ABSTRACT
AIM: To purify and refold the inclusion body of a human anti-HBsAg scFv with a 6?His tag, and to determine the affinity constant of the purified recombinant product.METHODS: Solubilizing in buffers containing urea or guanidine hydrochloride (GuHCl), the inclusion body was purified by IMAC, and then refolded by dialysis against urea or GuHCl, at the same time, Ni 2+ charged chelate column was utilized for in situ refolding. The affinity constant of the refolded scFv, polished by immune-affinity chromatography, was determined by non-competitive ELISA. RESULTS: The refolded scFv with highest specific bioactivity was produced by dialysis against GuHCl. Under this condition, the recovery of target protein reached (61.08?1 45)%. The affinity constant of the polished scFv was confirmed to be(2.30?0.32) ?10 7 L/mol. CONCLUSION: The inclusion body studied in this paper can be refolded efficiently under optimal dialysis condition in vitro . The antigen-binding property of this recombinant scFv is not affected by the purification tag fused to the N terminal of the protein.
ABSTRACT
AIM:To study the high-level HBV replication transgenic mice for evaluation of drugs treating hepatitis B virus.METHODS:The HBV transgenic mice were treated respectively with lamivudine,large dose recombinant hepatitis B protein vaccine,?-1b interferon,siRNA to evaluate their pharmacodynamics and mechanism of action.RESULTS:HBV DNA titre was reduced significantly in transgenic mice which were treated with lamivudine(100 mg?kg-1?d-1),recombinant hepatitis B protein vaccine(HBsAg 6 ?g/mouse),?-1b interferon(50 ?g /mouse),respectively.Recombinant hepatitis B protein vaccine and ?-1b interferon promoted the level of IL-2 and IFN-? and increased the Elispot number of spleen cells secreting IFN-? in the treated transgenic mice.HBV transgenic mice were treated with RNAi expression vector pU6-siHBV against HBV through vena caudalis by hydrodynamics technique.Five days later,the level of serum HBsAg was reduced by 56.7% and the inhibition lasted at least 14 days.The HbcAg(+)cells were decreased obviously by immunohistochemistry detection in liver tissue,but the RNAi did not reduce the serum HBV DNA titre.CONCLUSION:These inbreeding high-level HBV replication transgenic mice are reliable and feasible for evaluating the anti-HBV drugs and have its economical and convenient superiority.
ABSTRACT
AIM: Screening of phage antibodies against HBsAg from the constructed phage display library and sequencing of the positive clones.METHODS: RNAs were extracted from blood lymphocytes of a HBsAg-immunized volunteer. Then cDNAs were synthesized by RT-PCR. To construct the phage antibody display library, cDNAs of Fd fragments and ? chains of the antibodies were amplified through PCR and were inserted into vector pComb3H. Three rounds panning against coated HBsAg showed the specific enrichment of phage antibody. Positive clones were selected and sequenced.RESULTS: A phage antibody display library was constructed after amplifing of Fd fragments and ? chains of IgG1. Three Fab antibodies from the library were selected and sequenced. The result of sequencing showed that two of the three antibodies had the same Fd fragment and all of the three had the same light chain. CONCLUSION: The phage antibody display library was constructed successfully and three specific antibodies (Fab fragments) have been obtained from it.