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1.
Differences in susceptibility to the myxozoan parasite Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease (PKD), between four strains of rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta) were evaluated. Fish were exposed to water enzootic for the parasite in the field for 5 days and were subsequently transferred to the laboratory. Relative parasite load was determined after 2, 3 and 4 weeks post-exposure (wpe) by quantitative real-time PCR (qPCR) of kidney samples and number of parasite stages was determined in immunohistochemical stained sections of kidney, liver and spleen tissues. According to qPCR results, the highest amount of parasite DNA per equal amount of host tissue at all time points was measured in brown trout. Two of the rainbow trout strains showed lower relative parasite load than all other groups at the beginning of the experiment, but the parasite multiplied faster in these strains resulting in an equal level of relative parasite load for all rainbow trout strains at 4 wpe. A weak negative correlation of fish size and parasite load was detected. Only in samples of a few fish, single stages of T. bryosalmonae were found in sections stained by immunohistochemistry impeding quantitative evaluation of parasite numbers by this method. The results indicate a differential resistance to T. bryosalmonae between the rainbow trout strains investigated and between rainbow trout and brown trout.  相似文献   

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4.
Abstract

The expression of stress protein-70 (SP-70), also known as heat shock protein-70 (HSP-70), was measured by enzyme-linked immunosorbent assay in kidney and liver from coho salmon Oncorhynchus kisutch with bacterial kidney disease (BKD) experimentally induced by injection with Renibacterium salmoninarum. Fish with BKD had more SP-70 in both kidney and liver than did the control fish. The SP-70 measured was derived from the host tissue, not from the pathogen. In fish without clinical disease, SP-70 was not significantly elevated. Elevated stress protein (SP) levels in fish with BKD raise the possibility that BKD or other infectious diseases may interfere with the use of SP induction as a marker of environmental stress in fish and lead to statistical artifacts when the prevalence of disease is not considered.  相似文献   

5.
Abstract

Largemouth bass Micropterus salmoides presented with a history of inappetence, epidermal darkening, disorientation, recumbancy with intermittent muscular spasms, and then death. Internal examination revealed an enlarged, pale kidney. A wet mount preparation of kidney tissue demonstrated high numbers of adults and eggs of the monogenean Acolpenteron ureteroecetes. Bacteriology and virology were negative. Histological examination revealed degenerative renal changes associated with renal tubular and ureteral parasitism. This kidney disease was assumed to have resulted from an ascending urinary bladder infestation. Previous reports of Acolpenteron have included incidental findings restricted to the urinary bladder and ureters, without associated pathology. This is the first report of A. ureteroecetes infesting the renal tubules, and it documents the pathogenic potential of this organism in a recirculating system.  相似文献   

6.
Abstract

Blood parameters, disease resistance, and the immune response were sequentially evaluated in rainbow trout Oncorhynchus mykiss with proliferative kidney disease (PKD). The fish were maintained under laboratory conditions, and the study group went through a full cycle of the disease. Hematological and serological changes occurred primarily in those fish with severe kidney lesions. Fish infected with the parasite that causes PKD demonstrated a greater resistance to bacterial challenge, and their immune responses were heightened when compared with those of uninfected fish. These data suggest that PKD alone is not a predisposing factor for secondary infections if the fish does not incur severe renal lesions.  相似文献   

7.
Abstract

Various diagnostic methods used to detect Renibacterum salmoninarum, the causative agent of bacterial kidney disease (BKD), were compared. The most sensitive method was the enzyme immunoassay (the indirect dot blot assay), which could detect 102 bacterial cells per gram of kidney tissue. The minimum bacteria concentrations showing positive reactions to the indirect fluorescent antibody test (IFAT) and the coagglutination test were 103 and 104 cells/g kidney, respectively. The sensitivities of the Gram stain, immunodiffusion procedure, and latex agglutination test were low, and these methods could only be applied to fish with overt BKD symptoms. Altogether, 656 coho salmon Oncorhynchus kisutch were examined for R. salmoninarum antigen with the direct and indirect dot blot assays (DDBA and IDBA) and the IFAT. Among the fish sampled, positive reactions were obtained in 11.8% by the DDBA, 28.2% by the IDBA, and 12.9% by the IFAT.  相似文献   

8.
Abstract

Bacterial kidney disease (BKD) is an important contributor to mortality of salmonids in hatcheries in the Columbia River basin. However, the impact of BKD on the survival of downstream migrants is difficult to determine because there is little information on the disease-related mortality among these fish. In this study, the impact of BKD on juvenile salmonids was examined by determining the percentage of downriver migrants infected with Renibacterium salmoninarum (the causative agent of BKD) and evaluating the effects of salt water on the progress of the disease. During the 2 years of this study, approximately 20% of the three species of migrating hatchery and wild salmonids (Oncorhynchus spp.) collected were infected with R. salmoninarum. Mortality caused by BKD increased when fish were held in salt water.  相似文献   

9.
Abstract

Isolates of Flexibacter psychrophila were obtained from chinook salmon Oncorhynchus tshawytscha and coho salmon O. kisutch that had previously sustained epizootics of coldwater disease. The pathogen was readily isolated from kidney and mucus of convalescent fish. The organisms were relatively inert in most standard microbiological media but were structurally and serologically homogenous by examination of whole cell protein lysates by sodium dodecyl sulfate polyacrylamide gel electrophoresis. In contrast to the homogeneity observed in phenotypic and serologic assays, the isolates studied elaborated varied ribotypes. All isolates produced a single rDNA spacer amplification product of about 240 base pairs.  相似文献   

10.
Abstract

The cellular inflammatory response of rainbow trout Oncorhynchus mykiss (formerly Salmo gairdneri) to the myxozoan parasite PKX that causes proliferative kidney disease was investigated. The response was studied from 3 to 20 weeks after the fish were injected with infected kidney homogenate. Kidney samples were examined by light and electron microscopy. In contrast to most myxosporeans, PKX provoked a severe host response. Parasites were found in peritubular capillaries and sinusoids 3 weeks postinjection. The initial response to PKX was hemopoietic hyperplasia followed by a marked granulomatous nephritis that was resolved by termination of the study at 20 weeks postinjection. The macrophage was the predominant cell type involved in the inflammatory response to PKX. We presume that the macrophage effectively interrupts the development of PKX and eliminates the parasite from the host.  相似文献   

11.
Abstract

Chelonid herpesvirus 5 (ChHV5), the likely etiologic agent of sea turtle fibropapillomatosis (FP), is predicted to be unevenly distributed within an infected turtle, in which productive virus replication and virion shedding occurs in cutaneous tumor keratinocytes. In this study, we measured and compared ChHV5 DNA quantities in tumors, skin, urine, major organs, and nervous tissue samples from green turtles Chelonia mydas. These samples were taken from the carcasses of 10 juvenile green turtles with and without clinical signs of FP that stranded in Florida during 2014. Quantitative PCR for ChHV5 UL30 was used to identify ChHV5 DNA in tumors, skin, heart, kidney, nerves, and urine sampled from five out of five FP-positive and three out of five FP-free turtles. The most frequently co-occurring sites were cutaneous tumor and kidney (n = 4). Novel data presented here include the identification of ChHV5 DNA in kidney, heart, and nerve samples from three FP-free turtles. These data support candidate nontumored anatomic sites of ChHV5 DNA localization and mobilization during two different disease states that may be involved in the ChHV5 infection cycle.

Received September 8, 2016; accepted April 17, 2017 Published online July 26, 2017  相似文献   

12.
Abstract

We challenged duplicate groups of yearling smolts of chinook salmon Oncorhynchus tshawytscha held in seawater with an intraperitoneal inoculation of the kidney disease bacterium Renibacterium salmoninarum 1 d before and at intervals of 1, 11, and 29 d after a 21-d oral administration of erythromycin thiocyanate at 0.1 g/kg body weight per day. Most mortality attributable to bacterial kidney disease (BKD) in fish challenged with R. salmoninarum but not administered erythromycin occurred 2–3 weeks after challenge; the average survival 35 d after challenge was only 9%. Nearly 70% of the fish challenged 1 d before the erythromycin feeding were alive 35 d after the 21-d treatment, and more than 98% of the fish challenged the day after the 21-d erythromycin treatment survived a further 35 d. Fish challenged 29 d after the erythromycin treatment were not significantly protected against BKD. Chinook salmon that were not challenged with the bacterium but were injected with sterile phosphate-buffered saline and then fed a ration with erythromycin survived at a significantly higher rate than unchallenged fish injected with saline but not fed erythromycin. Fish that were not injected with saline or R. salmoninarum survived at a significantly higher rate than fish handled and injected with saline or pathogen. Because erythromycin protected fish challenged just before and immediately after treatment, the antibiotic should be useful early in an outbreak of BKD and as a prophylactic when stresses are expected.  相似文献   

13.
Abstract

Effects of prefiltration and enzyme treatment on the filtrability of kidney tissue of chinook salmon Oncorhynchus tshawytscha were examined. The clarification of kidney suspensions with a 5-μm prefilter did not affect microbial recovery from the samples examined. Samples of kidney suspensions inoculated with Renibacterium salmoninarum (102-105 cells/g) were prefiltered and then tested for their filtrability through a 0.2-μm membrane filter. Less than 50% of the samples could be filtered without enzyme treatment, but all samples were rendered filtrable by enzyme treatment. Inoculum levels of R. salmoninarum as low as 100 cells/g could be detected and quantified. The application of these procedures greatly enhances membrane filtration for the certification of R. salmoninarum-free fish.  相似文献   

14.
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15.
Abstract

Channel catfish Ictalurus punctatus (weight, 320–420 g) were fed diets with 100 or 1,000 mg ascorbic acid/kg of diet for 7 weeks in ponds. Anterior kidney neutrophil function was assessed by incubating the neutrophils with Edwardsiella ictaluri. Percent phagocytosis, phagocytic index (the mean number of bacteria phagocytized per cell by all neutrophils, including nonphagocytic ones), and bactericidal capabilities of the anterior kidney neutrophils were measured at 0, 90, 180, 270, and 360 min. Serum cortisol was also measured. No significant difference was observed between the two diets with respect to anterior kidney neutrophil function or serum cortisol levels. However, serum cortisol levels did affect mean phagocytic index of anterior kidney neutrophils. Catfish that had serum cortisol levels greater than 10 μg/dL displayed a significant decrease in the phagocytic index when compared with catfish that had cortisol levels less than 5 μg/dL.  相似文献   

16.
Abstract

Channel catfish Ictalurus punctatus were experimentally infected with Edwardsiella ictaluri by immersion exposure. After clinical disease ran its course for 52 d, the surviving fish were exposed to one of the following environmental regimes in troughs: 25°C with aeration, 25°C with no aeration, or variable temperature (18–23°C) with no aeration. After 29 d of exposure to the environmental regimes, various organs and tissues of the fish were assayed to determine the effects of these conditions on E. ictaluri concentrations (colony-forming units/mL of tissue sample). The concentrations of this pathogen were significantly (P < 0.05) higher in all tissues (trunk kidney, liver, head kidney, blood, spleen, gallbladder, muscle, brain, and gonad) 52 d postinfection than 29 d after exposure to any of the environmental regimes (81 d postinfection). Fish exposed to a near-normal concentration of dissolved oxygen (6.4 mg/L) and a constant temperature of 25°C had E. ictaluri concentrations that were significantly (P < 0.01) lower than those offish exposed to a low oxygen concentration (2.6 or 1.8 mg/L) and either a constant or a variable temperature.  相似文献   

17.
Abstract

The cause of an ongoing mortality of hybrid tilapias Tilapia nilotica × T. aurea in a Texas fish farm was a biotype of Streptococcus iniae. Identification was based upon classical biochemical and physiological analysis as well as ribosomal RNA gene sequencing. The causative agent, a β-hemolytic Streptococcus species, grew better at 37°C than at 10, 25, or 40°C, and its growth was inhibited at pH 9.6, in 6.5% NaCl, and in 40% bile. The bacterium was resistant to ampicillin and furazolidone but was susceptible to several antibiotics including tetracycline, oxytetracycline, and sulfadimethoxine-ormetoprim (5:1). This is the first record of this bacterial species affecting fish in the USA. External signs of disease in tilapia were loss of orientation, exophthalmia, corneal opacity, and petechia around the mouth, anus, and proximal margins of the pectoral fins. Internally, fluid accumulation in the peritoneal cavity and enlargement of the liver, spleen, and kidney were observed.  相似文献   

18.
Abstract

The effects of injectable vaccines against Aeromonas salmonicida on oxygen consumption, growth, kidney lysozyme activity, and anti-A. salmonicida plasma antibody titers of juvenile rainbow trout Oncorhynchus mykiss were examined. The vaccines were A. salmonicida bacterin only, bacterin adjuvanted with levamisole, bacterin in emulsified oil, microencapsulated bacterin, microencapsulated bacterin with muramyl dipeptide, microencapsulated bacterin with β-1,3-glucan, and microencapsulated bacterin with Vibrio anguillarum lipopolysaccharide (LPS). The greatest and broadest ranges of responses were caused by the microencapsulated bacterin with V. anguillarum LPS. Oxygen consumption rates and specific growth rates were significantly higher over the course of 1 month among fish treated with the LPS vaccine. These fish also maintained a higher anti-A. salmonicida plasma antibody titer and kidney lysozyme activity for a substantially longer period than fish receiving the other treatments.  相似文献   

19.
dAims:To determine the prevalence by isolation of Bordetella bronchiseptica infection in healthy cats and in cats showing signs of upper respiratory tract (URT) disease attended by a veterinary practice in the Manawatu region.

dMethods: The nasal cavity and oropharynx of 100 cats of mixed sex and age were swabbed and the swabs cultured for B. bronchiseptica. The population of cats surveyed was that attended by the Massey University Veterinary Teaching Hospital, and included healthy cats, cats with clinical signs of URT disease, cats with a recent history of URT disease, cats from single cat households, cats from multiple-cat households, and cats from a colony.

dResults: Bordetella bronchiseptica was recovered from 7 cats (5 from pharyngeal samples and 2 from nasal samples). Five of the 7 cats appeared to be healthy at the time of sampling, whilst 2 showed clinical signs of URT disease. Six of the 7 culture-positive cats were from a cat colony.The prevalence of B. bronchiseptica in healthy cats sampled was 7% and in cats with URT disease was 8%.

dConclusion: This study confirms that B. bronchiseptica infection is present, but the prevalence of infection is low, in both healthy cats and in cats with URT disease attended by the Massey University Veterinary Teaching Hospital. It is unlikely that B. bronchiseptica infection is a frequent cause of feline URT disease of cats in this region.  相似文献   

20.
Abstract

Mycobacteriosis can be a chronic wasting disease found in many species of fish examined from wild-caught, cultured, and aquarium-reared populations. An Atlantic menhaden Brevoortia tyrannus with an open ulcer from a wild-caught, laboratory-maintained population was sampled for microbiology. Mycobacterium spp. was recovered from the ulcer and M. fortuitum complex was recovered from the spleen of this fish. Subsequently, 20 additional fish were subsampled from this population to determine the prevalence of the infection. Bacteriology samples were taken from the brain, liver, and kidney. Spleens were homogenized and plated on media enriched for mycobacterial growth, full necropsies were performed, and samples were taken for histology. Bacteriology results showed 100% of the fish in the subsample were infected with mycobacteria. Three species of mycobacteria were isolated from the spleen tissues: M. marinum, M. fortuitum complex, and M. gordonae. Histology results revealed that granulomas, characteristic of mycobacteriosis, were most prevalent in livers but were also found in spleens, posterior kidneys, and hearts. This report adds Atlantic menhaden to the list of species susceptible to mycobacteria.  相似文献   

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