Studies On Delayed Tail Loss Of Schistosoma Japonicum Cercaria And Its Clinical Significance

Schistosomiasis is a serious disease to human. The parasite finding and invading human are adaptive behaviors developed over a long period of evolution. Understanding well the behaviors is not only helpful to the relationship between the parasite and host but also favor to control of the parasitic disease. In the project, we focus on studies on delayed tail loss of Schistosoma japonicum and its clinical significance.The research contents included the following4parts:Prat1. Studies on delayed tail loss of Schistosoma japonicum cercariaAim:Traditionally, schistosome cercariae would shed their propulsive tails as they penetrate the skin of host. While recently, contrary to this long-held assumptions, some new researches have shown that Schistosoma mansoni do not shed their tails at the onset of penetration. This phenomenon is termed as delayed tail loss (DTL). In the present study, we intend to explore DTL of Schistosoma japonicum cercariae.Methods:using a device Franz cell to observe the behavior of Schistosoma japonicum cercariae while S. japonicum cercariae penetrated a mouse skin in vitro.Rresults:DTL also happens with S. japonicum cercariae during penetration of mouse skin. It occurred at all cercarial densities tested from as few as10cercariae/2-25cm2of mouse skin up to200cercariae. Furthermore, it was demonstrated that there was a density-dependent increase in DTL as cercarial densities increased.Conclusion:The phenomenon of DTL also occurs in S. japonicum cercariaePart2. Studies on the relationship between DTL of S. japonicum cercariae and cercarial dermatitisAim:It has been demonstrated that cercarial dermatitis was caused by schistomulum died in skin. This research is to explore the relationship between cercarial dermatitis and tails lost in skin.Methods:The mice infected Schistosoma japonicum were injected with cercariae, cercarial bodies and tails respectively. The relationship between the dermatitis and cercaria, cercarial body and cercarial tail were observed, meanwhile, the cytokines IFN-γ, IL-4and IL-5were detected.Results:The local skin of mice stimulated by tails showed the red papules, tissue edema and eosinophilie infiltration, the levels of IFN-γ, IL-4and IL-5increased compared with the mice stimulated by cercariae or cercarial bodies.Conclusion:The tails lost in the host skin is involved in S. japonicum cercarial dermatitis, the inflammatory reaction in local skin is related with IL-4and IL-5, and the anaphylactic reaction is related with IFN-y. Part3. Studies on the effect of DTL of S. japonicum cercariae on detection of the early infectionAim:Schistosomiasis is a serious disease to human being, the major harm to human is induced by eggs. The laying eggs deposited in the liver cause fibrosis of the liver. Since Praziquntal can kill the adult worms, it is possible to eradicate the infection if the infection can be detected, if it can be done before laying eggs, the infected people can be protected from the damage of eggs. In this case, early diagnosis is very important for schistomiasis control. The aim of the research focuses on to identify an antigen which can early detect the corresponding antibody.Methods:Preparation of crude antigens from whole cercariae (SWA), the bodies of cercariae (SB A) and tails of cercariae (STA) respectively. Detection of the antibodies from the sera of mice infected with schisotome and evaluation of the value of the antigens to identify the early infection.Results:The levels of antibodies against STA is much higher than those against SWA or SB A (P<0.05), and100%of positive reaction is available2weeks post infection using STA detection.Conclusion:STA is superior to detect the early infection comparied with SWA and SBA.Part4. Studies on the infectious ability of Scistosoma japonicum cercariae without their tails.Aim:To explore the infectious ability of Scistosoma japonicum cercariae which lost their tails. Methods:Collect the cercariae lost their tails and infect the mice through the abdominal skin as routine way. Collect the adult worms and mice livers45day after infection. Comparison of the development and reproduction of the worms in the mice infected with normal cercariae and cercariae without tails. The pathological changes of the mouse liver after infected with cercariae without tails were performed.Results:The cercariae lost their tails still possess infectivity even though the successful infection is lower than that of the normal cercariae (10%vs47.5%). It has been demonstrated that the cercariae lost tails could develop normally and cause a typical schistosome pathological changes in mice livers. Conclusion:The cercariae lost their tails still possess infectivity, therefore it should be careful to evaluate their effects on investigation of infest water or cercaricide.In conclusion, the innovations of the research are:1. The phenomenon of DTL occurs in S. japonicum cercariae and it was demonstrated that there was a density-dependent increase in DTL as cercarial densities increased.2. The cercarial tails lost in the host skin is involved in S. japonicum cercarial dermatitis.3. Crude antigens from tails of cercariae (STA) are superior to detect the early infection compared with those from whole cercariae (SWA) and bodies of cercariae (SBA).4. The cercariae lost their tails still possess infectivity.