Abstract: Objective To develop a test reagent with high level expression and purification of HIV-2 gag protein in prokaryotic system.Methods Expression with inserting HIV-2 p55gag2 (G2) and truncated p55gag1 (G1) into down stream of T7 promoter of prokaryotic expression vector pET28a,induced by IPTG and analyzed with SDS PAGE and Western blot.Purification with Ni NTA affinity chromatography under the conditions of both denaturation and undenaturation.Results Two recombinant plasmids,pET28aG1 and pET28aG2,were constructed,which were highly expressed in BL21(DE3)plysS.The products of pET28aG1 and pET28aG2 were 55kDa and 61kDa in weight,respectively The former is 10% and the later is 6.8% in the total protein.It was shown by Western blot that the expressed recombinant protein could specifically react with HIV-2 antiserum.Conclusion HIV-2 gag protein,expressed and purified in E.coli,with good immunogenicity,could be used for the test reagent.

Key words: HIV-2 gag, E.coli, Expression, Purification