Molecular studies on the action of APOBEC3G against HIV-1 and development of an APOBEC-based anti-HIV approach

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2012-04, 2011-10
Wang, Xiaoxia
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American Society for Microbiology
Mary Ann Liebert, Inc.
Currently, the HIV pandemic remains a major global health challenge. In order to effectively control and cure HIV-1 infection, it is necessary to perform greater research on host-HIV interactions and develop novel preventive and therapeutic approaches. The human cytidine deaminase APOBEC3G (A3G) is the first identified host restriction factor, which can serve as an initial line of defense against HIV-1 by inducing lethal mutations on proviral DNA and disrupting viral reverse transcription and integration. In order to better understand the action of A3G on HIV-1 replication, my study was focused on characterizing the interplay between A3G and HIV-1 reverse transcriptase (RT). The results indicated that A3G directly bound to RT, which contributed to A3G-mediated inhibition of viral reverse transcription. Overexpression of the RT-binding polypeptide A3G65-132 was able to disrupt wild-type A3G and RT interaction, consequently attenuating the anti-HIV effect of A3G on HIV replication. While the potent antiviral activities of A3G make it an attractive candidate for gene therapy, the actions of A3G can be counteracted by HIV-1 Vif during wild-type HIV infection. In order to overcome Vif-mediated blockage and maximize the antiviral activity of A3G, this protein was fused with a virus-targeting polypeptide (R88) derived from HIV-1 Vpr, and various mutations were then introduced into R88-A3G fusion protein. Results showed that Vif binding mutants R88-A3GD128K and R88-A3GP129A exhibited very potent antiviral activity, and blocked HIV-1 replication in a CD4+ T lymphocyte cell line as well as human primary cells. In an attempt to further determine their potential against drug resistant viruses and viruses produced from latently infected cells, R88-A3GD128K was chosen and delivered by an inducible lentiviral vector system. Expression of R88-A3GD128K in actively and latently HIV-1 infected cells was shown to be able to inhibit the replication of both drug sensitive and resistant strains of HIV-1. In conclusion, this thesis has demonstrated one of the mechanisms that how A3G can disrupt HIV-1 reverse transcription. Meanwhile, an A3G-based anti-HIV-1 strategy has been developed, which provides a proof-of-principle for a new gene therapy approach against this deadly virus.
APOBEC3G, HIV-1, gene therapy
Xiaoxia Wang, Zhujun Ao, Liyu Chen, Gary Kobinger, Jinyu Peng and Xiaojian Yao. The cellular antiviral protein APOBEC3G interacts with HIV-1 reverse transcriptase and inhibits its function during viral replication. J Virol. 2012, Apr; 86(7):3777-86.
Zhujun Ao, Xiaoxia Wang, Alexander Bello, Kallesh Danappa Jayappa, Zhe Yu, Keith Fowke, Xinying He, Xi Chen, Junhua Li, Gary Kobinger, and Xiaojian Yao. Characterization of anti-HIV activity mediated by R88-Apobec3G mutant fusion proteins in CD4+ T cells, PBMCs and macrophages. Human Gene Therapy, 2011 Oct; 22(10):1225-37.