Effects of temperature and white sucker (Catostomus commersoni) serum supplement on the in vitro multiplication of Cryptobia catostomi in cell-free culture medium.

Cryptobia catostomi, a non-pathogenic haemoflagellate of white suckers (Catostomus commersoni) multiplied rapidly in modified TDL-15 medium supplemented with 10% fetal bovine serum and 1% heatinactivated white sucker serum (WSS) at 10 degrees C and 18 degrees C. The numbers of C. catostomi counted were significantly higher in cultures incubated at 10 degrees C than in those incubated at 18 degrees C beginning at 3 weeks post-incubation. The culture forms (from the eighth subculture at 9 months after isolation) were morphologically similar to blood forms and were infective to laboratory-raised white suckers. The parasite survived for about 4 weeks in the medium without WSS at 18 degrees C. The present study indicates that WSS supplement supports the in vitro multiplication of C. catostomi and that its multiplication is temperature-dependent.