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133 Aptamer-siRNA Chimera Therapy Suppresses HIV-1 Viral Loads and Protects from CD4 T-Cell Loss in Humanized (RAG-hu) Mice

Neff, C Preston1*; Zhou, Jiehua2*; Remling, Leila1; Kuruvilla, Jes1; Zhang, Jane2; Li, Haitang2; Smith, David D3; Swiderski, Piotr4; Rossi, John J2; Akkina, Ramesh1

JAIDS Journal of Acquired Immune Deficiency Syndromes: April 2011 - Volume 56 - Issue - p 54
doi: 10.1097/01.qai.0000397320.40083.fa
Abstracts
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1Department of Microbiology, Immunology and Pathology, Colorado State University; and 2Beckman Research Institute of the City of Hope

Therapeutic strategies designed to combat HIV/AIDS by siRNAs show considerable promise, but targeted delivery of these synthetic molecules into virus infected cells in vivo has been a formidable challenge. In addressing this need, using a humanized mouse model, we sought to evaluate the in vivo efficacy of a chimeric construct consisting of an HIV-1 gp120 directed aptamer with viral neutralization capacity fused to an siRNA with proven efficacy against tat/rev viral transcripts. Humanized Rag2-/- γc-/- (RAG-hu) mice with multilineage hematopoiesis were prepared by engrafting with human CD34+ hematopoietic progenitor cells. These animals were infected with HIV-1 NL4-3 virus to generate viremic mice. Subsequently, the viremic mice were injected intravenously with the aptamer-siRNA chimeras or control RNAs. The viral loads and CD4+ T-cell levels were monitored weekly. Our results show that both the aptamer and aptamer-siRNA chimera treatments markedly suppressed HIV-1 replication and prevented viral induced CD4 T-cell depletion. The addition of the siRNA to the aptamer added to the antiviral effect by triggering target specific knockdown of the HIV-1 encoded tat/rev transcripts, thus validating the dual inhibitory function of the chimeras. Moreover, the presence of siRNAs and target specific knockdown of HIV-1 tat/rev transcripts were detected in gp120 aptamer-siRNA chimera treated mice, but not in the aptamer alone-, mutated aptamer-siRNA chimeras- or naked siRNA-treated animal groups, thus validating systemic, HIV-1 infected cell specific aptamer mediated siRNA delivery. Using RACE PCR we verified the in vivo RNAi mediated cleavage of the HIV-1 tat/rev target transcripts. Collectively, this approach resulted in suppression of viral loads in vivo and most importantly resulted in protection of T-cell depletion, making the aptamer-siRNA chimeras attractive therapeutic candidates for the treatment of HIV-1 infection.

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