scholarly journals Exonuclease-Deficient Polymerase Mutant of Herpes Simplex Virus Type 1 Induces Altered Spectra of Mutations

2003 ◽  
Vol 77 (5) ◽  
pp. 2946-2955 ◽  
Author(s):  
Ying T. Hwang ◽  
Charles B. C. Hwang
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Target Genes ◽  
Exonuclease Activity ◽  
Wild Type ◽  
Assay Methods ◽  
Simplex Virus

ABSTRACT The effect of exonuclease activity of the herpes simplex virus DNA polymerase (Pol) on DNA replication fidelity was examined by using the supF mutagenesis assay. The recombinants with exonuclease-deficient Pol, containing an integrated supF gene in the thymidine kinase locus (tk), exhibited supF mutation frequencies ranging from 0.14 to 5.6%, consistent with the tk mutation frequencies reported previously (Y. T. Hwang, B.-Y. Liu, D. M. Coen, and C. B. C. Hwang, J. Virol. 71:7791-7798, 1997). The increased mutation frequencies were 10- to 500-fold higher than those observed for wild-type Pol recombinants. The increased mutation frequencies also were significantly higher than those of supF mutant replicated by exonuclease-deficient Pols in the plasmid-borne assay. Furthermore, characterization of supF mutants demonstrated that recombinants with a defective exonuclease induced types and distributions of supF mutations different from those induced by wild-type Pol recombinants. The types of supF mutations induced by exonuclease-deficient recombinants differed between the plasmid- and genome-based assays. The spectra of supF mutations also differed between the two assays. In addition, exonuclease-defective viruses also induced different spectra of supF and tk mutations. Therefore, both the assay methods and the target genes used for mutagenesis studies can affect the repication fidelity of herpes simplex virus type 1 Pol with defective exonuclease activity.

scholarly journals Mutation Spectra of Herpes Simplex Virus Type 1 Thymidine Kinase Mutants

2002 ◽  
Vol 76 (11) ◽  
pp. 5822-5828 ◽  
Author(s):  
Qiaosheng Lu ◽  
Ying T. Hwang ◽  
Charles B. C. Hwang
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Thymidine Kinase ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Wild Type Virus ◽  
Exonuclease Activity ◽  
Wild Type ◽  
Simplex Virus

ABSTRACT To examine whether the exonuclease activity intrinsic to the polymerase (Pol) of herpes simplex virus type 1 can influence the mutational spectra, we applied the denaturing gradient gel electrophoresis (DGGE) system combined with sequencing to characterize thymidine kinase mutants isolated from both the wild-type virus and a mutant deficient in exonuclease activity, Y7. Wild-type viruses produced predominately frameshift mutations (67%), whereas Y7 replicated a significantly lower proportion of frameshifts (21%; P < 0.005). Furthermore, the majority of substitutions were transitional changes in both groups, although they distributed differently. The implications of these findings are discussed.

scholarly journals Suppression of Proinflammatory Cytokine Expression by Herpes Simplex Virus Type 1

2004 ◽  
Vol 78 (11) ◽  
pp. 5883-5890 ◽  
Author(s):  
Trine H. Mogensen ◽  
Jesper Melchjorsen ◽  
Lene Malmgaard ◽  
Antonella Casola ◽  
Søren R. Paludan
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Virus Type ◽  
Proinflammatory Cytokines ◽  
Herpes Simplex Virus Type ◽  
Cytokine Expression ◽  
Wild Type ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT Viral immune evasion strategies are important for establishment and maintenance of infections. Many viruses are in possession of mechanisms to counteract the antiviral response raised by the infected host. Here we show that a herpes simplex virus type 1 (HSV-1) mutant lacking functional viral protein 16 (VP16)—a tegument protein promoting viral gene expression—induced significantly higher levels of proinflammatory cytokines than wild-type HSV-1. This was observed in several cell lines and primary murine macrophages, as well as in peritoneal cells harvested from mice infected in vivo. The enhanced ability to stimulate cytokine expression in the absence of VP16 was not mediated directly by VP16 but was dependent on the viral immediate-early genes for infected cell protein 4 (ICP4) and ICP27, which are expressed in a VP16-dependent manner during primary HSV infection. The virus appeared to target cellular factors other than interferon-induced double-stranded RNA-activated protein kinase R (PKR), since the virus mutants remained stronger inducers of cytokines in cells stably expressing a dominant-negative mutant form of PKR. Finally, mRNA stability assay revealed a significantly longer half-life for interleukin-6 mRNA after infection with the VP16 mutant than after infection with the wild-type virus. Thus, HSV is able to suppress expression of proinflammatory cytokines by decreasing the stability of mRNAs, thereby potentially impeding the antiviral host response to infection.

scholarly journals Evidence for Controlled Incorporation of Herpes Simplex Virus Type 1 UL26 Protease into Capsids

2000 ◽  
Vol 74 (15) ◽  
pp. 6838-6848 ◽  
Author(s):  
Amy K. Sheaffer ◽  
William W. Newcomb ◽  
Jay C. Brown ◽  
Min Gao ◽  
Sandra K. Weller ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Scaffold Proteins ◽  
Wild Type ◽  
Protease Domain ◽  
Capsid Shell ◽  
Simplex Virus

ABSTRACT Herpes simplex virus type 1 (HSV-1) capsids are initially assembled with an internal protein scaffold. The scaffold proteins, encoded by overlapping in-frame UL26 and UL26.5 transcripts, are essential for formation and efficient maturation of capsids. UL26 encodes an N-terminal protease domain, and its C-terminal oligomerization and capsid protein-binding domains are identical to those of UL26.5. The UL26 protease cleaves itself, releasing minor scaffold proteins VP24 and VP21, and the more abundant UL26.5 protein, releasing the major scaffold protein VP22a. Unlike VP21 and VP22a, which are removed from capsids upon DNA packaging, we demonstrate that VP24 (containing the protease domain) is quantitatively retained. To investigate factors controlling UL26 capsid incorporation and retention, we used a mutant virus that fails to express UL26.5 (ΔICP35 virus). Purified ΔICP35 B capsids showed altered sucrose gradient sedimentation and lacked the dense scaffold core seen in micrographs of wild-type B capsids but contained capsid shell proteins in wild-type amounts. Despite C-terminal sequence identity between UL26 and UL26.5, ΔICP35 capsids lacking UL26.5 products did not contain compensatory high levels of UL26 proteins. Therefore, HSV capsids can be maintained and/or assembled on a minimal scaffold containing only wild-type levels of UL26 proteins. In contrast to UL26.5, increased expression of UL26 did not compensate for the ΔICP35growth defect. While indirect, these findings are consistent with the view that UL26 products are restricted from occupying abundant UL26.5 binding sites within the capsid and that this restriction is not controlled by the level of UL26 protein expression. Additionally, ΔICP35 capsids contained an altered complement of DNA cleavage and packaging proteins, suggesting a previously unrecognized role for the scaffold in this process.

scholarly journals Herpes simplex virus type 1-encoded glycoprotein C contributes to direct coagulation Factor X–virus binding

2005 ◽  
Vol 393 (2) ◽  
pp. 529-535 ◽  
Author(s):  
Joel R. Livingston ◽  
Michael R. Sutherland ◽  
Harvey M. Friedman ◽  
Edward L. G. Pryzdial
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Binding Sites ◽  
Factor X ◽  
Wild Type ◽  
Glycoprotein C ◽  
Simplex Virus

The HSV1 (herpes simplex virus type 1) surface has been shown recently to initiate blood coagulation by FVIIa (activated Factor VII)-dependent proteolytic activation of FX (Factor X). At least two types of direct FX–HSV1 interactions were suggested by observing that host cell-encoded tissue factor and virus-encoded gC (glycoprotein C) independently enhance FVIIa function on the virus. Using differential sedimentation to separate bound from free 125I-ligand, we report in the present study that, in the presence of Ca2+, FX binds directly to purified wild-type HSV1 with an apparent dissociation constant (Kd) of 1.5±0.4 μM and 206±24 sites per virus at saturation. The number of FX-binding sites on gC-deficient virus was reduced to 43±5, and the remaining binding had a lower Kd (0.7±0.2 μM), demonstrating an involvement of gC. Engineering gC back into the deficient strain or addition of a truncated soluble recombinant form of gC (sgC), increased the Kd and the number of binding sites. Consistent with a gC/FX stoichiometry of approximately 1:1, 121±6 125I-sgC molecules were found to bind per wild-type HSV1. In the absence of Ca2+, the number of FX-binding sites on the wild-type virus was similar to the gC-deficient strain in the presence of Ca2+. Furthermore, in the absence of Ca2+, direct sgC binding to HSV1 was insignificant, although sgC was observed to inhibit the FX–virus association, suggesting a Ca2+-independent solution-phase FX–sgC interaction. Cumulatively, these data demonstrate that gC constitutes one type of direct FX–HSV1 interaction, possibly providing a molecular basis for clinical correlations between recurrent infection and vascular pathology.

scholarly journals Glycosaminoglycan-Binding Ability Is a Feature of Wild-Type Strains of Herpes Simplex Virus Type 1

Virology ◽  
2002 ◽  
Vol 302 (2) ◽  
pp. 413-419 ◽  
Author(s):  
Edward Trybala ◽  
Anette Roth ◽  
Maria Johansson ◽  
Jan-Åke Liljeqvist ◽  
Elham Rekabdar ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Wild Type ◽  
Binding Ability ◽  
Simplex Virus ◽  
Type Strains

scholarly journals Dephosphorylation of eIF-2α Mediated by the γ134.5 Protein of Herpes Simplex Virus Type 1 Is Required for Viral Response to Interferon but Is Not Sufficient for Efficient Viral Replication

2003 ◽  
Vol 77 (18) ◽  
pp. 10154-10161 ◽  
Author(s):  
Guofeng Cheng ◽  
Kui Yang ◽  
Bin He
Keyword(s):  
Amino Acids ◽  
Herpes Simplex Virus ◽  
Amino Acid ◽  
Herpes Simplex ◽  
Viral Replication ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Wild Type ◽  
Simplex Virus

ABSTRACT The γ134.5 protein of herpes simplex virus type 1 (HSV-1) functions to block the shutoff of protein synthesis involving double-stranded RNA-dependent protein kinase (PKR). In this process, the γ134.5 protein recruits cellular protein phosphatase 1 (PP1) to form a high-molecular-weight complex that dephosphorylates eIF-2α. Here we show that the γ134.5 protein is capable of mediating eIF-2α dephosphorylation without any other viral proteins. While deletion of amino acids 1 to 52 from the γ134.5 protein has no effect on eIF-2α dephosphorylation, further truncations up to amino acid 146 dramatically reduce the activity of the γ134.5 protein. An additional truncation up to amino acid 188 is deleterious, indicating that the carboxyl-terminal domain alone is not functional. Like wild-type HSV-1, the γ134.5 mutant with a truncation of amino acids 1 to 52 is resistant to interferon, and resistance to interferon is coupled to eIF-2α dephosphorylation. Intriguingly, this mutant exhibits a similar growth defect seen for the γ134.5 null mutant in infected cells. Restoration of the wild-type γ134.5 gene in the recombinant completely reverses the phenotype. These results indicate that eIF-2α dephosphorylation mediated by the γ134.5 protein is required for HSV response to interferon but is not sufficient for viral replication. Additional functions or activities of the γ134.5 protein contribute to efficient viral infection.

scholarly journals Herpes Simplex Virus Type 1 Latency-Associated Transcript Gene Promotes Neuronal Survival

2001 ◽  
Vol 75 (14) ◽  
pp. 6660-6675 ◽  
Author(s):  
R. L. Thompson ◽  
N. M. Sawtell
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Sensory Neurons ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Latent Infections ◽  
Wild Type ◽  
Simplex Virus ◽  
Null Mutants

ABSTRACT A complex interaction has evolved between the host's peripheral nervous system (PNS) and herpes simplex virus type 1 (HSV-1). Sensory neurons are permissive for viral replication, yet the virus can also enter a latent state in these cells. The interplay of viral and neuronal signals that regulate the switch between the viral lytic and latent states is not understood. The latency-associated transcript (LAT) regulates the establishment of the latent state and is required for >65% of the latent infections established by HSV-1 (R. L. Thompson and N. M. Sawtell, J. Virol. 71:5432–5440, 1997). To further investigate how LAT functions, a 1.9-kb deletion that includes the entire LAT promoter and 827 bp of the 5′ end of the primary LAT mRNA was introduced into strain 17syn+. The wild-type parent, three independently derived deletion mutants, and two independently derived genomically rescued variants of the mutants were analyzed in a mouse ocular model. The number of latent sites established in trigeminal ganglion (TG) neurons was determined using a single-cell quantitative PCR assay for the viral genome on purified TG neurons. It was found that the LAT null mutants established ∼75% fewer latent infections than the number established by the parental strain or rescued variant. The reduced establishment phenotype of LAT null mutants was due at least in part to a dramatic increase in the loss of TG neurons in animals infected with the LAT mutants. Over half of the neurons in the TG were destroyed following infection with the LAT mutants, and this was significantly more than were lost following infection with wild type. This is the first demonstration that the HSV LAT locus prevents the destruction of sensory neurons. The death of these neurons did not appear to be the result of increased apoptosis as measured by a terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling assay. Animals latently infected with the LAT null mutants reactivated less frequently in vivo and this was consistent with the reduction in the number of neurons in which latency was established. Thus, one function of the LAT gene is to protect sensory neurons and enhance the establishment of latency in the PNS.

scholarly journals During Herpes Simplex Virus Type 1 Infection of Rabbits, the Ability To Express the Latency-Associated Transcript Increases Latent-Phase Transcription of Lytic Genes

2008 ◽  
Vol 82 (12) ◽  
pp. 6056-6060 ◽  
Author(s):  
Nicole V. Giordani ◽  
Donna M. Neumann ◽  
Dacia L. Kwiatkowski ◽  
Partha S. Bhattacharjee ◽  
Peterjon K. McAnany ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Transcript Abundance ◽  
Pcr Analysis ◽  
Wild Type ◽  
Simplex Virus ◽  
Lytic Genes

ABSTRACT Trigeminal ganglia (TG) from rabbits latently infected with either wild-type herpes simplex virus type 1 (HSV-1) or the latency-associated transcript (LAT) promoter deletion mutant 17ΔPst were assessed for their viral chromatin profile and transcript abundance. The wild-type 17syn+ genomes were more enriched in the transcriptionally permissive mark dimethyl H3 K4 than were the 17ΔPst genomes at the 5′ exon and ICP0 and ICP27 promoters. Reverse transcription-PCR analysis revealed significantly more ICP4, tk, and glycoprotein C lytic transcripts in 17syn+ than in 17ΔPst. These results suggest that, for efficient reactivation from latency in rabbits, the LAT is important for increased transcription of lytic genes during latency.

scholarly journals Fusion-Deficient Insertion Mutants of Herpes Simplex Virus Type 1 Glycoprotein B Adopt the Trimeric Postfusion Conformation

2009 ◽  
Vol 84 (4) ◽  
pp. 2001-2012 ◽  
Author(s):  
Jessica L. Silverman ◽  
Sapna Sharma ◽  
Tina M. Cairns ◽  
Ekaterina E. Heldwein
Keyword(s):  
Crystal Structure ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Glycoprotein B ◽  
Wild Type ◽  
Simplex Virus ◽  
Insertion Mutants

ABSTRACT Glycoprotein B (gB) enables the fusion of viral and cell membranes during entry of herpesviruses. However, gB alone is insufficient for membrane fusion; the gH/gL heterodimer is also required. The crystal structure of the herpes simplex virus type 1 (HSV-1) gB ectodomain, gB730, has demonstrated similarities between gB and other viral fusion proteins, leading to the hypothesis that gB is a fusogen, presumably directly involved in bringing the membranes together by refolding from its initial or prefusion form to its final or postfusion form. The only available crystal structure likely represents the postfusion form of gB; the prefusion form has not yet been determined. Previously, a panel of HSV-1 gB mutants was generated by using random 5-amino-acid-linker insertion mutagenesis. Several mutants were unable to mediate cell-cell fusion despite being expressed on the cell surface. Mapping of the insertion sites onto the crystal structure of gB730 suggested that several insertions might not be accommodated in the postfusion form. Thus, we hypothesized that some insertion mutants were nonfunctional due to being “trapped” in a prefusion form. Here, we generated five insertion mutants as soluble ectodomains and characterized them biochemically. We show that the ectodomains of all five mutants assume conformations similar to that of the wild-type gB730. Four mutants have biochemical properties and overall structures that are indistinguishable from those of the wild-type gB730. We conclude that these mutants undergo only minor local conformational changes to relieve the steric strain resulting from the presence of 5 extra amino acids. Interestingly, one mutant, while able to adopt the overall postfusion structure, displays significant conformational differences in the vicinity of fusion loops, relative to wild-type gB730. Moreover, this mutant has a diminished ability to associate with liposomes, suggesting that the fusion loops in this mutant have decreased functional activity. We propose that these insertions cause a fusion-deficient phenotype not by preventing conversion of gB to a postfusion-like conformation but rather by interfering with other gB functions.

scholarly journals A Herpes Simplex Virus Type 1 Latency-Associated Transcript Mutant with Increased Virulence and Reduced Spontaneous Reactivation

1999 ◽  
Vol 73 (2) ◽  
pp. 920-929 ◽  
Author(s):  
Guey-Chuen Perng ◽  
Susan M. Slanina ◽  
Ada Yukht ◽  
Barbara S. Drolet ◽  
William Keleher ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Ocular Infection ◽  
Wild Type ◽  
Simplex Virus ◽  
Spontaneous Reactivation ◽  
Hsv 1

ABSTRACT The herpes simplex virus type 1 (HSV-1) latency-associated transcript (LAT) gene is essential for efficient spontaneous reactivation of HSV-1 from latency. We previously reported that insertion of the LAT promoter and just the first 1.5 kb of the 8.3-kb LAT gene into an ectopic location in the virus restored wild-type spontaneous reactivation to a LAT null mutant. This mutant, LAT3.3A (previously designated LAT1.5a), thus showed that the expression of just the first 1.5 kb of LAT is sufficient for wild-type spontaneous reactivation. We also showed that in the context of the entire LAT gene, deletion of LAT nucleotides 76 to 447 (LAT mutantdLAT371) had no effect on spontaneous reactivation or virulence. We report here on a LAT mutant designated LAT2.9A. This mutant is similar to LAT3.3A, except that the ectopic LAT insert contains the same 371-nucleotide deletion found in dLAT371. We found that LAT2.9A had a significantly reduced rate of spontaneous reactivation compared to marker-rescued and wild-type viruses. This was unexpected, since the combined results of dLAT371 and LAT3.3A predicted that spontaneous reactivation of LAT2.9A would be wild type. We also found that LAT2.9A was more virulent than wild-type or marker-rescued viruses after ocular infection of rabbits. This was unexpected, since LAT null mutants and LAT3.3A have wild-type virulence. These results suggest for the first time (i) that regions past the first 1.5 kb of LAT can compensate for deletions in the first 1.5kb of LAT and may therefore play a role in LAT dependent spontaneous reactivation and (ii) that regions of LAT affect viral virulence.

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