In vitro secretion of metallo-protease (200kDa) by the pathogenic piscine haemoflagellate, Cryptobia salmositica Katz, and stimulation of protease production by collagen

Cryptobia salmositica cultured in minimum essential medium secreted metallo-protease, and a significantly higher amount of the protease was found in media supplemented with either type I or type IV collagen. The enhancement of the protease secretion by type I collagen was dose-dependent. Using haemoglobin (substrate) SDS-PAGE, the secreted protease was detected as a single clear band (about 200 kDa). The 200 kDa metallo-protease was also detected on the C. salmositica surface membrane and the amount was increased by incubating the parasite with collagen. Collagen as a specific substrate may enhance the role of the C. salmositica metallo-protease in the disease process in infected fish.