Cell Surface Downregulation of NK Cell Ligands by Patient-Derived HIV-1 Vpu and Nef Alleles

Galaski, Johanna; Faried, Ahmad; Tibroni, Nadine; Pujol, François M.; Müller, Birthe; Schmidt, Reinhold; Fackler, Oliver T.

doi:10.1097/qai.0000000000000917

Cited by 27 publications

(32 citation statements)

References 63 publications

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“…nearly 8-fold reduction in CD4 median fluorescence intensity [MFI] between GFP high and GFP neg gates in the representative experiment shown in Figure 2A), and no receptor downregulation by empty vector. In line with studies that have assessed Vpu function by cloning the gene directly at the start codon (Chen et al, 2015; Galaski et al, 2016; Mwimanzi et al, 2016), pSel-NL4.3 Vpu displayed modest ( e.g. less than two-fold) CD4 downregulation function (Figure 2A).…”

Section: Resultssupporting

confidence: 82%

“…non-Rev/RRE-dependent) in vitro Vpu expression can be achieved by cloning the vpu open reading frame directly at the start codon (Chen et al, 2015; Douglas et al, 2013; Galaski et al, 2016; Mwimanzi et al, 2016; Verma et al, 2013), protein expression is generally not robust. Moreover, the extensive genetic diversity in and upstream of vpu 's 5' coding sequence necessitates the design of primers specific for each HIV-1 isolate (Chen et al, 2015; Douglas et al, 2013; Galaski et al, 2016), or panels of primers specific for each HIV-1 subtype (Verma et al, 2013), which limits scalability. Robust autonomous Vpu expression can be achieved by codon optimizing the vpu sequence to maximize expression in mammalian cells (Anson and Dunning, 2005; Nguyen et al, 2004), but this negates the purpose of assessing vpu sequences in their natural form.…”

Section: Introductionmentioning

confidence: 99%

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In vitro functional assessment of natural HIV-1 group M Vpu sequences using a universal priming approach

Rahimi

Anmole

Soto-Nava³

et al. 2017

Journal of Virological Methods

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The HIV-1 accessory protein Vpu exhibits high inter- and intra- subtype genetic diversity that may influence Vpu function and possibly contribute to HIV-1 pathogenesis. However, scalable methods to evaluate genotype/phenotype relationships in natural Vpu sequences are limited, particularly those expressing the protein in CD4+ T-cells, the natural target of HIV-1 infection. A major impediment to assay scalability is the extensive genetic diversity within, and immediately upstream of, Vpu's initial 5' coding region, which has necessitated the design of oligonucleotide primers specific for each individual HIV-1 isolate (or subtype). To address this, we developed two universal forward primers, located in relatively conserved regions 38 and 90 bases upstream of Vpu, and a single universal reverse primer downstream of Vpu, which are predicted to cover the vast majority of global HIV-1 group M sequence diversity. We show that inclusion of up to 90 upstream bases of HIV-1 genomic sequence does not significantly influence in vitro Vpu expression or function when a Rev/Rev Response Element (RRE)-dependent expression system is used. We further assess the function of four diverse HIV-1 Vpu sequences, revealing reproducible and significant differences between them. Our approach represents a scalable option to measure the in vitro function of genetically diverse natural Vpu isolates in a CD4+ T-cell line.

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Section: Resultssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

In vitro functional assessment of natural HIV-1 group M Vpu sequences using a universal priming approach

Rahimi

Anmole

Soto-Nava³

et al. 2017

Journal of Virological Methods

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“…It remains to be seen whether our conclusions are generalizable to all macaques undergoing treatment interruption and autologous stem cell transplantation and, more importantly, whether our findings are directly relevant to patients with HIV infection. Indeed, analogous data from HIV ϩ patient cohorts demonstrated lower average viral load set points following ATI in patients who did not receive a transplant (46). This discrepancy might be due to differences between SHIV and HIV infection or to a longer window between ART initiation and ATI in the human ATI studies.…”

Section: Discussionmentioning

confidence: 84%

Autologous Stem Cell Transplantation Disrupts Adaptive Immune Responses during Rebound Simian/Human Immunodeficiency Virus Viremia

Reeves

Peterson

Kiem

et al. 2017

J Virol

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Primary HIV-1 infection induces a virus-specific adaptive/cytolytic immune response that impacts the plasma viral load set point and the rate of progression to AIDS. Combination antiretroviral therapy (cART) suppresses plasma viremia to undetectable levels that rebound upon cART treatment interruption. Following cART withdrawal, the memory component of the virus-specific adaptive immune response may improve viral control compared to primary infection. Here, using primary infection and treatment interruption data from macaques infected with simian/human immunodeficiency virus (SHIV), we observe a lower peak viral load but an unchanged viral set point during viral rebound. The addition of an autologous stem cell transplant before cART withdrawal alters viral dynamics: we found a higher rebound set point but similar peak viral loads compared to the primary infection. Mathematical modeling of the data that accounts for fundamental immune parameters achieves excellent fit to heterogeneous viral loads. Analysis of model output suggests that the rapid memory immune response following treatment interruption does not ultimately lead to better viral containment. Transplantation decreases the durability of the adaptive immune response following cART withdrawal and viral rebound. Our model's results highlight the impact of the endogenous adaptive immune response during primary SHIV infection. Moreover, because we capture adaptive immune memory and the impact of transplantation, this model will provide insight into further studies of cure strategies inspired by the Berlin patient. HIV patients who interrupt combination antiretroviral therapy (cART) eventually experience viral rebound, the return of viral loads to pretreatment levels. However, the "Berlin patient" remained free of HIV rebound over a decade after stopping cART. His cure is attributed to leukemia treatment that included an HIV-resistant stem cell transplant. Inspired by this case, we studied the impact of stem cell transplantation in a macaque simian/HIV (SHIV) system. Using a mechanistic mathematical model, we found that while primary infection generates an adaptive immune memory response, stem cell transplantation disrupts this learned immunity. The results have implications for HIV cure regimens based on stem cell transplantation.

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“…This includes reducing cell surface densities of transmembrane receptors by molecular mechanisms that affect endocytosis, anterograde transport, and/or protein stability (6 -10). By modulating surface exposure of cell surface receptors, such as major histocompatibility complex I and II, CD4, chemokine receptors, co-stimulatory molecules such as CD80 and CD86, tetraspanins, and natural killer cell ligands, Nef acts to evade host cell immune responses and prevent superinfection of infected cells (7)(8)(9)(10)(11)(12)(13)(14)(15). In addition, Nef affects T cell activation and the responsiveness of T lymphocytes to TCR signaling by modifying vesicular transport and actin dynamics (16 -24).…”

mentioning

confidence: 99%

Intrinsic properties and plasma membrane trafficking route of Src family kinase SH4 domains sensitive to retargeting by HIV-1 Nef

Chase

Wombacher

Fackler

2018

Journal of Biological Chemistry

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The HIV type 1 pathogenicity factor Nef enhances viral replication by modulating multiple host cell pathways, including tuning the activation state of infected CD4 T lymphocytes to optimize virus spread. For this, Nef inhibits anterograde transport of the Src family kinase (SFK) Lck toward the plasma membrane (PM). This leads to retargeting of the kinase to the trans-Golgi network, whereas the intracellular transport of a related SFK, Fyn, is unaffected by Nef. The 18-amino acid Src homology 4 (SH4) domain membrane anchor of Lck is necessary and sufficient for Nef-mediated retargeting, but other details of this process are not known. The goal of this study was therefore to identify characteristics of SH4 domains responsive to Nef and the transport machinery used. Screening a panel of SFK SH4 domains revealed two groups that were sensitive or insensitive for trans-Golgi network retargeting by Nef as well as the importance of the amino acid at position 8 for determining Nef sensitivity. Anterograde transport of Nef-sensitive domains was characterized by slower delivery to the PM and initial targeting to Golgi membranes, where transport was arrested in the presence of Nef. For Nef-sensitive SH4 domains, ectopic expression of the lipoprotein binding chaperone Unc119a or the GTPase Arl3 or reduction of their endogenous expression phenocopied the effect of Nef. Together, these results suggest that, analogous to K-Ras, Nef-sensitive SH4 domains are transported to the PM by a cycle of solubilization and membrane insertion and that intrinsic properties define SH4 domains as cargo of this Nef-sensitive lipoprotein binding chaperone-GTPase transport cycle.

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Cell Surface Downregulation of NK Cell Ligands by Patient-Derived HIV-1 Vpu and Nef Alleles

Abstract: The conservation of downregulation of major NK cell ligands by either HIV-1 Vpu or Nef suggests an important pathophysiological role of this activity, which may impact the acute but not the chronic phase of HIV infection.

Cited by 27 publications

References 63 publications

In vitro functional assessment of natural HIV-1 group M Vpu sequences using a universal priming approach

In vitro functional assessment of natural HIV-1 group M Vpu sequences using a universal priming approach

Autologous Stem Cell Transplantation Disrupts Adaptive Immune Responses during Rebound Simian/Human Immunodeficiency Virus Viremia

Intrinsic properties and plasma membrane trafficking route of Src family kinase SH4 domains sensitive to retargeting by HIV-1 Nef

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