Screening and Primary Characterization of New Antigen Genes of Schistosoma Japonicum

To find Schistosoma japonicum(S.j)new antigen gene thus provide more useful vaccine candidates, the cDNA library of S.j adult worm was screened with sera of rabbits immunized with the membrane antigens of Schistosoma japonicum hepato-portal schistosomula (SjHmAg). The positive clones were amplified by PCR and sequenced, then the sequences of clones were compared with all sequences in GenBank database using Blast process. The new clones were submitted to GenBank for accession numbers. Fifteen positive clones were obtained after three rounds of immunoscreening. The size of S.j cDNA fragments in positive clones ranged from 0.7?kb-3.0?kb after automatically excised with the helper phage. Sequence analysis revealed that partial sequence of clone M5 had significant homology with S.j mitochondria mRNA, the other positive clones were new S.j genes. M2 clone sequence (GenBank accession number AF502579) was 730?bp long it had a 117?bp open reading frame (ORF). The sequence of M15 (GenBank accession number AF502582) has no transmembrane region and encodes 92 amino acids, and its protein contains a ferredoxins iron-sulfur binding region signature and two VWFC signal regions. The size of M1、M8、M9、M12(GenBank accession numbers: AF502578, AF502580, AF500622, AF502581) ranges from 402?bp to 766?bp. It concluded that the sera from rabbit immunized with SjHmAg could recognize S.j specific antigens molecules, and these antigens may induce the protective immunity against S.j infection.