TARGETED TRANSDUCTION OF CD34(-EXPRESSING RETROVIRUS YIELDS PARTIAL ANTI-HIV PROTECTION OF PROGENY MACROPHAGES() CELLS BY TRANSDOMINANT NEGATIVE REV)

Congenitally acquired HIV infection may be uniquely suited to treatmen t via genetic engineering of CD34(+) hematopoietic stem/progenitor cel ls, However, current technologies yield only a small percentage of mat ure cells that carry the inserted genes, and expression is frequently suppressed. Since clinical trials employing these methodologies have b een proposed for anti-HIV gene therapy of HIV-infected children, we wi shed to assess, by in vitro modeling, the expected limits of transduct ion efficiency, expression, and antiviral activity using currently ava ilable methods. We measured retrovirus-mediated transduction in cord b lood progenitors and their in vitro-derived progeny macrophages by Mo- MuLV vectors expressing a transdominant negative Rev (Rev(TD)), CFU-GM transduction efficiency ranged from 7 to 85%, with an average of 28%, Semiquantitative DNA PCR demonstrated less than or equal to 100 vecto r sequence copies per 1000 cells in monocyte/macrophage cultures, whic h mere grown without selection to better model in vivo conditions, Whe n challenged with the macrophage-tropic HIV-1(BaL) isolate, cultured m acrophages from mock-transduced CFU-GM colonies supported infection in eight of eight experimental cultures, control LXSN-transduced progeni tors supported infection in six of eight cultures, while macrophages d erived from Rev(TD)-transduced CFU-GM colonies supported infection in four of eight cultures, Although these results support the ability of neo(r) retroviral vectors containing Rev(TD) to inhibit HIV replicatio n, they indicate that further optimization of transduction efficiency and sustained expression will be required for effective anti-HIV prote ction in vivo.