HIV-1 Nef enhances the infectivity of cell-free virions by an incompletely understood process. The research proposed here is designed to continue an ongoing investigation of how Nef enhances viral infectivity. Preliminary data indicate that endosomal coat proteins termed adaptor protein (AP) complexes are key co-factors for the modulation of infectivity by Nef. The data also indicate that Nef affects viral entry into target cells, but this effect is not clearly attributable to an influence of Nef on the trafficking of Env. Finally, the data indicate that Nef is present at the plasma membrane within clathrin-coated pits. Overall, these data suggest that Nef modulates a currently unidentified transmembrane protein (or proteins) to enhance viral infectivity. The experiments proposed herein are designed to test the role of the plasma membrane associated adaptor protein complex AP-2 in the enhancement of viral infectivity by Nef;to identify the host cell protein(s) whose modulation is the basis of infectivity-enhancement;and to define the role of these host proteins in viral entry and replication rate.
Three specific aims are proposed to achieve these goals: 1) to determine whether AP-2 is a key Nef co-factor for the enhancement of viral infectivity using RNA interference and the expression of dominant negative proteins;2) to identify and correlate specific changes induced by Nef in the host cell plasma membrane- and virion-proteomes;and 3) to validate candidate cellular proteins as mediators of Nef's virologic effects using RNA interference and protein overexpression during in vitro assays of viral infectivity, entry, and replication rate.

Public Health Relevance

The Nef protein of HIV-1 increases the infectivity of the virus by unclear mechanisms. The research proposed here seeks to understand this phenomenon in molecular terms. We will test the hypothesis that Nef modulates the protein content of the host cell membrane, from which the HIV-1 virus buds, such that newly formed viruses enter uninfected cells more efficiently and are consequently more infectious. By uncovering the basis of this effect, new approaches to inhibiting the propagation of HIV-1 may become apparent.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Special Emphasis Panel (ZRG1-AARR-D (02))
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Miller, Roger H
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Veterans Medical Research Fdn/San Diego
San Diego
United States
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Sherrill-Mix, Scott; Lewinski, Mary K; Famiglietti, Marylinda et al. (2013) HIV latency and integration site placement in five cell-based models. Retrovirology 10:90
Jia, Xiaofei; Singh, Rajendra; Homann, Stefanie et al. (2012) Structural basis of evasion of cellular adaptive immunity by HIV-1 Nef. Nat Struct Mol Biol 19:701-6
Tokarev, Andrey; Guatelli, John (2011) Misdirection of membrane trafficking by HIV-1 Vpu and Nef: Keys to viral virulence and persistence. Cell Logist 1:90-102
Homann, Stefanie; Smith, Davey; Little, Susan et al. (2011) Upregulation of BST-2/Tetherin by HIV infection in vivo. J Virol 85:10659-68
Fitzpatrick, Kathleen; Skasko, Mark; Deerinck, Thomas J et al. (2010) Direct restriction of virus release and incorporation of the interferon-induced protein BST-2 into HIV-1 particles. PLoS Pathog 6:e1000701
Mitchell, Richard S; Katsura, Chris; Skasko, Mark A et al. (2009) Vpu antagonizes BST-2-mediated restriction of HIV-1 release via beta-TrCP and endo-lysosomal trafficking. PLoS Pathog 5:e1000450
Day, John R (2009) CCD camera detection of HIV infection. Methods Mol Biol 503:203-19
Guatelli, John C (2009) Interactions of viral protein U (Vpu) with cellular factors. Curr Top Microbiol Immunol 339:27-45
Van Damme, Nanette; Goff, Daniel; Katsura, Chris et al. (2008) The interferon-induced protein BST-2 restricts HIV-1 release and is downregulated from the cell surface by the viral Vpu protein. Cell Host Microbe 3:245-52
Dueck, Megan; Guatelli, John (2007) Evidence against a direct antiviral activity of the proteasome during the early steps of HIV-1 replication. Virology 361:1-8