Abstract: AIM:To obtain cDNA clones coding for S. japonicum(Sj) reinfection related specific
immunologic molecules for vaccination or diagnosis. METHODS: An adult S.japonicum cDNA library,
of which the cloning efficiency is 3.13×10 6, with directional inserts in the vector lambda
gt11, was screened with pooled serum from 43 reinfected human cases in a schistosomiasis endemic
area with high level of Sj specific lgG4 antibodies. Primers located several bases away from the insert position on the lambda gt11 arm were used to amplify the insert fragments by standard PCR. SILVER SEQUENCETM (PCR-silver) DNA sequencing system was then used to sequence selected positive clones with relatively large inserts and homology comparison with GenBank database was also carried out. RESULTS AND CONCLUSION: Eleven phage plaques were defined as positive out of the 8. 6×104 phage plaques immunoscreened by human specific lgG4 antibody. GenBank database retrieval showed that 4 new Sj gene clones including Sj reinfection-related specific protein-encoding gene and Sj mitochondrial protein-coding gene have been obtained.

Key words: Schistosoma japonjcum, reinfection, cDNA clone, sequencing, GenBabk database retrieval