Expression, purification, characterization and immunogenicity of human immunodeficiency virus-1 glycoprotein gp120 derived from insect cells

Objective To establish an efficient baculovirus-insect cell expression system for the production of human immunodeficiency virus-1 (HIV-1) envelope glycoprotein gp120 and to evaluate the physiochemical properties, antigenicity and immunogenicity of the recombinant protein. Methods The gene encoding HIV-1 NL4-3 gp120 was cloned into the downstream of pH promoter of the baculovirus transfer vector pAcgp67B to construct the recombinant transfer vector pAc-gp120. Expression of the protein of interest was induced in baculovirus-infected High Five™ insect cells. ELISA, analytical ultracentrifugation and size-exclusion chromatography were carried out to characterize physicochemical properties of the expressed gp120 protein. Immunogenicity of the recombinant gp120 protein was analyzed by HIV neutralization assay after immunizing BALB/c mice with it. Results The recombinant HIV-1 gp120 protein was successfully obtained from the established insect cell expression system with a purity of more than 90% and a mean yield of 13 mg/L in four batches. That recombinant HIV-1 gp120 protein was characterized by homogeneity in solution and possessed a good immunoreactivity to neutralizing antibodies and antisera against HIV. Immunogenicity analysis in BALB/c mice demonstrated that the recombinant gp120 protein could induce effective immune responses against HIV-1 NL4-3. Conclusion A simple and scalable approach to obtain homogeneous and immunogenic HIV-1 gp120 antigen is successfully established, which will promote further investigation of HIV vaccine candidates. Key words: Human immunodeficiency virus-1; Insect cell expression system; Glycoprotein; gp120; Immune response