摘要:

Abstract.Mutants ofAeromonas salmonicidastrains lacking either the A‐protein, O‐antigen or both of these major surface antigens were tested in rainbow trout,Oncorhynchus mykiss(Walbaum), for their suitability as live vaccines (LV). All of these mutants were shown to be attenuated, as fish receiving ∼5 × 107of the respective strains showed no clinical signs of furunculosis. Immersion vaccination of fish in 5 × 107cfu ml‐1of these strains with an identical immersion dose 14 days later resulted in significant protection by all strains from challenge with a heterologous virulent strain ofA. salmonicida5 weeks later. The levels of protection conferred were all greater than or equal to that provided by an injected bacterin using the same vaccination schedule. With one exception, all LV strains that still possessed a functional O‐antigen provided protective indices (PI) four‐ to seven‐fold greater than the PI for the fish injected with bacterin. When antibody responses of vaccinated fish were compared, it was found that only vaccination by bacterin gave rise to a measurable agglutinating litre. Western immunoblots using the immune fish sera failed to reveal any major differences in antigen recognition in fish that received any of the vaccines tested. These data suggest that the immune response generated by the use of live vaccine strains is different from that generated by a bacterin, and that these useful mutations may be incorporated into existing furunculosis LVs for furt

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00215.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.The epidemiology of epizootic haematopoietic necrosis virus (EHNV) infection was studied in farmed rainbow trout,Oncorhynchus mykiss(Walbaum). Estimates of mortality during five outbreaks on a commercial farm from 1986 to 1992 ranged from 0033 to 0.2% per day and total mortality did not exceed 3–4% in any outbreak. Affected fish were 0+ and less than 125 mm forklength. Clinical signs were non‐specific, and laboratory examination was required to confirm the diagnosis. At the height of the outbreak in 1992, EHNV was demonstrated by virus isolation and antigen capture ELISA in 89% of clinically affected fish and 51% of dead fish, while the prevalence of infection in apparently healthy in‐contact fish was 4%. Two and 4 months later the virus was not detected in a group of apparently healthy fish that had been affected earlier. Antibodies specific for EHNV were not found in rainbow trout from the infected farm; however, strong humoral responses were detected by ELISA in two immunized fish, indicating that the virus was immunogenic. These data suggested that EHNV was poorly infective but highly virulent in rainbow trout. Clinical EHNV infection was positively correlated with high rearing density and a low rate of water exchange, and therefore, with presumed poor water quality. Water temperature, which ranged from 11 to 17°C during outbreaks, did not appear to determine the incidence of clinical infection. EHNV infection in farmed rainbow trout was preceded by infection in free‐living redfin perch,Perca fluviatilisL., in the water catchment, but it was uncertain whether this represented the source of infection for rainb

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00216.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Alpha foetoprotein (AFP)‐like immunoreactivity was detected by double immunodiffusion in thesera of adult rainbow trout,Oncorhyachus mykiss(Walbaum) with histologically confirmed hepatocellular carcinoma experimentally induced in microinjection of embryos with aflatoxin B1(AFB1). Partial characterization indicated that this AFP‐like immunoreactivity gave immunologic cross‐reaction of partial identity with human AFP. had alpha1electrophorctic mobility, and an estimated molecular weight of 72kDa. Elevated serum AFP‐like immunoreactivity levels were also measured by RIA in seven out of eight adult rainbow trout with hepatocellular carcinoma, and in three out of 17 AFB1‐exposed trout without demonstrable grosws or microscopic evidence for hepatocellular neoplasms. No serum AFP‐like immunoreactivity was detected or measured in normal healthy age matched DMSO‐control rainbow trout. These data are consistent with the following conelusions: (1) AFP‐like immunoreactivity detected and measured in the sera of rainbow trout with hepaloecllular careinoma is an analogue to human AFP; and (2) the elevated serum AFP levels measured in adult rainbow trout wilh hepatocellular careinoma resrmble those found in humans with this same malignancy. These data further suggest that serum AFP measurements might be useful to confirm the appearance of hepatocellular carcinoma in experimental fish carcinogen‐assay systems, and to detect hepatocellular neoplasia in high‐risk wild fish populations exposed to carc

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00217.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Juvenile Atlantic salmon from a number of freshwater hatcheries in Scotland were found to be infected by a myxosporean parasite of the genusSphaerospora.Fish first became infected in June by extrasporogonic stages which could be found in the blood and kidney interstitium. These consisted of a primary cell containing one to over one hundred secondary cells. Some secondary cells contained one or two tertiary cells. Sporogony was disporous and occurred later in the kidney tubules. The development of both extrasporogonic and sporogonic stages was studied by light and transmission electron microscopy.

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00218.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.The efficacy of florfenicol in the control of natural outbreaks of furunculosis in Atlantic sallmon,Salmo salarL. was evaluated on five Norwegian farms during the summer of 1992. A total of 115 245 first‐ or second‐generation fish received florfenicol with feed at a dose rate of 10mgkg1body weight daily for 10 consecutive days. Comparisons were made with similar pens of fish medicated with the preferred treatment for eaeh location. In the 10 days following introduction of therapy, all treatments were associated with a rapid decline in mortality caused by infection withAeromonas salmonicida.Florfenicol‐medicated salmon had a lower specific mortality than those given oxolinie acid, flumequine or a trimethoprim and sulphadiazine eombination. No adverse reactions to treatment with florfenicol were obs

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00219.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.The influence of dietary carbohydrate (CHO) on blood chemistry, immunity and disease resistance was studied in two experiments with Atlantic salmon,Salmo salarL. Moist diets with increasing amounts of digestible CHO ranging from 0 to 30% (dry weight) were used. In the first experiment with adult (0.5 kg) fish, blood haemoglobin concentration was negatively correlated with increasing dietary CHO level, while serum glucose and protein did not differ between the groups. Serum cortisol increased linearly in fish fed from 5 to 30% CHO. Serum haemolytic activity was negatively correlated with dietary levels of CHO. Humoral immune responses elicited after vaccination by intraperitoneal injection or by dip immersion withVibrio salmonicidashowed no differences according to diet 10 and 17 weeks post‐vaccination. Mortality after challenge with liveAeromonas salmonicidaby intraperitoneal injection was lowest in fish fed 10% CHO. In the second experiment with juvenile Atlantic salmon (3g), there were minor differences in body and organ weights. Plasma glucose, protein and cholesterol were elevated in fish fed the highest CHO levels. Fish exposed to immersion challenge with different water concentrations ofVibrio anguillarumshowed no statistical differences in mortality. The studies indicate that varying dietary levels of CHO affected immunity and resistance to bacterial infections to a minor extent in Atlantic salmon at low water temperatures during freshwater and seawater stage

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00220.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.A total of 517Vibrio anguillarumstrains isolated from discased fish together with 14 V.anguillarumserogroup O2 andV. ordaliitype strains were serotyped using the European scrotyping system. Marked species differences were recorded. In isolates from salmonids serovar O1 (70.2%) and O2 (20.2%) were dominantwhilst a minor proportion belonged to other serogroups or were non‐typeable. Figures for turbot were similar to those from salmonids. In 32 isolates from sea bass, sea bream and mullet, most strains belonged to serogroup O1. while one was O2a. one O7, and the rest non‐typeable In cod serovar O2 was dominant while only a minor proportion belonged to other serogroups or were non‐typeable. The ecl isolates belonged equally to serovars O2 and O3. All O2 strain were subtyped with absorbed O2a and O2b antisera. O2a was dominant in all fish species. but in cod. the relative number of O2b isolates was considerably higher than in other fish species. The applicability of the European serotyping system is discussed and compared with other serotyping sy

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00221.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.A rapid, sensitive and highly specific detection method for infectious pancreatic neerosis virus (IPNV), based on reverse transcription (RT) polymerase chain reaction (PCR) has been developed. The specificity of the assay is provided by the oligonucleotide primers selected from the IPNV major capsid polypeptide VP2 gene. For each primer combination only one major product is obtained when amplifieation is performed using IPNV double‐stranded RNA from two different viral strains, Sp and VR‐299, as the initial template. No products were detected when genomie nueleic acids other than IPNV RNA were used as RT‐PCR templates. The specificity of the amplification products were confirmed by Southern hybridization using a specific cDNA probe. To assess the sensitivity of the method, dilutions of purified IPNV dsRNA total genome were amplified and quantities of as little as 1 pg of purified dsRNA were detected when the amplification product was visualized by silver‐stained polyacrylamidc gel electrophoresis. This technique detected IPNV directly in infected coho salmon,Oncorhynchus kisutch(Walbaum), and rainbow trout,Oncorhynchus mykiss(Walbaum), tissues and fish egg samples, avoiding viral propagation in cell culture. The results show that this RT‐PCR amplification method is useful for the direct tissue detectio

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00222.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.During two summers in Portugal, intertidal fishes were captured with anaesthetic at four sites along the Portuguese Atlantic West Coast. They were examined for the blood parasiteHaemogregarina bigemina, for other haematozoa, and for haematophagous eetoparasitcs.Haemogregarina bigeminawas found only in biennies,Lipophrys pholis(L.) andCoryphoblennius galerita(L.), and infections in these fish were similar. No other haematozoa were detected. Ectoparasites found attached to biennies included haematophagous praniza larvae of the isopodGnathia maxillarisand a single leech. Gametocytes like those of fish haemogregarines were found in the anterior hindgut of 25% of pranizae and one contained gametoeytes and stages resembling early oocysts. The leech showed none of these stages. It is concluded that gnathiid pranizae should be considered as possible vectors ofH. bigeminain Portugal.

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00223.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00224.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY