| Lentiviral vectors have rapidly become a favored vehicle for gene transfer due to their ability to stably integrate into the chromosome of both dividing and non-dividing cells and thereby establish stable, persistent transgene expression. Since Naldini et al's groundbreaking work describing the first vesicular stomatitis virus G protein (VSV-G) pseudotyped lentiviral vector, a flurry of effort has been devoted to the design and refinement of next generation lentiviral vectors. This body of work describes one such effort, focusing on recent advances in the design, expression and application of HIV-2-based lentiviral vectors. Specific hypotheses which were tested in the process proposed: (1) the bulk of the lentiviral genome is dispensable in terms of vector design and transduction efficiency; (2) elements within the lentiviral vector which play a requisite role in viral replication may be replaced, substituting for their activities with elements from other viruses without adversely affecting titer; (3) mutations may be introduced into lentiviral vectors which improve vector biosafety and/or titer; (4) current vector titers may be improved by modulating the expression or activity of cellular factors which participate in viral replication; and, (5) HIV-2 vectors can effectively deliver therapeutic genes targeting HIV-1 although those same genes would be refractory within a comparable HIV-1 packaging system. The results obtained through testing of these hypotheses are discussed in detail, as are their implications. |
