Studies On The Simulated Epitopes Of Protective Antigens Of Schistosoma Japonicum

Objective: To obtain the simulated Sj antigen epitopes and to identify their antigenicities and to estimate their immuno-protection against SchistosomajaponicumMethods: Infected with 800 cercariaes every rabbit, after 20d of infection the new model rabbits were injected with Allyl thiourea at the dose of 300mg/kg every other day by intraperitoneal injection while the normal model rabbits were free from Allyl thiourea. After 42d of the infection, the rabbits were sacrificed and their serum was collected. When the serum was absorbed by E.coli antibody, we screen the phage random 12-mer peptide library. Through three rounds of biopaning and enriching, lots of positive phages were obtained and their antigenicities were tested by the technology of ELISA. After five rounds of biopaning and enriching, 20 Kunming mice of new model were immunized by subcutaneously injecting l.1014 pfu positive phages from the new model rabbit serum respectively at 0-2-4th week. After 4 weeks of the last immunization, the challenge infection was performed and several control groups including the group immunized the phages from the rabbit serum of the normal model and the group immunized the original 12 mers-phage random peptide library and group of the challenge infection were arranged. After 42d of infection, the mice were killed and the reduction rates of adult worms and the liver eggs were observed. Use SEA immune rabbit serum to absorb the phage clones recognized by the SEA antibody in the pool positive phage clones and compare the antigenic changes. Select 14 clones randomly from them and identify their antigenic ability with technology of ELISA. Select the two best positive monoclonal phages (No8, No 13) recongnized by the new model rabbit serum to respectively immunized Kunming mice by subcutaneously injecting l.10I5 pfu positive phages at 0-2-4th week After 2 weeks of the last immunity, the challenge infection was performed and the group immunized the original 12 mers-phage random peptide library was arranged too. After 42d of infection, the mice were killed and the reduction rates of adult worms and the liver eggs were observed.Results: After three rounds biopanning and enriching, the phages had been enriched approximately 500 times and the positive clones of phages (1x10'') screened with the new model rabbit serum were strongly recognized by the new model rabbit serum, weakly recognized by the normal model rabbit serum, but not recognized by the healthy rabbit serum. The reduction rates of adult worms and the liver eggs induced by phages of the new model, the normal infecting model and the original peptide library were respectively 27.2% and 38.8 %, 17.8% and 35 %, 4.5% and 6%. The pool positive phage clones after immune adsorption strongly recognized by the rabbit serum of the new model and the normal model, weakly recognized by the SEA immune rabbit serum. All the 14 monoclonal phages were recognized by the rabbit serum of the new model and the normal model, weakly recognized by the SEA immune rabbit serum. Two of them were strongly recognized by the rabbit serum of the new model and the normal model, weakly recognized by the SEA immune rabbit serum. The reduction rate of adult worms and liver eggs induced by the monoclonal phage!3, the monoclonal phage8 and the original peptide library were respectively 35.81% and 63.32%, 32.09% and 52.02%, 14.90% and 30.64%.Conclusion: The phages from the new model contain the simulated Sj. antigen epitopes and got a higher reduction rate of the adult worms and the eggs than the normal model group and the original 12 mers-phage random peptide library group. All the 14 monoclonal phages contain the simulated Sj. epitope and the purifier monoclonal phage can be obtained by being absorbed the SEA antibody, that the monoclonal phage 13 and the monoclonal phage8 got a higher reduction rate of adult worms and egg than original 12 mers-phage random peptide library.