The involvement of the cysteine proteases of Clonorchis sinensis metacercariae in excystment.
The effects of trypsin, bile, trypsin-bile, pepsin, dithiothreitol (DTT) and metacercarial excretory-secretory product (ESP) on the in vitro excystment of Clonorchis sinensis metacercariae were investigated. The majority of metacercariae excysted immediately in trypsin-bile in PBS solution, a process which was complete after 30 min of incubation. When incubated in metacercarial ESP in PBS, excystment was potentiated in the presence of 5 mM DTT, but was inhibited dose-dependently by a cysteine protease inhibitor, iodoacetic acid. Two active protease bands of 28 and 40 kDa were identified in the ESP of metacercariae by gelatin substrate SDS-PAGE. Scanning electron microscopy demonstrated that the larvae in solutions of DTT and ESP migrated through a small hole on the metacercarial wall, whereas larvae were liberated by entire wall disruption in trypsin solution. These results suggest that trypsin is a major extrinsic factor of the rapid excystment of C. sinensis metacercariae, and that endogenous cysteine proteases are also involved in metacercarial excystment.
Li
Shunyu
S
Department of Parasitology and Tropical Medicine, Seoul National University College of Medicine and Institute of Endemic Diseases, Seoul National University Medical Research Center, Seoul 110-799, Korea.
Chung
Young-Bae
YB
Chung
Byung-Suk
BS
Choi
Min-Ho
MH
Yu
Jae-Ran
JR
Hong
Sung-Tae
ST
D000818:Animals; D001647:Bile Acids and Salts / Q000494:pharmacology; D003004:Clonorchis sinensis / Q000201:enzymology / Q000502:physiology*; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D015801:Helminth Proteins / Q000494:pharmacology; D010434:Pepsin A / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology
D001647:Bile Acids and Salts; D015853:Cysteine Proteinase Inhibitors; D015801:Helminth Proteins; D014357:Trypsin; D003546:Cysteine Endopeptidases; D010434:Pepsin A; D004229:Dithiothreitol