| Schistosomiasis has been the most important human helminth contagious disease in the world. Approximately 250 million people in 74 countries are infected with schistosomes; 120 million are symptomatic, and 20 million suffer severe illness. Schistosome is digenetic trematodes living as adults in the blood vessels of mammals, birds, and crocodilians, and it exhibit a complicated life cycle including two free-living stages in water and parasitic stages in the intermediate snail host and definitive verterbrate host. Five schistosome species infect humans; they are Schistosoma mansoni, S.japonicum, S.mekongi, S.intercalatum, and S. haematobium. The first four species have well described associations with chronic hepatic and intestinal fibrosis and their attendant consequences. Traditionally Schistosoma species have been arranged in groups based on egg morphology and the genus or family of intermediate host utilized.At the same time, Paragonimiasis is also a tropical parasitic disease, which has been neglected for a long time, caused by lung glukes of the genus Paragonimus. There are different prevalence in 24 provinces, municipalities and autonomous regions in China. Pagumogonimus skrjabini is the unique species found in China, which is the main pathogen causing extrapulmonary paragonimiasis in human.It has been prove that Schistosomiasis remains a serious public health problem in the southwest provinces of China without Chongqing at present. However, the Three-Gorge reservoir has effected on the environment of Chongqing and increased the probability of Schisitosomiasis epidemic area. Schistosomiasis has become a potential threat to the public health of locals. Worsemore, it is known that S.japonicum and P.skrjabini are closed in the relationship of the genetic polymorphism. Especially, past investigations pointed out that, cross-reactions were found between the two diseases, which were derived from China, that will increase the difficulties in diagnosing.In our experiment we try to study the differences between S.japonicum and P.skrjabini from gene level and perspective of proteome.In the beginning, we find out the trace of cross-reactions happened to the two diseases in the level of gene, and prepare for the potential epidemic in the Three-Gorge reservoir. Our study invested the genetic polymorphism of S.japonicum and P.skrjabini, and the molecular mechanism of the immune cross-reactions from the level of gene. It will help to diagnose these two epidemics in the Three-Gorge reservoir. The results of phylogenic trees, which were construced for rDNA-ITS2 genes of S.japonicum and P.skrjabini by method NJ and MP, were similar. And the distance between S.japonicum and P.skrjabini was longer than others, though there was 42.7% similarity between the parts of their rDNA-ITS2 gene. 12 same transcription factors were found in the sequences of S.japonicum as well as P.skrjabini , which were aipha-INF.2,AP-2CS6,bHLH-CS, and so on. Though there were obviously differences between the S.japonicum and P.skrjabini in the level of gene, they had significantly similarity on transcription factors of rDNA-ITS2 sequences. More significantly, they had the same transcription factors of cox1 sequences. It may provide valuable theoretical information for studies on cross-reactive antigen between S.japonicum and P.skrjabini on gene level.And then we found that the combination of proteomics and serology should provide a powerful tool to identify antibody targets among schistosome proteins and glycans. In the second part of our study, sera from human patients of Schistosomiasis,Paragonimiasis and health people were respectively used to detect specific antigens in a soluble extract of adult S. japonicum and eggs of S.japonicum in the Western blotting experiments. Then found out the corresponding antigens proteins in the combination of twe-dimensional gel electrophoresis (2-DE) separation of soluble proteins were identified by De Novo. In this part, we found 7 kinds of proteins are related with proteins of adult worms and eggs, which could only be identified by the Schistosomiasis patients'blood serum in the Western blotting experiments. SJCHGC00820 protein and Actin 5C protein have high scores with the proteins of adult worms of S.japonicum while Tubulin beta-2C and Beat-tubulin, which derived from S.haematobium, have high scores with the proteins of eggs of S.japonicum. According to the studies of proteins of S.japonicum, these 4 proteins were probably membrane proteins, which might represent important vaccine candidates. Especially for that these kinds of proteins were solubility and could be detected by the sera of patients. It is means that these proteins would provide undestroyed conformational epitopes. We could believe that the 4 kinds of proteins could be identified as specific antigens of S. japonicum.In conclusion, we compared the differences of rDNA-ITS2 and cox1 gene of S.japonicum and P.skrjabini, invested their genetic polymorphism, and the molecular mechanism of the immune cross-reactions from the level of gene. In the other hand, we found 4 kinds of proteins derived from S. japonicum and S. japonicum'eggs which could treated as specific antigen candidates. This will provide us a stronger theory foundation for the developement of all potential specific diagnose antigens and vaccines. |
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