Platelet-derived growth factor-α receptor is the cellular receptor for human cytomegalovirus gHgLgO trimer.
TL;DR: These findings help explain the broad tropism of human cytomegalovirus and indicate that PDGFRα and the viral gO subunit could be targeted by novel anti-viral therapies.
Abstract: Human cytomegalovirus encodes at least 25 membrane glycoproteins that are found in the viral envelope1. While gB represents the fusion protein, two glycoprotein complexes control the tropism of the virus: the gHgLgO trimer is involved in the infection of fibroblasts, and the gHgLpUL128L pentamer is required for infection of endothelial, epithelial and myeloid cells2–5. Two reports suggested that gB binds to ErbB1 and PDGFRα (refs 6,7); however, these results do not explain the tropism of the virus and were recently challenged8,9. Here, we provide a 19 A reconstruction for the gHgLgO trimer and show that it binds with high affinity through the gO subunit to PDGFRα, which is expressed on fibroblasts but not on epithelial cells. We also provide evidence that the trimer is essential for viral entry in both fibroblasts and epithelial cells. Furthermore, we identify the pentamer, which is essential for infection of epithelial cells, as a trigger for the ErbB pathway. These findings help explain the broad tropism of human cytomegalovirus and indicate that PDGFRα and the viral gO subunit could be targeted by novel anti-viral therapies. The human cytomegalovirus (HCMV) gHgLgO trimer binds with high affinity through the gO subunit to platelet-derived growth factor-α receptor (PDGFRα), which is expressed on fibroblasts but not on epithelial cells.
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TL;DR: A library consisting of most single transmembrane human receptors is built and a workflow for unbiased and high-sensitivity detection of receptor-ligand interactions is implemented to elucidate the long-sought receptor of human cytomegalovirus (HCMV), the leading viral cause of congenital birth defects.
155 citations
Cites background or methods or result from "Platelet-derived growth factor-α re..."
...F) ARPE-19, HUVEC and MRC-9 cells were exposed to VR1814 virus that had been pre-incubated with different concentrations of antibodies or soluble ligands....
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...Generation of HCMV glycoprotein and Fab constructs Codon-optimized (for expression in human cells) HCMV VR1814 and Merlin gH, gL, UL128, UL130, UL131A and Nrp2 genes, were synthesized and subcloned into the plasmid expression vector pRK5 (Genentech)....
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...Prior structural studies of the Nrp2 domains have demonstrated that the a1 (G) MRC-9 cells were infected for 48 hr with VR1814 virus that had been pre-incub mix of both proteins....
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...Specifically, gHgLgO (trimer) is primarily required for infection in fibroblasts, whereas gHgLpUL128-131A (pentamer) is required for viral entry in epithelial, endothelial, and myeloid cells (Kabanova et al., 2016; Ryckman et al., 2008)....
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...Moreover, overexpression of Nrp2 in HAP-1 cells where Nrp2 had been previously knocked out and rescued and significantly increased VR1814 infection (Figures 4A, 4B, and S6D), similarly to Nrp2 lentiviral overexpression in ARPE-19 (Figure 3B)....
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TL;DR: It is shown for the first time that virion gH/gL/gO binds to platelet-derived growth factor-α (PDGFR-α) on the surface of fibroblasts and that gB either directly or indirectly recruits gB to this complex, which could have implications for the design of future HCMV vaccines or anti-HCMV drugs.
Abstract: Herpesvirus gH/gL envelope glycoprotein complexes are key players in virus entry as ligands for host cell receptors and by promoting fusion of viral envelopes with cellular membranes. Human cytomegalovirus ( HCMV) has two alternative gH/gL complexes, gH/gL/gO and gH/gL/UL128,130,131A which both shape the HCMV tropism. By studying binding of HCMV particles to fibroblasts, we could for the first time show that virion gH/gL/gO binds to platelet-derived growth factor-alpha (PDGFR-alpha) on the surface of fibroblasts and that gH/gL/gO either directly or indirectly recruits gB to this complex. PDGFR-alpha functions as an entry receptor for HCMV expressing gH/gL/gO, but not for HCMV mutants lacking the gH/gL/gO complex. PDGFR-alpha-dependent entry is not dependent on activation of PDGFR-alpha. We could also show that the gH/gL/gO-PDGFR-alpha interaction starts the predominant entry pathway for infection of fibroblasts with free virus. Cell-associated virus spread is either driven by gH/gL/gO interacting with PDGFR-alpha or by the gH/gL/UL128,130,131A complex. PDGFR-alpha-positive cells may thus be preferred first target cells for infections with free virus which might have implications for the design of future HCMV vaccines or anti-HCMV drugs.
136 citations
TL;DR: In this Review, Connolly, Jardetzky and Longnecker discuss recent insights into herpesvirus entry by analysing the structures of entry glycoproteins, including the diverse receptor-binding glyCoproteins and conserved fusion proteins.
Abstract: Herpesviruses are ubiquitous, double-stranded DNA, enveloped viruses that establish lifelong infections and cause a range of diseases. Entry into host cells requires binding of the virus to specific receptors, followed by the coordinated action of multiple viral entry glycoproteins to trigger membrane fusion. Although the core fusion machinery is conserved for all herpesviruses, each species uses distinct receptors and receptor-binding glycoproteins. Structural studies of the prototypical herpesviruses herpes simplex virus 1 (HSV-1), HSV-2, human cytomegalovirus (HCMV) and Epstein–Barr virus (EBV) entry glycoproteins have defined the interaction sites for glycoprotein complexes and receptors, and have revealed conformational changes that occur on receptor binding. Recent crystallography and electron microscopy studies have refined our model of herpesvirus entry into cells, clarifying both the conserved features and the unique features. In this Review, we discuss recent insights into herpesvirus entry by analysing the structures of entry glycoproteins, including the diverse receptor-binding glycoproteins (HSV-1 glycoprotein D (gD), EBV glycoprotein 42 (gp42) and HCMV gH–gL–gO trimer and gH–gL–UL128–UL130–UL131A pentamer), as well gH–gL and the fusion protein gB, which are conserved in all herpesviruses. Recent crystallography and electron microscopy studies have refined our model of herpesvirus entry into cells. In this Review, Connolly, Jardetzky and Longnecker discuss recent insights into herpesvirus entry by analysing the structures of entry glycoproteins, including the diverse receptor-binding glycoproteins and conserved fusion proteins.
119 citations
TL;DR: CMV has evolved a complex relationship with the host immune response, in which it exploits cell type specific mechanisms of gene regulation to establish latency and to disseminate infection systemically, and also uses the inflammatory response to infection as an early warning system which allows the virus to escape from situations in which its survival is threatened.
Abstract: CMV is an ancient herpesvirus that has co-evolved with its host over millions of years. The 236 kbp genome encodes at least 165 genes, four non-coding RNAs and 14 miRNAs. Of the protein-coding genes, 43-44 are core replication genes common to all herpesviruses, while ~30 are unique to betaherpesviruses. Many CMV genes are involved in evading detection by the host immune response, and others have roles in cell tropism. CMV replicates systemically, and thus, has adapted to various biological niches within the host. Different biological niches may place competing demands on the virus, such that genes that are favorable in some contexts are unfavorable in others. The outcome of infection is dependent on the cell type. In fibroblasts, the virus replicates lytically to produce infectious virus. In other cell types, such as myeloid progenitor cells, there is an initial burst of lytic gene expression, which is subsequently silenced through epigenetic repression, leading to establishment of latency. Latently infected monocytes disseminate the virus to various organs. Latency is established through cell type specific mechanisms of transcriptional silencing. In contrast, reactivation is triggered through pathways activated by inflammation, infection, and injury that are common to many cell types, as well as differentiation of myeloid cells to dendritic cells. Thus, CMV has evolved a complex relationship with the host immune response, in which it exploits cell type specific mechanisms of gene regulation to establish latency and to disseminate infection systemically, and also uses the inflammatory response to infection as an early warning system which allows the virus to escape from situations in which its survival is threatened, either by cellular damage or infection of the host with another pathogen. Spontaneous reactivation induced by cellular aging/damage may explain why extensive expression of lytic genes has been observed in recent studies using highly sensitive transcriptome analyses of cells from latently infected individuals. Recent studies with animal models highlight the potential for harnessing the host immune response to blunt cellular injury induced by organ transplantation, and thus, prevent reactivation of CMV and its sequelae.
90 citations
Cites background from "Platelet-derived growth factor-α re..."
...There is considerable evidence that host intrinsic immunity recognizes histone-free viral DNA penetrating the nuclear pore complex and ND10 proteins act to chromatinize viral genomes and inactivate gene expression at the outset of infection (reviewed in Kalejta, 2013)....
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TL;DR: The complex persistence of HCMV is reviewed with consideration of latent reservoirs, viral determinants and their host interactions, and host signaling and the control of cellular and viral gene expression that contributes to the establishment of and reactivation from latency.
Abstract: Human cytomegalovirus (HCMV) is a beta herpesvirus that establishes a life-long persistence in the host, like all herpesviruses, by way of a latent infection. During latency, viral genomes are maintained in a quieted state. Virus replication can be reactivated from latency in response to changes in cellular signaling caused by stress or differentiation. The past decade has brought great insights into the molecular basis of HCMV latency. Here, we review the complex persistence of HCMV with consideration of latent reservoirs, viral determinants and their host interactions, and host signaling and the control of cellular and viral gene expression that contributes to the establishment of and reactivation from latency.
90 citations
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TL;DR: Two unusual extensions are presented: Multiscale, which adds the ability to visualize large‐scale molecular assemblies such as viral coats, and Collaboratory, which allows researchers to share a Chimera session interactively despite being at separate locales.
Abstract: The design, implementation, and capabilities of an extensible visualization system, UCSF Chimera, are discussed. Chimera is segmented into a core that provides basic services and visualization, and extensions that provide most higher level functionality. This architecture ensures that the extension mechanism satisfies the demands of outside developers who wish to incorporate new features. Two unusual extensions are presented: Multiscale, which adds the ability to visualize large-scale molecular assemblies such as viral coats, and Collaboratory, which allows researchers to share a Chimera session interactively despite being at separate locales. Other extensions include Multalign Viewer, for showing multiple sequence alignments and associated structures; ViewDock, for screening docked ligand orientations; Movie, for replaying molecular dynamics trajectories; and Volume Viewer, for display and analysis of volumetric data. A discussion of the usage of Chimera in real-world situations is given, along with anticipated future directions. Chimera includes full user documentation, is free to academic and nonprofit users, and is available for Microsoft Windows, Linux, Apple Mac OS X, SGI IRIX, and HP Tru64 Unix from http://www.cgl.ucsf.edu/chimera/.
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TL;DR: CMV is a common congenital infection worldwide that can lead to permanent disabilities and there is an urgent need for interventions that can reduce the substantial burden of this often overlooked disease.
Abstract: SUMMARY We reviewed studies that reported results of systematic cytomegalovirus (CMV) screening on fetuses and/or liveborn infants. The overall birth prevalence of congenital CMV infection was 0.64%, but varied considerably among different study populations. About 11% of live-born infants with congenital CMV infection were symptomatic, but the inter-study differences in definitions of symptomatic cases limit the interpretation of these data. Non-white race, low socioeconomic status (SES), premature birth, and neonatal intensive care unit admittance were risk factors for congenital CMV infection. Birth prevalence increased with maternal CMV seroprevalence. Maternal seroprevalence accounted for 29% of the variance in birth prevalence between study populations. Maternal seroprevalence and birth prevalence were both higher in study populations that were ascertained at birth rather than in the prenatal period. Thus, timing of ascertainment should be considered when interpreting birth prevalence estimates. Birth prevalence was inversely correlated with mean maternal age, but this relationship was not significant when controlling for maternal seroprevalence. The rate of transmission to infants born to mothers who had a primary infection or a recurrent infection during pregnancy was 32% and 1.4%, respectively. Possible maternal primary infections (i.e. seropositive mother with CMV IgM) resulted in congenital infections about 20% of the time, but are likely to represent a mixture of primary and recurrent infections. In summary, CMV is a common congenital infection worldwide that can lead to permanent disabilities. There is an urgent need for interventions that can reduce the substantial burden of this often overlooked disease. Copyright # 2007 John Wiley & Sons, Ltd.
1,411 citations