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  • 1
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. A method for purification of the 70-KDa extracellular serine protease of Aeromonas salmonicida by hydrophobic chromatography and ion exchange is described. The purified protease, adsorbed onto mineral particles, was used for immunization of salmon. Other groups of salmon were immunized with particles coated with purified glycerophospholipid:cholesterol acyltransferase (GCAT) or with the acyltransferase complexed with LPS (GCAT-LPS). Humoral immune responses assayed after 6 weeks by ELISA, showed relatively good responses against GCAT-LPS, while titres of antisera against the purified protease and GCAT were scarcely above those of control sera. However, the antibody responses to each toxin were shown by Western blotting to be specific and qualitatively similar to responses seen in rabbits. The toxin preparations were also used (in combination with whole bacteria) for vaccination of salmon. On challenge 3 months later, only GCAT-LPS elicited significant immunological protection. However, a more convincing protection was seen when total extracellular product was present in the vaccine.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. Consumptive coagulopathy was induced within 4 h in Atlantic salmon, Salmo salar L., by injecting purified serine protease from Aeromonas salmonicida into the dorsal aorta. Pretreatment with a bolus intravascular injection of (human) antithrombin (AT) or (bovine) α2-macroglobulin (α2M) just prior to injection of the protease alleviated the in vivo pro-coagulant effects of the enzyme, but could not hinder the development of consumptive coagulopathy. In fish receiving only saline as pretreatment, the coagulopathy was evident even after 28h, but the fish were not overtly sick. The addition of the exogenous inhibitors increased the fish's natural protection against the bacterial exotoxin, suggesting that both AT and α2M are of importance for the outcome of the pathologic process. Results further indicate that while AT in vivo was mainly directed against generated thrombin and activated coagulation factor X (FXa), α2M inhibited the protease directly.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. Extracellular hacmolytic activities of Aeromonas salmonicida ssp. salmonicida to salmon red blood cells were shown to be due to different forms of the membrane-active enzyme glyccrophospholipidrcholcstcrol acyltransferase (GCAT). About 10% of the total haemolytic activity was due to a high molecular mass complex of LPS and GCAT (mol. mass 〉1000kDa), containing 35–50% neutral sugars and 1.5–2.0% protein. Some haemolytic activity (30–40% of total), corresponding to 50–70kDa by gel filtration, also contained GCAT-activity and may represent aggregated forms of GCAT. However, about 50% or more of the haemolytie activity was due to a protein of 26kDa free GCAT. Rabbit antibodies to GCAT neutralized the hacmolytic activity of both GCAT and GCAT-LPS. A transposon-produccd serinc protease negative mutant of the same A. salmonicida strain showed reduced haemolytic activity. The mutant produced a 38-kDa GCAT proform of low hacmolytic activity. The proform was processed by autogenous scrinc protease to a highly hacmolytic 26-kDa molecule with pl 6.3, similar to GCAT of the parent strain. The weakly haemolytic GCAT-LPS analogue of the mutant strain did not contain detectable amounts of the 26-kDa molecule and was not activated by proteases.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 13 (1990), S. 0 
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. Immunohistochcmical examination showed that trypsin was present in mucus-secreting cell layers of Atlantic salmon, such as surface epithelial cells of gills and intestine, and epidermal cells of dorsal skin. Trypsin in tissue slices was identified by an immunohisto-chemical technique which used affinity purified immunoglobulins from rabbit antisera against purified salmon pancreatic trypsin as primary antibodies. Most of the positively stained cells appeared to be granulated and secretory. The authors hypothesize that trypsin in mucus-secreting cell layers is a part of the non-specific immune defence of the fish.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science, Ltd
    Journal of fish diseases 22 (1999), S. 0 
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Two extracellular metalloproteases were purified from a culture filtrate derived from Aeromonas salmonicida ssp. salmonicida. One enzyme, leucine aminopeptidase (LAP), which had a molecular mass 37 kDa, hydrolysed aminoterminal l-leucine and l-phenylalanine. The activity was inhibited by 1,10-o-phenanthroline, but not by EDTA. The addition of excess Zn2+ to an o-phenanthroline-inhibited enzyme restored most of its activity. The peptidase was temperature stable, and had an optimum temperature and pH of 60 °C and 8, respectively. The other enzyme, metalloprotease 3 (MP3), which had a molecular mass 20 kDa, was an endoprotease, and hydrolysed azocoll and hide powder-azure, but not gelatine. The MP3 enzyme had an optimum temperature and pH of ≈40 °C and 7.5, respectively, and a cationic isoelectrical point.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 18 (1995), S. 0 
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. Aeromonas salmonicida ssp, salmonicida is shown to produce several extracellular proteins having gelatinolytic activity. Among the six isolates tested, two (NCMB 1102 and 84–14–R) produced both high (89–100 kDa) and low molecular (37 kDa) weight gelatinases, while the other four demonstrated only the 89–100 kDa forms. The low molecular form (metalloprotease 1: MP 1, 37 kDa) was isolated by ammonium sulphate precipitation, hydrophobic, ion exchange and size exclusion chromatography. The isolated enzyme was inhibited by the metal-chelating agents o-phenantroline and EDTA, and by excess Zn ions, and thus was defined as a metalloprotease. Its pH-optimum was 7–5, optimal activity was at 40°C and its pI 5.2. Specificity studies demonstrated cleavage of gelatin and azocoll, but not casein.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. Intravascular injection of purified 70-kDa protease or GCAT-LPS from Aeromonas salmonicida, or both, invariably led to consumptive coagulopathy within 2h in Atlantic salmon, Salmo salar L. By entering the coagulation cascade at two different levels, the two enzymes work in concert in thrombus formation, the significance being that circulatory failure is probably the major cause of death in acute furunculosis. Only intravascular injection of GCAT-LPS led to consumptive coagulopathy in rainbow trout, Oncorhynchus mykiss (Walbaum), despite the fact that trout received only half the GCAT dose, and/or four times the protease activity administered to salmon. These results indicate that salmon is, by far, the most susceptible to protease and suggest that rainbow trout is the most susceptible to GCAT-LPS. The substrate profile of the purified protease gave supporting evidence that it works as activated coagulation factor X. The protease is inhibited in vitro by antithrombin and by α2-macroglobulin and both inhibitors are consumed in vivo in response to intravascular administration of the enzymes, thus showing a potential for AT and α2M to inhibit the protease also in vivo. Provided such plasma antiprotease activities are correlated with resistance to the disease, and the inhibitors show genetic variation they would be promising candidates for indirect selection and hence a means to prevent furunculosis independently of vaccines. Circulating inhibitors of GCAT-LPS remain to be identified.
    Type of Medium: Electronic Resource
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