A molecular approach to understanding the pathogenesis of : relevance to vaccine development

Trust, Trevor J.; Noonan, Brian; Chu, Shijian; Lutwyche, Peter; Umelo, Elizabeth

doi:10.1006/fsim.1996.0028

Cited by 8 publications

(4 citation statements)

References 18 publications

(27 reference statements)

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“…Proliferation and dissemination of the organism might then lead to mortality through acute bacteremia. The requirement for possession of a surface A-layer for the virulence of most strains of A. salmonicida (34) is certainly consistent with this notion.…”

Section: Discussionsupporting

confidence: 55%

“…The absence of any significant effect of satA deletion on the virulence of two different isolates of A. salmonicida demonstrates that the lipase, GCAT, is not, as might be predicted from the toxicity studies (24), a major virulence factor of this bacterium. (For comparison, loss of the A-layer is generally associated with an increase in the LD 50 from approximately 10 2 or less to Ͼ10 6 [34].) The possibility that the nonessential role of GCAT is a reflection of the challenge model is highly unlikely.…”

Section: Discussionmentioning

confidence: 99%

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Defined Deletion Mutants Demonstrate that the Major Secreted Toxins Are Not Essential for the Virulence of Aeromonas salmonicida

et al. 1998

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The importance of the two major extracellular enzymes ofAeromonas salmonicida, glycerophospholipid:cholesterol acyltransferase (GCAT) and a serine protease (AspA), to the pathology and mortality of salmonid fish with furunculosis had been indicated in toxicity studies. In this study, the genes encoding GCAT (satA) and AspA (aspA) have been cloned and mutagenized by marker replacement of internal deletions, and the constructs have been used for the creation of isogenic satAand aspA mutants of A. salmonicida. A pSUP202 derivative (pSUP202sac) carrying the sacRB genes was constructed to facilitate the selection of mutants. The requirement of serine protease for processing of pro-GCAT was demonstrated. Processing involved the removal of a short internal fragment. Surprisingly, pathogenicity trials revealed no major decrease in virulence of theA. salmonicida ΔsatA::kan orA. salmonicida ΔaspA::kan mutants compared to the wild-type parent strains when Atlantic salmon (Salmo salar L.) were challenged by intraperitoneal injection. Moreover, using a cohabitation model, which more closely mimics the natural disease, there was also no significant decrease in the relative cumulative mortality following infection with either of the deletion mutants compared to the parent strain. Thus, although these two toxins may confer some competitive advantage to A. salmonicida, neither toxin is essential for the very high virulence of A. salmonicida in Atlantic salmon. This first report of defined deletion mutations within any proposed extracellular virulence factor of A. salmonicida raises crucial questions about the pathogenesis of this important fish pathogen.

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Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 99%

Defined Deletion Mutants Demonstrate that the Major Secreted Toxins Are Not Essential for the Virulence of Aeromonas salmonicida

et al. 1998

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“…These include lipopolysaccharide (Munn et al, 1982), the paracrystalline surface array protein (A-layer) (Evenberg & Lugtenberg, 1982), ironregulated outer membrane proteins (Aoki & Holland, 1985;Hirst & Ellis 1994), serine protease (Fyfe et al, 1986;Price et al, 1989;Ellis, 1991) and glycerophospholipid: cholesterol acyl transferase (GCAT) (Lee & Ellis, 1990). Of these factors the A-layer appears to be the most important determinant of virulence since loss of the A-layer leads to an increase in LD 50 of at least 10 4 -fold (Trust et al, 1996). Both protease and GCAT are lethal for smolts of Atlantic salmon with LD50s of 2400 and 44 ng g 1 fish weight, respectively (Lee & Ellis, 1989).…”

Section: Introductionmentioning

confidence: 97%

Suppression of the humoral immune response of Atlantic salmon, Salmo salar L. by the 64kDa serine protease of Aeromonas salmonicida

Hussaın

Mackie

Cox

et al. 2000

Fish & Shellfish Immunology

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“…This ability is probably related to the virulence of A. salmonicida , but also the resistance against enzymatic degradation has been suggested as important in this respect (Bjørnsdottir, Eggset, Ni lsen & Jørgensen 1992). However, expression of both A‐layer and LPS O‐chains is crucial to the ability of A. salmonicida to induce disease in fish ( Trust, Noonan, Chu, Lutwyche & Umelo 1996).…”

Section: Introductionmentioning

confidence: 99%

Localization of purified surface molecules (lipopolysaccharide and A‐protein) from Aeromonas salmonicida in the kidney and spleen from Atlantic salmon, Salmo salar L.

Stensvåg

Arnesen

Bøgwald

et al. 1999

Journal of Fish Diseases

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Lipopolysaccharide (LPS) and A‐layer protein purified from Aeromonas salmonicida were administered intravenously in Atlantic salmon, Salmo salar L., either alone or in combination. Tissues from each organ were examined by immunohistochemical techniques, using a polyclonal antiserum against A‐protein and a monoclonal antibody against LPS. When given simultaneously, the antigens seemed to be taken up by different cells in both the head and trunk kidney. The most striking finding was that A‐protein was located in epithelial cells in renal proximal tubules, in contrast to LPS, which was not detected in this location. The amount of A‐protein in the tissue increased with time until 2 h after injection. Autoradiography of SDS polyacrylamide gel electrophoresis of head kidney homogenates showed that in vivo processing of A‐protein coupled to iodinated tyramine cellobiose (125I‐TC‐A‐protein) was completed within 24 h, in contrast to LPS, which was maintained in tissues. The findings of the present study suggest that cells of the head kidney of Atlantic salmon are capable of taking up and processing the A‐protein.

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A molecular approach to understanding the pathogenesis of : relevance to vaccine development

Cited by 8 publications

References 18 publications

Defined Deletion Mutants Demonstrate that the Major Secreted Toxins Are Not Essential for the Virulence of Aeromonas salmonicida

Defined Deletion Mutants Demonstrate that the Major Secreted Toxins Are Not Essential for the Virulence of Aeromonas salmonicida

Suppression of the humoral immune response of Atlantic salmon, Salmo salar L. by the 64kDa serine protease of Aeromonas salmonicida

Localization of purified surface molecules (lipopolysaccharide and A‐protein) from Aeromonas salmonicida in the kidney and spleen from Atlantic salmon, Salmo salar L.

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