Influences of Aeromonas salmonicida lipopolysaccharide, prednisolone and water temperature on plasma protein composition in salmonids

Abstract

To further characterize the putative role of constitutive and inducible plasma proteins in innate resistance to furunculosis, the present authors compared the alterations in profiles of plasma proteins in resistant and susceptible salmonids, i.e. rainbow trout, Oncorhynchus mykiss (Walbaum), and brook trout, Salvelinus fontinalis (Mitchill), respectively. Rainbow trout were injected with prednisolone acetate and exposed to higher water temperature (18 °C versus 10 °C), or injected with purified lipopolysaccharide (LPS) from a virulent strain of Aeromonas salmonicida, and plasma components were examined by two‐dimensional polyacrylamide electrophoresis. Two days after A. salmonicida LPS exposure, rainbow trout had a four‐ to five‐fold increase in concentrations of plasma proteins composed of p48, p19 and p16 subunits, and a significant decrease in a 100‐kDa protein group. Consistent elevation or depletion of proteins corresponding to previously reported rainbow trout A. salmonicida LPS‐binding pentraxins and lectins in plasma were not observed. Brook trout exposed to A. salmonicida LPS did not have any consistent plasma protein changes. There were no significant alterations in major plasma proteins following temperature shock and prednisolone acetate administration in rainbow trout plasma. These studies demonstrate that rainbow trout with LPS‐induced sterile inflammation have few alterations in major plasma proteins or LPS‐binding proteins, and do not exhibit the spectrum of acute phase changes induced by inflammation in mammals.

Plasma protein changes in Atlantic salmon, Salmo salar L., with infectious salmon anaemia

“…It is possible that the length of time taken for the spread of infection to individual ®sh inherent in any cohabitation experiment interfered with detection of acute phase protein changes in this study. Alternatively, acute phase protein pro-duction could be absent or minimal during an acute phase response in Atlantic salmon affected by ISA, a situation similar to that seen in brook trout, Salvelinus fontinalis (Mitchill), injected by LPS (Simko et al 1999b).…”

“…Linear correlation coef®cient (R) and its 95% con®dence interval were calculated for haematocrit values and total plasma protein concentrations using Pearson (parametric) correlation. Individual plasma protein changes between control and infected ®sh were determined by densitometry (AlphaImager TM , Alpha Innotech Corporation, San Leandro, CA, USA) and analysed as previously described (Simko et al 1999a;Simko, Kocal, Quinn, Ostland, Ferguson & Hayes 1999b). Brie¯y, the integrated intensity of Coomassiestained protein bands/dots was expressed as pixel density.…”

“…Individual plasma protein changes between control and infected fish were determined by densitometry (AlphaImager TM , Alpha Innotech Corporation, San Leandro, CA, USA) and analysed as previously described (Simko et al . 1999a; Simko, Kocal, Quinn, Ostland, Ferguson & Hayes 1999b). Briefly, the integrated intensity of Coomassie‐stained protein bands/dots was expressed as pixel density.…”

Plasma ladderlectin concentration following sterile inflammation and Aeromonas salmonicida subsp. salmonicida infection

“…The purified smooth and rough LPS (Darveau & Hancock 1983) was isolated from a virulent strain of A. salmonicida subsp. salmonicida (B18–94) previously described and used by Simko et al. (1999b).…”

“…Previous studies of rainbow trout APRs have used two‐dimensional SDS polyacrylamide gel electrophoresis (2D‐PAGE) analysis to identify altered plasma proteins during sterile peritoneal inflammation. Minimal changes were observed in Coomassie‐stained proteins following the injection of purified bacterial products to stimulate an inflammatory response (Simko, El‐Mowafi, Bettger, Ostland, Ferguson & Hayes 1999a; Simko, Kocal, Quinn, Ostland, Ferguson & Hayes 1999b). A similar protocol identified a panel of protein spots that underwent at least a three‐fold increase following sterile intraperitoneal (i.p.)…”