Engineered lentiviral vectors pseudotyped with a CD4 receptor and a fusogenic protein can target cells expressing HIV-1 envelope proteins

Lentiviral vectors (LVs) derived from human immunodeficiency virus type 1 (HIV-1) are promising vehicles for gene delivery because they not only efficiently transduce both dividing and non-dividing cells, but also maintain long-term transgene expression. Development of an LV system capable of transducing cells in a cell type-specific manner can be beneficial for certain applications that rely on targeted gene delivery. Previously it was shown that an inverse fusion strategy that incorporated an HIV-1 receptor (CD4) and its co-receptor (CXCR4 or CCR5) onto vector surfaces could confer to LVs the ability to selectively deliver genes to HIV-1 envelope-expressing cells. To build upon this work, we aim to improve its relatively low transduction efficiency and circumvent its inability to target multiple tropisms of HIV-1 by a single vector. We investigated a method to create LVs co-enveloped with the HIV-1 cellular receptor CD4 and a fusogenic protein derived from the Sindbis virus glycoprotein and tested its efficiency to selectively deliver genes into cells expressing HIV-1 envelope proteins. The engineered LV system yields a higher level of transduction efficiency and a broader tropism towards cells displaying the HIV-1 envelope protein (Env) than the previously developed system. Furthermore, we demonstrated in vitro that this engineered LV can preferentially deliver suicide gene therapy to HIV-1 envelope-expressing cells. We conclude that it is potentially feasible to target LVs towards HIV-1-infected cells by functional co-incorporation of the CD4 and fusogenic proteins, and provide preliminary evidence for further investigation on a potential alternative treatment for eradicating HIV-1-infected cells that produce drug-resistant viruses after highly active antiretroviral therapy (HAART).