Interaction Of gD Research Articles

Functional Interaction between Herpes Simplex Virus Type 2 gD and HVEM Transiently Dampens Local Chemokine Production after Murine Mucosal Infection

Herpes virus entry mediator (HVEM) is one of two principal receptors mediating herpes simplex virus (HSV) entry into murine and human cells. It functions naturally as an immune signaling co-receptor, and may participate in enhancing or repressing immune responses depending on the natural ligand used. To investigate whether engagement of HVEM by HSV affects the in vivo response to HSV infection, we generated recombinants of HSV-2(333) that expressed wild-type gD (HSV-2/gD) or mutant gD able to bind to nectin-1 (the other principal entry receptor) but not HVEM. Replication kinetics and yields of the recombinant strains on Vero cells were indistinguishable from those of wild-type HSV-2(333). After intravaginal inoculation with mutant or wild-type virus, adult female C57BL/6 mice developed vaginal lesions and mortality in similar proportions, and mucosal viral titers were similar or lower for mutant strains at different times. Relative to HSV-2/gD, percentages of HSV-specific CD8+ T-cells were similar or only slightly reduced after infection with the mutant strain HSV-2/gD-Δ7-15, in all tissues up to 9 days after infection. Levels of HSV-specific CD4+ T-cells five days after infection also did not differ after infection with either strain. Levels of the cytokine IL-6 and of the chemokines CXCL9, CXCL10, and CCL4 were significantly lower in vaginal washes one day after infection with HSV-2/gD compared with HSV-2/gD-Δ7-15. We conclude that the interaction of HSV gD with HVEM may alter early innate events in the murine immune response to infection, without significantly affecting acute mortality, morbidity, or initial T-cell responses after lethal challenge.

Strong metal adatom–substrate interaction of Gd and Fe with graphene

Graphene is a unique 2D system of confined electrons with an unusual electronic structureof two inverted Dirac cones touching at a single point, with high electron mobilityand promising microelectronics applications. The clean system has been studiedextensively, but metal adsorption studies in controlled experiments have beenlimited; such experiments are important to grow uniform metallic films, metalcontacts, carrier doping, etc. Two non-free-electron-like metals (rare earth Gd andtransition metal Fe) were grown epitaxially on graphene as a function of temperatureT andcoverage θ. By measuring the nucleated island density and its variation with growth conditions, informationabout the metal–graphene interaction (terrace diffusion, detachment energy) is extracted. Thenucleated island densities at room temperature (RT) are stable and do not coarsen, at least up to400 °C, which shows an unusually strong metal–graphene bond; mostlikely it is a result of C atom rebonding from the pure graphenesp2 C–C configuration to one of lower energy.

Magnetic properties of new filled skutterudite compounds GdFe4As12 and TbFe4As12

New As-based filled skutterudite compounds GdFe4As12 and TbFe4As12 have been synthesized under high pressure. The samples have a cubic structure with lattice parameters a=8.3024 Å, and 8.2961 Å, respectively. Both compounds show metallic behavior and a pronounced kink at low temperature in the temperature dependence of resistivity. Magnetic measurements revel that GdFe4As12 and TbFe4As12 exhibit a ferromagnetic-like phase transition at 56K and 38K, respectively. The unexpectedly high transition temperatures could be related to the interaction of Gd (or Tb) 4f moments with Fe 3d moments.

Noncovalent Binding of Some New Lipophilic Gadolinium DTPA Complexes to Human Serum Albumin. A Structure-Affinity Relationship

Four Gadolinium⋅DTPA complexes bearing long lipophilic alkyl chains were synthesized: two bis[amide] and two 4-substituted derivatives. In two of them (one bis[amide] and one 4-substituted), the alkyl chain ends with a carboxylate function. Their relaxometric properties in H₂O show the self aggregation of Gd⋅DTPA-BdodecylAmide, the better stability of the 4-substituted derivatives vs. Zn transmetallation, and the very good stability of Gd⋅(4-(carboxyundecylisothiourea-Bz)DTPA). Amongst the four compounds, only Gd⋅(4-(carboxyundecylisothiourea-Bz)DTPA) shows a strong interaction with human serum albumin (HSA) as demonstrated by proton relaxometry and ESI mass spectrometry. These data highlight the importance of the negative charge on the alkyl chain in the context of the interaction of Gd⋅(4-substituted DTPA) derivatives with HSA.

Herpes Simplex Virus Glycoprotein D Interferes with Binding of Herpesvirus Entry Mediator to Its Ligands through Downregulation and Direct Competition

To initiate membrane fusion and virus entry, herpes simplex virus (HSV) gD binds to a cellular receptor such as herpesvirus entry mediator (HVEM). HVEM is a tumor necrosis factor (TNF) receptor family member with four natural ligands that either stimulate (LIGHT and LTα) or inhibit (BTLA and CD160) T cell function. We hypothesized that the interaction of gD with HVEM affects the binding of natural ligands, thereby modulating the immune response during infection. Here, we investigated the effect that gD has on the interaction of HVEM with its natural ligands. First, HSV gD on virions or cells downregulates HVEM from the cell surface. Similarly, trans-interaction with BTLA or LIGHT also downregulates HVEM from the cell surface, suggesting that HSV may subvert a natural mechanism for regulating HVEM activity. Second, we showed that wild-type gD had the lowest affinity for HVEM compared with the four natural ligands. Moreover, gD directly competed for binding to HVEM with BTLA but not LTα or LIGHT, indicating the possibility that gD selectively controls HVEM signals. On the other hand, natural ligands influence the use of HVEM by HSV. For instance, soluble BTLA, LTα, and LIGHT inhibited the binding of wild-type gD to HVEM, and soluble BTLA and LTα blocked HSV infection of HVEM-expressing cells. Thus, gD is at the center of the interplay between HVEM and its ligands. It can interfere with HVEM function in two ways, by competing with the natural ligands and by downregulating HVEM from the cell surface.

New cadmium and rare-earth metal molybdates with scheelite-type structure

New cadmium and rare-earth metal molybdates with the formula Cd 0.25 RE 0.50MoO 4 ( RE = Pr, Nd, Sm–Dy) were synthesized by the solid-state reaction of CdMoO 4 with corresponding RE 2(MoO 4) 3. The obtained compounds crystallize in the scheelite-type structure. They were characterized here by XRD, DTA-TG, IR and EPR methods. The Cd 0.25 RE 0.50MoO 4 compounds showed solubility in CdMoO 4 forming the Cd x RE 2−2 x (MoO 4) 3−2 x (0.50 < x < 1.00) solid solutions. It can be found from EPR measurements of the samples with volatile Gd 3+ ions content, that Gd 3+ ions can be located at sites of octahedral symmetry, and both temperature and gadolinium content have an influence on local magnetic interaction and relaxation processes of Gd 3+ ions.

Interaction of herpes simplex virus type 2 (HSV-2) glycoprotein D with the host cell surface is sufficient to induce Chlamydia trachomatis persistence

When presented with certain unfavourable environmental conditions, Chlamydia trachomatis reticulate bodies (RBs) enter into a viable, yet non-cultivable state called persistence. Previously, we established an in vitro C. trachomatis and herpes simplex virus type 2 (HSV-2) co-infection model. These data indicate that (i) viral co-infection stimulates chlamydial persistence, (ii) productive HSV replication is not required for persistence induction, and (iii) HSV-induced persistence is not mediated by any currently characterized anti-chlamydial pathway or persistence inducer. In this study we demonstrated that chlamydial infectivity, though initially suppressed, recovered within 44 h of co-infection with UV-inactivated HSV-2, demonstrating that HSV-induced persistence is reversible. Co-incubation of chemically fixed, HSV-2-infected inducer cells with viable, C. trachomatis-infected responder cells both suppressed production of infectious chlamydial progeny and stimulated formation of swollen, aberrantly shaped RBs. In addition, pre-incubation of viral particles with viral glycoprotein D (gD)-specific neutralizing antibody prevented co-infection-induced persistence. Finally, exposure of C. trachomatis-infected cells to a soluble, recombinant HSV-2 gD : Fc fusion protein decreased production of infectious EBs to a degree similar to that observed in co-infected cultures. Thus, we conclude that interaction of HSV gD with the host cell surface is sufficient to trigger a novel host anti-chlamydial response that restricts chlamydial development.

Synthesis, DNA interaction and antibacterial activities of La(III) and Gd(III) complexes of Schiff base derived from o-vanillin and lysine

AbstractTwo novel complexes, [La(HL)(H2O)2NO3] · NO3 · H2O and [Gd(HL)(H2O)2NO3] · NO3 · H2O, where HL is a Schiff base derived from o-vanillin and lysine, have been synthesized and characterized by elemental analysis, conductivity measurements, IR, 1H NMR and thermogravimetric analyses (TGA). The Schiff base ligand behaves as a tetradentate, coordinating through azomethine nitrogen, phenolic oxygen and two carboxylic oxygen atoms. The interaction of these complexes with calf thymus DNA (CT-DNA) was also investigated by spectrometric titration and viscometric measurements. The faint hypochromism of the complexes in the absorption spectra, the remarkable reduction of fluorescence intensity of ethidium bromide (EB) bound DNA, together with a small decrease in the viscosity of the DNA suggest that a partial intercalation may be the preferred binding mode between these two complexes and DNA. The antibacterial activity testing revealed that the complexes and their precursor Schiff base show a weak to moderate activity against Bacillus subtilis, Staphylococcus aureus and Escherichia coli.

The herpesvirus glycoproteins B and H·L are sequentially recruited to the receptor-bound gD to effect membrane fusion at virus entry

Four glycoproteins (gD, gB, gH, and gL) are required for herpes simplex virus entry into the cell or for cell-cell fusion in transfected cells. gD serves as the receptor-binding glycoprotein and as the trigger of fusion; the other three execute fusion between the viral envelope and the plasma and endocytic membranes or the membranes of adjacent cells and are highly conserved among members of the herpesvirus family. Details of the interaction of gD with gB, gH, and gL were not known. Here, we report that the four glycoproteins assemble into a complex initiated by the interaction of gD with its cellular receptor. gB is recruited to the gD-receptor complex next, even in the absence of gH.gL. gH.gL is recruited next, but only to the receptor-gD-gB ensemble. A complex with the composition receptor-gD-gB-gH.gL is assembled transiently with a life span of 15-30 min in cells exposed to virus but can also be found in infected cells and in cells committed to form polykaryocytes after transfection of the glycoprotein quartet. The results indicate that the complex assembly is a critical step in the process of virus entry and fusion, and that no viral protein other than those that participate in the complex itself is required for complex assembly. These findings imply critical protein-protein interactions among the quartet as herpes simplex virions enter the cells and at cell-cell fusion, define a specific order of recruitment, and place gH.gL as the last link in the process of glycoprotein recruitment to the complex.

Molecular gymnastics at the herpesvirus surface

This review analyses recent structural results that provide clues about a possible molecular mechanism for the transmission of a fusogenic signal among the envelope glycoproteins of the herpes simplex virus on receptor binding by glycoprotein gD. This signal triggers the membrane-fusion machinery of the virus—contained in glycoproteins gB, gH and gL—to induce the merging of viral and cellular membranes, and to allow virus entry into target cells. This activating process parallels that of γ-retroviruses, in which receptor binding by the amino-terminal domain of the envelope protein activates the fusogenic potential of the virion in a similar way, despite the different organization of the envelope complexes of these two types of viruses. Therefore, the new structural results on the interaction of gD with its receptors might also provide insights into the mechanism of fusogenic signal transmission in γ-retroviruses. Furthermore, the fusion activation parallels with retroviruses, together with the recently reported structural homology of gB with the rhabdovirus envelope glycoprotein indicate that the complex entry apparatus of herpesviruses appears to be functionally related to that of simpler enveloped viruses.

Structures, magnetic properties, and XPS of cyanide-bridged Nd III/Sm III/Gd III–Cr III complexes

Synthesis, structural characterization, and spectroscopic and magnetic properties of three new cyano-bridged 3d–4f bimetallic complexes, Ln III(DMF) 4(H 2O) 3Cr III (CN) 6 · nH 2O (Ln = Nd, Sm, Gd), have been described. The Nd–Cr complex crystallizes in the monoclinic P2 1/ n space group with the following unit cell parameters: a = 20.063(7) Å, b = 8.967(4) Å, c = 18.023(6) Å, b = 96.12(3)°, V = 3224(2) Å 3, and Z = 4. The neodymium (III) ion, which adopts anti-prism eight-coordination environment, is linked to the [Cr III(CN) 6] 3− moiety through a bridging cyanide ligand with Nd–N = 2.550(4) Å and Nd–N–C = 164.4(4)°. The variable-temperature (0.5 T at 2–300 K) and variable-field (0–5 T at 2 and 5 K) magnetic measurements reveal that the weak interaction of Gd–Cr complexes differs from that of Nd–Cr and Sm–Cr ones mainly because of the lack of orbital angular momentum. The XPS and diffuse reflectance electronic spectra were also measured to discuss charge transfer transitions concerning π-backdonation from the viewpoint of magneto-optical functions.

155. Soluble HVEM Mediates Herpes Simplex Virus 1 (HSV-1) Infection of gD Receptor-Negative Cells

Herpes simplex virus infects a broad range of mammalian cells, including epithelial cells, lymphocytes, and postmitotic neurons. HSV-1 entry into cells is initiated by the binding of viral envelope glycoprotein D (gD) to one of three known HSV entry receptors, nectin-1/HveC, HVEM/HveA, and 3-O-sulfotransferase-modified heparan sulfate. Interaction of gD with these entry receptors is believed to cause a conformational change in gD, enabling it to interact with other envelope components which ultimately results in fusion of the viral envelope with the cell membrane.

Soluble V domain of Nectin-1/HveC enables entry of herpes simplex virus type 1 (HSV-1) into HSV-resistant cells by binding to viral glycoprotein D.

Interaction of herpes simplex virus (HSV) glycoprotein D (gD) with specific cellular receptors is essential for HSV infection of susceptible cells. Virus mutants that lack gD can bind to the cell surface (attachment) but do not enter, implying that interaction of gD with its receptor(s) initiates the postattachment (entry) phase of HSV infection. In this report, we have studied HSV entry in the presence of the gD-binding variable (V) domain of the common gD receptor nectin-1/HveC to determine whether cell association of the gD receptor is required for HSV infection. In the presence of increasing amounts of the soluble nectin-1 V domain (sNec1(123)), increasing viral entry into HSV-resistant CHO-K1 cells was observed. At a multiplicity of 3 in the presence of optimal amounts of sNec1(123), approximately 90% of the cells were infected. The soluble V domain of nectin-2, a strain-specific HSV entry receptor, promoted entry of the HSV type 1 (HSV-1) Rid-1 mutant strain, but not of wild-type HSV-1. Preincubation and immunofluorescence studies indicated that free or gD-bound sNec1(123) did not associate with the cell surface. sNec1(123)-mediated entry was highly impaired by interference with the cell-binding activities of viral glycoproteins B and C. While gD has at least two functions, virus attachment to the cell and initiation of the virus entry process, our results demonstrate that the attachment function of gD is dispensable for entry provided that other means of attachment are available, such as gB and gC binding to cell surface glycosaminoglycans.

The pro-fusion domain of herpes simplex virus glycoprotein D (gD) interacts with the gD N terminus and is displaced by soluble forms of viral receptors

Entry of herpes simplex virus into the cell requires the interaction of gD with one of its receptors, herpesvirus entry mediator or nectin 1, and the intervention of gB, gH, or gL, required to execute fusion of the virion envelope with cell membranes. The gD ectodomain is organized in two structurally and functionally differentiated regions. The N terminus (residues 1-260) carries the receptor binding sites, and the C terminus (residues 260-310) functions as the pro-fusion domain (PFD), which is required for viral infectivity and fusion but not for receptor binding. The objective of our studies is to elucidate how gD links receptor recognition to the triggering of fusion. Here, we show that PFD is made of subdomains 1 and 2 (amino acids 260-285 and 285-310). Each one partially contributed to herpes simplex virus infectivity. By means of glutathione S-transferase (GST) fusion proteins, we show that PFD bound soluble forms of gD, truncated at residue 260 (gD260t) or downstream. Both PFD subdomains bound gD260t, highlighting multiple contact sites between the N and C termini of gD. When gD260t was in complex with either receptor, it failed to bind GST-PFD. In turn, the receptors did not bind GST-PFD, irrespective of whether they were in complex with gD. Thus, gD260t interacted with the C terminus only if unbound to the receptor. We propose that (i) before receptor binding, gD adopts a "closed" conformation in which the N and C termini interact; and (ii) on encounter with a receptor, gD modifies its conformation and the N and C termini are released from reciprocal interactions ("opened" conformation) and enabled to trigger fusion.

New Insights for Pursuing High Relaxivity MRI Agents from Modelling the Binding Interaction of GdIII Chelates to HSA

New Insights for Pursuing High Relaxivity MRI Agents from Modelling the Binding Interaction of Gd^III Chelates to HSA

Herpes Simplex Virus Targeting to the EGF Receptor by a gD-Specific Soluble Bridging Molecule

Herpes simplex virus 1 (HSV-1) enters cells via initial binding of envelope glycoproteins (g) C and B to cell-surface glycosaminoglycans (GAGs) and subsequent membrane fusion involving envelope gD, gB, and gH/gL. Current insights suggest that the fusion process is initiated by interaction of gD with a cognate cellular receptor, such as the widely distributed cell adhesion molecule nectin-1. To redirect the tropism of HSV-1, we have generated a soluble adapter protein (P-V528LH) comprising the gD-binding variable domain of nectin-1 fused to a single-chain antibody (528LH) recognizing the EGF receptor. The adapter molecule enabled HSV-1 entry into naturally nonpermissive CHO cells expressing the human EGF receptor, but not into CHO cells lacking the receptor, and entry was not observed when the antibody portion of the adapter was replaced with an antibody of different specificity. Adapter-mediated entry increased with the viral dose and was nearly as efficient as direct viral entry into nectin-1-bearing CHO cells. Entry depended on viral gD and was diminished in the absence of cellular GAGs. These experiments represent the first demonstration that a soluble molecule can direct HSV infection via a new receptor, supporting the possible utility of this approach for HSV retargeting.

The soluble ectodomain of herpes simplex virus gD contains a membrane-proximal pro-fusion domain and suffices to mediate virus entry.

Entry of herpes simplex virus (HSV) 1 into cells requires the interaction of HSV gD with herpesvirus entry mediator or nectin1 receptors, and fusion with cell membrane mediated by the fusion glycoproteins gB, gH, and gL. We report that the gD ectodomain in soluble form (amino acids 1-305) was sufficient to rescue the infectivity of a gD-null HSV mutant, indicating that gD does not need to be anchored to the virion envelope to mediate entry. Entry mediated by soluble gD required, in addition to the receptor-binding sites contained within residues 1-250, a discrete downstream portion (amino acids 261-305), located proximal to the transmembrane segment in full-length gD. We named it as profusion domain. The pro-fusion domain was required for entry mediated by virion-bound gD, because its substitution with the corresponding region of CD8 failed to complement the infectivity of gD(-/+) HSV. Furthermore, a receptor-negative gD (gD(Delta6-259)) inhibited virus infectivity when coexpressed with wild-type gD; i.e., it acted as a dominant-negative gD mutant. The pro-fusion domain is proline-rich, which is characteristic of regions involved in protein-protein interactions. P291L-P292A substitutions diminished the gD capacity to complement gD(-/+) HSV infectivity. We propose that gD forms a tripartite complex with its receptor and, by way of the proline-rich pro-fusion domain, with the fusion glycoproteins, or with one of them. The tripartite complex would serve to recruit/activate the fusion glycoproteins and bring them from a fusion-inactive to a fusion-active state, such that they execute fusion of the virion envelope with cell membrane.

62. Ras Signaling as a Marker for Application of Oncolytic Herpes Mutant Against Lymphoma

Herpes simplex virus (HSV) enters cells via initial binding of envelope glycoproteins C and B to cell-surface glycosaminoglycans (GAGs) and subsequent membrane fusion involving gD, gB and gH/gL. Current insights suggest that the fusion process is initiated by interaction of gD with a cognate cellular receptor, such as the widely-distributed cell adhesion molecule nectin-1/CD115. To re-direct the tropism of HSV-1, we have generated a soluble adapter protein comprising the gD-binding variable (V) domain of nectin-1 fused to a single-chain antibody (V528LH) recognizing the EGF receptor. The adapter molecule enabled HSV-1 entry into naturally non-permissive CHO cells expressing the EGF receptor, but not into CHO cells lacking the receptor. Furthermore, entry was not observed when the antibody portion of the adapter was replaced with an antibody of different specificity. The degree of P-V528LH-adapter-mediated entry increased with the viral dose, reaching approximately 65% infected cells at a multiplicity of 3. Entry depended on viral gD and the availability of cellular GAGs. Although the adapter molecule did not block nectin-1-mediated cellular susceptibility to HSV-1, preconditioning of nectin-1-bearing cells with competitive inhibitors of the normal nectin-1/gD interaction reduced nectin-1-mediated entry without limiting adapter-mediated entry via the EGF receptor. These results indicate that an adapter molecule along with nectin-1 blocking agents can re-direct HSV infection.

Complexation of lanthanide(III) with a tripodal polyaza polycatecholate ligand

The interaction of La(III), Gd(III), and Yb(III) with Tris((2,3-dihydroxybenzylamino)ethyl)amine) (TRENCAT) was investigated by means of potentiometric measurements in 0.1 mol dm −3 aqueous solution of sodium perchlorate at 25 °C. The formation of complexes between the partially protonated ligand and lanthanides has been observed and the values of their formation constants are reported.

FT–IR and Raman spectra of Gd phosphate crystals and glasses

IR and Raman spectra of xGd 2O 3(1− x)P 2O 5 glasses ( x=0.22–0.31) are reported with emphasis on glassy Gd(PO 3) 3 and the crystalline forms emerging upon its devitrification. Increasing the concentration of Gd 2O 3 from 0.22 to 0.26 mole fractions leads to an abrupt lowering of the highest observed P–O stretching frequency of 25 cm −1. The spectral shift is related to changes in both the coordination of the lanthanide ion and the increase in metal to phosphorus ratio. The comparison of vibrational spectra of vitreous gadolinium metaphosphate ( x=0.25) with those of its crystalline analogs reveals a decrease in POP and PO 2 bond angles in glass. The changes observed are consistent with an elongation of P–O − terminal and P–O–P bridging bonds in the PO 4 tetrahedra. The redistribution of band frequencies is explained with the more covalent interaction of Gd 3+ with polyphosphate anions in glasses. The spectra of (Gd 2O 3) 0.27(P 2O 5) 0.73 and (Gd 2O 3) 0.31(P 2O 5) 0.69 glasses contain the characteristic bands of the metaphosphate structure along with features due to vibrations of PO 3 end groups. Their presence is interpreted in terms of the progressive fragmentation of the polyphosphate chains at these glass compositions.