Mature HIV-like Particles Produced from Single Semliki Forest Virus-DerivedExpression Vector

Human immunodeficiency virus-like particles (HIVVLPs)with native conformations similar to that of the wildtypevirion could be valid candidates for vaccine development.To this end, we used a Semliki Forest Virus (SFV) expressionsystem to produce HIV-VLPs containing high quantities ofnative envelope proteins. Here, we described a single SFVreplicon containing the HIV gagpol and env genes under thecontrol of separate subgenomic promoters. Mature VLPsincorporating the Gag and Env proteins were detected in thesupernatant of replicon-expressing cells by Western blotanalysis. The HIV-VLPs showed the expected moleculardensity (1.14-1.18 g/ml) on a 20-60% sucrose gradient; theparticles were 100-120 nm in diameter and Env proteinswere observed on their surfaces by immunogold electronmicroscopy. RT-PCR analysis of VLP-associated RNAs inmature HIV-VLPs revealed two SFV-derived RNA species(full-length and subgenomic). Immunization studies in Balb/cmice showed that these HIV-VLPs were capable of inducingboth HIV-specific antibodies and cell-mediated immuneresponses. Taken together, our results indicate that the SFVreplicon system is useful for the production of HIV-VLPs,which may be valuable candidates for an HIV vaccine. KCI Citation Count: 2