Production of HIV-2 vectors. The HIV-2 vectors are produced by (1) transfecting 293T producer cells with the HIV-2 vector, packaging (HIV-2∆4), and the envelope plasmid (VSV-G). Next, the transfected cell transcribes the respective plasmids (2&3) subsequently producing the packaging co-factors (4) and vector RNA which is then packaged into the budding particles (4&5). Forty-eight to 72 hrs later the culture supernatants are collected and the vector particles are used to transduce target cells (5). Forty eight hours following transduction, at a time when ample vector integration has occurred (6), the respective vector titers are determined by measuring GFP expression (7).









Vector mobilization in an HIV-1 infected cell. Initial stages of HIV-1 infection involve an interaction of the virion with the target cell CD4 and CCR5 co-receptor (A), followed by adsorption of the virion, reverse transcription of the viral RNAs (B), pre-integration complex and integration (C). The conditionally replicating vector (crHIV vector) also undergoes similar cell surface binding, although non-specifically with VSV-G pseudotyped envelope, reverse transcription and integration (1). Once the virus and vector are integrated transcription and export of viral/ vector RNA occurs and is facilitated by HIV-1 Tat and Rev respectively (1). Both full length viral and crHIV vector mRNAs are produced. Any anti-viral moieties such as siRNAs would also be expressed at this stage (2). Next vector and viral RNA are either translated or processed and packaged (5) into the forming virion (6). Finally, three possible species of virions would be expected to be produced from this vector and virus containing cell; (a) either containing 2 viral copies (HIV), or (b) one crHIV vector and one viral RNA (Vector/HIV), or (c) two crHIV vector copies (Vector). These particles would then be expected to spread to other target cells, i.e. containing CD4 and the respective HIV-1 co-receptors CCR5 or CXCR4.