1. ¹Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
2. ²Department of Molecular Biology, La Jolla, CA, USA
3. ³Department of Molecular Pathology, University of California, San Diego, La Jolla, CA, USA

Correspondence: Professor BE Torbett, Department of Molecular and Experimental Medicine, The Scripps Research Institute, University of California, San Diego MEM L55, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA. E-mail: betorbet@scripps.edu

⁴These authors contributed equally to this work.

Received 20 December 2005; Revised 19 April 2006; Accepted 20 April 2006; Published online 1 June 2006.

Abstract

CCR5 is the chemokine co-receptor for R5-tropic human immunodeficiency virus type 1 (HIV-1) isolates most often associated with primary infection. We have developed an HIV-1 self-inactivating vector, CAD-R5, containing a CCR5 single-chain antibody (intrabody) gene, which when expressed in T-cell lines and primary CD4⁺ T cells disrupts CCR5 cell surface expression and provides protection from R5-tropic isolate exposure. Furthermore, CAD-R5 intrabody expression in primary CD4⁺ T cells supports significant growth and enrichment over time during HIV-1-pulsed dendritic cell–T-cell interactions. These results indicate that CCR5 intrabody-expressing CD4⁺ T cells are refractory against this highly efficient primary route of infection. CD34⁺ cells transduced with the CAD-R5 vector gave rise to CD4⁺ and CD8⁺ thymocytes in non-obese diabetic (NOD)/ severely combined-immunodeficient (SCID)-human thymus/liver (hu thy/liv) mice, suggesting that CCR5 intrabody expression can be maintained throughout differentiation without obvious cellular effects. CD4⁺ T cells isolated from NOD/SCID-hu thy/liv mice were resistant to R5-tropic HIV-1 challenge demonstrating the maintenance of protection. Our findings demonstrate delivery of anti-HIV-1 activity through CCR5 intrabodies in primary CD4⁺ T cells and CD34⁺ cell-derived T-cell progeny. Thus, gene delivery strategies that provide a selective survival and growth advantage for T effector cells may provide a therapeutic benefit for HIV-1-infected individuals who have failed conventional therapies.