  
Vol 39 (6) ◽  
pp. 926-928 ◽  
Author(s):  
Ken Wolf ◽  
Maria E. Markiw
Keyword(s):  
Rainbow Trout ◽  
Aquatic Environment ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Soil Samples ◽  
Healthy Tissue ◽  
Salmo Gairdneri ◽  
Heat Inactivation ◽  
Whirling Disease

We processed 2-yr-old rainbow trout (Salmo gairdneri) and brook trout (Salvelinus fontinalis) with clinical whirling disease, which is caused by Myxosoma cerebralis, in one of the following ways: iced, iced and brined, or iced, brined, and hot smoked at 66 °C for 40 min. Skeletal elements of each group were added to tanks containing soil samples from an aquatic environment free of M. cerebralis and aged for 4 mo at 12.5 °C. Following this we assayed for infectivity by holding susceptible rainbow trout fry for 3 mo in the tanks of aquatic soil and skeletal elements. The fry were then examined for M. cerebralis spores. Spores were found in the fry from tanks that had received iced and iced and brined samples, but not in fry from the tanks containing hot smoked tissue, healthy tissue, or no tissue — the last two being negative controls.Key words: whirling disease, Myxosoma cerebralis, heat inactivation, hot smoking

Obligate Anaerobic Bacteria in the Gastrointestinal Microflora of the Grass Carp (Ctenopharyngodon idella), Goldfish (Carassius auratus), and Rainbow Trout (Salmo gairdneri)

1979 ◽  
Vol 36 (10) ◽  
pp. 1174-1179 ◽  
Author(s):  
T. J. Trust ◽  
L. M. Bull ◽  
B. R. Currie ◽  
J. T. Buckley
Keyword(s):  
Rainbow Trout ◽  
Aeromonas Hydrophila ◽  
Grass Carp ◽  
Carassius Auratus ◽  
Anaerobic Bacteria ◽  
Ctenopharyngodon Idella ◽  
Salmo Gairdneri ◽  
Goldfish Carassius Auratus ◽  
Grass Carp Ctenopharyngodon Idella ◽  
Gastrointestinal Microflora

Grass carp (Ctenopharyngodon idella), bred in Arkansas and maintained in British Columbia under defined culture conditions on pelleted diets and on aquatic weeds, were examined to determine their commensal gastrointestinal bacterial flora. Using anaerobic incubation, the total bacterial numbers cultured ranged from 6 × 104 to 4 × 108 (average 4 × 106) per g of alimentary tract plus contents. Obligately anaerobic bacteria were isolated and identified as species of Actinomyces, Bacteroides, Eubacterium, Fusobacterium, and Peptostreptococcus. This is the first description of the presence of these strictly anaerobic organisms in the gastrointestinal tract of fish. Indeed, many of the anaerobes isolated did not conform to previously described species. Members of the Genus Clostridium were also isolated by enrichment culture and appeared to be associated with a pond weed diet. A wide variety of facultative anaerobic bacteria were also isolated, with Aeromonas hydrophila predominating. The gastrointestinal tracts of goldfish (Carassius auratus) were also found to contain sizable numbers of obligate anaerobes, but the gastrointestinal tracts of hatchery-cultured rainbow trout (Salmo gairdneri) contained insignificant numbers. Key words: grass carp, anaerobic bacteria, gastrointestinal microflora, Aeromonas hydrophila, rainbow trout, goldfish

Isolation of Infectious Pancreatic Necrosis Virus from the Blood and Blood Components of Experimentally Infected Trout

1982 ◽  
Vol 39 (1) ◽  
pp. 225-228 ◽  
Author(s):  
Robert N. Swanson ◽  
James H. Gillespie
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Pancreatic Necrosis ◽  
Salvelinus Fontinalis ◽  
Infectious Pancreatic Necrosis Virus ◽  
Salmo Gairdneri ◽  
Blood Components ◽  
Necrosis Virus ◽  
Infectious Pancreatic Necrosis ◽  
Pancreatic Necrosis Virus

Experimental infection with infectious pancreatic necrosis virus (IPNV) was achieved in yearling rainbow trout (Salmo gairdneri) and 7-mo-old brook trout (Salvelinus fontinalis) by intraperitoneal inoculation and by water contact, respectively. Blood removed periodically from both groups of fish was fractionated and various blood components examined for virus. IPNV was recovered consistently from the plasma and mononuclear-enriched blood fractions of the rainbow trout from 1 to 19 d postinoculation (DPI) and also was detected in the mononuclear fraction on 33 DPI. In the brook trout virus was recovered from 3 to 40 DPI in the plasma and from 7 to 40 DPI in the mononuclear fraction. Thus a viremia appeared to be important in the early stages of experimental IPNV infection and infectious virus was found both free in the plasma and in association with an undetermined cell population present in the mononuclear component of blood.Key words: infectious pancreatic necrosis, blood, fish disease, Salmo gairdneri, Salvelinus fontinalis

Serum Proteins and Antibody Production in Rainbow Trout (Salmo gairdneri)

1966 ◽  
Vol 23 (12) ◽  
pp. 1957-1963 ◽  
Author(s):  
George Post
Keyword(s):  
Rainbow Trout ◽  
Specific Antibody ◽  
Aeromonas Hydrophila ◽  
Serum Proteins ◽  
Immune Serum ◽  
Salmo Gairdneri ◽  
Antibody Activity ◽  
Major Protein ◽  
Humoral Antibodies ◽  
Protein Components

Rainbow trout serum was shown to be made up of three major protein components. These three major components did not coincide by electrophoretic mobility or by relative salt solubility with the classic albumin, α-, β-, and γ-globulin separation of the sera of higher animals. A component equivalent to γ-globulin of higher animals was found to be completely lacking in the sera of both immunized and non-immunized rainbow trout.Specific humoral antibodies in rainbow trout immune sera were found to be contained in the electrophoretically least mobile proteins. These proteins coincided most nearly to the β-globulins and possibly the least electrophoretically mobile α-globulins of higher animals. Salt solubility of the serum proteins containing the specific antibody assisted in this conclusion. The electrophoretically least mobile major serum protein components were found to contain all of the antibody activity. These proteins could be removed from immune serum by 20% sodium sulfate. The assumption was made that Aeromonas hydrophila antibodies in immunized rainbow trout blood serum may be made up of a complex of serum proteins with a broad range of salt solubility and electrophoretic mobilities.Serum proteins of rainbow trout could also be classified as euglobulins or pseudoglobulins. The serum proteins which contained the A. hydrophila antibodies were found to be euglobulins.

Response of Rainbow Trout (Salmo gairdneri) to Antigens of Aeromonas hydrophila

1966 ◽  
Vol 23 (10) ◽  
pp. 1487-1494 ◽  
Author(s):  
George Post
Keyword(s):  
Rainbow Trout ◽  
Antibody Titer ◽  
Aeromonas Hydrophila ◽  
Synthesis Method ◽  
Phagocytic Index ◽  
Salmo Gairdneri ◽  
Antibody Synthesis ◽  
Humoral Antibody ◽  
Antibody Titers ◽  
Immunization Procedure

Rainbow trout (Salmo gairdneri) produced antibodies specific for Aeromonas hydrophila. Two parenteral routes yielded no measurable difference in rate of antibody synthesis. Method of bacterin suspension indicated adjuvant suspension was superior in maintenance of humoral antibody and challenge protection when compared to saline suspension of the organism.Antibody synthesis from adjuvant-suspended bacterin lagged approximately 30 days behind the rate of synthesis by fish receiving saline suspended bacteria. The highest measurable antibody titer reached by an individual was 1:64. Individuals receiving saline suspended bacterin showed evidence of loss of titer approximately 2 months after the last antigen inoculation. Definite decrease in titer was noted 5 months after the last antigen inoculation and the return to a probable nonimmune class by approximately one-half of the individuals 7 months after the last inoculation. All individuals receiving adjuvant-suspended bacterin remained in the probable immune class for as long as 6 months following the last bacterin inoculation, but only approximately one-half of the individuals remained in the probable immune class 7 months postinoculation.All fish receiving a weighed quantity of killed A. hydrophila orally each day for 9 consecutive months showed presence of humoral A. hydrophila antibody. This immunization procedure produced 50% of the individuals with humoral antibody titers considered to be in the probable immune class.Fish receiving no immunization remained with negative antibody titers throughout the experimental period.Definite protection was given fish which had been immunized by parenteral inoculation.Similar protection was given after immunization by either intramuscular or intraperitoneal routes. Fish receiving either saline or adjuvant-suspended bacterin parenterally showed analogous protection when challenged by the specific bacteria. Fish receiving oral bacterin received questionable protection against parenteral challenge of the specific organism.Phagocytosis was found to occur to a greater extent in immunized rainbow trout than in nonimmunized rainbow trout. An average phagocytic index of parenterally immunized rainbow trout was 1.08. Nonimmunized rainbow trout of the same age and egg source had an average phagocytic index of 0.30. The opsonic index was 3.6.

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