Early steps in human immunodeficiency virus (HIV-1) replication involve delivery of the viral core into the cytoplasm of the host cell. When the viral core has reached the cytoplasm a process known as "uncoating" takes place. Uncoating is the process by which monomeric capsid sheds from the retroviral core. Simultaneously, the viral RNA genome is converted into viral DNA (vDNA), which is subsequently translocated to the nucleus and integrated into the cellular DNA, allowing expression and production of new viral particles. Although the relationship between capsid shedding and synthesis of viral DNA (vDNA) is not understood, the stability of the viral core in the cytoplasm seems to be important for productive infection. Changes in stability of the retroviral core seem to affect vDNA synthesis: 1) mutations in the capsid protein of HIV-1 that diminish (or increase) the stability of the HIV-1 core interfere with vDNA synthesis;2) TRIM51 proteins block HIV-1 replication by altering the stability of the retroviral core and disrupt vDNA synthesis;3) HIV-1 cores isolated from particles produced in the absence of accessory proteins such as vif, vpr or nef exhibit low stability and are poorly infectious due to a defect in vDNA synthesis;4) the use of proteasome inhibitors during HIV-1 infection increases the stability of the core, and at the same time augments the synthesis of vDNA;5) Isolated HIV-1 cores require cellular extracts in order to undergo vDNA synthesis, indicating the requirement of host factors;and 6) isolated retroviral cores last longer in cytosolic extracts than in isotonic buffer, suggesting the existence of core-stabilizing factors that are essential for vDNA synthesis. Altogether, this evidence indicates that viral core stability and successful vDNA synthesis involve a delicate balance of tightly interwoven events. In this proposal we will test the hypothesis that optimal stability of the retroviral core and cellular factors modulate the rate and extent of uncoating in the cytoplasm, and that this rate and extent of uncoating is required for the occurrence of complete viral DNA synthesis. We will test this hypothesis by performing the following experiments: 1) we will study the effect of factors that destabilize the retroviral core on viral DNA synthesis, 2) we will study the contribution of the proteasome to retroviral uncoating, and 3) we will study the modulation of vDNA synthesis by the interaction of reverse transcriptase with the retroviral ribonucleoprotein complex. The results from these experiments will generate basic knowledge in the uncoating of HIV-1. Uncoating is a poorly explored step on HIV-1 therapeutics;however, we have learned from restriction factors, such as TRIM5, that uncoating is potentially a very effective target for HIV-1 therapeutics.

Public Health Relevance

The main goal of this proposal is to gain understanding on the uncoating process of HIV-1, a poorly studied process. The great therapeutic potential of uncoating was revealed by the discov- ery of natural factors that block HIV-1 replication, such as TRIM5. Because proteins like TRIM5 target HIV-1 uncoating achieving a very strong block in replication, we believe that a thorough un- derstanding of retroviral uncoating will generate new opportunities to develop effective HIV-1 con- trol and AIDS prevention.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
AIDS Molecular and Cellular Biology Study Section (AMCB)
Program Officer
Embry, Alan C
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Albert Einstein College of Medicine
Schools of Medicine
United States
Zip Code
Yang, Yang; Brandariz-Nunez, Alberto; Fricke, Thomas et al. (2014) Binding of the rhesus TRIM5* PRYSPRY domain to capsid is necessary but not sufficient for HIV-1 restriction. Virology 448:217-28
Sastri, Jaya; Johnsen, Laura; Smolin, Nikolai et al. (2014) Restriction of HIV-1 by rhesus TRIM5? is governed by alpha helices in the Linker2 region. J Virol 88:8911-23
Brojatsch, Jürgen; Lima, Heriberto; Kar, Alak K et al. (2014) A proteolytic cascade controls lysosome rupture and necrotic cell death mediated by lysosome-destabilizing adjuvants. PLoS One 9:e95032
White, Tommy E; Brandariz-Nuñez, Alberto; Valle-Casuso, Jose Carlos et al. (2014) Effects of human SAMHD1 polymorphisms on HIV-1 susceptibility. Virology 460-461:34-44
Fricke, Thomas; White, Tommy E; Schulte, Bianca et al. (2014) MxB binds to the HIV-1 core and prevents the uncoating process of HIV-1. Retrovirology 11:68
Yang, Yang; Luban, Jeremy; Diaz-Griffero, Felipe (2014) The fate of HIV-1 capsid: a biochemical assay for HIV-1 uncoating. Methods Mol Biol 1087:29-36
St Gelais, Corine; de Silva, Suresh; Hach, Jocelyn C et al. (2014) Identification of cellular proteins interacting with the retroviral restriction factor SAMHD1. J Virol 88:5834-44
Fricke, Thomas; Valle-Casuso, Jose Carlos; White, Tommy E et al. (2013) The ability of TNPO3-depleted cells to inhibit HIV-1 infection requires CPSF6. Retrovirology 10:46
Fassler, Michael; Weissberg, Itai; Levy, Nitzan et al. (2013) Preferential lentiviral targeting of astrocytes in the central nervous system. PLoS One 8:e76092
Biris, Nikolaos; Tomashevski, Andrei; Bhattacharya, Akash et al. (2013) Rhesus monkey TRIM5* SPRY domain recognizes multiple epitopes that span several capsid monomers on the surface of the HIV-1 mature viral core. J Mol Biol 425:5032-44

Showing the most recent 10 out of 21 publications