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KMID : 0352519840210030029
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Korea Univercity Medical Journal
1984 Volume.21 No. 3 p.29 ~ p.38
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Studies on the acquired resistance in rats to Clonorchis sinensis
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趙星煥/Jo, Sung-Whan
朱炅煥/林漢鍾/Joo, Kyoung-Hwan/Rim, Han-Jong
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Abstract
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The development of acquired resistance in clonorchiasis was studied in rats experimentally infected with Clonorchis sinensis. The induction of acquired resistance was attempted by first exposing adult rats to 15 or 50 metacercariae of C. sinensis from naturally infected Pseudorasbora parva and then treated with praziquantel prior being challenged. The reinfection was performed at 1, 2, 4, and 8 weeks after elimination of flukes.
Worm recovery rates and growth of the worms obtained from rats necropsied at 4 weeks .after reinfection were compared to those of control group. End point titers of rat´s serum were studied by ELISA at the time of reinfection and morphological findings of bile ducts were also studied by the light microscope.
In other experiments, rats were infected repeatedly with 5 or 10 metcercariae at 1 week interval for 5 times. Animals were killed 4 weeks after the last exposure and the results were compared to a single infection of 25 or 50 metacercariae.
Worm collection was failed in rats challenged with 50 metacercariae at 1 or 2 weeks after treatment. Worm recovery rates were 3.5 and 20.05o in rats reinfected at 4 and 8 weeks respectively after treatment, while 41.5% in control rats. In another experiments, 15.6%, 18.3% and 33.3% in worm recovery rates were obtained in rats, challenged with reinfections at 2, 4, and 8 weeks respectively after treatment of these rats initially infected with 15 metacercariae. Recovery rates were 50.061 in control group.
Worms recovered in this experiment were found retarded in growth compared to control group. High end point antibody titers of the rat serum at the time of reinfections were presented by ELISA and it seemed to suppress maturation of the worms. Histopathological recovery
of the bile ducts were not remarkable until 4 weeks after treatment and it may be contributed to reinfection as an another protecting factor.
Multiple low dose repeated infection showed lower recovery rates compared to high dose single infection.
Worm recovery rates of animals infected 5 times with 5 metacercariae were 11.0% and single infection of 25 were 53.0%. That of animals infected 5 times with 10 metacercariae was 13.0% compared to 41.5% of single infection of 50 metacercariae. In conclusion, the data presented in this study indicate that during the course of infection by C. sinensis acquired resistance is induced by preceding infection although complete protection may not be elicited.
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