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Baldauf, H.M.* ; Stegmann, L.* ; Schwarz, S.M.* ; Ambiel, I.* ; Trotard, M.* ; Martin, M.* ; Burggraf, M.* ; Lenzi, G.M.* ; Lejk, H. ; Pan, X.* ; Fregoso, O.I.* ; Lim, E.S.* ; Abraham, L.* ; Nguyen, L.A.* ; Rutsch, F.* ; König, R.* ; Kim, B.* ; Emerman, M.* ; Fackler, O.T.*

Vpx overcomes a SAMHD1-independent block to HIV reverse transcription that is specific to resting CD4 T cells.

Proc. Natl. Acad. Sci. U.S.A. 114, 2729-2734 (2017)
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Early after entry into monocytes, macrophages, dendritic cells, and resting CD4 T cells, HIV encounters a block, limiting reverse transcription (RT) of the incoming viral RNA genome. In this context, dNTP triphosphohydrolase SAM domain and HD domain-containing protein 1 (SAMHD1) has been identified as a restriction factor, lowering the concentration of dNTP substrates to limit RT. The accessory lentiviral protein X (Vpx) proteins from the major simian immunodeficiency virus of rhesus macaque, sooty mangabey, and HIV-2 (SIVsmm/SIVmac/HIV-2) lineage packaged into virions target SAMHD1 for proteasomal degradation, increase intracellular dNTP pools, and facilitate HIV cDNA synthesis. We find that virion-packaged Vpx proteins from a second SIV lineage, SIV of red-capped mangabeys or mandrills (SIVrcm/mnd-2), increased HIV infection in resting CD4 T cells, but not in macrophages, and, unexpectedly, acted in the absence of SAMHD1 degradation, dNTP pool elevation, or changes in SAMHD1 phosphorylation. Vpx rcm/mnd-2 virion incorporation resulted in a dramatic increase of HIV-1 RT intermediates and viral cDNA in infected resting CD4 T cells. These analyses also revealed a barrier limiting HIV-1 infection of resting CD4 T cells at the level of nuclear import. Single amino acid changes in the SAMHD1-degrading Vpx mac239 allowed it to enhance early postentry steps in a Vpx rcm/mnd-2-like fashion. Moreover, Vpx enhanced HIV-1 infection of SAMHD1-deficient resting CD4 T cells of a patient with Aicardi-Goutières syndrome. These results indicate that Vpx, in addition to SAMHD1, overcomes a previously unappreciated restriction for lentiviruses at the level of RT that acts independently of dNTP concentrations and is specific to resting CD4 T cells.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords Hiv ; Samhd1 ; Vpx ; Resting Cd4 T Cells ; Restriction Factors
ISSN (print) / ISBN 0027-8424
e-ISSN 1091-6490
Journal Proceedings of the National Academy of Sciences of the United States of America
Quellenangaben Volume: 114, Issue: 10, Pages: 2729-2734 Article Number: , Supplement: ,
Publisher National Academy of Sciences
Non-patent literature Publications
Reviewing status Peer reviewed
Institute(s) Institute of Virology (VIRO)