Myburgh, RenierIvic, SandraGers-Huber, GustavoLi, DuoAudige, AnnetteRochat, Mary-AudeJaquet, VincentRegenass, StephanManz, Markus G.Pepper, Michael SeanSalmon, PatrickKrause, Karl-HeinzSpeck, Roberto F.2015-07-132015-07-132015-07Myburgh, R, Ivic, S, Pepper, MS, Gers-Huber, G, Li, D, Audige, A, Rochat, MA, Jaquet, V, Regenass, S, Manz, MG, Salmon, P, Krause, KH & Speck, RF 2015, 'Lentivector knockdown of CCR5 in hematopoietic stem and progenitor cells confers functional and persistent HIV-1 resistance in humanized mice', Journal of Virology, vol. 89, no. 3, pp. 6761-6772.0022-538X (print)1098-5514 (online)10.1128/JVI.00277-15http://hdl.handle.net/2263/48186Gene-engineered CD34(+) hematopoietic stem and progenitor cells (HSPCs) can be used to generate an HIV-1-resistant immune system. However, a certain threshold of transduced HSPCs might be required for transplantation into mice for creating an HIV-resistant immune system. In this study, we combined CCR5 knockdown by a highly efficient microRNA (miRNA) lentivector with pretransplantation selection of transduced HSPCs to obtain a rather pure population of gene engineered CD34(+) cells. Low-level transduction of HSPCs and subsequent sorting by flow cytometry yielded >70% transduced cells. Mice transplanted with these cells showed functional and persistent resistance to a CCR5-tropic HIV strain: viral load was significantly decreased over months, and human CD4(+) T cells were preserved. In one mouse, viral mutations, resulting presumably in a CXCR4-tropic strain, overcame HIV resistance. Our results suggest that HSPC-based CCR5 knockdown may lead to efficient control of HIV in vivo. We overcame a major limitation of previous HIV gene therapy in humanized mice in which only a proportion of the cells in chimeric mice in vivo are anti-HIV engineered. Our strategy underlines the promising future of gene engineering HIV-resistant CD34(+) cells that produce a constant supply of HIV-resistant progeny.en© 2015, American Society for Microbiology. All Rights Reserved.Hematopoietic stem and progenitor cells (HSPCs)Gene-engineered CD34(+)HIV-1-resistant immune systemCCR5 knockdownHIV gene therapymicroRNA (miRNA)Postprint Article