Vpr14-88-Apobec3G fusion protein is efficiently incorporated into Vif-positive HIV-1 particles and inhibits viral infection.

Abstract

BACKGROUND:

APOBEC3G (A3G), a deoxycytidine deaminase, is a potent host antiviral factor that can restrict HIV-1 infection. During Vif-negative HIV-1 replication, A3G is incorporated into HIV-1 particles, induces mutations in reverse transcribed viral DNA and inhibits reverse transcription. However, HIV-1 Vif counteracts A3G's activities by inducing its degradation and by blocking its incorporation into HIV-1 particles. Thus, it is interesting to elucidate a mechanism that would allow A3G to escape the effects of Vif in order to rescue its potent antiviral activity and to provide a possible novel therapeutic strategy for treating HIV-1 infection.

METHODS AND FINDINGS:

In this study, we generated an R88-A3G fusion protein by fusing A3G to a virion-targeting polypeptide (R14-88) derived from HIV-1 Vpr protein and compared its antiviral effects relative to those of HA-tagged native A3G (HA-A3G). Our study showed that transient expression of the R88-A3G fusion protein in both Vif(-) and Vif(+) HIV-1 producing cells drastically inhibited viral infection in HeLa-CD4-CCR5-cells, CD4(+) C8166 T cells and human primary PBMCs. Moreover, we established CD4(+) C8166 T cell lines that stably express either R88-A3G or HA-A3G by transduction with VSV-G-pseudotyped lentiviral vector that harbor expression cassettes for R88-A3G or HA-A3G, respectively, and tested their susceptibility to Vif(+) HIV-1 infection. Our results clearly reveal that expression of R88-A3G in transduced CD4(+) C8166 cells significantly blocked Vif(+) HIV-1 infection. In an attempt to understand the mechanism underlying the antiviral activity of R88-A3G, we demonstrated that R88-A3G was efficiently incorporated into viral particles in the presence of Vif. Moreover, PCR analysis revealed that R88-A3G significantly inhibited viral cDNA synthesis during the early stage of Vif(+) virus infection.

CONCLUSIONS:

Our results clearly indicate that R88 delivers A3G into Vif(+) HIV-1 particles and inhibits infectivity and spread of the virions among CD4(+) T cells. This study provides evidence for an effective strategy to modify a host protein with innate anti-HIV-1 activity and rescue its potent anti-HIV potential in the presence of Vif. Further characterization and optimization of this system may lead to the development of an effective therapeutic approach against HIV-1 infection.

• Authors: Zhujun Ao, Zhe Yu, Lina Wang, Yingfeng Zheng, Xiaojian Yao
• Journal: PloS one (PLoS One) Vol. 3 Issue 4 Pg. e1995 (Apr 16 2008) ISSN: 1932-6203 [Electronic] United States
• PMID: 18414671 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Gene Products, vif
• Recombinant Fusion Proteins
• vpr Gene Products, Human Immunodeficiency Virus
• vpr protein, Human immunodeficiency virus 1
• APOBEC-3G Deaminase
• APOBEC3G protein, human
• Cytidine Deaminase

Topics

• APOBEC-3G Deaminase
• CD4-Positive T-Lymphocytes (virology)
• Cell Line
• Cytidine Deaminase (chemistry, genetics)
• Gene Products, vif (chemistry, genetics)
• HIV Infections (metabolism)
• HIV-1 (metabolism)
• HeLa Cells
• Humans
• Leukocytes, Mononuclear (virology)
• Mutation
• Plasmids (metabolism)
• Recombinant Fusion Proteins (chemistry)
• Transcription, Genetic
• vpr Gene Products, Human Immunodeficiency Virus (chemistry, metabolism)