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Molecular characteristics of HIV-2

Molecular characteristics of HIV-2. Frank Kirchhoff Institute of Molecular Virology Ulm Medical Center, Germany 7 /11 . HIV-2: Origin. Highly pathogenic. Non- pathogenic High VLs. Moderately Pathogenic 80% LTNPs, lowVLs.

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Molecular characteristics of HIV-2

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  1. Molecular characteristics of HIV-2 Frank Kirchhoff Institute of MolecularVirology Ulm Medical Center, Germany 7/11

  2. HIV-2: Origin Highly pathogenic Non-pathogenic High VLs Moderately Pathogenic 80% LTNPs, lowVLs Only HIV-2 groups A and B havespreadsignificantly in humans

  3. HIV-2: molecularcharacteristics • Vpx: antagonizes SAMHD1 (Laguetteet al., 2011; Hreckaet al., 2011) • NoVpu: CD4 degradationandtetherinantagonism in HIV-1 • Nef: effective down-modulationof TCR-CD3 and CD28

  4. HIV-2: absenceofVpu • HIV-1 M strainsuseVputoantagonizetetherin • HIV-2 A usesEnv • Unclearwhether HIV-2 B-H counteracttetherin Perez-Caballero et al., 2009

  5. HIV-2: absenceofVpu • HIV-1 M strainsuseVputoantagonizetetherin • HIV-2 A usesEnv • Unclearwhether HIV-2 B-H counteracttetherin Perez-Caballero et al., 2009 Nef, Env Nef Nef,Vpu

  6. HIV-2: absenceofVpu • HIV-1 M strainsuseVputoantagonizetetherin • HIV-2 A usesEnv • Unclearwhether HIV-2 B-H counteracttetherin Perez-Caballero et al., 2009 Nef, Env Nef Nef,Vpu ?? ?

  7. HIV-2: absenceofVpu • HIV-1 M strainsuseVputoantagonizetetherin • HIV-2 A usesEnv • Unclearwhether HIV-2 B-H counteracttetherin Perez-Caballero et al., 2009 Nef, Env Nef Nef,Vpu

  8. HIV-2: effective Nef-mediated down-modulationof TCR-CD3 and CD28

  9. HIV-1 SIVcpz Antigen presenting cell CD3 Activated T cell Antigen presenting cell Activation induced cell death Resting T cell HIV-2 SIVsmm CD3 Antigen presenting cell “Resting“ T cell Antigen presenting cell Resting T cell Antigen presenting cell “Resting“ T cell HIV-2: effective Nef-mediated down-modulationof TCR-CD3 and CD28 Infected PBMC little activationT cells survivetolerance chronic activationdeath of T cellsAIDS

  10. HIV-2: effective Nef-mediated down-modulationof TCR-CD3 and CD28 Disruptionofthe immune synapsebetweenviallyinfected T cellsandAPCs(Arhelet al., J. Clin. Invest. 2009) HIV-2 preventstheinteractionbetweenT cellsandAPCs, whereasHIV-1 just deregulatesit

  11. Inefficient Nef-mediated downmodulation of CD3 correlates with loss of CD4+T cells in natural SIV infection (Schindler et al. PLOS Path. 2008) Nef may protect the natural hosts of SIV against the loss of CD4+ T cells by down-modulation of TCR-CD3 to prevent activation-induced cell death

  12. Downregulation of CD3 by HIV-2 Nef does not protect against disease (Feldmannet al., JVI 2009) BUT • Most HIV-2-infected individuals had low VLs and high CD4+ T cell counts and the nef alleles were only examined using expression constructs in Jurkat T cells • The efficiency of TCR-CD3 downregulation by Nef correlated with low levels of immune activation in vivo

  13. Downregulation of CD3 by HIV-2 Nef does not protect against disease (Feldmannet al., JVI 2009) BUT • Most HIV-2-infected individuals had low VLs and high CD4+ T cell counts and the nef alleles were only examined using expression constructs in Jurkat T cells • The efficiency of TCR-CD3 downregulation by Nef correlated with low levels of immune activation in vivo

  14. Downregulation of CD3 by HIV-2 Nef does not protect against disease (Feldmannet al., JVI 2009) BUT • Most HIV-2-infected individuals had low VLs and high CD4+ T cell counts and the nef alleles were only examined using expression constructs in Jurkat T cells • The efficiency of TCR-CD3 downregulation by Nef correlated with low levels of immune activation in vivo Analysis of nef alleles from 20 viremic (VL >500/ml) and 16 non-viremic (<500/ml) HIV-2-infected individuals (Feldmann et al., 2009; Guillonet al., 1998; Blaak et al., 2008)

  15. Nef-mediateddownmodulationofTCR-CD3correlateswithhighnumbersof CD4+ T cells in viremic HIV-2-infected individuals All Non-viremicViremic

  16. Nef-mediateddownmodulationofCD28correlateswithhighnumbersof CD4+ T cells in viremic HIV-2-infected individuals All Non-viremic Viremic Other Nef functions(modulationof CD4 & MHC-I, enhancementofinfectivity & replication) did not correlatewiththe CD4+ T cellcounts in infectedindividuals

  17. T cellsinfectedwithvirusescontaining HIV-2 nef genes express lowlevelsofdeathreceptors and activationmarkers

  18. PBMC culturesinfectedwithvirusescontaining HIV-2 nef genes express lowlevelsof type I interferons

  19. Characteristicsof HIV-2: Summary • Effectiveinfectionof MPs and DCs byVpx-mediateddegradationof SAMHD1 • Antagonismof human tetherinbytheEnvelopeglycoprotein (HIV-2 group A; B-H unclear) • Potent suppressionof T cellactivationby Nef-mediated down-modulationof TCR-CD3 & CD28 • (Preliminary) conclusions • Tetherinantagonismmayplay a role in thespreadof HIV-2 • Nef mayhelpviremic HIV-2-infected individualstomaintain normal CD4+ T cellcountsbypreventing T cellactivation & apoptosis

  20. Characteristicsof HIV-2: Summary • Effectiveinfectionof MPs and DCs byVpx-mediateddegradationof SAMHD1 • Antagonismof human tetherinbytheEnvelopeglycoprotein (HIV-2 group A; B-H unclear) • Potent suppressionof T cellactivationby Nef-mediated down-modulationof TCR-CD3 & CD28 • (Preliminary) conclusions • Tetherinantagonismmayplay a role in thespreadof HIV-2 • Nef mayhelpviremic HIV-2-infected individualstomaintain normal CD4+ T cellcountsbypreventing T cellactivation & apoptosis

  21. Efficient Nef-mediated downmodulation of TCR-CD3 is associated with high CD4+ T cell counts in viremic HIV-2-infected individuals Mohammad Khalid,1 Jerome Feldman,2 Rob A. Gruters,3Hetty Blaak,3 Marchina E. van der Ende,4 Sarah Rowland-Jones,5,6Albert D. Osterhaus,3 and Frank Kirchhoff1 1Institute of Molecular Virology, University Clinic Ulm, Germany; 2Unité Virus et Immunité, Institut Pasteur, Paris, France; 3Dep. of Virology and 4 Dep. of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands; 5MRC Laboratories, Fajara, The Gambia; 6MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, United Kingdom Deutsche Forschungsgemeinschaft

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