Eukaryotic expression and serodiagnostic potential of HIV-1 p24 antigen

Objective To express HIV-1 capsid p24 antigen in an eukaryotic expression system and to evaluate its antigenicity and potential in the early diagnosis of HIV. Methods The full-length gene of HIV-1 p24 and the signal peptide DRVI gene were amplified by PCR. The signal peptide DRVI preceding the p24 gene was introduced using fusion PCR, and cloned into vector pDRVI1.0. Two recombinant plasmids pDRVI-p24 and pDRVI-p24s were constructed and transfected into 293F cells. Expression and secretion of p24 protein were detected by SDS-PAGE, Ni-NTA column chromatography and molecular sieve were used to purify p24s protein. The purified protein was identified by Western blot and indirect ELISA using human/mouse HIV-1-positive serum samples. Results The eukaryotic expression system for HIV-1 p24 antigen was successfully established with high efficiency. The target protein of interest with the signal peptide DRVI was obviously detected in the supernatants of cell culture. The recombinant protein had good specificity and sensitivity based on the results of serological tests using serum samples of five HIV-1-positive and five HIV-negative mice, 30 HIV-1-positive patients and 50 HIV-1-negative healthy individuals. Conclusions The eukaryotic expression system for HIV-1 p24 antigen was successfully established. The purified HIV-1 p24s antigen had good antigenicity. An indirect ELISA assay with good specificity and sensitivity for the detection of HIV-1 was preliminarily constructed and showed great potential for application. Key words: HIV-1; p24 core antigen; Eukaryotic expression; Serological diagnosis