NATURAL ANTI-PROTEASES IN RAINBOW-TROUT, ONCORHYNCHUS-MYKISS AND BROOK CHARR, SALVELINUS-FONTINALIS AND THE IN-VITRO NEUTRALIZATION OF FISHALPHA-2-MACROGLOBULIN BY THE METALLOPROTEASE FROM THE PATHOGENIC HEMOFLAGELLATE, CRYPTOBIA-SALMOSITICA
X. Zuo et Ptk. Woo, NATURAL ANTI-PROTEASES IN RAINBOW-TROUT, ONCORHYNCHUS-MYKISS AND BROOK CHARR, SALVELINUS-FONTINALIS AND THE IN-VITRO NEUTRALIZATION OF FISHALPHA-2-MACROGLOBULIN BY THE METALLOPROTEASE FROM THE PATHOGENIC HEMOFLAGELLATE, CRYPTOBIA-SALMOSITICA, Parasitology, 114, 1997, pp. 375-381
Natural anti-proteases (alpha 1-protease inhibitor (alpha 1-PI; alpha
1-antitrypsin) and alpha 2-macroglobulin (alpha 2-M)) were found in th
e blood of rainbow trout, Oncorhynchus mykiss and brook charr, Salveli
nus fontinalis. The alpha 2-M inhibited Cryptobia salmositica protease
s and was significantly higher in brook charr than in rainbow trout. U
nder in vitro conditions it took longer for the same number of parasit
es to neutralize the alpha 2-M in charr than in trout blood. The haemo
lysis which occurred when C. salmositica was incubated in the blood of
rainbow trout was due to neutralization of alpha 2-M. This in vitro s
tudy also showed that it was the metalloprotease of C. salmositica tha
t lysed red blood cells and the plasma of the two species of fishes in
itially prevented haemolysis by inhibiting the proteolytic activity. W
e suggest that the natural plasma alpha 2-M: plays an important role i
n defence against cryptobiosis in fishes.