AEGiS-11IAC: Improved anti-HIV efficacy of retroviral gene therapy vectors carrying a Tat-responsive promoter and a conserved HIV packaging signal.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Improved anti-HIV efficacy of retroviral gene therapy vectors carrying a Tat-responsive promoter and a conserved HIV packaging signal.

Int Conf AIDS 1996 Jul 7-12; 11:10 (abstract no. We.A.274)
Robinson DR, Chang LJ; Heritage Medical Research Centre, Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta. Fax: (403) 492-9828. E-mail: derobins@gpu.srv.ualberta.ca.

OBJECTIVE: To determine the anti-HIV efficacy of an improved retroviral gene therapy vector that contains a Tat-inducible LTR and a conserved HIV packaging signal.

METHODS: To improve the retroviral vector for HIV gene therapy, two elements were added. The promoter was modified to respond to Tat by cloning the TAR element into the long terminal repeat of the murine leukemia virus (MLV) vector. A conserved HIV packaging signal (PAK 140) was inserted to interfere with the HIV packaging function. Two vectors were constructed, PAK140 (without TAR) and TAR-PAK140, and transduced into different human lymphoid cell lines which were later challenged with different HIV strains. Production of reverse transcriptase and infectious particles, packaging of the TAR-PAK RNA into HIV particles, and the long term inhibition were studied.

RESULTS: H9 and AA2 human lymphoid cells transduced with the TAR-PAK140 vector, but not the PAK140 were protected from HIV challenge for as long as five months. In human lymphoid cells which were chronic HIV producers, the TAR-PAK140 vector suppressed virus production by about 70%. The TAR-PAK140 RNA was shown to be packaged into HIV-1 particles by RT-PCR. Analysis of mRNA from TAR-PAK140 or PAK140 transduced cells which were chronically infected with wild type or Tat-minus HIV-1 indicates that the TAR-PAK140 responded to Tat.

CONCLUSIONS: The anti-HIV vector, TAR-PAK140, is able to protect different human lymphoid cell lines from HIV infection for long term, and is able to suppress virus production from chronically infected cells. The mechanisms of inhibition appear to be interference with HIV packaging and the improved expression of vector RNA by the TAR insertion. Insertion of other anti-HIV genes into the TAR-PAK140 vector should increase its anti-HIV properties. This vector is potentially useful for HIV gene therapy.

Keywords: AEGIS, HIV, Gene Therapy, Genetic Vectors, Promoter Regions (Genetics), HIV-1, Antithrombin III, Peptide Hydrolases, HIV Infections, Terminal Repeat Sequences, Leukemia Virus, Murine, antithrombin III-protease complex, Human, genetics, ICA11

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