Abstract: AIM: To screen and identify genes encoding vaccine candidates and molecules with diagnostic potential from S.japonicum(S.j) egg cDNA library. METHODS: S.j egg cDNA library was screened by sera from SEA immunized rabbits. Positive clones were identified after three rounds of screening and were excised automatically in vivo with helper phage. Products of PCR were used to detect insert sizes by agarose gel electrophoresis. DNA samples were obtained by purification using mini prep kit Automatic sequencing was carried out and the sequence data were analysed using GCG softw are. RESULTS: Twelve clones were identified as positive and the inserts were around 1. 2 kb in size. Compared with DNA sequences in GenBank, eight clones were homologous to a 70 kDa S. j heatshock protein (S. j H sP70). C18 exhibited 97. 8% homology with S. j 23. C22 and C23 shared 82. 4% and 89. 5% homology with S. j calreticulin, respectively. C12w as homologous to S. mansoni (S. m. ) immunophilin. CONCLUSION: This paper first reported the results of
immuno screening S. j egg cDNA library by anti-SEA sera. Twelve positive clones were found to be related to protective immunity and/or immunodiagnosis of schistosomiasis.

Key words: Schistosoma japonicum, egg, cDNA library, immunoscreening