scholarly journals Insertion Mutations in Herpes Simplex Virus 1 Glycoprotein H Reduce Cell Surface Expression, Slow the Rate of Cell Fusion, or Abrogate Functions in Cell Fusion and Viral Entry

2009 ◽  
Vol 84 (4) ◽  
pp. 2038-2046 ◽  
Author(s):  
Julia O. Jackson ◽  
Erick Lin ◽  
Patricia G. Spear ◽  
Richard Longnecker
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Cell Surface ◽  
Cell Fusion ◽  
Viral Entry ◽  
Cytoplasmic Tail ◽  
Target Cells ◽  
Simplex Virus ◽  
Insertion Mutations ◽  
Hsv 1

ABSTRACT Of the four required herpes simplex virus (HSV) entry glycoproteins, the precise role of gH-gL in fusion remains the most elusive. The heterodimer gH-gL has been proposed to mediate hemifusion after the interaction of another required glycoprotein, gD, with a receptor. To identify functional domains of HSV-1 gH, we generated 22 randomized linker-insertion mutants. Analyses of 22 gH mutants revealed that gH is relatively tolerant of insertion mutations, as 15 of 22 mutants permitted normal processing and transport of gH-gL to the cell surface. gH mutants that were not expressed well at the cell surface did not function in fusion or viral entry. The screening of gH mutants for function revealed the following: (i) for wild-type gH and some gH mutants, fusion with nectin-1-expressing target cells occurred more rapidly than with herpesvirus entry mediator (HVEM)-expressing target cells; (ii) some gH mutants reduced the rate of cell fusion without abrogating fusion completely, indicating that gH may play a role in governing the kinetics of fusion and may be responsible for a rate-limiting first stage in HSV-1 fusion; and (iii) only one gH mutant, located within the short cytoplasmic tail, completely abrogated function, indicating that the gH cytoplasmic tail is crucial for cell fusion and viral infectivity.

scholarly journals 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

2006 ◽  
Vol 80 (1) ◽  
pp. 138-148 ◽  
Author(s):  
Heechung Kwon ◽  
Qing Bai ◽  
Hyun-Jung Baek ◽  
Kelly Felmet ◽  
Edward A. Burton ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Cell Surface ◽  
Viral Entry ◽  
Glycoprotein D ◽  
Viral Glycoprotein ◽  
Virus Attachment ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT 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 (sNec1123), increasing viral entry into HSV-resistant CHO-K1 cells was observed. At a multiplicity of 3 in the presence of optimal amounts of sNec1123, 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 sNec1123 did not associate with the cell surface. sNec1123-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.

scholarly journals Insertional Mutations in Herpes Simplex Virus Type 1 gL Identify Functional Domains for Association with gH and for Membrane Fusion

2009 ◽  
Vol 83 (22) ◽  
pp. 11607-11615 ◽  
Author(s):  
Qing Fan ◽  
Erick Lin ◽  
Patricia G. Spear
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Cell Surface ◽  
Membrane Fusion ◽  
Cell Fusion ◽  
Viral Entry ◽  
Cell Surface Receptor ◽  
Cell Surface Expression ◽  
Conserved Domain ◽  
Simplex Virus

ABSTRACT Glycoprotein L (gL) is one of four glycoproteins required for the entry of herpes simplex virus (HSV) into cells and for virus-induced cell fusion. This glycoprotein oligomerizes with gH to form a membrane-bound heterodimer but can be secreted when expressed without gH. Twelve unique gL linker-insertion mutants were generated to identify regions critical for gH binding and gH/gL processing and regions essential for cell fusion and viral entry. All gL mutants were detected on the cell surface in the absence of gH, suggesting incomplete cleavage of the signal peptide or the presence of a cell surface receptor for secreted gL. Coexpression with gH enhanced the levels of cell surface gL detected by antibodies for all gL mutants except those that were defective in their interactions with gH. Two insertions into a conserved region of gL abrogated the binding of gL to gH and prevented gH expression on the cell surface. Three other insertions reduced the cell surface expression of gH and/or altered the properties of gH/gL heterodimers. Altered or absent interaction of gL with gH was correlated with reduced or absent cell fusion activity and impaired complementation of virion infectivity. These results identify a conserved domain of gL that is critical for its binding to gH and two noncontiguous regions of gL, one of which contains the conserved domain, that are critical for the gH/gL complex to perform its role in membrane fusion.

scholarly journals Structure-Function Analysis of Herpes Simplex Virus Type 1 gD and gH-gL: Clues from gDgH Chimeras

2003 ◽  
Vol 77 (12) ◽  
pp. 6731-6742 ◽  
Author(s):  
Tina M. Cairns ◽  
Richard S. B. Milne ◽  
Manuel Ponce-de-Leon ◽  
Deanna K. Tobin ◽  
Gary H. Cohen ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Cell Surface ◽  
Cell Fusion ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Simplex Virus ◽  
Hsv 1 ◽  
Cell Cell

ABSTRACT In alphaherpesviruses, glycoprotein B (gB), gD, gH, and gL are essential for virus entry. A replication-competent gL-null pseudorabies virus (PrV) (B. G. Klupp and T. C. Mettenleiter, J. Virol. 73:3014-3022, 1999) was shown to express a gDgH hybrid protein that could replace gD, gH, and gL in cell-cell fusion and null virus complementation assays. To study this phenomenon in herpes simplex virus type 1 (HSV-1), we constructed four gDgH chimeras, joining the first 308 gD amino acids to various gH N-terminal truncations. The chimeras were named for the first amino acid of gH at which each was truncated: 22, 259, 388, and 432. All chimeras were immunoprecipitated with both gD and gH antibodies to conformational epitopes. Normally, transport of gH to the cell surface requires gH-gL complex formation. Chimera 22 contains full-length gH fused to gD308. Unlike PrV gDgH, chimera 22 required gL for transport to the surface of transfected Vero cells. Interestingly, although chimera 259 failed to reach the cell surface, chimeras 388 and 432 exhibited gL-independent transport. To examine gD and gH domain function, each chimera was tested in cell-cell fusion and null virus complementation assays. Unlike PrV gDgH, none of the HSV-1 chimeras substituted for gL for fusion. Only chimera 22 was able to replace gH for fusion and could also replace either gH or gD in the complementation assay. Surprisingly, this chimera performed very poorly as a substitute for gD in the fusion assay despite its ability to complement gD-null virus and bind HSV entry receptors (HveA and nectin-1). Chimeras 388 and 432, which contain the same portion of gD as that in chimera 22, substituted for gD for fusion at 25 to 50% of wild-type levels. However, these chimeras functioned poorly in gD-null virus complementation assays. The results highlight the fact that these two functional assays are measuring two related but distinct processes.

scholarly journals HveA (Herpesvirus Entry Mediator A), a Coreceptor for Herpes Simplex Virus Entry, also Participates in Virus-Induced Cell Fusion

1998 ◽  
Vol 72 (7) ◽  
pp. 5802-5810 ◽  
Author(s):  
Tracy Terry-Allison ◽  
Rebecca I. Montgomery ◽  
J. Charles Whitbeck ◽  
Ruliang Xu ◽  
Gary H. Cohen ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Cell Fusion ◽  
Viral Entry ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Simplex Virus ◽  
Herpesvirus Entry Mediator ◽  
Hsv 1 ◽  
Cell Cell

ABSTRACT The purpose of this study was to determine whether a cell surface protein that can serve as coreceptor for herpes simplex virus type 1 (HSV-1) entry, herpesvirus entry mediator (previously designated HVEM but renamed HveA), also mediates HSV-1-induced cell-cell fusion. We found that transfection of DNA from KOS-804, a previously described HSV-1 syncytial (Syn) strain whose Syn mutation was mapped to an amino acid substitution in gK, induced numerous large syncytia on HveA-expressing Chinese hamster ovary cells (CHO-HVEM12) but not on control cells (CHO-C8). Antibodies specific for gD as well as for HveA were effective inhibitors of KOS-804-induced fusion, consistent with previously described direct interactions between gD and HveA. Since mutations in gD determine the ability of HSV-1 to utilize HveA for entry, we examined whether the form of virally expressed gD also influenced the ability of HveA to mediate fusion. We produced a recombinant virus carrying the KOS-804 Syn mutation and the KOS-Rid1 gD mutation, which significantly reduces viral entry via HveA, and designated it KOS-SR1. KOS-SR1 DNA had a markedly reduced ability to induce syncytia on CHO-HVEM12 cells and a somewhat enhanced ability to induce syncytia on CHO-C8 cells. These results support previous findings concerning the relative abilities of KOS and KOS-Rid1 to infect CHO-HVEM12 and CHO-C8 cells. Thus, HveA mediates cell-cell fusion as well as viral entry and both activities of HveA are contingent upon the form of gD expressed by the virus.

scholarly journals Differential Effects on Cell Fusion Activity of Mutations in Herpes Simplex Virus 1 Glycoprotein B (gB) Dependent on Whether a gD Receptor or a gB Receptor Is Overexpressed

2009 ◽  
Vol 83 (15) ◽  
pp. 7384-7390 ◽  
Author(s):  
Qing Fan ◽  
Erick Lin ◽  
Takeshi Satoh ◽  
Hisashi Arase ◽  
Patricia G. Spear
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Cell Fusion ◽  
Viral Entry ◽  
Selective Reduction ◽  
Glycoprotein B ◽  
Fusion Activity ◽  
Differential Effects ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT Glycoprotein B (gB) of herpes simplex virus (HSV) is one of four glycoproteins essential for viral entry and cell fusion. Recently, paired immunoglobulin-like type 2 receptor (PILRα) was identified as a receptor for HSV type 1 (HSV-1) gB. Both PILRα and a gD receptor were shown to participate in HSV-1 entry into certain cell types. The purpose of this study was to determine whether insertional mutations in gB had differential effects on its function with PILRα and the gD receptor, nectin-1. Previously described gB mutants and additional newly characterized mutants were used in this study. We found that insertional mutations near the N terminus and C terminus of gB and especially in the central region of the ectodomain reduced cell fusion activity when PILRα was overexpressed much more than when nectin-1 was overexpressed. Most of the insertions reduced the binding of gB to PILRα, for at least some forms of gB, but this reduction did not necessarily correlate with the selective reduction in cell fusion activity with PILRα. These results suggest that the regions targeted by the relevant mutations are critical for functional activity with PILRα. They also suggest that, although both the binding of gB to a gB receptor and the binding of gD to a gD receptor may be required for HSV-induced cell fusion, the two receptor-binding activities may have unequal weights in triggering fusogenic activity, depending on the ratios of gB and gD receptors or other factors.

scholarly journals Cbl E3 Ligase Mediates the Removal of Nectin-1 from the Surface of Herpes Simplex Virus 1-Infected Cells

2017 ◽  
Vol 91 (12) ◽  
Author(s):  
Thibaut Deschamps ◽  
Christos Dogrammatzis ◽  
Ranajoy Mullick ◽  
Maria Kalamvoki
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Growth Factor ◽  
Cell Surface ◽  
E3 Ligase ◽  
Herpes Simplex Virus 1 ◽  
Infected Cells ◽  
Simplex Virus ◽  
Entry Receptor ◽  
Hsv 1

ABSTRACT The Cbl E3 ligase has been linked to the down-modulation of surface signaling responses by inducing internalization of surface receptors. The adaptor protein CIN85 is a partner of Cbl that augments many of these interactions. Previously, an interaction was demonstrated between ICP0 and CIN85, which results in the removal of epidermal growth factor receptor (EGFR) from the surface of the infected cells with a concomitant attenuation of EGFR signaling. Here, we examined whether Cbl mediates the removal of the herpes simplex virus 1 (HSV-1) entry receptor Nectin-1 from the surface of infected cells. We found the following: (i) that Cbl, Nectin-1, and the viral glycoprotein D (gD) form a complex in infected cells; (ii) that during infection Nectin-1 is removed from the surface of the infected cells but is retained on the surface of cells that have been depleted of Cbl; and (iii) that in cells infected with a ΔICP0 mutant virus, Nectin-1 remained on the cell surface. Thus, Cbl is necessary but not sufficient for the removal of Nectin-1 from the cell surface. In addition, we observed that in Cbl-depleted cells there was enhanced entry after infection. These cells were susceptible to secondary infections by HSV-1. Viral entry in CIN85-depleted cells was only moderately enhanced compared to that in the Cbl-depleted cells, suggesting that the Cbl–Nectin-1 interaction is likely the key to the downregulation of surface Nectin-1. The removal of the HSV-1 entry receptor Nectin-1 from the surface of the infected cells may be part of the strategy of the virus to efficiently spread to uninfected cells. IMPORTANCE The Cbl E3 ligase suppresses surface signaling responses by inducing internalization of surface components. The targets of Cbl include such components as immune system receptors, growth factor receptors, adhesion, and cell-to-cell contact molecules. The immediate early protein ICP0 of herpes simplex virus 1 (HSV-1) interacts with CIN85, an adaptor protein that augments Cbl functions. The consequence of this interaction is the removal of the epidermal growth factor receptor (EGFR) from the surface of the infected cells with concomitant suppression of the EGF ligand signaling. The viral entry receptor Nectin-1 is also internalized during HSV-1 infection in a Cbl-dependent mechanism, and that increases the opportunity of the virus to spread to uninfected cells. The diversion of the Cbl/CIN85 endocytic machinery may be a strategy utilized by the virus to alter the cell surface pattern to prevent detrimental host responses.

scholarly journals Contribution of Endocytic Motifs in the Cytoplasmic Tail of Herpes Simplex Virus Type 1 Glycoprotein B to Virus Replication and Cell-Cell Fusion

2007 ◽  
Vol 81 (24) ◽  
pp. 13889-13903 ◽  
Author(s):  
Igor Beitia Ortiz de Zarate ◽  
Lilia Cantero-Aguilar ◽  
Magalie Longo ◽  
Clarisse Berlioz-Torrent ◽  
Flore Rozenberg
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Cell Surface ◽  
Cell Fusion ◽  
Virus Replication ◽  
Herpes Simplex Virus Type ◽  
Wild Type ◽  
Simplex Virus ◽  
Cell Cell

ABSTRACT The use of endocytic pathways by viral glycoproteins is thought to play various functions during viral infection. We previously showed in transfection assays that herpes simplex virus type 1 (HSV-1) glycoprotein B (gB) is transported from the cell surface back to the trans-Golgi network (TGN) and that two motifs of gB cytoplasmic tail, YTQV and LL, function distinctly in this process. To investigate the role of each of these gB trafficking signals in HSV-1 infection, we constructed recombinant viruses in which each motif was rendered nonfunctional by alanine mutagenesis. In infected cells, wild-type gB was internalized from the cell surface and concentrated in the TGN. Disruption of YTQV abolished internalization of gB during infection, whereas disruption of LL induced accumulation of internalized gB in early recycling endosomes and impaired its return to the TGN. The growth of both recombinants was moderately diminished. Moreover, the fusion phenotype of cells infected with the gB recombinants differed from that of cells infected with the wild-type virus. Cells infected with the YTQV-mutated virus displayed reduced cell-cell fusion, whereas giant syncytia were observed in cells infected with the LL-mutated virus. Furthermore, blocking gB internalization or impairing gB recycling to the cell surface, using drugs or a transdominant negative form of Rab11, significantly reduced cell-cell fusion. These results favor a role for endocytosis in virus replication and suggest that gB intracellular trafficking is involved in the regulation of cell-cell fusion.

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