With a little help from a friend: increasing HIV transduction of monocyte-derived dendritic cells with virion-like particles of SIVMAC

Abstract

Modification of dendritic cells (DCs) is a promising avenue for gene therapy purposes, given the versatility and the multiplicity of functions of these cells. In this study, we show that preincubation of monocyte-derived DCs with low amounts of non-infectious virion-like particles derived from the simian immunodeficiency virus (SIV MAC VLPs) increases up to 10-fold the efficiency of transduction by HIV-1 lentiviral vectors at low multiplicity of infections yielding up to 90% of transduced cells, in the absence of alterations of DCs behavior. This effect is restricted to DCs and specified by the viral accessory protein Vpx. Thus, preincubation with empty VLPs of SIV MAC can be used in transduction protocols to increase the efficacy of HIV-1-mediated modification of DCs. Gene Therapy (2006) 13, 991-994.

SIVMAC Vpx improves the transduction of dendritic cells with nonintegrative HIV-1-derived vectors

“…14 Overall, the data presented here indicate that transduction of DCs and, to a lower extent, of macrophages with nonintegrative HIV-1 vectors can be substantially improved using noninfectious SIV MAC VLPs carrying Vpx, thereby extending our previous observations on integrative HIV-1 vectors. 13,14 The positive effect of Vpx-VLPs on nonintegrative vectors was not totally unexpected in light of our previous findings. 13 Yet, the possibility existed that Vpx required a functional integration complex to exert its function, or that nonintegrative vectors were submitted to defects other than integration that were not sensitive to Vpx.…”

“…Accordingly, the percentage of macrophages transduced with the IN-D116A mutant in the presence of Vpx-VLPs increased, although to a lower extent than with DCs (three-to fivefold). 13 As expected in light of the cell-type-specific function of Vpx-VLPs, no effect was observed on stimulated PBLs. Of note, transduction with the IN-D116A mutant virus yielded a substantially lower percentage of transduced cells than WT, even if analysis was carried out 3 days postinfection, that is, prior to substantial dilution of episomal DNA following cell division.…”

“…As we had previously reported, Vpx-VLPs increased by over 10-fold the percentage of GFP-positive DCs following infection with WT HIV-1 vectors. 13 When compared to WT, similar amounts of GFP-expressing cells were also obtained following transduction of DCs with the IN-D116A mutant. Similar to WT, the addition of Vpx-VLPs during IN-D116A LV infection dramatically increased the percentage of transduced cells at all viral inputs tested (by 10-to 20-fold).…”

“…11,12 We have previously reported that members of the SIV SM /HIV-2 lineage code for a protein, Vpx, are capable of relieving the restriction that is responsible for the poor susceptibility of DCs to lentiviral-mediated modification. 13,14 Indeed, Vpx augments the efficacy of infection of DCs with integrationcompetent HIV-1 vectors when it is added in trans onto DCs via noninfectious virion-like particles (VLPs) derived from SIV MAC (Vpx-VLPs). In this setting, Vpx promotes the accumulation of viral DNA.…”

“…We have previously documented that Vpx is the protein responsible for the positive effect of VLPs on the infectivity of incoming HIV-1 LVs. 13 Virions were purified by ultracentrifugation on a double step sucrose cushion (45-25%) and normalized by protein content against standards of known infectivity, or by their infectious titers on HeLa cells, as previously described. 17 Infections were carried out on 10 5 cells for 2 h prior to extensive cell washing.…”