Isolation and identification of expressed Schistosoma japonicum Chinese strain genes from a directional cDNA library by EST strategy.

Aim To isolate and identify expressed Schistosoma japonicum(Chinese strain) genes from a directional cDNA library by expressed sequence Tags (EST) strategy for searching Schistosoma vaccine candidates and Schistosoma Genome Project Methods the cDNA clones were selected randomly,and the ESTs were obtained by PCR directed sequencing from 5’ end of the sequence,then the ESTs were compared with all sequences in GenBank data bases The novel ESTs were submitted to NCBI dbEST and GenBank for obtaining accession numbers Results 100 recombinant clones were picked up from the cDNA,and the inserts of cDNA were identified by PCR 25 ESTs were generated by PCR directed sequencing Among them,2 ESTs belonged to“identified genes of Schistosoma mansoni”for they showed matched with Schistosome sequences in the databases 19 ESTs were defined as novel genes EST sequences for they showed only partial homology with non Schistosome genes or other organism in the database These novel genes ESTs were submitted into NCBI dbEST and were given the accession numbers of sequence in GenBank Conclusion This study shows that EST strategy,i e picking up recombinant cDNA clones and obtaining partial sequences of cDNAS can been used to discover Schistosoma japonicum expressed genes