A simple human immunodeficiency virus vector system for selective infection of CD4(+) cells and inducible expression of foreign genes

The alteration of T lymphocyte functions as a consequence of human immunodeficiency virus (HIV) infection is a potential target for the genetic treatment of the acquired immunodeficiency syndrome (AIDS). One approach to the gene therapy for AIDS is to block the replication of HIV-1. Tat-dependent expression of forein gene and selective infection of CD4(+) cells by retroviral vector might be useful for abrogating the production of HIV-1 from cells. As part of studies to examine the feasibility of this concept, I constructed tat(+) and tat(-) HIV-1 proviral vectors that express all HIV-1 genes except for env and/or tat gene. When tat(+) or tat(-) HIV-1 particles were used for infection of HeLa T4 cells containing the endogenous β-galactosidase (lacZ) gene under the control of the HIV-1 promoter and transactivation response element sequences, only the tat(+) HIV-1 particles transactivated the lacZ gene expression. This activation of lacZ expression following HIV infection of Tat(-) cells that stably contained but did not express the lacZ construct was determined to be an efficient process. I also constructed simple HIV-1 vectors that express the lacZ gene in a Tat-dependent manner or the hygromycin B phosphostransferase gene (Hyg(r)) under the control of the SV40 early promoter. The Tat-dependent vector conferring the lacZ(+) phenotype was assayed by β-gal staining after infection of Tat(+) or Tat(-) cells. The activation of lacZ expression was observed only in tat(+) cells. Another simple HIV-1 vector containing the Hyg(r) gene was used for retroviral production from HeLa cells expressing the HIV-1 env gene and infection of CD4(+) or CD4(-) cells, but Hyg(r) colony was observed only from CD4(+) cells. These results provide a rationale for the use of HIV-1 retroviral vector system in the design of gene therapy of HIV infection.