Dr. Murai Éva szerk.: Parasitologia Hungarica 12. (Budapest, 1979)

fluke extracts (Fasciola hepatica and F. gigantica

), but this failed altogether (KLIMENKO and KENINA, 1971). Studies on the proteolytic enzymes of the liver fluke, with special regard to neutral proteases, and investigations into its supposed protease inhibitor activités are reported in this paper. Material and Methods Adult specimens of liver fluke were collected from naturally infected cattle in the Budapest abattoir. The parasites were washed in three changes of sterile physiological saline, and were processed further as follows: Table 1 BAEE-splitting activity, measured in 0. 2M Na-phosphate and NA-phosphate-HCl buffer pH 2 3 4 5 6 7 8 9 BAEE-splitting activity U/

g 0 0.2 0. 42 0.05 0 0 0. 25 0.05 I. Preparation of liver fluke extracts The washed parasites were homogenized in fivefold volume of distilled water related to their weight. The homogenate was centrifuged at 19 000 g for 60 min. at + 5°C. The supernatant was collected for enzyme assays. Table 2 BTEE-splitting activity, measured in 0. 6M citric-acid-NaOH buffer pH 1. 5 2 3 4 5 6 7 8 9 BTEE-splitting activity U/g 0 0 11.15 19.9 2.7 1.52 1. 0 1. 2 0. 45 II. Incubation in maintenance medium Group 1 Single washed parasites were incubated either in 1 ml sterile Tyrode solution (pH 7. 5), containing 0. 3 M TRIS-HC1 buffer, for 4 hours at 37°C, or in TC 135 (Difco) medium, containing 2000 IU/ml penicillin, 1 jug/ml Streptomycin and 100 jug/ml Nystatin, for 24 hours. Group 2 Washed flukes were incubated in Tyrode medium as above, except that their oral sucker was closed with Histoacryl (Braun, GFR) tissue cement. Sealing was performed under a SM XX binocular stereomicroscope, and was rechecked for tightness at the conclusion of the experiment.