bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth Transformation of Human T Cells by Herpesvirus Saimiri Requires Multiple Tip-Lck Interaction Motifs
Authors: Heck Elke , Friedrich Ute , Gack Michaela U. , Lengenfelder Doris , Schmidt Monika , Müller-Fleckenstein Ingrid , Fleckenstein Bernhard , Ensser Armin , Biesinger Brigitte 
Published: September 2006

ABSTRACTLymphoma induction and T-cell transformation by herpesvirus saimiri strain C488 depends on two viral oncoproteins, StpC and Tip. The major interaction partner of Tip is the protein tyrosine kinase Lck, a key regulator of T-cell activation. The Lck binding domain (LBD) of Tip comprises two interaction motifs, a proline-rich SH3 domain-binding sequence (SH3B) and a region with homology to the C terminus of Src family kinase domains (CSKH). In addition, biophysical binding analyses with purified Lck-SH2 domain suggest the phosphorylated tyrosine residue 127 of Tip (pY127) as a potential third Lck interaction site. Here, we addressed the relevance of the individual binding motifs, SH3B, CSKH, and pY127, for Tip-Lck interaction and for human T-cell transformation. Both motifs within the LBD displayed Lck binding activities and cooperated to achieve a highly efficient interaction, while pY127, the major tyrosine phosphorylation site of Tip, did not enhance Lck binding in T cells. Herpesvirus saimiri strain C488 recombinants lacking one or both LBD motifs of Tip lost their transforming potential on human cord blood lymphocytes. Recombinant virus expressing Tip with a mutation at position Y127 was still able to transform human T lymphocytes but, in contrast to wild-type virus, was strictly dependent on exogenous interleukin-2. Thus, the strong Lck binding mediated by cooperation of both LBD motifs was essential for the transformation of human T cells by herpesvirus saimiri C488. The major tyrosine phosphorylation site Y127 of Tip was particularly required for transformation in the absence of exogenous interleukin-2, suggesting its involvement in cytokine signaling pathways.
Isolation and Characterization of an Infectious Replication-Competent Molecular Clone of Ecotropic Porcine Endogenous Retrovirus Class C
Authors: Preuss Thomas , Fischer Nicole , Boller Klaus , Tönjes Ralf R. 
Published: September 2006

ABSTRACT

Xenotransplantation of pig organs is complicated by the existence of polytropic replication-competent porcine endogenous retroviruses (PERV) capable of infecting human cells. The potential for recombination between ecotropic PERV-C and human-tropic PERV-A and PERV-B adds another level of infectious risk. Proviral PERV-C were characterized in MAX-T cells derived from
d
/
d
haplotype miniature swine. Three proviruses were cloned from a genomic library. Clone PERV-C(1312) generated infectious particles after transfection into porcine ST-IOWA cells. Electron microscopy revealed the same morphologies of virions in MAX-T cells and in ST-IOWA cells infected with cell-free PERV-C(1312) particles, indicating that MAX-T cells harbor one functional PERV-C provirus.
Packaging of Brome Mosaic Virus Subgenomic RNA Is Functionally Coupled to Replication-Dependent Transcription and Translation of Coat Protein
Authors: Annamalai Padmanaban , Rao A. L. N. 
Published: September 2006

ABSTRACT

In
Brome mosaic virus
(BMV), genomic RNA1 (gB1) and RNA2 (gB2), encoding the replication factors, are packaged into two separate virions, whereas genomic RNA3 (gB3) and its subgenomic coat protein (CP) mRNA (sgB4) are copackaged into a third virion. In vitro assembly assays performed between a series of deletion variants of sgB4 and wild-type (wt) CP subunits demonstrated that packaging of sgB4 is independent of sequences encoding the CP open reading frame. To confirm these observations in vivo and to unravel the mechanism of sgB4 copackaging, an
Agrobacterium
-mediated transient in vivo expression system (P. Annamalai and A. L. N. Rao, Virology
338:
96-111, 2005) that effectively uncouples replication from packaging was used. Cultures of agrotransformants, engineered to express sgB4 and CP subunits either transiently (sgB4
Trans
and CP
Trans
) or in replication-dependent transcription and translation when complemented with gB1 and gB2 (sgB4
Rep
and CP
Rep
), were mixed in all four pair-wise combinations and infiltrated to
Nicotiana benthamiana
leaves to systematically evaluate requirements regulating sgB4 packaging. The data revealed that (i) in the absence of replication, packaging was nonspecific, since transiently expressed CP subunits efficiently packaged ubiquitous cellular RNA as well as transiently expressed sgB4 and its deletion variants; (ii) induction of viral replication increased specificity of RNA packaging; and most importantly, (iii) efficient packaging of sgB4, reminiscent of the wt scenario, is functionally coupled not only to its transcription via replication but also to translation of CP from replication-derived mRNA, a mechanism that appears to be conserved among positive-strand RNA viruses of plants (this study), animals (flock house virus), and humans (poliovirus).
Rabies Virus Infection of Primary Neuronal Cultures and Adult Mice: Failure To Demonstrate Evidence of Excitotoxicity
Authors: Weli Simon C. , Scott Courtney A. , Ward Christopher A. , Jackson Alan C. 
Published: September 2006

ABSTRACT

Cultures derived from the cerebral cortices and hippocampi of 17-day-old mouse fetuses infected with the CVS strain of rabies virus showed loss of trypan blue exclusion, morphological apoptotic features, and activated caspase 3 expression, indicating apoptosis. The NMDA (
N
-methyl-
d
-aspartate acid) antagonists ketamine (125 μM) and MK-801 (60 μM) were found to have no significant neuroprotective effect on CVS-infected neurons, while the caspase inhibitor Ac-Asp-Glu-Val aspartic acid aldehyde (25 μM) exerted a marked neuroprotective effect. Glutamate-stimulated increases in levels of intracellular calcium were reduced in CVS-infected hippocampal neurons. Ketamine (120 mg/kg of body weight/day intraperitoneally) given to CVS-infected adult mice produced no beneficial effects. We have found no supportive evidence that excitotoxicity plays an important role in rabies virus infection.
Autorepression of the Human Cytomegalovirus Major Immediate-Early Promoter/Enhancer at Late Times of Infection Is Mediated by the Recruitment of Chromatin Remodeling Enzymes by IE86
Authors: Reeves Matthew , Murphy Jane , Greaves Richard , Fairley Jennifer , Brehm Alex , Sinclair John 
Published: September 2006

ABSTRACTThe human cytomegalovirus major immediate-early protein IE86 is pivotal for coordinated regulation of viral gene expression throughout infection. A relatively promiscuous transactivator of viral early and late gene transcription, IE86 also acts during infection to negatively regulate its own promoter via direct binding to a 14-bp palindromic IE86-binding site, thecisrepression sequence (crs), located between the major immediate-early promoter (MIEP) TATA box and the start of transcription. Although such autoregulation does not involve changes in the binding of basal transcription factors to the MIEP in vitro, it does appear to involve selective inhibition of RNA polymerase II recruitment. However, how this occurs is unclear. We show that autorepression by IE86 at late times of infection correlates with changes in chromatin structure around the MIEP during the course of infection and that this is likely to result from physical and functional interactions between IE86 and chromatin remodeling enzymes normally associated with transcriptional repression of cellular promoters. Firstly, we show that IE86-mediated autorepression is inhibited by histone deacetylase inhibitors. We also show that IE86 interacts, in vitro and in vivo, with the histone deacetylase HDAC1 and histone methyltransferases G9a and Suvar(3-9)H1 and that coexpression of these chromatin remodeling enzymes with IE86 increases autorepression of the MIEP. Finally, we show that mutation of the crs in the context of the virus abrogates the transcriptionally repressive chromatin phenotype normally found around the MIEP at late times of infection, suggesting that negative autoregulation by IE86 results, at least in part, from IE86-mediated changes in chromatin structure of the viral MIEP.
Repression of HMGA2 Gene Expression by Human Cytomegalovirus Involves the IE2 86-Kilodalton Protein and Is Necessary for Efficient Viral Replication and Inhibition of Cyclin A Transcription
Authors: Shlapobersky Mark , Sanders Rebecca , Clark Charles , Spector Deborah H. 
Published: September 2006

ABSTRACTHuman cytomegalovirus (HCMV) infection results in dysregulation of several cell cycle genes, including inhibition of cyclin A transcription. In this work, we examine the effect of the HCMV infection on expression of the high-mobility group A2 (HMGA2) gene, which encodes an architectural transcription factor that is involved in cyclin A promoter activation. We find that expression of HMGA2 RNA is repressed in infected cells. To determine whether repression of HMGA2 is directly related to the inhibition of cyclin A expression and impacts on the progression of the infection, we constructed an HCMV recombinant that expressed HMGA2. In cells infected with the recombinant virus, cyclin A mRNA and protein are induced, and there is a significant delay in viral early gene expression and DNA replication. To determine the mechanism of HMGA2 repression, we used recombinant viruses that expressed either no IE1 72-kDa protein (CR208) or greatly reduced levels of IE2 86-kDa (IE2 86) protein (IE2 86ΔSX-EGFP). At a high multiplicity of infection, the IE1 deletion mutant is comparable to the wild type with respect to inhibition of HMGA2. In contrast, the IE2 86ΔSX-EGFP mutant does not significantly repress HMGA2 expression, suggesting that IE2 86 is involved in the regulation of this gene. Cyclin A expression is also induced in cells infected with this mutant virus. Since HMGA2 is important for cell proliferation and differentiation, particularly during embryogenesis, it is possible that the repression of HMGA2 expression during fetal development could contribute to the specific birth defects in HCMV-infected neonates.
Characterization of a Novel Transferable CRM-1-Independent Nuclear Export Signal in a Herpesvirus Tegument Protein That Shuttles between the Nucleus and Cytoplasm
Authors: Verhagen Janneke , Donnelly Michelle , Elliott Gillian 
Published: September 2006

ABSTRACT
A new group of nucleocytoplasmic shuttling proteins has recently been identified in the structural proteins encoded by several alphaherpesvirus UL47 genes. Nuclear import and export signals for the bovine herpesvirus type 1 UL47 protein (VP8 or bUL47) have been described previously. Here, we study the trafficking of bUL47 in detail and identify an import signal different from that shown before. It comprises a 20-residue N-terminal peptide that is fully transferable and targets a large, normally cytosolic protein to the nucleus. A conserved RRPRRS motif within this peptide was shown to be essential but not sufficient for nuclear targeting. Using interspecies heterokaryon assays, we further demonstrate that the export activity of the published leucine-rich nuclear export signal (NES) is also transferable to a large protein but is functionally weak compared to the activity of the HIV-1 Rev NES. We show that nuclear export dictated by this bUL47 NES is sensitive to leptomycin B (LMB) and therefore dependent on the export receptor CRM-1. However, nuclear export of full-length bUL47 is fully resistant to LMB, suggesting the presence of an additional NES. We go on to identify a second NES in bUL47 within a 28-residue peptide that is in close proximity to but entirely separable from the N-terminal import signal, and we use fluorescence loss in photobleaching to confirm its activity. This NES is resistant to leptomycin B, and therefore utilizes an export receptor other than CRM-1. As this new sequence bears little similarity to other export signals so far defined, we suggest it may be involved in bUL47 export from the nucleus via a novel cellular receptor.
Differential Signaling Networks Induced by Mild and Lethal Hemorrhagic Fever Virus Infections
Authors: Bowick Gavin C. , Fennewald Susan M. , Elsom Barry L. , Aronson Judith F. , Luxon Bruce A. , Gorenstein David G. , Herzog Norbert K. 
Published: September 2006

ABSTRACT

The family
Arenaviridae
includes several National Institutes of Allergy and Infections Diseases category A select agents which cause hemorrhagic fever. There are few vaccines available, and treatment is limited to ribavirin, which varies in efficacy. Development of new antiviral compounds has been hindered by a lack of understanding of the molecular basis of pathogenesis. We used two variants of Pichinde virus, one attenuated and one virulent in the guinea pig model, to delineate the host determinants which lead to either viral clearance or lethal disease. By analyzing protein level changes using pathway analysis, we have identified key intermediates which may be targets for therapeutic intervention.
CD127+CCR5+CD38+++CD4+Th1 Effector Cells Are an Early Component of the Primary Immune Response to Vaccinia Virus and Precede Development of Interleukin-2+Memory CD4+T Cells
Authors: Zaunders John J. , Dyer Wayne B. , Munier Mee Ling , Ip Susanna , Liu Jie , Amyes Elisabeth , Rawlinson William , De Rose Robert , Kent Stephen J. , Sullivan John S. , Cooper David A. , Kelleher Anthony D. 
Published: September 2006

ABSTRACTThe stages of development of human antigen-specific CD4+T cells responding to viral infection and their differentiation into long-term memory cells are not well understood. The inoculation of healthy adults with vaccinia virus presents an opportunity to study these events intensively. Between days 11 and 14 postinoculation, there was a peak of proliferating CCR5+CD38+++CD4+effector cells which contained the cytotoxic granule marker T-cell intracellular antigen 1 and included gamma interferon (IFN-γ)-producing vaccinia virus-specific CD4+T cells. The majority of these initial vaccinia virus-specific CD4+T cells were CD127+and produced interleukin-2 (IL-2) but not CTLA-4 in response to restimulation in vitro. Between days 14 and 21, there was a switch from IFN-γ and IL-2 coexpression to IL-2 production only, coinciding with a resting phenotype and an increased in vitro proliferation response. The early CCR5+CD38+++vaccinia virus-specific CD4+T cells were similar to our previous observations of human immunodeficiency virus (HIV)-specific CD4+T cells in primary HIV type 1 (HIV-1) infection, but the vaccinia virus-specific cells expressed much more CD127 and IL-2 than we previously found in their HIV-specific counterparts. The current study provides important information on the differentiation of IL-2+vaccinia virus-specific memory cells, allowing further study of antiviral effector CD4+T cells in healthy adults and their dysfunction in HIV-1 infection.
Time-optimal Trajectories for an Omni-directional Vehicle
Authors: Balkcom Devin J. , Kavathekar Paritosh A. , Mason Matthew T. 
Published: September 2006

A common mobile robot design consists of three ‘omniwheels’ arranged at the vertices of an equilateral triangle, with wheel axles aligned with the rays from the center of the triangle to each wheel. Omniwheels, like standard wheels, are driven by the motors in a direction perpendicular to the wheel axle, but unlike standard wheels, can slip in a direction parallel to the axle. Unlike a steered car, a vehicle with this design can move in any direction without needing to rotate first, and can spin as it does so. The shortest paths for this vehicle are straight lines. However, the vehicle can move more quickly in some directions than in others. What are the fastest trajectories? We consider a kinematic model of the vehicle and place independent bounds on the speeds of the wheels, but do not consider dynamics or bound accelerations. We derive the analytical fastest trajectories between configurations. The time-optimal trajectories contain only spins in place, circular arcs, and straight lines parallel to the wheel axles. We classify optimal trajectories by the order and type of the segments; there are four such classes, and there are no more than 18 control switches in any optimal trajectory.
The PVT, an Elastic Conservative Transmission
Authors: Ingvast Johan , Wikander Jan , Ridderström Christian 
Published: September 2006

This paper presents an innovative transmission called the passively variable transmission (PVT) that has a high torque ratio for large loads and a low velocity ratio for small loads. The change in these ratios depends passively on the load, in contrast to the continuous variable transmission (CVT), where the transmission ratio is controlled explicitly. Another difference from the CVT is that the PVT is elastic and the term transmission ratio is therefore not applicable. A theory section formulates alternative ways of describing the torque and velocity relations for elastic conservative transmisions as well as other important properties. This theory is used to analyze and illustrate the characteristics of a PVT. The theory is also used to compare the PVT with another novel elastic conservative transmission, called load sensitive CVT. The nonlinearities and elasticity of the PVT make it difficult to control using linear control theory. Feedback linearization was therefore used to design a torque controller, and experimental results show low impedance at small loads. Further, the controller tracks a reference torque well as long as the reference rate does not cause motor saturation. The abilities of the PVT are also illustrated by comparing it with an actuator having a traditional transmission. The load case is recorded joint torques and angles from the carpus joint of a walking horse. Simulation show that the required peak power is reduced by more than 20% and the product of the maximum torque and the maximum angular velocity is reduced by approximately 30%.
Enhancing Flame-resistance and Antibacterial Properties of Cotton Fabric
Authors: Gouda M. 
Published: September 2006

The main purpose of this work is to enhance the flame resistance and antibacterial properties of cotton fabric via treatment with carbamoylguanidine phosphate using the pad-dry technique followed by after treatment with some transition metal chlorides. The effects of pH, curing conditions, and carbamoylguanidine phosphate on the extent of modification are evaluated. Analyses of the data reveal that: I. the limiting oxygen index of the treated fabric samples follows a decreasing order: carbamoylguanidine phosphate-Al complex4carbamoylguanidine phosphate4carbamoylguanidine phosphate-Ni complex4carbamoylguanidine phosphate-Cu complex, II. antibacterial properties of the treated cotton fabric samples follow a decreasing order: carbamoylguanidine phosphate-Cu complex4carbamoylguanidine phosphate-Ni complex4carbamoylguanidine phosphate-Al complex4carbamoylguanidine phosphate, and III. such finished fabrics show high durability to washing.
Early FDG-PET assessment in combination with clinical risk scores determines prognosis in recurring lymphoma
Authors: Schot Bart W. , Zijlstra Josée M. , Sluiter Wim J. , van Imhoff Gustaaf W. , Pruim Jan , Vaalburg Willem , Vellenga Edo 
Published: September 2006

Abstract
This study was set up to demonstrate whether prognostic classification based on the secondary age-adjusted International Prognostic Index (sAA-IPI) for recurring aggressive non-Hodgkin lymphoma (NHL) or the prognostic score for recurring Hodgkin lymphoma (HL) can be improved by including the midtreatment results of fluorine-18-fluorodeoxy-glucose–positron emission tomography (FDG-PET). Clinical data on patients with recurring lymphoma who were treated with second-line chemotherapy (DHAP-VIM-DHAP) followed by autologous stem cell transplantation (ASCT) were collected and combined with the results of FDG-PET performed before and after 2 cycles of reinduction chemotherapy. PET responses after 2 courses were scored as complete remission (CR), partial remission (PR), or no response (NR). A multivariate analysis was performed to design a predictive model. The number of patients (101 of 117) included those (78 patients with aggressive NHL and 23 patients with HL) that could be analyzed according to protocol. Of these, 80 patients were chemosensitive and 77 received transplants. Both secondary clinical risk score (P < .001) and FDG-PET response (P < .001) were independent predictive factors for the total evaluable group of patients with lymphoma and for patients with NHL alone. The combined use of the clinical risk score and FDG-PET response after 2 chemotherapy courses identified at least 4 categories of patients with a failure-free survival varying between 5% to 100% after transplantation (P < .001). These data indicate that the secondary clinical risk score in conjunction with FDG-PET response provides a more accurate prognostic instrument for the outcome of second-line treatment at least in patients with recurring NHL.
The THAP–zinc finger protein THAP1 regulates endothelial cell proliferation through modulation of pRB/E2F cell-cycle target genes
Authors: Cayrol Corinne , Lacroix Chrystelle , Mathe Catherine , Ecochard Vincent , Ceribelli Michele , Loreau Emilie , Lazar Vladimir , Dessen Philippe , Mantovani Roberto , Aguilar Luc , Girard Jean-Philippe 
Published: September 2006

AbstractWe recently cloned a novel human nuclear factor (designated THAP1) from postcapillary venule endothelial cells (ECs) that contains a DNA-binding THAP domain, shared with zebrafish E2F6 and several Caenorhabditis elegans proteins interacting genetically with retinoblastoma gene product (pRB). Here, we show that THAP1 is a physiologic regulator of EC proliferation and cell-cycle progression, 2 essential processes for angiogenesis. Retroviral-mediated gene transfer of THAP1 into primary human ECs inhibited proliferation, and large-scale expression profiling with microarrays revealed that THAP1-mediated growth inhibition is due to coordinated repression of pRB/E2F cell-cycle target genes. Silencing of endogenous THAP1 through RNA interference similarly inhibited EC proliferation and G1/S cell-cycle progression, and resulted in down-regulation of several pRB/E2F cell-cycle target genes, including RRM1, a gene required for S-phase DNA synthesis. Chromatin immunoprecipitation assays in proliferating ECs showed that endogenous THAP1 associates in vivo with a consensus THAP1-binding site found in the RRM1 promoter, indicating that RRM1 is a direct transcriptional target of THAP1. The similar phenotypes observed after THAP1 overexpression and silencing suggest that an optimal range of THAP1 expression is essential for EC proliferation. Together, these data provide the first links in mammals among THAP proteins, cell proliferation, and pRB/E2F cell-cycle pathways.