Expression in Escherichia coli and in vitro processing of HIV-1 p24 fusion protein.

Recombinant HIV-1 p24/p25 gag proteins were obtained from Escherichia coli using a cleavable fusion strategy. The fusion protein contains 280 amino acid residues of staphylococcal Protein A and 317 amino acid residues of p24/p25 flanking with the recognition/cleavage sequences for HIV protease. Fusion protein expressed under the control of lambda phage promoter PR was purified by IgG-Sepharose affinity chromatography. The p24/p25 part of the fusion protein was released by recombinant HIV protease in vitro. After a second IgG-Sepharose affinity chromatography, the purified p24/p25 proteins were obtained in milligram quantities. The HIV-1 p24/p25 protein displayed antigenicity similar to those of native counterparts confirmed by Western blot assays and the Abbott antigen test.