摘要:

Abstract.The serological relationship of rhabdovirus of penaeid shrimp (RPS) to three fish rhabdoviruses was determined by plaque‐reduction and neutralization kinetics techniques using polyclonal antiserum against RPS. Although RPS was found to be serologically related toRhabdovirus carpio(RC), aVesiculovirustype, the two viruses were clearly distinguishable from one another, RPS was unrelated to two other fish rhabdoviruses of theLyssavirustype, infectious haematopoietic necrosis virus (IHNV) and viral haemorrhagic septicaemia virus (VHSV). Under single cycle growth conditions, immunofluorescence studies showed the appearance of RPS viral antigens as early as 3h post‐infection (pi). The degree of fluorescence and the number of fluorescing cells progressively increased until 24 h pi when more than 90% of the cells showed viral antig

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00226.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Thirty strains ofV. anguillarumwere tested for the production of inhibitory substances against closely‐related bacteria using the deferred antagonism test. Only one strain,Vibrio anguillarumVL4355, inhibited strains ofV. ordaliiand this effect was blocked by the addition of iron salts to the culture medium. Siderophore production was investigated for this strain. Results from bioassays suggested that strain VL4355 produced a siderophore related to anguibactin, the plasmid‐encoded phenolate siderophore produced byV. anguillarumstrain 775. However, when plasmid DNA was compared for strains 775 and VL4355 theBamHI‐generated restriction profiles were different, although hybridization experiments indicated some homology. Using the chrome‐azurol sulphate assay to measure siderophore production, strain VL4355 yielded significantly higher values than otherV. anguillarumstrains. Amberlite XAD‐2 was used to produce concentrated siderophore preparations from strains VL4355 and 775. Both preparations were inhibitory to the growth of strains ofV. ordalii, but notV. anguillarum, as were solutions of the iron chelator ethylenediamine‐di(o‐hydroxyphenylacetic acid). The difference in sensitivity to iron‐limiting conditions forV. ordaliiandV. anguillarum, coupled with the inability ofV. ordaliito utilize ferric‐anguibactin, could reflect different mechanisms of iron uptake for th

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00227.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.In recent years, jaundice disease in farmed hybrid catfish in Thailand has caused high levels of mortalities. Affected fish are lethargic and anorexic and show yellow pigmentation of the skin and gills. Internally, the spleen, kidney and gall bladder are enlarged, and the spleen, kidney, liver and body fat are a pale yellow colour. Most fish contain a yellow ascitic fluid in their abdomen. Histological examination of tissues from diseased fish revealed heavy deposits of haemosiderin and ceroid in the spleen, kidney and liver. Haematological measurements showed that haematocrit values, RBC count, haemoglobin concentration, MCH and MCHC were significantly decreased in affected fish while MCV, total bilirubin and direct reacting bilirubin were significantly increased. The results indicate that the fish are suffering from a haemolytic anaemia associated with lipoid liver degeneration. The disease is thought to be due to the feeding of rancid chicken viscera.

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00228.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Steelhead trout,Oncorhynchus mykiss(Walbaum), fry were experimentally infected with infectious haematopoietic necrosis virus (IHNV) Round Butte 1983 (Type 1). Fry were sampled daily, before and during the epizootic. Fish tissues were tested for infectious virus by tissue culture assay and for IHNV nucleocapsid protein by alkaline phosphatase immunohistochemistry (APIH). The progression of virus through the tissues was followed by APIH until the fourteenth day. Viral infection progressed from two major sites: from the gills into the circulatory system; and from the oral region into the gastrointestinal tract and then into the circulatory system. Once in the blood, virus was disseminated to virtually every organ. Progression of IHNV within and between organs is discussed.

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00229.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.A hot‐water extract ofUndaria pinnatifidawas found to contain polysaccharide(s) which showed immunostimulating activity in fish. In order to identify the effective component(s), the hot‐water extract was fractionated and acid‐soluble (Fraction I) and acid‐insoluble (Fraction II) polysaccharides were evaluated for their potential to enhance protection againstEdwardsiella tardainfection in common carp. Intraperitoneal injection of Fraction II in carp 6 and 3 days prior to challenge withE. tardaresulted in a significantly greater survival rate than that of control fish at doses of 10–30mgkg‐1. On the other hand, Fraction I was not effective at any dose. Chemical and physicochemical analyses revealed that Fraction II was sodium alginate with a high degree of purity, with a molecular weight of 45000 and an M/G ratio of 0.8. Some commercial alginates were similarly evaluated for their efficacy. Alginates fromMacrocystis pyrifera(MW, 146000‐264000; M/G ratio, 0.9–1.0) significantly increased survival rate, but alginates fromLessonia nigrescens(MW, 177000–290000; M/G ratio, 1.3) had little effect. There are indications that the efficacy (protective effect) of alginates has some relationship to

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00230.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Eighty isolates ofAeromonas salmonicida, recovered from separate outbreaks of furunculosis in farmed and wild salmon in Scotland during 1988 and 1989, were examined for susceptibility to the β‐lactam antibiotic amoxycillin. Susceptibility was determined in terms of minimum inhibitory concentration (MIC). All of theA. salmonicidasubsp.salmonicidaisolates investigated were susceptible to amoxycillin, with MICs of 0.30–1.50mg1‐1. All of theA. salmonicidasubsp.achromogenesisolates tested were resistant to amoxycillin, with MICs in excess of 500mgl‐1. TheA. salmonicidasubsp.achromogenesproduced a β‐lactamase enzyme with a pI of approximately 8.0. The enzyme was inducible and its production was unaffected by plasmid curing with ethidium bromide, suggesting that resistance was chromosomal rather than plasm

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00231.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.The ability of A‐layer‐positi ve (A+) and A‐layer‐negative (A−) strains ofAeromonas salmonicidato utilize haem sources of iron under conditions of iron‐restriction was evaluated. In a plate bioassay, only A+strains ofA. salmonicidawere able to utilize haem from a variety of sources including haem, haemin, myoglobin, haemoglobin, haemoglobin‐ haptoglobin and haem‐albumin complexes. Trypsin‐digestion of whole cells abolished haem‐ binding, indicating that binding was cell‐surface associated, involving a protein binding site or receptor. Competitive binding studies indicated that all haem compounds were bound by a common receptor, which was not iron‐regulated and was associated with the presence of the 49‐kDa A‐layer protein. The ability of both typical A+(siderophore‐positive) and atypical A+(siderophore‐negative) strains to utilize haem indicated that the mechanism of haem utilization was not siderophore‐mediated and thatA. salmonicidapossesses both siderophore‐dependent and siderophore‐independent mechanisms to overcome iron‐r

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00232.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.The fate of the fish pathogenAeromonas salmonicidain the marine environment was examined by culture, epifluorcscence microscopy, the indirect fluorescent antibody technique (1FAT), direct viable counts (= Kogure technique) and the assessment of respiratory activity by the reduction of tetrazolium compounds to coloured formazans. In laboratory‐ based systems containing sediment, water, algae and invertebrates, cells ofA. salmonicidawere observed microscopically after plate counts on tryptone soya agar declined to zero. Survival was maximal at a salinity of 25%o, and in wood and sediment, notably mud, rather than the water colum

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00233.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.A collection of 130 strains of the bacterial fish pathogenAeromonas salmonicidasubsp.salmonicidaisolated from diseased salmonids in Denmark, Norway, North America and Scotland has been characterized with regard to protein patterns, antibiotic resistance and exoprotease activity. Whole cell and outer membrane protein profiling could distinguish three different profiles inA. salmonicida.Eight outer membrane proteins were demonstrated (49, 40, 38, 37, 33, 31, 30 and 29 kDa). One protein profile was deficient in a 38 kDa outer membrane protein and instead contained an outer membrane protein of 37 kDa which was not detectable among the other protein profiles. Strains with the 37 kDa outer membrane protein showed multiple low‐level antibiotic resistance towards cephalothin, penicillin, chloramp‐henicol, tetracycline and quinolones. In addition, these strains were exoprotease deficient. Strains with the 37 kDa protein were unable to degrade cattle and trout serum proteins and displayed a delayed degradation of casein. Haemolysis on cattle blood agar plates was similarly delayed.In vivoexamination of extracellular products from a normal protein profile strain and one with the 37 kDa outer membrane protein demonstrated major differences in pathological effects in rainbow trout. The strain possessing the 37 kDa outer membrane protein produced almost no pathological effects while the normal protein profile strain produced typical furunc

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00234.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.An enzyme‐linked immunosorbent assay using dried blood on filter paper, was developed for the detection of antibodies against the haemoflagellateCryptobia salmositicain juvenile rainbow trout,Oncorhynchus mykiss(Walbaum). Each fish (average weight about 5g) in three experimental groups was either inoculated with 20000 attenuated liveC. salmositicavaccine, or inoculated with 2000 or 20000 pathogenic parasites per fish. The vaccine was effective in protecting juvenile trout 4 weeks after vaccination and antibody titers were higher in vaccinated and challenged fish than in unvaccinated and infected ones. Specific antibodies were detected one week post‐infection (w.p.i.) with the pathogen and declined to low levels at 6 w.p.i. The high‐dose group (20000 per fish) had antibody titres comparable to those of the vaccinated and challenged

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1994.tb00235.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY