title: Vpx overcomes a SAMHD1-independent block to HIV reverse transcription that is specific to resting CD4 T cells.
abstract: 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.
authors.affiliation: Institute of Medical Virology, University Hospital Frankfurt, 60596 Frankfurt, Germany.|Max von Pettenkofer-Institute, Department of Virology, Ludwig Maximilians University, 80336 Munich, Germany.|Institute of Virology, Technische Universität München/Helmholtz Zentrum, 81675 Munich, Germany.
authors.forename: Hanna-Mari
authors.initials: HM
authors.lastname: Baldauf
authors.affiliation: Institute of Medical Virology, University Hospital Frankfurt, 60596 Frankfurt, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Stegmann
authors.affiliation: Institute of Medical Virology, University Hospital Frankfurt, 60596 Frankfurt, Germany.
authors.forename: Sarah-Marie
authors.initials: SM
authors.lastname: Schwarz
authors.affiliation: Institute of Medical Virology, University Hospital Frankfurt, 60596 Frankfurt, Germany.|Center for Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany.
authors.forename: Ina
authors.initials: I
authors.lastname: Ambiel
authors.affiliation: Center for Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany.
authors.forename: Maud
authors.initials: M
authors.lastname: Trotard
authors.affiliation: Institute of Medical Virology, University Hospital Frankfurt, 60596 Frankfurt, Germany.
authors.forename: Margarethe
authors.initials: M
authors.lastname: Martin
authors.affiliation: Host-Pathogen Interactions, Paul Ehrlich Institute, 63225 Langen, Germany.
authors.forename: Manja
authors.initials: M
authors.lastname: Burggraf
authors.affiliation: Center for Drug Discovery, Department of Pediatrics, Emory Center for AIDS Research, Emory University, Children's Healthcare of Atlanta, Atlanta, GA 30322.
authors.forename: Gina M
authors.initials: GM
authors.lastname: Lenzi
authors.affiliation: Max von Pettenkofer-Institute, Department of Virology, Ludwig Maximilians University, 80336 Munich, Germany.|Institute of Virology, Technische Universität München/Helmholtz Zentrum, 81675 Munich, Germany.
authors.forename: Helena
authors.initials: H
authors.lastname: Lejk
authors.affiliation: Center for Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Pan
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, WA 98109.
authors.forename: Oliver I
authors.initials: OI
authors.lastname: Fregoso
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, WA 98109.
authors.forename: Efrem S
authors.initials: ES
authors.lastname: Lim
authors.affiliation: Center for Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany.
authors.forename: Libin
authors.initials: L
authors.lastname: Abraham
authors.affiliation: Center for Drug Discovery, Department of Pediatrics, Emory Center for AIDS Research, Emory University, Children's Healthcare of Atlanta, Atlanta, GA 30322.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Nguyen
authors.affiliation: Department of General Pediatrics, Münster University Children's Hospital, 48149 Munster, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Rutsch
authors.affiliation: Host-Pathogen Interactions, Paul Ehrlich Institute, 63225 Langen, Germany.|Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037.|German Center for Infection Research (DZIF), Langen, Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: König
authors.affiliation: Center for Drug Discovery, Department of Pediatrics, Emory Center for AIDS Research, Emory University, Children's Healthcare of Atlanta, Atlanta, GA 30322.
authors.forename: Baek
authors.initials: B
authors.lastname: Kim
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, WA 98109.
authors.forename: Michael
authors.initials: M
authors.lastname: Emerman
authors.affiliation: Center for Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany; oliver.fackler@med.uni-heidelberg.de Keppler@mvp.uni-muenchen.de.|German Center for Infection Research (DZIF), Heidelberg, Germany.
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Fackler
authors.affiliation: Institute of Medical Virology, University Hospital Frankfurt, 60596 Frankfurt, Germany; oliver.fackler@med.uni-heidelberg.de Keppler@mvp.uni-muenchen.de.|Max von Pettenkofer-Institute, Department of Virology, Ludwig Maximilians University, 80336 Munich, Germany.|Institute of Virology, Technische Universität München/Helmholtz Zentrum, 81675 Munich, Germany.|German Center for Infection Research (DZIF), Munich, Germany.
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Keppler
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000821:virology; D016679:Genome, Viral / Q000235:genetics; D015658:HIV Infections / Q000235:genetics* / Q000821:virology; D015497:HIV-1 / Q000235:genetics / Q000472:pathogenicity; D015498:HIV-2 / Q000235:genetics / Q000472:pathogenicity; D054884:Host-Pathogen Interactions / Q000235:genetics; D006801:Humans; D008253:Macaca mulatta / Q000235:genetics / Q000821:virology; D009000:Monocytes / Q000821:virology; D059748:Proteolysis; D012367:RNA, Viral / Q000235:genetics; D048348:Reverse Transcription / Q000235:genetics*; D000076106:SAM Domain and HD Domain-Containing Protein 1 / Q000235:genetics*; D054334:Viral Regulatory and Accessory Proteins / Q000235:genetics*; D014771:Virion / Q000235:genetics / Q000472:pathogenicity; D014779:Virus Replication / Q000235:genetics
chemical_list: D012367:RNA, Viral; C074286:VPX protein, Human immunodeficiency virus 2; D054334:Viral Regulatory and Accessory Proteins; D000076106:SAM Domain and HD Domain-Containing Protein 1; C484280:SAMHD1 protein, human
keywords: HIV; SAMHD1; Vpx; resting CD4 T cells; restriction factors