83 Dendritic Cell-Specific Delivery of siRNA Targeting SOCS1 Enhances HIV Gag-Specific CD8 T Cell Response

Wednesday, November 4, 2009: 9:00 AM
Kohlberg (Camino Real Hotel)
Sandesh Subramanya , Biomedical Sciences, Texas Tech University Health Sciences Center, El Paso, TX
Myriam Armant , Immune Disease Institute, Boston, MA
Sang-Soo Kim , Biomedical Sciences, Texas Tech University Health Sciences Center, El Paso, TX
Chunting Ye , Biomedical Sciences, Texas Tech University Health Sciences Center, El Paso, TX
Premlata Shankar , Immune Disease Institute, Boston, MA
A small animal model would greatly facilitate testing of novel vaccine strategies against uniquely human tropic viruses like HIV. Here we show that targeted RNAi-mediated silencing of negative immunoregulatory molecule SOCS-1 in antigen-pulsed human dendritic cells can induce protective CD8 T cell-mediated immune response to HIV-1 in a novel HLA-A2 transgenic humanized mouse model. A chimeric peptide containing a 12-mer DC binding moiety fused to nonamer D-arginine residues (9dR) was developed for potential DC-specific siRNA delivery in vivo. Targeted silencing of SOCS-1 in human DCs a) enhanced their cytokine responses to LPS and stimulated a strong mixed lymphocyte reaction in vitro, b) elicited a strong primary in vitro response to HLA-A2-restricted Melan-A/MART-1 and HIV Gag SL9 epitope in naïve CD8+ T cells from healthy donors and c) increased the HIV gag-specific cytokine response in CD8 T cells from seropositive subjects. More importantly, in HLA-A2 transgenic NOD/SCID-iL2rg-/- mice reconstituted with CD34 HSC from HLA-A2 donors, injection of SOCS-1 silenced DCs pulsed with HIV A2-restricted gag peptides, but not the irrelevant flu peptide, gave rise to a robust HIV specific CD8 T cell response which protected effectively against lethal challenge with recombinant HIV Gag-vaccinia. These results demonstrate the feasibility of using targeted RNAi to manipulate DC as a strategy to boost the immunogenicity of CTL epitope vaccines for HIV and attest to the value of the novel HLA-transgenic humanized mouse model in dissecting the protective role of HIV specific CD8 T cells restricted by specific HLA- alleles.