bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcription Program of Murine Gammaherpesvirus 68
Authors: Martinez-Guzman DeeAnn , Rickabaugh Tammy , Wu Ting-Ting , Brown Helen , Cole Steven , Song Moon Jung , Tong Leming , Sun Ren 
Published: September 2003

ABSTRACT
Murine gammaherpesvirus 68 (MHV-68 [also referred to as γHV68]) is phylogenetically related to Kaposi's sarcoma-associated herpesvirus (KSHV [also referred to as HHV-8]) and Epstein-Barr virus (EBV). However, unlike KSHV or EBV, MHV-68 readily infects fibroblast and epithelial cell lines derived from several mammalian species, providing a system to study productive and latent infections as well as reactivation of gammaherpesviruses in vivo and in vitro. To carry out rapid genome-wide analysis of MHV-68 gene expression, we made DNA arrays containing nearly all of the known and predicted open reading frames (ORFs) of the virus. RNA obtained from an MHV-68 latently infected cell line, from cells lytically infected with MHV-68 in culture, and from the lung tissue of infected mice was used to probe the MHV-68 arrays. Using a tightly latent B-cell line (S11E), the MHV-68 latent transcription program was quantitatively described. Using BHK-21 cells and infected mice, we demonstrated that latent genes are transcribed during lytic replication and are relatively independent of de novo protein synthesis. We determined that the transcription profiles at the peak of lytic gene expression are similar in cultured fibroblast and in the lung of infected mice. Finally, the MHV-68 DNA arrays were used to examine the gene expression profile of a recombinant virus that overexpresses replication and transcription activator (RTA), C-RTA/MHV-68, during lytic replication in cell culture. The recombinant virus replicates faster then the parental strain and the DNA arrays revealed that nearly every MHV-68 ORF examined was activated by RTA overexpression. Examination of the gene expression patterns of C-RTA/MHV-68 over a time course led to the finding that the M3 promoter is RTA responsive in the absence of other viral factors.
Evolutionary Pressure of a Receptor Competitor Selects Different Subgroup A Avian Leukosis Virus Escape Variants with Altered Receptor Interactions
Authors: Melder Deborah C. , Pankratz V. Shane , Federspiel Mark J. 
Published: September 2003

ABSTRACT

A complex interaction between the retroviral envelope glycoproteins and a specific cell surface protein initiates viral entry into cells. The avian leukosis-sarcoma virus (ALV) group of retroviruses provides a useful experimental system for studying the retroviral entry process and the evolution of receptor usage. In this study, we demonstrate that evolutionary pressure on subgroup A ALV [ALV(A)] entry exerted by the presence of a competitive inhibitor, a soluble form of the ALV(A) Tva receptor linked to a mouse immunoglobulin G tag (quail sTva-mIgG), can select different populations of escape variants. This escape population contained three abundant ALV(A) variant viruses, all with mutations in the surface glycoprotein hypervariable regions: a previously identified variant containing the Y142N mutation in the hr1 region; a new variant with two mutations, W141G in hr1 and K261E in vr3; and another new variant with two mutations, W145R in hr1 and K261E. The W141G K261E and W145R K261E viruses escape primarily by lowering their binding affinities for the quail Tva receptor competitive inhibitor while retaining wild-type levels of binding affinity for the chicken Tva receptor. A secondary phenotype of the new variants was an alteration in receptor interference patterns from that of wild-type ALV(A), indicating that the mutant glycoproteins are possibly interacting with other cellular proteins. One result of these altered interactions was that the variants caused a transient period of cytotoxicity. We could also directly demonstrate that the W141G K261E variant glycoproteins bound significant levels of a soluble form of the Tvb
S3
ALV receptor in a binding assay. Alterations in the normally extreme specificity of the ALV(A) glycoproteins for Tva may represent an evolutionary first step toward expanding viral receptor usage in response to inefficient viral entry.
Biochemical and Genetic Characterizations of a Novel Human Immunodeficiency Virus Type 1 Inhibitor That Blocks gp120-CD4 Interactions
Authors: Guo Qi , Ho Hsu-Tso , Dicker Ira , Fan Li , Zhou Nannan , Friborg Jacques , Wang Tao , McAuliffe Brian V. , Wang Hwei-gene Heidi , Rose Ronald E. , Fang Hua , Scarnati Helen T. , Langley David R. , Meanwell Nicholas A. , Abraham Ralph , Colonno Richard J. , Lin Pin-fang 
Published: September 2003

ABSTRACTBMS-378806 is a recently discovered small-molecule human immunodeficiency virus type 1 (HIV-1) attachment inhibitor with good antiviral activity and pharmacokinetic properties. Here, we demonstrate that the compound targets viral entry by inhibiting the binding of the HIV-1 envelope gp120 protein to cellular CD4 receptors via a specific and competitive mechanism. BMS-378806 binds directly to gp120 at a stoichiometry of approximately 1:1, with a binding affinity similar to that of soluble CD4. The potential BMS-378806 target site was localized to a specific region within the CD4 binding pocket of gp120 by using HIV-1 gp120 variants carrying either compound-selected resistant substitutions or gp120-CD4 contact site mutations. Mapping of resistance substitutions to the HIV-1 envelope, and the lack of compound activity against a CD4-independent viral infection confirm the gp120-CD4 interactions as the target in infected cells. BMS-378806 therefore serves as a prototype for this new class of antiretroviral agents and validates gp120 as a viable target for small-molecule inhibitors.
Glycoprotein of Nonpathogenic Rabies Viruses Is a Key Determinant of Human Cell Apoptosis
Authors: Préhaud Christophe , Lay Stéphanie , Dietzschold Bernhard , Lafon Monique 
Published: September 2003

ABSTRACTWe showed that, unlike pathogenic rabies virus (RV) strain CVS, attenuated RV strain ERA triggers the caspase-dependent apoptosis of human cells. Furthermore, we observed that the induction of apoptosis is correlated with a particular virus antigen distribution: the overexpression of the viral G protein on the cell surface, with continuous localization on the cytoplasmic membrane, and large cytoplasmic inclusions of the N protein. To determine whether one of these two major RV proteins (G and N proteins) triggers apoptosis, we constructed transgenic Jurkat T-cell lines that drive tetracycline-inducible gene expression to produce the G and N proteins of ERA and CVS individually. The induction of ERA G protein (G-ERA) expression but not of ERA N protein expression resulted in apoptosis, and G-ERA was more efficient at triggering apoptosis than was CVS G protein. To test whether other viral proteins participated in the induction of apoptosis, human cells were infected with recombinant RV in which the G protein gene from the attenuated strain had been replaced by its virulent strain counterpart (CVS). Only RV containing the G protein from the nonpathogenic RV strain was able to trigger the apoptosis of human cells. Thus, the ability of RV strains to induce apoptosis is largely determined by the viral G protein.
Direct Activation of Cyclin-Dependent Kinase 2 by Human Papillomavirus E7
Authors: He Wanxia , Staples Doug , Smith Clark , Fisher Chris 
Published: September 2003

ABSTRACT
Addition of human papillomavirus (HPV) E7 CDK2/cyclin A or CDK2/cyclin E, purified from either insect cells or bacteria, dramatically upregulates histone H1 kinase activity. Activation is substrate specific, with a smaller effect noted for retinoblastoma protein (Rb). The CDK2 stimulatory activity is equivalent in high-risk (HPV type 16 [HPV16] and HPV31) and low-risk (HPV6b) E7. Mutational analyses of HPV16 E7 indicate that the major activity resides in amino acids 9 to 38, spanning CR1 and CR2, and does not require casein kinase II or Rb-binding domain functions. Synthetic peptides spanning HPV16 amino acid residues 9 to 38 also activate CDK2. Peptides containing this sequence that carry biotin on the carboxy terminus, as well as a photoactivated cross-linking group (benzophenone), also activate the complex and covalently associate with the CDK2/cyclin A complex in a specific manner requiring UV. Cross-linking studies that use protein monomers detect association of the E7 peptides with cyclin A but not CDK2. Together, our results indicate a novel mechanism whereby E7 promotes HPV replication by directly altering CDK2 activity and substrate specificity.
Multiple Type A/B Heterogeneous Nuclear Ribonucleoproteins (hnRNPs) Can Replace hnRNP A1 in Mouse Hepatitis Virus RNA Synthesis
Authors: Shi Stephanie T. , Yu Guann-Yi , Lai Michael M. C. 
Published: September 2003

ABSTRACT
Heterogeneous nuclear ribonucleoprotein (hnRNP) A1 has previously been shown to bind mouse hepatitis virus (MHV) RNA at the 3′ end of both plus and minus strands and modulate MHV RNA synthesis. However, a mouse erythroleukemia cell line, CB3, does not express hnRNP A1 but still supports MHV replication, suggesting that alternative proteins can replace hnRNP A1 in cellular functions and viral infection. In this study, we set out to identify these proteins. UV cross-linking experiments revealed that several CB3 cellular proteins similar in size to hnRNP A1 interacted with the MHV RNA. These proteins were purified by RNA affinity column with biotinylated negative-strand MHV leader RNA and identified by mass spectrometry to be hnRNP A2/B1, hnRNP A/B, and hnRNP A3, all of which belong to the type A/B hnRNPs. All of these proteins contain amino acid sequences with strong similarity to the RNA-binding domains of hnRNP A1. Some of these hnRNPs have previously been shown to replace hnRNP A1 in regulating RNA splicing. These proteins displayed MHV RNA-binding affinity and specificity similar to those of hnRNP A1. hnRNP A2/B1, which is predominantly localized to the nucleus and shuttles between the nucleus and the cytoplasm, was shown to relocalize to the cytoplasm in MHV-infected CB3 cells. Furthermore, overexpression of hnRNP A/B in cells enhanced MHV RNA synthesis. Our findings demonstrate that the functions of hnRNP A1 in MHV RNA synthesis can be replaced by other closely related hnRNPs, further supporting the roles of cellular proteins in MHV RNA synthesis.
Differences in Virus-Induced Cell Morphology and in Virus Maturation between MVA and Other Strains (WR, Ankara, and NYCBH) of Vaccinia Virus in Infected Human Cells
Authors: Gallego-Gómez Juan Carlos , Risco Cristina , Rodríguez Dolores , Cabezas Pilar , Guerra Susana , Carrascosa José L. , Esteban Mariano 
Published: September 2003

ABSTRACT
Live recombinants based on attenuated modified vaccinia virus Ankara (MVA) are potential vaccine candidates against a broad spectrum of diseases and tumors. To better understand the efficacy of MVA as a human vaccine, we analyzed by confocal and electron microscopy approaches MVA-induced morphological changes and morphogenetic stages during infection of human HeLa cells in comparison to other strains of vaccinia virus (VV): the wild-type Western Reserve (WR), Ankara, and the New York City Board of Health (NYCBH) strains. Confocal microscopy studies revealed that MVA infection alters the cytoskeleton producing elongated cells (bipolar), which do not form the characteristic actin tails. Few virions are detected in the projections connecting neighboring cells. In contrast, cells infected with the WR, Ankara, and NYCBH strains exhibit a stellated (multipolar) or rounded morphology with actin tails. A detailed transmission electron microscopy analysis of HeLa cells infected with MVA showed important differences in fine ultrastructure and amounts of the viral intermediates compared to cells infected with the other VV strains. In HeLa cells infected with MVA, the most abundant viral forms are intracellular immature virus, with few intermediates reaching the intracellular mature virus (IMV) form, at various stages of maturation, which exhibit a more rounded shape than IMVs from cells infected with the other VV strains. The “IMVs” from MVA-infected cells have an abnormal internal structure (“atypical” viruses) with potential alterations in the core-envelope interactions and are unable to significantly acquire the additional double envelope to render intracellular envelope virus. The presence of potential cell-associated envelope virus is very scarce. Our findings revealed that MVA in human cells promotes characteristic morphological changes to the cells and is able to reach the IMV stage, but these virions were not structurally normal and the subsequent steps in the morphogenetic pathway are blocked.
Significance in Replication of the Terminal Nucleotides of the
Flavivirus
Genome
Authors: Khromykh Alexander A , Kondratieva Natasha , Sgro Jean-Yves , Palmenberg Ann , Westaway Edwin G 
Published: September 2003

ABSTRACT

Point mutations that resulted in a substitution of the conserved 3′-penultimate cytidine in genomic RNA or the RNA negative strand of the self-amplifying replicon of the
Flavivirus Kunjin virus
completely blocked in vivo replication. Similarly, substitutions of the conserved 3′-terminal uridine in the RNA negative or positive strand completely blocked replication or caused much-reduced replication, respectively. The same preference for cytidine in the 3′-terminal dinucleotide was noted in reports of the in vitro activity of the RNA-dependent RNA polymerase (RdRp) for the other genera of
Flaviviridae
that also employ a double-stranded RNA (dsRNA) template to initiate asymmetric semiconservative RNA positive-strand synthesis. The
Kunjin virus
replicon results were interpreted in the context of a proposed model for initiation of RNA synthesis based on the solved crystal structure of the RdRp of φ6 bacteriophage, which also replicates efficiently using a dsRNA template with conserved 3′-penultimate cytidines and a 3′-terminal pyrimidine. A previously untested substitution of the conserved pentanucleotide at the top of the 3′-terminal stem-loop of all
Flavivirus
species also blocked detectable in vivo replication of the
Kunjin virus
replicon RNA.
Cell-Derived Sequences in the N-Terminal Region of the Polyprotein of a Cytopathogenic Pestivirus
Authors: Müller A. , Rinck G. , Thiel H.-J. , Tautz N. 
Published: September 2003

ABSTRACTEfficient proteolytic release of nonstructural protein 3 (NS3) from the viral polyprotein is considered to be crucial for the cytopathogenicity of pestiviruses. Here we describe a novel cytopathogenic (cp) bovine viral diarrhea virus strain (BVDV CP8) with a complex insertion composed of viral and cell-derived sequences, including two fragments of the cellular J-domain protein Jiv (J-domain protein interacting with viral protein) located in the N-terminal region of the polyprotein. BVDV CP8 expresses a Jiv fusion protein of 513 amino acids in addition to a complete set of viral proteins. This protein has the capacity to induce NS2-3 cleavage intrans. Accordingly, CP8 is a representative of a novel type of cp pestivirus with a cp-specific mutation located outside of the NS2-3 gene.
CD81-Dependent Binding of Hepatitis C Virus E1E2 Heterodimers
Authors: Cocquerel Laurence , Kuo Chiung-Chi , Dubuisson Jean , Levy Shoshana 
Published: September 2003

ABSTRACTHepatitis C virus (HCV) is the leading cause of chronic liver disease worldwide. HCV is also the major cause of mixed cryoglobulinemia, a B-lymphocyte proliferative disorder. Direct experimentation with native viral proteins is not feasible. Truncated versions of recombinant E2 envelope proteins, used as surrogates for viral particles, were shown to bind specifically to human CD81. However, truncated E2 may not fully mimic the surface of HCV virions because the virus encodes two envelope glycoproteins that associate with each other as E1E2 heterodimers. Here we show that E1E2 complexes efficiently bind to CD81 whereas truncated E2 is a weak binder, suggesting that truncated E2 is probably not the best tool with which to study cellular interactions. To gain better insight into virus-cell interactions, we developed a method by which to isolate E1E2 complexes that are properly folded. We demonstrate that purified E1E2 heterodimers bind to cells in a CD81-dependent manner. Furthermore, engagement of B cells by purified E1E2 heterodimers results in their aggregation and in protein tyrosine phosphorylation, a hallmark of B-cell activation. These studies provide a possible clue to the etiology of HCV-associated B-cell lymphoproliferative diseases. They also delineate a method by which to isolate biologically functional E1E2 complexes for the study of virus-host cell interaction in other cell types.
Lassa Virus Z Protein Is a Matrix Protein Sufficient for the Release of Virus-Like Particles
Authors: Strecker Thomas , Eichler Robert , Meulen Jan ter , Weissenhorn Winfried , Dieter Klenk Hans , Garten Wolfgang , Lenz Oliver 
Published: September 2003

ABSTRACT
Lassa virus is an enveloped virus with glycoprotein spikes on its surface. It contains an RNA ambisense genome that encodes the glycoprotein precursor GP-C, the nucleoprotein NP, the polymerase L, and the Z protein. Here we demonstrate that the Lassa virus Z protein (i) is abundant in viral particles, (ii) is strongly membrane associated, (iii) is sufficient in the absence of all other viral proteins to release enveloped particles, and (iv) contains two late domains, PTAP and PPXY, necessary for the release of virus-like particles. Our data provide evidence that Z is the Lassa virus matrix protein that is the driving force for virus particle release.
Nietzsche and the Eternal Return of Sacrifice
Authors: Keenan Dennis King 
Published: September 2003

AbstractIn the work of Nietzsche, sacrifice can only sacrifice itself over and over (in an eternal return of the same) because what it seeks to overcome (the nihilistic revelation of truth that sublates sacrifice's negation) makes this sacrifice of itself both necessary and useless. The truth is eternally postponed in a necessary sacrificial gesture that can only sacrifice itself, thereby rendering itself useless. In the attempt to step beyond nihilism, that is, in the attempt to negate (or sacrifice) nihilism, one repeats the negation characteristic of nihilism. One becomes inextricably implicated in the move of nihilistic sacrifice. The sacrifice of the sacrifice characteristic of nihilism, that is, the sacrifice of sacrifice, can only take place as (perform itself as) the impossibility (or eternally postponed possibility) of its realization. One, therefore, produces or performs an interminable step/not beyond, an incessant step beyond that eternally returns.
Phenotypic identification of rat rostroventrolateral medullary presympathetic vasomotor neurons inhibited by exogenous cholecystokinin
Authors: Sartor Daniela M. , Verberne Anthony J.M. 
Published: September 2003

AbstractSystemic administration of the gastrointestinal hormone cholecystokinin (CCK) selectively inhibits splanchnic sympathetic vasomotor discharge and differentially affects presympathetic vasomotor neurons of the rostroventrolateral medulla (RVLM). Stimulation of the sympathoexcitatory region of the periaqueductal grey (PAG) produces profound mesenteric vasoconstriction. In this study, our aim was to identify phenotypically different populations of RVLM presympathetic vasomotor neurons using juxtacellular neuronal labelling and immunohistochemical detection of the adrenergic neuronal marker phenylethanolamine‐N‐methyl transferase (PNMT) and to determine whether the PAG provides functional excitatory input to these neurons. Fifty‐eight percent (36/62) of RVLM presympathetic neurons were inhibited by systemic administration of CCK. These cells had conduction velocities (3.6 ± 0.2 m/sec) in the non‐C‐fiber range consistent with neurons possessing lightly myelinated spinal axons. Of these, 79% (22/28) were excited by PAG stimulation, and 59% (10/17) were not immunoreactive for PNMT. Conversely, 42% (26/62) of RVLM presympathetic neurons were either unaffected or activated by CCK administration and had slower conduction velocities (1.4 ± 0.3 m/sec) than cells inhibited by CCK. Fifty percent (11/22) of these cells were driven by PAG stimulation, and most (11/14 or 79%) were PNMT‐positive. These results suggest that cardiovascular responses elicited by PAG stimulation occur via activation of non‐C1 and C1 RVLM presympathetic neurons. RVLM neurons inhibited by CCK were more likely to be driven by PAG stimulation and may be a subset of neurons responsible for driving gastrointestinal sympathetic vasomotor tone. CCK‐induced inhibition of a subpopulation of RVLM presympathetic neurons may be implicated in postprandial hyperemia and postprandial hypotension. J. Comp. Neurol. 465:467–479, 2003. © 2003 Wiley‐Liss, Inc.
Innervation of the heart of the adult fruit fly, Drosophila melanogaster
Authors: Dulcis Davide , Levine Richard B. 
Published: September 2003

AbstractThe innervation of the adult abdominal heart of Drosophila melanogaster was studied by neuronal staining with green fluorescent protein and immunocytochemical techniques. The investigation was undertaken to determine whether the adult heart receives neuronal input or whether its complex activity must be considered independent from the nervous system. The larval heart lacks innervation, suggesting that the cardiac impulse is totally myogenic. At metamorphosis, segmental neural processes grow onto the myocardium. A pair of transverse nerves innervates bilaterally each cardiac chamber and its alary muscles. These nerve terminals are immunoreactive to glutamate and form unique synaptic structures on the ventral layer of longitudinal cardiac muscles of the conical chamber. This characteristic cardiac synapse may represent part of the neural mechanism controlling the retrograde heartbeat, and, thus, the cardiac reversal that is characteristic of adults. In addition, crustacean cardioactive peptide–immunoreactive fibers originating from peripheral, bipolar neurons (BpNs) fasciculate with the transverse nerve projections and terminate segmentally throughout the abdominal heart. An additional cluster composed of four large, CCAP‐positive neurons innervates the terminal chamber. The cardioacceleratory effect of CCAP release at this location may modulate the properties of a pacemaker producing the anterograde heartbeat. J. Comp. Neurol. 465:560–578, 2003. © 2003 Wiley‐Liss, Inc.
Time‐Resolved Spectroscopic Study on Photoinduced Electron‐Transfer Processes in Zn(II)porphyrin–Zn(II)chlorin–Fullerene Triad
Authors: Ha Jeong‐Hyon , Cho Hyun Sun , Kim Dongho , Lee Jong‐Cheol , Kim Tae‐Young , Shim Young Key 
Published: September 2003

AbstractFemtosecond time‐resolved transient absorption studies have been performed to investigate the photoinduced energy and electron‐transfer processes in Zn(II)porphyrin–Zn(II)chlorin–fullerene triad in which energy and oxidation potential gradients are directed along the donor–acceptor‐linked arrays. Fast energy transfer (≈450 fs) from photoexcited Zn(II)porphyrin to Zn(II)chlorin was observed upon selective photoexcitation of Zn(II)porphyrin unit in the triad. In a nonpolar solvent such as toluene, the energy transfer from the excited singlet state of Zn(II)chlorin to fullerene occurs and is followed by the formation of an intermediate state with a time constant of nanoseconds, which was attributed to the intramolecular exciplex between Zn(II)chlorin and fullerene. In benzonitrile, on the other hand, the photoexcitation of the triad results in the fast electron transfer (<1 ps) from photoexcited Zn(II)chlorin to fullerene. The generated charge‐separated species recombine with a time constant of ≈12 ps. The relatively fast charge separation and charge recombination rates imply that the strong electronic coupling between Zn(II)chlorin and fullerene moieties is probably induced by the folded conformation between Zn(II)chlorin and fullerene moieties which enhances direct through‐space interaction between the proximately contacted π systems.