Abstract
BackgroundIntegrase defective lentiviral vectors (IDLV) represent a promising delivery system for immunization purposes. Human dendritic cells (DC) are the main cell types mediating the immune response and are readily transduced by IDLV, allowing effective triggering of in vitro expansion of antigen-specific primed CD8+ T cells. However, IDLV expression in transduced DC is at lower levels than those of the integrase (IN) competent counterpart, thus requiring further improvement of IDLV for future use in the clinic.ResultsIn this paper we show that the addition of simian immunodeficiency (SIV)-Vpx protein in the vector preparation greatly improves transduction of human and simian DC, but not of murine DC, thus increasing the ability of transduced DC to act as functional antigen presenting cells, in the absence of integrated vector sequences. Importantly, the presence of SIV-Vpx allows for using lower dose of input IDLV during in vitro transduction, thus further improving the IDLV safety profile.ConclusionsThese results have significant implications for the development of IDLV-based vaccines.
Highlights
Integrase defective lentiviral vectors (IDLV) represent a promising delivery system for immunization purposes
These data indicated that inclusion of SIV-Vpx during vector preparation induced a statistically significant increment in the efficiency of transduction (IDLV/Vpx vs IDLV, P < 0.05), confirming data already shown by other groups using SIV-Vpx virus like particles (VLP) [21]
mean of fluorescence intensity (MFI) in dendritic cells (DC) transduced with the integrating LV-GFP was higher than MFI in DC transduced with IDLV-GFP or IDLV-GFP/Vpx (179 MFI vs 53 MFI and 100 MFI, respectively) (Figure 2b)
Summary
Integrase defective lentiviral vectors (IDLV) represent a promising delivery system for immunization purposes. Non-integrated DNA forms of IDLV have been shown to be long-lasting and transcriptionally active, both in vitro and in vivo, as long as the transduced cells are not dividing, even if at lower levels than those of the IN competent counterpart [12,13,14]. From the standpoint of immunization, we demonstrated that a single inoculum with an IDLV expressing the human immunodeficiency type 1 (HIV-1) envelope protein in the mouse immunogenicity model was able to elicit strong and long lasting specific immune responses in the absence of vector integration, providing a safe and efficient delivery for vaccine purposes [9,10,11]. Concerning the potential use in a human setting, we recently demonstrated that IDLV-transduced human antigen presenting cells, such as monocyte-derived dendritic cells (DC) and macrophages, were able to induce antigen-specific T cells expansion of primed T cells in vitro using Influenza Matrix 1 protein (Flu-M1) as a model antigen [20]
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