A Lentiviral Vector That Activates Latent Human Immunodeficiency Virus-1 Proviruses by the Overexpression of Tat and That Kills the Infected Cells

Despite the efficient HIV-1 replication blockage achieved with current highly active antiretroviral therapy (HAART) therapies, HIV-1 persists in the body and survives in a latent state that can last for the entire life of the patient. A long-lived reservoir of latently infected CD4(+) memory T cells represents the most important sanctuary for the virus and the greatest obstacle for viral eradication. In this work, we present an initial step toward a gene therapy approach aimed at the activation of latent provirus to induce the death of latently infected T cells. Latent HIV-1 infection is characterized by the failure of viral gene expression as a consequence of uninitiated or aborted transcription. We have constructed an HIV-1- based lentiviral vector (p5p53RTAT3) that expresses the viral transactivating protein Tat in a drug-regulated manner and p53 in a Rev-dependent manner. We have demonstrated that the Tat-expressed protein from p5p53RTAT3 vector reactivates latent HIV-1 proviruses in J1.1 and ACH-2 cell lines and promotes p53-induced apoptosis in the presence of Rev. Our system was able to trigger the trans-activation of the provirus 50 long terminal repeat (LTR), stimulate the expression of the Rev protein from a tat-defective provirus, and provoke apoptosis selectively in the cells transfected with a tat-defective HIV-1 provirus in contrast to those with no HIV-1 provirus. However, the Rev-dependent p53 killing of latently infected cells was not effective enough for complete elimination of the awakened HIV-1 viruses. In summary, we have developed a vector system that is efficient in activating latent HIV-1 proviruses but that needs further improvement to kill infected cells.