Objective To express P30 surface antigen of RH strain of Toxoplasma gondii in E.coli BL21(DE3). Methods The P30 gene from Toxoplasma gondii was cloned to the pET28b vector after PCR, and the recombinant expression plasmid pET28b-P30 was constructed. Then the recombinants were transformed into E.coli BL21(DE3) after identified by the restriction enzyme digestion, PCR and DNA sequence determination annlysis. A single colony of E.coli BL21(DE3) containing the recombinant plasmid, pET28b-P30 was inoculated in LB culture, then diluted 1∶100 into 2 ml LB culture and induced by 0.2 mmol/L IPTG, and the expression product was identified by SDS-PAGE and Western blot. Results The recombinant plasmid of pET28b-P30 was constructed. ② Plasmid pET28b-P30 could express a specific 30 kDa fusion protein in E.coli BL21(DE3). Conclusions The expression plasmid which contains the gene fragment encoding P30 surface antigen of Toxoplasma gondii has been successfully constructed and is highly expressed in E.coli BL21(DE3) as an inclusion body.

Subjective To acquire and analyze adult stage Schistosoma japonicum (Chinese strain) expressed sequence tags and new genes from an adult S. japonicum cDNA library, and to search new vaccine candidates and drug targets. Methods A cDNA library was constructed from adult stage S. japonicum. Clones were selected randomly from the cDNA library and were se-quenced. ESTs and new genes were acquired after analysis in GenBank databases by BLAST and other programs. All ESTs and new genes were submitted to GenBank and received accession numbers. Results 149 ESTs were acquired from a total 382 clones that were randomly selected from the adult S. japonicum cDNA library. All ESTs were successfully submitted to the dbEST at Genbank. Some of them were homologous with sequences of male, female, egg, schistosomula, cercaria and miracidia of S. japonicum. 18 new genes of adult S. japonicum were acquired. Some genes were housekeeping genes and some genes might be interesting as vaccine candidates or drugs targets. Conclusions The EST straltegy is a rapid, efficient and economical method to acquire ESTs and to discover new genes of adult stage S. japonicum from cDNA libraries.[