Multigene/Multisubtype HIV-1 Vaccine Induces Potent Cellular and Humoral Immune Responses by Needle-Free Intradermal Delivery

Abstract

Gene vaccination encounters problems different from those of gene therapy since both a short half-life of the gene and a strong immune response to the gene product are desirable. We have evaluated a DNA vaccine consisting of seven plasmids encoding nine HIV-1 proteins. Using a needle-free delivery device, the Biojector, together with recombinant mouse GM-CSF, this vaccine induced strong gp160 Env- and p24 Gag-specific cellular and humoral immune responses in mice. The rGM-CSF was crucial for inducing both antibodies and antigen-specific CD8(+) T cell responses against both gp160 and p24. A GMP-produced lot of this vaccine, intended for human use, was delivered intradermally or intramuscularly into BALB/c mice at a GLP-accredited animal facility. This vaccine induced strong cellular responses independent of the route of immunization; moreover, no signs of toxicity were detected after histopathological examination of various tissues. Overall, the results indicate that the intradermal delivery of multigene/multisubtype HIV DNA in combination with recombinant GM-CSF is a safe and efficacious strategy for inducing high levels of specific CD8(+) T cells and unusually high titers of antibodies. This vaccine has been approved by the Swedish Medicinal Products Agency and is currently in a Phase I clinical trial.

Increased Immunogenicity of a DNA-Launched Venezuelan Equine Encephalitis Virus-Based Replicon DNA Vaccine

“…This gene has been thoroughly investigated in the context of a conventional DNA vaccine and is currently in clinical trials in Tanzania in a multigene, multisubtype vaccine (12). Here, a total of 60 mice were immunized with the gp160 gene encoded by a conventional DNA vaccine plasmid, and none of them developed any demonstrable antibody titers, although IFN-␥-and IL-2-producing T cells were readily detectable at the highest dose, consistent with previous findings (32,39).…”

“…The anamnestic response thus elicited to the vectored antigen would then be much more efficient than the primary response to the vector itself. Mixed-modality prime-boost strategies increased the potencies of several gene-based vaccine strategies, including immunity to the gp160 gene described here (2,12,15,35,42). Here, we show that a mixed-modality regimen with a relatively low dose (10 g) of VEE DNA delivered as a prime, followed by a VRP boost, induces very strong cellular and humoral immune responses to HIV-1 gp160.…”

“…Vero cells were transfected with Lipofectamine 2000 (Invitrogen), and expression of the cloned HIV-1 envelope gene was assessed in cell lysates by Galanthus nivalis agglutinin lectin precipitation, followed by Western blotting, as described previously (32). Subsequently, the cells were washed with phosphate-buffered saline (PBS), harvested, and either fixed in 2% paraformaldehyde at various time points (6,12,18,24,36,48,72, and 96 h) and kept at ϩ4°C until they were read or read unfixed immediately after being harvested.…”

Human Immunodeficiency Virus Type 1 Subtype Distribution in the Worldwide Epidemic: Pathogenetic and Therapeutic Implications

“…The first approach is based on using envelope molecules from different HIV-1 subtypes in order to induce antibodies with a broader breadth of neutralizing activities (15,24,25,49,111,112,115). The second approach is based on computer-derived sequences ("consensus sequences") generated by aligning circulating primary isolates and selecting the most common nucleotide at each position.…”

The Signal Peptide Sequence Impacts the Immune Response Elicited by a DNA Epitope Vaccine

“…An advantage of DNA vaccines is the ease with which one can introduce changes to qualitatively and quantitatively affect their immunogenicity (13,23,35). A number of approaches have been employed to enhance the efficacy of DNA vaccines, which include optimizing antigen processing (24) and presentation (5, 9, 17, 27, 29-31, 33, 37), using epitope-carrier protein fusion molecules (41), employing different delivery methods (18,21,22,28,34), and introducing immunomodulatory sequences in the plasmid vaccines (3,8,10,13,19,22,23,40). In both full-length and minigene DNA vaccines, leader sequences have been used to directly target the encoded antigen/epitope to the endoplasmic reticulum (ER) for major histocompatibility complex class I (MHC I) presentation with mixed success (5,7,9,17,33).…”