bluuebunny/crossref_metadata_2025_split huggingface dataset:
State and Role of Src Family Kinases in Replication of Herpes Simplex Virus 1
Authors: Liang Yu , Roizman Bernard 
Published: March 2006

ABSTRACT

An earlier report showed that infected cell protein no. 0 (ICP0) of herpes simplex virus 1 (HSV-1) interacts with the SH3 domains of a recently discovered adaptor protein, CIN85. Here, we report the following. (i) ICP0 also interacts with other SH3 domain-containing proteins and, in particular, with nonneuronal members of the Src kinase family. (ii) HSV-1 infection enhanced the activating phosphorylation of Tyr416 of the members of the Src kinase family, modestly enhanced the kinase activity of Src, and posttranslationally modified at least one additional member of the Src kinase family by phosphorylation in a manner dependent on the viral gene products ICP0, unique short 3 (U
S
3), and unique long 13 (U
L
13). (iii) To define the roles of Src kinase family members, we examined the accumulation of viral proteins, DNA, and mRNA and virus yields from wild-type mouse embryo fibroblasts and sibling cells lacking Src, Fyn, and Yes (SYF
−
); a mutant cell line, +Src, in which Src was restored to SYF
−
cells; and the mutant cell line (CSK
−
) lacking the negative regulator Csk gene of the Src kinase family. Representative α, β, and γ
2
proteins accumulated in the largest amounts in SYF
−
cells and the smallest amounts in +Src compared to wild-type cells. The CSK
−
cells yielded smaller amounts of the γ
2
protein and at least 10-fold less virus than wild-type cells. We conclude that HSV-1 proteins regulate the activities of Src family kinases to achieve optimal viral yields in the course of viral replication.
ICP0 Is Not Required for Efficient Stress-Induced Reactivation of Herpes Simplex Virus Type 1 from Cultured Quiescently Infected Neuronal Cells
Authors: Miller Craig S. , Danaher Robert J. , Jacob Robert J. 
Published: March 2006

ABSTRACT

Viral genes sufficient and required for herpes simplex virus type 1 (HSV-1) reactivation were identified using neuronally differentiated PC12 cells (ND-PC12 cells) in which quiescent infections with wild-type and recombinant strains were established. In this model, the expression of ICP0, VP16, and ICP4 from adenovirus vectors was sufficient to reactivate strains 17
+
and KOS. The transactivators induced similar levels of reactivation with KOS; however, 17
+
responded more efficiently to ICP0. To identify viral transactivators required for reactivation, we examined quiescently infected PC12 cell cultures (QIF-PC12 cell cultures) established with HSV-1 deletion mutants R7910 (ΔICP0), KD6 (ΔICP4), and
in
1814, a virus containing an insertion mutation in VP16. Although growth of these mutant viruses was impaired in ND-PC12 cells, R7910 and
in
1814 reactivated at levels equivalent to or better than their respective parental controls following stress (i.e., heat or forskolin) treatment. After treatment with trichostatin A,
in
1814 and 17
+
reactivated efficiently, whereas the F strain and R7910 reactivated inefficiently. In contrast, KD6 failed to reactivate. In experiments with the recombinant KM100, which contains the
in
1814 mutation in VP16 and the n212 mutation in ICP0, spontaneous and stress-induced reactivation was observed. However, two strains, V422 and KM110, which lack the acidic activation domain of VP16, did not reactivate above low spontaneous levels after stress. These results demonstrate that in QIF-PC12 cells ICP0 is not required for efficient reactivation of HSV-1, the acidic activation domain of VP16 is essential for stress-induced HSV-1 reactivation, and HSV-1 reactivation is modulated uniquely by different treatment constraints and phenotypes.
A Putative Thiamine Transport Protein Is a Receptor for Feline Leukemia Virus Subgroup A
Authors: Mendoza Ramon , Anderson Maria M. , Overbaugh Julie 
Published: March 2006

ABSTRACTFeline leukemia virus (FeLV) is a horizontally transmitted virus that causes a variety of proliferative and immunosuppressive diseases in cats. There are four subgroups of FeLV, A, B, C, and T, each of which has a distinct receptor requirement. The receptors for all but the FeLV-A subgroup have been defined previously. Here, we report the identification of the cellular receptor for FeLV-A, which is the most transmissible form of FeLV. The receptor cDNA was isolated using a gene transfer approach, which involved introducing sequences from a feline cell line permissive to FeLV-A into a murine cell line that was not permissive. The feline cDNA identified by this method was approximately 3.5 kb, and included an open reading frame predicted to encode a protein of 490 amino acids. This feline cDNA conferred susceptibility to FeLV-A when reintroduced into nonpermissive cells, but it did not render these cells permissive to any other FeLV subgroup. Moreover, these cells specifically bound FeLV-A-pseudotyped virus particles, indicating that the cDNA encodes a binding receptor for FeLV-A. The feline cDNA shares ∼93% amino acid sequence identity with the human thiamine transport protein 1 (THTR1). The human THTR1 receptor was also functional as a receptor for FeLV-A, albeit with reduced efficiency compared to the feline orthologue. On the basis of these data, which strongly suggest the feline protein is the orthologue of human THTR1, we have named the feline receptor feTHTR1. Identification of this receptor will allow more detailed studies of the early events in FeLV transmission and may provide insights into FeLV pathogenesis.
Differential Utilization of CD134 as a Functional Receptor by Diverse Strains of Feline Immunodeficiency Virus
Authors: Willett Brian J. , McMonagle Elizabeth L. , Ridha Susan , Hosie Margaret J. 
Published: March 2006

ABSTRACT

The feline homologue of CD134 (fCD134) is the primary binding receptor for feline immunodeficiency virus (FIV), targeting the virus preferentially to activated CD4
+
helper T cells. However, with disease progression, the cell tropism of FIV broadens such that B cells and monocytes/macrophages become significant reservoirs of proviral DNA, suggesting that receptor utilization may alter with disease progression. We examined the receptor utilization of diverse strains of FIV and found that all strains tested utilized CD134 as the primary receptor. Using chimeric feline × human CD134 receptors, the primary determinant of receptor function was mapped to the first cysteine-rich domain (CRD1) of fCD134. For the PPR and B2542 strains, the replacement of CDR1 of fCD134 (amino acids 1 to 64) with human CD134 (hCD134) alone was sufficient to confer nearly optimal receptor function. However, evidence of differential utilization of CD134 was revealed, since strains GL8, CPGammer (CPG41), TM2, 0827, and NCSU1 required determinants in the region spanning amino acids 65 to 85, indicating that these strains may require a more stringent interaction for infection to proceed.
Effects of Type I Interferons on Friend Retrovirus Infection
Authors: Gerlach Nicole , Schimmer Simone , Weiss Siegfried , Kalinke Ulrich , Dittmer Ulf 
Published: March 2006

ABSTRACT

The type I interferon (IFN) response plays an important role in the control of many viral infections. However, since there is no rodent animal model for human immunodeficiency virus, the antiviral effect of IFN-α and IFN-β in retroviral infections is not well characterized. In the current study we have used the Friend virus (FV) model to determine the activity of type I interferons against a murine retrovirus. After FV infection of mice, IFN-α and IFN-β could be measured between 12 and 48 h in the serum. The important role of type I IFN in the early immune defense against FV became evident when mice deficient in IFN type I receptor (IFNAR
−/−
) or IFN-β (IFN-β
−/−
) were infected. The levels of FV infection in plasma and in spleen were higher in both strains of knockout mice than in C57BL/6 wild-type mice. This difference was induced by an antiviral effect of IFN-α and IFN-β and was most likely mediated by antiviral enzymes as well as by an effect of these IFNs on T-cell responses. Interestingly, the lack of IFNAR and IFN-β enhanced viral loads during acute and chronic FV infection. Exogenous IFN-α could be used therapeutically to reduce FV replication during acute but not chronic infection. These findings indicate that type I IFN plays an important role in the immediate antiviral defense against Friend retrovirus infection.
Downregulation of Varicella-Zoster Virus (VZV) Immediate-Early ORF62 Transcription by VZV ORF63 Correlates with Virus Replication In Vitro and with Latency
Authors: Hoover Susan E. , Cohrs Randall J. , Rangel Zoila G. , Gilden Donald H. , Munson Peter , Cohen Jeffrey I. 
Published: March 2006

ABSTRACTVaricella-zoster virus (VZV) open reading frame 63 (ORF63) protein is expressed during latency in human sensory ganglia. Deletion of ORF63 impairs virus replication in cell culture and establishment of latency in cotton rats. We found that cells infected with a VZV ORF63 deletion mutant yielded low titers of cell-free virus and produced very few enveloped virions detectable by electron microscopy compared with those infected with parental virus. Microarray analysis of cells infected with a recombinant adenovirus expressing ORF63 showed that transcription of few human genes was affected by ORF63; a heat shock 70-kDa protein gene was downregulated, and several histone genes were upregulated. In experiments using VZV transcription arrays, deletion of ORF63 from VZV resulted in a fourfold increase in expression of ORF62, the major viral transcriptional activator. A threefold increase in ORF62 protein was observed in cells infected with the ORF63 deletion mutant compared with those infected with parental virus. Cells infected with ORF63 mutants impaired for replication and latency (J. I. Cohen, T. Krogmann, S. Bontems, C. Sadzot-Delvaux, and L. Pesnicak, J. Virol.79:5069-5077, 2005) showed an increase in ORF62 transcription compared with those infected with parental virus. In contrast, cells infected with an ORF63 mutant that is not impaired for replication or latency showed ORF62 RNA levels equivalent to those in cells infected with parental virus. The ability of ORF63 to downregulate ORF62 transcription may play an important role in virus replication and latency.
Human T-Lymphotropic Virus Type 1 Mitochondrion-Localizing Protein p13
II
Is Required for Viral Infectivity In Vivo
Authors: Hiraragi Hajime , Kim Seung-Jae , Phipps Andrew J. , Silic-Benussi Micol , Ciminale Vincenzo , Ratner Lee , Green Patrick L. , Lairmore Michael D. 
Published: March 2006

ABSTRACT

Human T-lymphotropic virus type 1 (HTLV-1), the etiological agent of adult T-cell leukemia, encodes unique regulatory and accessory proteins in the pX region of the provirus, including the open reading frame II product p13
II
. p13
II
localizes to mitochondria, binds farnesyl pyrophosphate synthetase, an enzyme involved in posttranslational farnesylation of Ras, and alters Ras-dependent cell signaling and control of apoptosis. The role of p13
II
in virus infection in vivo remains undetermined. Herein, we analyzed the functional significance of p13
II
in HTLV-1 infection. We compared the infectivity of a human B-cell line that harbors an infectious molecular clone of HTLV-1 with a selective mutation that prevents the translation of p13
II
(729.ACH.p13) to the infectivity of a wild-type HTLV-1-expressing cell line (729.ACH). 729.ACH and 729.ACH.p13 producer lines had comparable infectivities for cultured rabbit peripheral blood mononuclear cells (PBMC), and the fidelity of the start codon mutation in ACH.p13 was maintained after PBMC passage. In contrast, zero of six rabbits inoculated with 729.ACH.p13 cells failed to establish viral infection, whereas six of six rabbits inoculated with wild-type HTLV-1-expressing cells (729.ACH) were infected as measured by antibody responses, proviral load, and HTLV-1 p19 matrix antigen production from ex vivo-cultured PBMC. Our data are the first to indicate that the HTLV-1 mitochondrion-localizing protein p13
II
has an essential biological role during the early phase of virus infection in vivo.
Measles Virus Targets DC-SIGN To Enhance Dendritic Cell Infection
Authors: de Witte Lot , Abt Marion , Schneider-Schaulies Sibylle , van Kooyk Yvette , Geijtenbeek Teunis B. H. 
Published: March 2006

ABSTRACT

Dendritic cells (DCs) are involved in the pathogenesis of measles virus (MV) infection by inducing immune suppression and possibly spreading the virus from the respiratory tract to lymphatic tissues. It is becoming evident that DC function can be modulated by the involvement of different receptors in pathogen interaction. Therefore, we have investigated the relative contributions of different MV-specific receptors on DCs to MV uptake into and infection of these cells. DCs express the MV receptors CD46 and CD150, and we demonstrate that the C-type lectin DC-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) is a novel receptor for laboratory-adapted and wild-type MV strains. The ligands for DC-SIGN are both MV glycoproteins F and H. In contrast to CD46 and CD150, DC-SIGN does not support MV entry, since DC-SIGN does not confer susceptibility when stably expressed in CHO cells. However, DC-SIGN is important for the infection of immature DCs with MV, since both attachment and infection of immature DCs with MV are blocked in the presence of DC-SIGN inhibitors. Our data demonstrate that DC-SIGN is crucial as an attachment receptor to enhance CD46/CD150-mediated infection of DCs in
cis
. Moreover, MV might not only target DC-SIGN to infect DCs but may also use DC-SIGN for viral transmission and immune suppression.
Porcine Circovirus 2 Uses Heparan Sulfate and Chondroitin Sulfate B Glycosaminoglycans as Receptors for Its Attachment to Host Cells
Authors: Misinzo Gerald , Delputte Peter L. , Meerts Peter , Lefebvre David J. , Nauwynck Hans J. 
Published: March 2006

ABSTRACT
Monocyte/macrophage lineage cells are target cells in vivo for porcine circovirus 2 (PCV2) replication. The porcine monocytic cell line 3D4/31 supports PCV2 replication in vitro, and attachment and internalization kinetics of PCV2 have been established in these cells. However, PCV2 receptors remain unknown. Glycosaminoglycans (GAG) are used by several viruses as receptors. The present study examined the role of GAG in attachment and infection of PCV2. Heparin, heparan sulfate (HS), chondroitin sulfate B (CS-B), but not CS-A, and keratan sulfate reduced PCV2 infection when these GAG were incubated with PCV2 prior to and during inoculation of 3D4/31 cells. Enzymatic removal of HS and CS-B prior to PCV2 inoculation of 3D4/31 cells significantly reduced PCV2 infection. Similarly, when PCV2 virus-like particles (VLP) were allowed to bind onto 3D4/31 cells in the presence of heparin and CS-B, attachment was strongly reduced. Titration of field isolates and low- and high-passage laboratory strains of PCV2 in the presence of heparin significantly reduced PCV2 titers, showing that the capacity of PCV2 to bind GAG was not acquired during in vitro cultivation but is an intrinsic feature of wild-type virus. When Chinese hamster ovary (CHO) cells were inoculated with PCV2, relative percentages of PCV2-infected cells were 27% ± 8% for HS-deficient and 12% ± 10% for GAG-deficient cells compared to wild-type cells (100%). Furthermore, it was shown using heparin-Sepharose chromatography that both PCV2 and PCV2 VLP directly interacted with heparin. Together, these results show that HS and CS-B are attachment receptors for PCV2.
Expression of the Interleukin-7 Receptor Alpha Chain (CD127) on Virus-Specific CD8
+
T Cells Identifies Functionally and Phenotypically Defined Memory T Cells during Acute Resolving Hepatitis B Virus Infection
Authors: Boettler Tobias , Panther Elisabeth , Bengsch Bertram , Nazarova Natalja , Spangenberg Hans Christian , Blum Hubert E. , Thimme Robert 
Published: March 2006

ABSTRACT

Virus-specific CD8
+
T cells play a central role in the outcome of several viral infections, including hepatitis B virus (HBV) infection. A key feature of virus-specific CD8
+
T cells is the development of memory. The mechanisms resulting in the establishment of T-cell memory are still only poorly understood. It has been suggested that T-cell memory may depend on the survival of virus-specific CD8
+
T cells in the contraction phase. Indeed, a population of effector cells that express high levels of the interleukin-7 receptor alpha chain (CD127) as the precursors of memory CD8
+
T cells has recently been identified in mice. However, very little information is currently available about the kinetics of CD127 expression in an acute resolving viral infection in humans and its association with disease pathogenesis, viral load, and functional and phenotypical T-cell characteristics. To address these important issues, we analyzed the HBV-specific CD8
+
T-cell response longitudinally in a cohort of six patients with acute HBV infection who spontaneously cleared the virus. We observed the emergence of CD127 expression on antigen-specific CD8
+
memory T cells during the course of infection. Importantly, the up-regulation of CD127 correlated phenotypically with a loss of CD38 and PD-1 expression and acquisition of CCR7 expression: functionally with an enhanced proliferative capacity and clinically with the decline in serum alanine aminotransferase levels and viral clearance. These results suggest that the expression of CD127 is a marker for the development of functionally and phenotypically defined antigen-specific CD8
+
memory T cells in cleared human viral infections.
UL26-Deficient Human Cytomegalovirus Produces Virions with Hypophosphorylated pp28 Tegument Protein That Is Unstable within Newly Infected Cells
Authors: Munger Joshua , Yu Dong , Shenk Thomas 
Published: March 2006

ABSTRACT
The human cytomegalovirus UL26 open reading frame encodes proteins of 21 and 27 kDa that result from the use of two different in-frame initiation codons. The UL26 protein is a constituent of the virion and thus is delivered to cells upon viral entry. We have characterized a mutant of human cytomegalovirus in which the UL26 open reading frame has been deleted. The UL26 deletion mutant has a profound growth defect, the magnitude of which is dependent on the multiplicity of infection. Two very early defects were discovered. First, even though they were present in normal amounts within mutant virions, the UL99-coded pp28 and UL83-coded pp65 tegument proteins were present in reduced amounts at the earliest times assayed within newly infected cells; second, there was a delay in immediate-early mRNA and protein accumulation. Further analysis revealed that although wild-type levels of the pp28 tegument protein were present in UL26 deletion mutant virions, the protein was hypophosphorylated. We conclude that the UL26 protein influences the normal phosphorylation of at least pp28 in virions and possibly additional tegument proteins. We propose that the hypophosphorylation of tegument proteins causes their destabilization within newly infected cells, perhaps disrupting the normal detegumentation process and leading to a delay in the onset of immediate-early gene expression.
ICP27 Interacts with the C-Terminal Domain of RNA Polymerase II and Facilitates Its Recruitment to Herpes Simplex Virus 1 Transcription Sites, Where It Undergoes Proteasomal Degradation during Infection
Authors: Dai-Ju Jenny Q. , Li Ling , Johnson Lisa A. , Sandri-Goldin Rozanne M. 
Published: March 2006

ABSTRACT
Herpes simplex virus 1 (HSV-1) ICP27 has been shown to interact with RNA polymerase II (RNAP II) holoenzyme. Here, we show that ICP27 interacts with the C-terminal domain (CTD) of RNAP II and that ICP27 mutants that cannot interact fail to relocalize RNAP II to viral transcription sites, suggesting a role for ICP27 in RNAP II recruitment. Using monoclonal antibodies specific for different phosphorylated forms of the RNAP II CTD, we found that the serine-2 phosphorylated form, which is found predominantly in elongating complexes, was not recruited to viral transcription sites. Further, there was an overall reduction in phosphoserine-2 staining. Western blot analysis revealed that there was a pronounced decrease in the phosphoserine-2 form and in overall RNAP II levels in lysates from cells infected with wild-type HSV-1. There was no appreciable difference in cdk9 levels, suggesting that protein degradation rather than dephosphorylation was occurring. Treatment of infected cells with proteasome inhibitors MG-132 and lactacystin prevented the decrease in the phosphoserine-2 form and in overall RNAP II levels; however, there was a concomitant decrease in the levels of several HSV-1 late proteins and in virus yield. Proteasomal degradation has been shown to resolve stalled RNAP II complexes at sites of DNA damage to allow 3′ processing of transcripts. Thus, we propose that at later times of infection when robust transcription and DNA replication are occurring, elongating complexes may collide and proteasomal degradation may be required for resolution.
Fitness Cost of Escape Mutations in p24 Gag in Association with Control of Human Immunodeficiency Virus Type 1
Authors: Martinez-Picado Javier , Prado Julia G. , Fry Elizabeth E. , Pfafferott Katja , Leslie Alasdair , Chetty Senica , Thobakgale Christina , Honeyborne Isobel , Crawford Hayley , Matthews Philippa , Pillay Tilly , Rousseau Christine , Mullins James I. , Brander Christian , Walker Bruce D. , Stuart David I. , Kiepiela Photini , Goulder Philip 
Published: March 2006

ABSTRACT

Mutational escape by human immunodeficiency virus (HIV) from cytotoxic T-lymphocyte (CTL) recognition is a major challenge for vaccine design. However, recent studies suggest that CTL escape may carry a sufficient cost to viral replicative capacity to facilitate subsequent immune control of a now attenuated virus. In order to examine how limitations can be imposed on viral escape, the epitope TSTLQEQIGW (TW10 [Gag residues 240 to 249]), presented by two HLA alleles associated with effective control of HIV, HLA-B*57 and -B*5801, was investigated. The in vitro experiments described here demonstrate that the dominant TW10 escape mutation, T242N, reduces viral replicative capacity. Structural analysis reveals that T242 plays a critical role in defining the start point and in stabilizing helix 6 within p24 Gag, ensuring that escape occurs at a significant cost. A very similar role is played by Thr-180, which is also an escape residue, but within a second p24 Gag epitope associated with immune control. Analysis of HIV type 1
gag
in 206 B*57/5801-positive subjects reveals three principle alternative TW10-associated variants, and each is strongly linked to concomitant additional variants within p24 Gag, suggesting that functional constraints operate against their occurrence alone. The extreme conservation of p24 Gag and the predictable nature of escape variation resulting from these tight functional constraints indicate that p24 Gag may be a critical immunogen in vaccine design and suggest novel vaccination strategies to limit viral escape options from such epitopes.