DAO 29:57-65 (1997)  -  doi:10.3354/dao029057

Proteases in pathogenic and nonpathogenic haemoflagellates, Cryptobia spp. (Sarcomastigophora: Kinetoplastida), of fishes

Zuo X, Woo PTK

Proteases were detected in Cryptobia salmositica (pathogenic and nonpathogenic vaccine strains), C. bullocki, and C. catostomi using azocasein and hide powder azure as substrates. Maximum activity occurred in acidic pH and the pathogenic strain of C. salmositica had the highest activity. Cysteine protease was found in pathogenic and nonpathogenic Cryptobia spp., but metallo-protease was only present in the pathogenic strain of C. salmositica. Five enzymatic bands were detected in the pathogenic C. salmositica using haemoglobin-SDS-PAGE: four of these were cysteine proteases (49, 60, 66 and 97 kDa) and the other was a metallo-protease (200 kDa). The pathogenic C. salmositica lost the metallo-protease after 10 mo of in vitro culture. We suggest that the metallo-protease of the pathogenic C. salmositica is related to pathogenicity of the parasite.


Cryptobia salmositica · C. bullocki · C. catostomi · Cysteine protease · Metallo-protease


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