Successful Immunization with a Single Injection of Non-integrating Lentiviral Vector

Abstract

We evaluated the ability of an integrase (IN)-defective self-inactivating lentiviral vector (sinLV) for the delivery of human immunodeficiency virus-1 (HIV-1) envelope sequences in mice to elicit specific immune responses. BALB/c mice were immunized with a single intramuscular injection of the IN-defective sinLV expressing the codon optimized HIV-1(JR-FL) gp120 sequence, and results were compared with those for the IN-competent counterpart. The IN-defective sinLV elicited specific and long-lasting immune responses, as evaluated up to 90 days from the immunization by enzyme-linked immunosorbent spot (ELISPOT) and intracellular staining (ICS) for interferon-gamma (IFN-gamma) assays in both splenocytes and bone marrow (BM) cells, chromium release assay in splenocytes, and antibody detection in sera, without integration of the vector into the host genome. These data provide evidence that a single administration of an IN-defective sinLV elicits a significant immune response in the absence of vector integration and may be a safe and useful strategy for vaccine development.

Integrase-defective lentiviral vectors: progress and applications

“…22,51 Observations that an IDLV generated reduced humoral immune responses may also indicate reduced protein expression. 54 The results from our laboratory indicate that FIV IDLV luciferase reporter transgene expression is B10-fold less than a matched integrating FIV LV control (MB Banasik and PB McCray, unpublished observation).…”

“…[47][48][49] Several reports have detailed the production of HIV IDLVs. 13,22,44,[47][48][49][50][51][52][53][54][55][56][57][58][59][60] In addition, feline immunodeficiency virus (FIV) IDLVs are also described. 48 Integrase-defective LVs: progress and applications MB Banasik and PB McCray Jr studies ( Figure 1).…”

“…Of these potential mutation target sites, D64 is most commonly altered, 13,22,44,[48][49][50][51][52][53][55][56][57]60 but mutations to D116 have also been reported. 51,54,58,59 Additional mutations affect IN DNA binding, linear episome processing or IN multimerization ( Figure 2). IN must successfully bind both vector DNA and genomic DNA to support integration.…”

“…The most common titering method is a p24 ELISA assay, 13,50,52,53,57 with additional comparisons of RT activity, 48,54 vector genomes 53 and transducing units as determined by a visual marker. 13,22,50 Three groups report lower transduction efficiency in IDLVs as compared with LVs when normalized to p24 content.…”

Recombinant lentivector as a genetic immunization vehicle for antitumor immunity

“…Since DCs (the most potent Ag presenting cells) are non-dividing, it is likely that non-integrating lentivector will be equally effective in stimulating Ag specific immune responses. Indeed, Negri et al showed that single immunization with non-integrating lentivector stimulate potent and persistent T cell responses and antibody production at day 30 and day 90 comparable to that induced by integrated lentivector although they did not examine if effector function early time points was similar 37 .…”