Schistosoma Japonicum: Studies On Mucosal Immunization With Recombinant Vaccines And Cloning Of Novel Genes

AIMS1 To test the immune protection against challenge infection in mice vaccinated intranasally or intragastrically with S. j recombinant proteins, S. j nucleic acid vaccines and recombinant streptococcus expressing SjCA and Sj31.2 Obtain novel genes coding new and potential protective antigens.METHODS1 S. j nucleic acid vaccines and recombinant streptococcus expressing SjCA and Sj31 were constructed by routine methods.2 Mice for experiments were immunized mucosally with rsjFer, rSjGST-CA (adjuvant,CTB) and SjTS-l/pc, Sj31/VR1012, SjCA/pc , SjMfl/pc(adjuvant,MPL), and recombinant streptococcus expressing SjCA and Sj31 on surface. The mice were challenged with 40 ?S.j cercariae per mouse 2 wk after the third vaccination. Forty-five days later, mice were killed and perfused, the adult worms and eggs were counted. Serum and feces or saliva samples were collected before the first immunization and the challenge infection. IgA and IgG in sera and slgA in feces or saliva were detected by ELISA.3 Schistosoma japonicum adult worm cDNA library was immunoscreened with sera from rabbits repeatedly infected by Schistosoma japonicum. Six positive clones were obtained after three rounds of immunoscreening and were excised automatically by helper phage.The inserts of positive clones were amplified by PCR and sequenced.The data btained were analyzed by bioinformatics.RSULTS1 The level of IgA and IgG in sera and slgA in feces or saliva increased after innunzation with nS/Fer and rSjGST-CA. And the worm reduction rate and the egg reduction rate were 25.57% ,34.75% and 33.35%, 63.34%in the intragastric and intranasal vaccination groups with rSjFer +CTB and nS/GST-CA +CTB.2 SjTs-1/pc, SjCA/pc, Sj31/VR1012 and SjMfl/pc induced mucosal and systemic immune reponse and partial protection against challege of S.j by intransal vaccinations of mice.3 The recombinant streptococcus expressed SjCA and Sj31 on surface . The live recombinant streyptococcus colonized in oral and pharyngeal cavity by intranasal vaccination of mice and induced mucosal and systemic immune respones to SjCA and Sj31 And the worm reduction rate and the egg reduction rate were 25.57%,34.75% and 21.73%,35.07% in the intranasal vaccination groups with the recombinant streptococcus expressed SjCA and Sj31 on surface.c4 Four genes of Schistosoma juponicum ,named IR1 % IR2, IR3 (GeneBank accession number:AY170313 , AY173930 , AY251481) and serin proteinase inhibtor(SPI) gene,were obtained. IRK IR2 and IR3 were novel genes which had not showen similar to previously reported genes in GeneBank. IR3 had a completed gene sequence of 897 bases coding a protein with 299 amino acides,pI6.21 and MW53.3kD.CONCLUSIONS1 A significant immune protection against Schistosoma japonicum infection was induced by mucosal (intragastic and intranasal) vaccination with rSjFer+CTB and intranasal vaccination with rSjGST-CA+CTB.2 SjTs-1/pc, SjCA/pc, Sj31/VR1012 and SjMfl/pcinduced mucosal and systemic immune reponse and partial protection against challege of S.j by intransal vaccinations of mice.3 Recombinant streptococcus were good carriers of S.j vaccines .4 The specific antigens ( proteins coded by IR1, IR2, IR3 and SPI) of Schistosoma japonicum were identified by sera from rabbits repeatedly infected by Schistosoma japonicum.lt was voluable to further study immuno-protection of these antigen.