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Analysis of the human immunodeficiency virus type 1 M group Vpu domains involved in antagonizing tetherin

Sarah J Petit1, Caroline Blondeau1, Greg J Towers1

  • 1MRC Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, Cruciform Building, 90 Gower Street, London WC1E 6BT, UK.

The Journal of General Virology
|September 9, 2011
PubMed

Insights

Human immunodeficiency virus type-1 (HIV) O group Vpu proteins cannot antagonize tetherin, potentially explaining their limited human-to-human transmission. This study reveals key Vpu domains for tetherin interaction and HIV pandemic spread.

Area of Science:

  • Virology
  • Molecular Biology
  • Immunology

Background:

  • Human immunodeficiency virus type-1 (HIV) originated from simian immunodeficiency virus (SIVcpz) in chimpanzees, leading to pandemic (HIV-1 group M) and non-pandemic (groups O, N, P) strains.
  • The accessory protein Vpu is crucial for HIV replication, mediating CD4 downregulation and virion release by antagonizing tetherin (BST2).

Purpose of the Study:

  • To investigate why HIV-1 group O Vpu proteins are less effective at antagonizing tetherin compared to group M.
  • To identify the molecular mechanisms underlying Vpu's interaction with tetherin and its role in HIV pandemic potential.

Main Methods:

  • Comparative analysis of Vpu proteins from HIV-1 group O and group M viruses.
  • Construction and characterization of chimeric Vpu proteins and Vpu mutants.
  • Assessment of Vpu's ability to counteract tetherin, downregulate cell-surface CD4, and promote virion release.
  • Investigation of Vpu's cellular localization, particularly its interaction with the trans-Golgi network.

Main Results:

  • HIV-1 group O Vpu proteins (Ca9, BCF06) failed to antagonize tetherin or downregulate it from the cell surface, despite reducing cell-surface CD4 levels.
  • Chimeric Vpu proteins and mutants revealed that specific residues in the transmembrane proximal region and the transmembrane domain are critical for tetherin antagonism and enhanced virion release.
  • Group M Vpu localization to the trans-Golgi network is essential for tetherin relocalization and antagonism.

Conclusions:

  • The inability of group O Vpu to antagonize tetherin is a significant factor limiting the pandemic potential of these viruses.
  • The Vpu-tetherin interaction is complex, involving specific molecular domains and cellular localization, which are key determinants of HIV pandemic spread.

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