Tat-dependent Conditionally Replicating Adenoviruses Expressing Diphtheria Toxin A for Specifically Killing HIV-1 Infected Cells

HIV-1 infection remains a public health problem with no cure. Although antiretroviral therapy (ART) is effective for suppressing HIV-1 replication, it requires lifelong drug administration due to a stable reservoir of latent proviruses and may cause serious side effect and drive the emergence of drug resistant HIV-1 variants. Gene therapy represents an alternative approach to overcome the limitations of conventional treatments against HIV-1 infection. In this study, we constructed and investigated the antiviral effects of an HIV-1 Tat-dependent conditionally replicating adenovirus, which selectively replicates and expresses the diphtheria toxin A chain (Tat-CRAds-DTA) in HIV-1 infected cells both in vitro and in vivo. We found that Tat-CRAds-DTA could specifically induce cell death and inhibit virus replication in HIV-1 infected cells mediated by adenovirus proliferation and DTA expression. A low titer of progeny Tat-CRAds-DTA was also detected in HIV-1 infected cells. In addition, Tat-CRAds-DTA showed no apparent cytotoxicity to HIV-1 negative cells and demonstrated significant therapeutic efficacy against HIV-1 infection in a humanized mouse model. Findings in this study highlight the potential of Tat-CRAds-DTA as a new gene therapy for the treatment of HIV-1 infection.