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ABSTRACT: Rats develop resistance to re-infection by Clonorchis sinensis while humans do not. We investigated factors involved in the development of resistance to re-infection and super-infection in rats. Sprague-Dawley rats were infected by C. sinensis metacercariae and treated with praziquantel, then re-infected after immune modulation. The rats were also subjected to super-imposed infection after primary infection. Resistance to re-infection was observed by lowered rates of worm recovery after various durations from treatment; 1% at 5days and 24.4% at 11months vs 56.2% in the control. Similar significant resistance was observed in the super-infected rats after 3weeks of primary infection. The re-infected or super-infected worms grew very slowly and remained immature. Resistance disappeared in immune-suppressed and nude rats but not in splenectomized rats. Immunization with antigens of C. sinensis produced no resistance. Local tissue reaction and immune response in the infected bile duct may play an important role in the resistance, although the crowding effect may also be implicated in resistance in super-infected rats.
Parasitology Research 06/2008; 102(6):1111-7. · 2.15 Impact Factor
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ABSTRACT: Rats develop strong resistance to re-infection and super-infection by Clonorchis sinensis. The present study investigated the antibodies present in the sera and bile juice of rats that were primary infected and re-infected with C. sinensis. The serum level of specific IgG antibodies, which were elevated 2 wk of the primary infection, peaked at 4 wk and subsequently remained unchanged even during re-infection. The total IgE level in serum increased slowly from 388 ng / ml to 3,426 ng / ml beginning 2 wk after the primary infection, and remained high up to 8 wk but dropped to a normal level (259 ng / ml) after treatment. In resistant re-infected rats, the serum IgE level increased rapidly and peaked within 1 wk, whereas no increase was observed in immunosuppressed rats. The serum level of specific IgA antibodies was elevated beginning 1 wk after infection, and decreased 4 wk after treatment. The total bile IgA level unchanged during the primary infection but increased in treated and re-infected rats. The elevated levels of serum IgE and bile IgA indicate that these immunoglobulins may be correlated with the development of resistance to re-infection by C. sinensis in rats.
The Korean Journal of Parasitology 04/2008; 46(1):17-22. · 1.04 Impact Factor
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ABSTRACT: The present study observed the resistance to reinfection with Clonorchis sinensis in various experimental animals including mice, guinea pigs, rabbits, and dogs, as well as rats and hamsters. The resistance rates to reinfection in rats, mice, hamsters, guinea pigs, rabbits, and dogs were 79.7%, 58.0%, -12.6%, 54.8%, 62.6%, and 6.0%, respectively. Worms recovered from reinfected rats and mice were immature, and significantly smaller than those from the primarily infected (P < 0.01), whereas those from other animals were fully matured to adults. These findings indicate that the protective response against reinfection with C. sinensis is prominent in rats and mice, and that they may be a good animal model to investigate the mechanism of resistance to reinfection with C. sinensis.
The Korean Journal of Parasitology 07/2006; 44(2):163-6. · 1.04 Impact Factor
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ABSTRACT: We investigated the induction of resistance to Clonorchis sinensis infection by prior infection in rat and hamster models. Animals were challenged with C. sinensis metacercariae, then treated with praziquantel and reinfected. Worm recovery rate in reinfected animals was used to estimate resistance to reinfection. The determined resistance rates to reinfection in rats and hamsters were 97.7% and 10.3%, respectively. In rats, cure from the primary infection of C. sinensis increased resistant to reinfection, and the greater the worm burden and the longer the duration of primary infection, the higher was the resistance rate. For primary infection doses of 10, 40 and 100 metacercariae per rat, the resistance rates were 87.4%, 93.8% and 98.4%, respectively. The resistance rates in rats after 2 or 8-week primary infection were 78.7% and 95.3%, respectively. All worms recovered from reinfected rats were immature. When cured rats were administered with methylprednisolone, resistance to reinfection became impaired. These findings indicate that rats develop a high degree of resistance to reinfection by C. sinensis after cure. The growths and maturations of reinfected worms were also impaired.
The Korean Journal of Parasitology 04/2004; 42(1):19-26. · 1.04 Impact Factor
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ABSTRACT: The effect of endogenous ammonia produced in dead fish or ammonia in ammonium bicarbonate solutions was evaluated on the viability of Clonorchis sinensis metacercariae. Viability was determined by worm recovery in rats infected with metacercariae exposed to ammonia in decaying fish or in vitro solutions. The recovery rates were 58%, 48%, 44% and 2% in fish that had been allowed to decay for 5, 10, 20 and 30 days at 4 degrees C, respectively, and this rate ( Y) was inversely correlated with the ammonia concentration ( X) in fish muscle extract ( Y=80.62-0.0667 X, r(2)=0.905, P=0.049). C. sinensis metacercariae barely survived in ammonia solutions with concentrations exceeding 1 g N/l. Our results indicate that the ammonia produced in dead fish is lethal to the viability of C. sinensis metacercariae.
Parasitology Research 09/2003; 90(5):421-2. · 2.15 Impact Factor
