Human immunodeficiency virus type 1 (HIV-1) encodes for a small membrane protein known as Vpu and has two major functions in the infected cell. Vpu is known to interact with and shunt the CD4 molecule from the rough endoplasmic reticulum (RER) to the proteasome for degradation. In addition, Vpu is known to enhance virus release from infected cells. The assembly of HIV-1 viruses in CD4+ T cells lacking a vpu gene is characterized by the maturation of viruses into intracellular vesicles and the accumulation of virus particles at the cell surface. This enhanced release function of Vpu has been associated with the transmembrane domain of the Vpu molecule and investigators have shown that Vpu TM has ion channel properties (also known as a viroporin). Using pathogenic molecular clones of simian human immunodeficiency viruses (SHIV) known as SHIVKu-ibMC33, we have shown that both the transmembrane (TM) and cytoplasmic domains of Vpu protein contribute to the pathogenesis of this virus in macaques. Further, we have shown that substitution of the subtype B vpu gene from SHIVKu-ibMC33 with vpu from a subtype C HIV-1 isolate reduces the rate of CD4+ T cell loss in macaques. In the first two Specific Aims, we propose to continue our studies on the TM/ion channel of the Vpu protein in virion release. We have recently obtained a novel compound, BIT225 (from Biotron LTD.), which in our preliminary studies inhibits the release of viral particles from cultures inoculated with SHIVKu-ibwc33 but not a SHIV expressing a Vpu with a scrambled TM domain (SHIVrw)- In Specific Aim 1, we propose to examine the site/mechanism by which BIT225 inhibits SHIVKu-ibMcss replication and virus release. In the Specific Aim 2, we propose to examine the ability of these compounds to decrease replication of mutant and parental SHIVs in macaque macrophage cultures. In the third and fourth Aims, we propose to continue our studies on the biological properties of the subtype C Vpu.
In Specific Aim 3, we propose to examine the role of the highly conserved dileucine motif with adaptor complexes (AP-1, AP-2, and AP-3) and to determine if this domain influences virus release from infected cells.
In Specific Aim 4, we propose to generate a series of SHIVs expressing chimeric subtype B/C Vpu proteins to determine what domain is responsible for the decreased rate of CD4+ T cell loss in macaques. The results of these studies will provide novel information of the Vpu protein from the subtype C HIV-1, which accounts for the most HIV-1 infections worldwide.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI051981-09
Application #
7870488
Study Section
Special Emphasis Panel (ZRG1-AARR-D (07))
Program Officer
Sharma, Opendra K
Project Start
2002-06-01
Project End
2012-05-31
Budget Start
2010-06-01
Budget End
2011-05-31
Support Year
9
Fiscal Year
2010
Total Cost
$356,913
Indirect Cost
Name
University of Kansas
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
016060860
City
Kansas City
State
KS
Country
United States
Zip Code
66160
Ruiz, Autumn; Schmitt, Kimberly; Culley, Nathan et al. (2013) Simian-Human immunodeficiency viruses expressing chimeric subtype B/C Vpu proteins demonstrate the importance of the amino terminal and transmembrane domains in the rate of CD4(+) T cell loss in macaques. Virology 435:395-405
Skasko, Mark; Wang, Yan; Tian, Ye et al. (2012) HIV-1 Vpu protein antagonizes innate restriction factor BST-2 via lipid-embedded helix-helix interactions. J Biol Chem 287:58-67
Schmitt, Kimberly; Guo, Kejun; Algaier, Malinda et al. (2011) Differential virus restriction patterns of rhesus macaque and human APOBEC3A: implications for lentivirus evolution. Virology 419:24-42
Ruiz, Autumn; Hill, M Sarah; Schmitt, Kimberly et al. (2010) Membrane raft association of the Vpu protein of human immunodeficiency virus type 1 correlates with enhanced virus release. Virology 408:89-102
Schmitt, Kimberly; Hill, M Sarah; Liu, Zhenqian et al. (2010) Comparison of the replication and persistence of simian-human immunodeficiency viruses expressing Vif proteins with mutation of the SLQYLA or HCCH domains in macaques. Virology 404:187-203
Ruiz, Autumn; Lau, David; Mitchell, Richard S et al. (2010) BST-2 mediated restriction of simian-human immunodeficiency virus. Virology 406:312-21
Hill, M Sarah; Ruiz, Autumn; Schmitt, Kimberly et al. (2010) Identification of amino acids within the second alpha helical domain of the human immunodeficiency virus type 1 Vpu that are critical for preventing CD4 cell surface expression. Virology 397:104-12
Ruiz, Autumn; Guatelli, John C; Stephens, Edward B (2010) The Vpu protein: new concepts in virus release and CD4 down-modulation. Curr HIV Res 8:240-52
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
Schmitt, Kimberly; Hill, M Sarah; Ruiz, Autumn et al. (2009) Mutations in the highly conserved SLQYLA motif of Vif in a simian-human immunodeficiency virus result in a less pathogenic virus and are associated with G-to-A mutations in the viral genome. Virology 383:362-72

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