Abstract: Objective   To clone and express S-dsRNA gene of Cryptosporidium parvum virus， and investigate the reactionogenicity of the recombinant.  Methods   Total RNA was extracted from Cryptosporidium parvum and S-dsRNA gene was amplified by RT-PCR. The PCR product was cloned into pET-28a（+） expression vector. The recombinant plasmid pET-28a（+）-S was transformed into E. coli BL21 （DE3） and induced with IPTG. The expression situation of recombinant protein was analyzed by SDS-PAGE. Its reactionogenicity was examined by Western blotting analysis.   Results   pET-28a（+）-S was identified by PCR and double endonuclease digestion. SDS-PAGE result showed that the recombinant protein （M_r 37 000） was expressed in the form of inclusion body. High level expression of recombinant protein was found at 1 mmol/L IPTG condition after incubation at 37 ℃ for 4 h and reached up to 72.6 % of the total protein. The protein was recognized by the antisera from mice immunized with antigens from Cryptosporidium parvum oocysts.  Conclusion   The S-dsRNA gene of Cryptosporidium parvum virus has been expressed with adequate reactionogenicity.

Key words: Cryptosporidium parvum, dsRNA virus, S-dsRNA, Prokaryotic expression