14 results on '"Avitabile E"'
Search Results
2. The herpes simplex virus UL20 protein compensates for the differential disruption of exocytosis of virions and viral membrane glycoproteins associated with fragmentation of the Golgi apparatus
- Author
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Avitabile, E, primary, Ward, P L, additional, Di Lazzaro, C, additional, Torrisi, M R, additional, Roizman, B, additional, and Campadelli-Fiume, G, additional
- Published
- 1994
- Full Text
- View/download PDF
3. Localization and putative function of the UL20 membrane protein in cells infected with herpes simplex virus 1
- Author
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Ward, P L, primary, Campadelli-Fiume, G, additional, Avitabile, E, additional, and Roizman, B, additional
- Published
- 1994
- Full Text
- View/download PDF
4. Glycoprotein D of herpes simplex virus encodes a domain which precludes penetration of cells expressing the glycoprotein by superinfecting herpes simplex virus
- Author
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Campadelli-Fiume, G, primary, Qi, S, additional, Avitabile, E, additional, Foà-Tomasi, L, additional, Brandimarti, R, additional, and Roizman, B, additional
- Published
- 1990
- Full Text
- View/download PDF
5. Coexpression of UL20p and gK Inhibits Cell-Cell Fusion Mediated by Herpes Simplex Virus Glycoproteins gD, gH-gL, and Wild-Type gB or an Endocytosis-Defective gB Mutant and Downmodulates Their Cell Surface Expression
- Author
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Gabriella Campadelli-Fiume, Elisa Avitabile, Giulia Lombardi, Miriam Capri, Tatiana Gianni, AVITABILE E., LOMBARDI G., GIANNI T., CAPRI M., and CAMPADELLI-FIUME G.
- Subjects
DOWN-REGULATION ,Syncytium ,Cell fusion ,HERPES SIMPLEX ,MEMBRANE FUSION ,ENDOCYTOSIS ,Endoplasmic reticulum ,Immunology ,Lipid bilayer fusion ,Biology ,Endocytosis ,Microbiology ,Herpesvirus glycoprotein B ,Molecular biology ,Virus-Cell Interactions ,Cell Line ,VIRAL GLYCOPROTEINS ,Viral Proteins ,Viral Envelope Proteins ,Cytoplasm ,Cell culture ,Virology ,Insect Science ,Animals - Abstract
Syncytium formation in cells that express herpes simplex virus glycoprotein B (gB), gD, gH, and gL is blocked by gK (E. Avitabile, G. Lombardi, and G. Campadelli-Fiume, J. Virol. 77: 6836-6844, 2003). Here, we report the results of two series of experiments. First, UL20 protein (UL20p) expression weakly inhibited cell-cell fusion. Coexpression of UL20p and gK drastically reduced fusion in a cell-line-dependent manner, with the highest inhibition in BHK cells. Singly expressed UL20p and gK localized at the endoplasmic reticulum and nuclear membranes. When they were coexpressed, both proteins relocalized to the Golgi apparatus. Remarkably, in cells that coexpressed UL20p and gK, the antifusion activity correlated with a downmodulation of gD, gB, gH, and gL cell surface expression. Second, gB Δ867 has a partial deletion in the cytoplasmic tail that removed endocytosis motifs. Whereas wild-type (wt) gB was internalized in vesicles lined with the endosomal marker Rab5, gB Δ867 was not internalized, exhibited enhanced cell surface expression, and was more efficient in mediating cell-cell fusion than wt gB. The antifusion activity of UL20p and gK was also exerted when gB Δ867 replaced wt gB in the cell fusion assay. These studies show that the gB C tail carries a functional endocytosis motif(s) and that the removal of the motif correlated with increased gB surface expression and increased fusion activity. We conclude that cell-cell fusion in wt-virus-infected cells is negatively controlled by at least two mechanisms. The novel mechanism described here involves the concerted action of UL20p and gK and correlates with a moderate but consistent reduction in the cell surface expression of the fusion glycoproteins. This mechanism is independent of the one exerted through endocytosis-mediated downmodulation of gB from the plasma membrane.
- Published
- 2004
6. The Domains of Glycoprotein D Required To Block Apoptosis Induced by Herpes Simplex Virus 1 Are Largely Distinct from Those Involved in Cell-Cell Fusion and Binding to Nectin1
- Author
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Elisa Avitabile, Bernard Roizman, Gabriella Campadelli-Fiume, Guoying Zhou, Zhou G., Avitabile E., Campadelli-Fiume G., and Roizman B.
- Subjects
Glycosylation ,Nectins ,Immunology ,Mutant ,Glycoprotein D (gD), nectin1, herpes simplex virus (HSV), cell-cell fusion, apoptosis, gD-/+ virus ,Apoptosis ,Herpesvirus 1, Human ,Spodoptera ,Biology ,medicine.disease_cause ,Microbiology ,Cell Line ,Cell Fusion ,chemistry.chemical_compound ,Viral Envelope Proteins ,Cricetinae ,Virology ,medicine ,Animals ,Humans ,Receptor ,chemistry.chemical_classification ,Mutation ,Cell fusion ,Herpesvirus glycoprotein B ,Molecular biology ,Virus-Cell Interactions ,chemistry ,Ectodomain ,Insect Science ,Receptors, Virus ,Glycoprotein ,Cell Adhesion Molecules - Abstract
Glycoprotein D (gD) interacts with two alternative protein receptors, nectin1 and HveA, to mediate herpes simplex virus (HSV) entry into cells. Fusion of the envelope with the plasma membrane requires, in addition to gD, glycoproteins gB, gH, and gL. Coexpression of the four glycoproteins (gD, gB, gH, and gL) promotes cell-cell fusion. gD delivered in trans is also capable of blocking the apoptosis induced by gD deletion viruses grown either in noncomplementing cells (gD −/− ) or in complementing cells (gD −/+ ). While ectopic expression of cation-independent mannose-6 phosphate receptor blocks apoptosis induced by both stocks, other requirements differ. Thus, apoptosis induced by gD −/− virus is blocked by full-length gD (or two gD fragments reconstituting a full-length molecule), whereas ectopic expression of the gD ectodomain is sufficient to block apoptosis induced by gD −/+ virus. In this report we took advantage of a set of gD insertion-deletion mutants to map the domains of gD required to block apoptosis by gD −/− and gD −/+ viruses and those involved in cell-cell fusion. The mutations that resulted in failure to block apoptosis were the same for gD −/− and gD −/+ viruses and were located in three sites, one within the immunoglobulin-type core region (residues 125, 126, and 151), one in the upstream connector region (residues 34 and 43), and one in the C-terminal portion of the ectodomain (residue 277). A mutant that carried amino acid substitutions at the three glycosylation sites failed to block apoptosis but behaved like wild-type gD in all other assays. The mutations that inhibited polykaryocyte formation were located in the upstream connector region (residues 34 and 43), at the α1 helix (residue 77), in the immunoglobulin core and downstream regions (residue 151 and 187), and at the α3 helix (residues 243 and 246). Binding of soluble nectin1-Fc to cells expressing the mutant gDs was generally affected by the same mutations that affected fusion, with one notable exception (Δ277-310), which affected fusion without hampering nectin1 binding. This deletion likely identifies a region of gD involved in fusion activity at a post-nectin1-binding step. We conclude that whereas mutations that affected all functions (e.g., upstream connector region and residue 151) may be detrimental to overall gD structure, the mutations that affect specific activities identify domains of gD involved in the interactions with entry receptors and fusogenic glycoproteins and with cellular proteins required to block apoptosis. The evidence that glycosylation of gD is required for blocking apoptosis supports the conclusion that the interacting protein is the mannose-6 phosphate receptor.
- Published
- 2003
7. Herpes simplex virus glycoprotein K, but not its syncytial allele, inhibits cell-cell fusion mediated by the four fusogenic glycoproteins, gD, gB, gH, and gL
- Author
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Elisa Avitabile, Gabriella Campadelli-Fiume, Giulia Lombardi, Avitabile E., Lombardi G., and Campadelli-Fiume G.
- Subjects
viruses ,Immunology ,Herpesvirus 1, Human ,Biology ,medicine.disease_cause ,Microbiology ,Giant Cells ,Membrane Fusion ,Cell Line ,herpes simplex virus type 1 (HSV-1), glycoprotein K (gK), cell-cell fusion, fusogenic glycoproteins ,Cell Fusion ,Viral Proteins ,Viral Envelope Proteins ,Virology ,Cricetinae ,Chlorocebus aethiops ,Baby hamster kidney cell ,medicine ,Animals ,Humans ,Vero Cells ,Alleles ,chemistry.chemical_classification ,Syncytium ,Cell fusion ,Lipid bilayer fusion ,Molecular biology ,Herpesvirus glycoprotein B ,Virus-Cell Interactions ,Herpes simplex virus ,chemistry ,Insect Science ,Vero cell ,Glycoprotein - Abstract
A Myc epitope was inserted at residue 283 of herpes simplex virus type 1 (HSV-1) glycoprotein K (gK), a position previously shown not to interfere with gK activity. The Myc-tagged gK localized predominantly to the endoplasmic reticulum, both in uninfected and in HSV-infected cells. gK, coexpressed with the four HSV fusogenic glycoproteins, gD, gB, gH, and gL, inhibited cell-cell fusion. The effect was partially dose dependent and was observed both in baby hamster kidney (BHK) and in Vero cells, indicating that the antifusion activity of gK may be cell line independent. The antifusion activity of gK did not require viral proteins other than the four fusogenic glycoproteins. A syncytial ( syn ) allele of gK ( syn -gK) carrying the A40V substitution present in HSV-1(MP) did not block fusion to the extent seen with the wild-type (wt) gK, indicating that the syn mutation ablated, at least in part, the antifusogenic activity of wt gK. We conclude that gK is part of the mechanism whereby HSV negatively regulates its own fusion activity. Its effect accounts for the notion that cells infected with wt HSV do not fuse with adjacent, uninfected cells into multinucleated giant cells or syncytia. gK may also function to preclude fusion between virion envelope and the virion-encasing vesicles during virus transport to the extracellular compartment, thus preventing nucleocapsid de-envelopment in the cytoplasm.
- Published
- 2003
8. Cross talk among the glycoproteins involved in herpes simplex virus entry and fusion: the interaction between gB and gH/gL does not necessarily require gD.
- Author
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Avitabile E, Forghieri C, and Campadelli-Fiume G
- Subjects
- Animals, COS Cells, Cell Line, Chlorocebus aethiops, Glycoproteins genetics, Glycoproteins metabolism, Humans, Membrane Fusion, Viral Envelope Proteins genetics, Virus Internalization, Simplexvirus genetics, Simplexvirus metabolism, Simplexvirus pathogenicity, Simplexvirus physiology, Viral Envelope Proteins metabolism
- Abstract
The gD, gB, and gH/gL glycoprotein quartet constitutes the basic apparatus for herpes simplex virus (HSV) entry into the cell and fusion. gD serves as a receptor binding glycoprotein and trigger of fusion. The conserved gB and gH/gL execute fusion. Central to understanding HSV entry/fusion has become the dissection of how the four glycoproteins engage in cross talk. While the independent interactions of gD with gB and gD with gH/gL have been documented, less is known of the interaction of gB with gH/gL. So far, this interaction has been detected only in the presence of gD by means of a split green fluorescent protein complementation assay. Here, we show that gB interacts with gH/gL in the absence of gD. The gB-gH/gL complex was best detected with a form of gB in which the endocytosis and phosphorylation motif have been deleted; this form of gB persists in the membranes of the exocytic pathway and is not endocytosed. The gB-gH/gL interaction was detected both in whole transfected cells by means of a split yellow fluorescent protein complementation assay and, biochemically, by a pull-down assay. Results with a panel of chimeric forms of gB, in which portions of the glycoprotein bracketed by consecutive cysteines were replaced with the corresponding portions from human herpesvirus 8 gB, favor the view that gB carries multiple sites for interaction with gH/gL, and one of these sites is located in the pleckstrin-like domain 1 carrying the bipartite fusion loop.
- Published
- 2009
- Full Text
- View/download PDF
9. Complexes between herpes simplex virus glycoproteins gD, gB, and gH detected in cells by complementation of split enhanced green fluorescent protein.
- Author
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Avitabile E, Forghieri C, and Campadelli-Fiume G
- Subjects
- Animals, Cell Line, Glycoproteins metabolism, Green Fluorescent Proteins, Protein Binding, Recombinant Fusion Proteins, Simplexvirus pathogenicity, Transduction, Genetic, Simplexvirus chemistry, Viral Envelope Proteins metabolism, Viral Proteins metabolism
- Abstract
The interactions between herpes simplex virus gD and its nectin1 receptor or between gD, gB, and gH were analyzed by complementation of the N and C portions of split enhanced green fluorescent protein (EGFP) fused to the glycoproteins. The gD(N)-Nect(C) complex was readily detected; the gD(N)-gC(C) complex was undetectable, highlighting the specificity of the assay. Split EGFP complementation was detected between proteins designated gD(N)+gH(C), gD(N)+gB(C), and gH(N)+gB(C)+wtgD (gB was deleted of endocytosis motifs), both in cells transfected with two-tree glycoproteins and in syncytia. The in situ assay provides evidence that gD interacts with gH and gB independently of each other and supports a model whereby gH and gB in complex exert their activities to gD.
- Published
- 2007
- Full Text
- View/download PDF
10. Coexpression of UL20p and gK inhibits cell-cell fusion mediated by herpes simplex virus glycoproteins gD, gH-gL, and wild-type gB or an endocytosis-defective gB mutant and downmodulates their cell surface expression.
- Author
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Avitabile E, Lombardi G, Gianni T, Capri M, and Campadelli-Fiume G
- Subjects
- Animals, Cell Line, Down-Regulation, Endocytosis, Membrane Fusion, Viral Envelope Proteins physiology, Viral Proteins physiology
- Abstract
Syncytium formation in cells that express herpes simplex virus glycoprotein B (gB), gD, gH, and gL is blocked by gK (E. Avitabile, G. Lombardi, and G. Campadelli-Fiume, J. Virol. 77:6836-6844, 2003). Here, we report the results of two series of experiments. First, UL20 protein (UL20p) expression weakly inhibited cell-cell fusion. Coexpression of UL20p and gK drastically reduced fusion in a cell-line-dependent manner, with the highest inhibition in BHK cells. Singly expressed UL20p and gK localized at the endoplasmic reticulum and nuclear membranes. When they were coexpressed, both proteins relocalized to the Golgi apparatus. Remarkably, in cells that coexpressed UL20p and gK, the antifusion activity correlated with a downmodulation of gD, gB, gH, and gL cell surface expression. Second, gB(Delta867) has a partial deletion in the cytoplasmic tail that removed endocytosis motifs. Whereas wild-type (wt) gB was internalized in vesicles lined with the endosomal marker Rab5, gB(delta867) was not internalized, exhibited enhanced cell surface expression, and was more efficient in mediating cell-cell fusion than wt gB. The antifusion activity of UL20p and gK was also exerted when gB(delta867) replaced wt gB in the cell fusion assay. These studies show that the gB C tail carries a functional endocytosis motif(s) and that the removal of the motif correlated with increased gB surface expression and increased fusion activity. We conclude that cell-cell fusion in wt-virus-infected cells is negatively controlled by at least two mechanisms. The novel mechanism described here involves the concerted action of UL20p and gK and correlates with a moderate but consistent reduction in the cell surface expression of the fusion glycoproteins. This mechanism is independent of the one exerted through endocytosis-mediated downmodulation of gB from the plasma membrane.
- Published
- 2004
- Full Text
- View/download PDF
11. Herpes simplex virus glycoprotein K, but not its syncytial allele, inhibits cell-cell fusion mediated by the four fusogenic glycoproteins, gD, gB, gH, and gL.
- Author
-
Avitabile E, Lombardi G, and Campadelli-Fiume G
- Subjects
- Animals, Cell Fusion, Cell Line, Chlorocebus aethiops, Cricetinae, Herpesvirus 1, Human genetics, Humans, Membrane Fusion, Vero Cells, Viral Envelope Proteins genetics, Viral Proteins genetics, Viral Proteins metabolism, Alleles, Giant Cells physiology, Herpesvirus 1, Human physiology, Viral Envelope Proteins metabolism, Viral Proteins pharmacology
- Abstract
A Myc epitope was inserted at residue 283 of herpes simplex virus type 1 (HSV-1) glycoprotein K (gK), a position previously shown not to interfere with gK activity. The Myc-tagged gK localized predominantly to the endoplasmic reticulum, both in uninfected and in HSV-infected cells. gK, coexpressed with the four HSV fusogenic glycoproteins, gD, gB, gH, and gL, inhibited cell-cell fusion. The effect was partially dose dependent and was observed both in baby hamster kidney (BHK) and in Vero cells, indicating that the antifusion activity of gK may be cell line independent. The antifusion activity of gK did not require viral proteins other than the four fusogenic glycoproteins. A syncytial (syn) allele of gK (syn-gK) carrying the A40V substitution present in HSV-1(MP) did not block fusion to the extent seen with the wild-type (wt) gK, indicating that the syn mutation ablated, at least in part, the antifusogenic activity of wt gK. We conclude that gK is part of the mechanism whereby HSV negatively regulates its own fusion activity. Its effect accounts for the notion that cells infected with wt HSV do not fuse with adjacent, uninfected cells into multinucleated giant cells or syncytia. gK may also function to preclude fusion between virion envelope and the virion-encasing vesicles during virus transport to the extracellular compartment, thus preventing nucleocapsid de-envelopment in the cytoplasm.
- Published
- 2003
- Full Text
- View/download PDF
12. The domains of glycoprotein D required to block apoptosis induced by herpes simplex virus 1 are largely distinct from those involved in cell-cell fusion and binding to nectin1.
- Author
-
Zhou G, Avitabile E, Campadelli-Fiume G, and Roizman B
- Subjects
- Animals, Cell Line, Cricetinae, Humans, Mutation, Nectins, Receptors, Virus metabolism, Spodoptera, Viral Envelope Proteins genetics, Apoptosis, Cell Adhesion Molecules metabolism, Cell Fusion, Herpesvirus 1, Human pathogenicity, Viral Envelope Proteins chemistry, Viral Envelope Proteins metabolism
- Abstract
Glycoprotein D (gD) interacts with two alternative protein receptors, nectin1 and HveA, to mediate herpes simplex virus (HSV) entry into cells. Fusion of the envelope with the plasma membrane requires, in addition to gD, glycoproteins gB, gH, and gL. Coexpression of the four glycoproteins (gD, gB, gH, and gL) promotes cell-cell fusion. gD delivered in trans is also capable of blocking the apoptosis induced by gD deletion viruses grown either in noncomplementing cells (gD(-/-)) or in complementing cells (gD(-/+)). While ectopic expression of cation-independent mannose-6 phosphate receptor blocks apoptosis induced by both stocks, other requirements differ. Thus, apoptosis induced by gD(-/-) virus is blocked by full-length gD (or two gD fragments reconstituting a full-length molecule), whereas ectopic expression of the gD ectodomain is sufficient to block apoptosis induced by gD(-/+) virus. In this report we took advantage of a set of gD insertion-deletion mutants to map the domains of gD required to block apoptosis by gD(-/-) and gD(-/+) viruses and those involved in cell-cell fusion. The mutations that resulted in failure to block apoptosis were the same for gD(-/-) and gD(-/+) viruses and were located in three sites, one within the immunoglobulin-type core region (residues 125, 126, and 151), one in the upstream connector region (residues 34 and 43), and one in the C-terminal portion of the ectodomain (residue 277). A mutant that carried amino acid substitutions at the three glycosylation sites failed to block apoptosis but behaved like wild-type gD in all other assays. The mutations that inhibited polykaryocyte formation were located in the upstream connector region (residues 34 and 43), at the alpha1 helix (residue 77), in the immunoglobulin core and downstream regions (residue 151 and 187), and at the alpha3 helix (residues 243 and 246). Binding of soluble nectin1-Fc to cells expressing the mutant gDs was generally affected by the same mutations that affected fusion, with one notable exception (Delta277-310), which affected fusion without hampering nectin1 binding. This deletion likely identifies a region of gD involved in fusion activity at a post-nectin1-binding step. We conclude that whereas mutations that affected all functions (e.g., upstream connector region and residue 151) may be detrimental to overall gD structure, the mutations that affect specific activities identify domains of gD involved in the interactions with entry receptors and fusogenic glycoproteins and with cellular proteins required to block apoptosis. The evidence that glycosylation of gD is required for blocking apoptosis supports the conclusion that the interacting protein is the mannose-6 phosphate receptor.
- Published
- 2003
- Full Text
- View/download PDF
13. Novel, soluble isoform of the herpes simplex virus (HSV) receptor nectin1 (or PRR1-HIgR-HveC) modulates positively and negatively susceptibility to HSV infection.
- Author
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Lopez M, Cocchi F, Avitabile E, Leclerc A, Adelaide J, Campadelli-Fiume G, and Dubreuil P
- Subjects
- Amino Acid Sequence, Animals, Base Sequence, Cell Adhesion Molecules genetics, Cell Line, Cloning, Molecular, Culture Media, Herpes Simplex virology, Humans, Molecular Sequence Data, Nectins, Protein Isoforms metabolism, Reverse Transcriptase Polymerase Chain Reaction, Sequence Analysis, DNA, Solubility, Cell Adhesion Molecules metabolism, Herpes Simplex immunology, Receptors, Virus metabolism, Simplexvirus pathogenicity
- Abstract
A novel member of the nectin family, nectin1gamma, was molecularly cloned. The cDNA has the same ectodomain as nectin1alpha and nectin1beta, the two known transmembrane isoforms that serve as receptors for herpes simplex virus (HSV) entry into human cell lines (nectin1alpha and nectin1beta, also called PRR1-HveC and HIgR, respectively). The 1.4-kb transcript, which originated by alternative splicing, is expressed in human cell lines, and appears to have a narrow distribution in human tissues. The sequence does not have a hydrophobic anchoring region, and the protein is secreted in the culture medium of cells transfected with the cDNA. Nectin1gamma, purified from culture medium, can compete with membrane-bound nectin1beta and reduce HSV infectivity. The expression of nectin1gamma cDNA in cells resistant to HSV infection and lacking HSV receptors enables HSV to enter the cell, which implies that it is present at the cell surface. Thus, nectin1gamma has the potential both to mediate and to reduce HSV entry into cells.
- Published
- 2001
- Full Text
- View/download PDF
14. Nectin2alpha (PRR2alpha or HveB) and nectin2delta are low-efficiency mediators for entry of herpes simplex virus mutants carrying the Leu25Pro substitution in glycoprotein D.
- Author
-
Lopez M, Cocchi F, Menotti L, Avitabile E, Dubreuil P, and Campadelli-Fiume G
- Subjects
- Amino Acid Substitution, Antibodies, Monoclonal immunology, Cell Adhesion Molecules chemistry, Cell Adhesion Molecules immunology, Cell Line, Herpesvirus 1, Human genetics, Humans, Leucine, Mutation, Nectins, Proline, Protein Isoforms, Protein Structure, Tertiary, Transfection, Cell Adhesion Molecules metabolism, Herpesvirus 1, Human metabolism, Receptors, Virus metabolism, Viral Envelope Proteins genetics
- Abstract
The receptors for entry of herpes simplex viruses 1 and 2 (HSV-1 and -2), widely expressed in human cell lines, are members of a subset of the immunoglobulin superfamily exemplified by herpesvirus entry mediator C (HveC) and the herpesvirus immunoglobulin-like receptor (HIgR). This report focuses on two members of this subset, herpesvirus entry mediator B (HveB), recently designated nectin2/PRR2alpha, and its splice variant isoform, nectin2/PRR2delta. Nectin2alpha and -delta share the ectodomain but differ in the transmembrane and cytoplasmic regions. HveB was reported to enable entry of HSV-1 carrying mutations in glycoprotein D (gD) and of HSV-2, but not of wild-type (wt) HSV-1. We report that (i) both nectin2alpha and -delta served as receptors for the entry of HSV-1 mutant viruses HSV-1(U10) and -(U21) and AP7(r) that carry the Leu25Pro substitution in gD but not for HSV-1 mutants U30 and R5000 that carry the Ser140 or Ala185 substitution in gD. All of these mutants were able to overcome the block to entry mediated by expression of wt gD. (ii) Infection of cells expressing nectin2alpha or -delta required exposure to multiplicities of infection about 100-fold higher than those required to infect cells expressing HveC or HIgR. (iii) gD from HSV-1(U21) bound in vitro soluble forms of nectin2. The association was weaker than that to the soluble form of HveC/HIgR. Binding of wt HSV-1 gD to soluble nectin2 was not detectable. (iv) A major region of nectin2 functional in virus entry mapped to the V domain, located at the N terminus.
- Published
- 2000
- Full Text
- View/download PDF
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