OBJECTIVETo express N51 derived from the N-terminal heptad repeat (NHR) domain in gp41 of the HIV-1 CRF07_BC strain and analyze its molecular structure and antigenicity.

METHODSOverlapping PCR was used to amplify the DNA fragment encoding N51Fd gene, which was then subcloned into the vector pFUSE-hIgG1-Fc2. The construct was confirmed by DNA sequencing. The structure and antigenicity of the recombinant protein N51FdFc-BC were analyzed using bioinformatic software, circular dichroism, and Western blotting.

RESULTSA recombinant expression vector pFUSE/N51Fd-BC was successfully constructed. N51FdFc-BC recombinant protein with a relative molecular mass of about 35 000 was effectively expressed in mammalian 293T cells and could be recognized by rabbit antibodies against HIV-1 gp41 N/C peptides as shown by Western blotting. Bioinformatic analysis showed that the recombinant protein N51FdFc-BC, with a relative molecular mass of 34 315.1 and a PI of 7.59, formed a secondary structure of random coil to allow its interactions as an antigen with antibodies. Circular dichroism measurement confirmed the random coil structure of N51FdFc-BC protein.

CONCLUSIONThe recombinant protein N51FdFc-BC has a random coil structure and can be used as an immunogen for development of HIV-1 subunit vaccine.