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

Yeon-Soo Kim

doi:10.1038/emm.1997.15

Abstract

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.

Highlights

The acquired immunodeficiency sysdrome (AIDS), caused by human immunodeficiency virus (HIV), is a chronic disease primarily characterized by a decrease in CD4+ T lymphocytes
Many earlier studies had addressed the importance of the Tat protein in trans-activation of gene expression from HIV-1 LTR, the HIV-1 promoter is not completely silent in the absence of Tat
Two alternative Tat expression constructs were used in an attempt to transactivate reporter gene expression; pTat120B encodes the 73 amino acid Tat peptide derived from the first tat coding exon, whereas pTat120K encodes the full-length 86 amino acid Tat protein

Summary

Introduction

The acquired immunodeficiency sysdrome (AIDS), caused by human immunodeficiency virus (HIV), is a chronic disease primarily characterized by a decrease in CD4+ T lymphocytes. Since the discovery of HIV in 1983, significant progress has been made toward the discovery and development of anti-HIV drugs. Considerable progress has been made in the development of treatments for various opportunistic infections. These treatments can delay desease progression, side effects associated with their use and the development of viral resistance to these drugs may inevitably lead to treatment failure. For these reasons, alternate therapies for HIV infection are needed. Since the immunodeficiency results when the HIV makes T lymphocytes sick, genetically altering HIV-infected T lymphocytes may be a useful therapy. Several approaches have succeeded in producing anti-HIV activity in cultured cells by transfection with vectors containing diphtheria toxin A gene, HIV-specific ribozyme, herpes simplex virustype 1 thymidine kinase (HSV1-TK), interferon gene, or antisense gene (Harrison et al, 1991a; Caruso and Klatzmann 1992; Rossi et al, 1992; Lisziewicz et al, 1995; Su et al, 1995), the difficulty in obtaining sufficient expression of the desired gene in a sufficient number of cells in vivo has remained an obstacle

Methods

Results

Conclusion