bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Putative Terminase Subunit of Herpes Simplex Virus 1 Encoded by U
L
28 Is Necessary and Sufficient To Mediate Interaction between pU
L
15 and pU
L
33
Authors: Yang Kui , Baines Joel D. 
Published: May 2006

ABSTRACT

Viral terminases play essential roles as components of molecular motors that package viral DNA into capsids. Previous results indicated that the putative terminase subunits of herpes simplex virus 1 (HSV-1) encoded by U
L
15 and U
L
28 (designated pU
L
15 and pU
L
28, respectively) coimmunoprecipitate with the U
L
33 protein from lysates of infected cells. All three proteins are among six required for HSV-1 DNA packaging but dispensable for assembly of immature capsids. The current results show that in both infected- and uninfected-cell lysates, pU
L
28 coimmunoprecipitates with either pU
L
33 or pU
L
15, whereas pU
L
15 and pU
L
33 do not coimmunoprecipitate unless pU
L
28 is present. The U
L
28 protein was sufficient to stabilize pU
L
33 from proteasomal degradation in an engineered cell line and was necessary to stabilize pU
L
33 in infected cells, whereas pU
L
15 had no such effects. The presence of pU
L
33 was dispensable for the pU
L
15/pU
L
28 interaction in lysates of both infected and uninfected cells but augmented the tendency for pU
L
15 and pU
L
28 to coimmunoprecipitate. These data suggest that pU
L
28 and pU
L
33 interact directly and that pU
L
15 interacts directly with pU
L
28 but only indirectly with pU
L
33. It is logical to propose that the indirect interaction of pU
L
15 and pU
L
33 is mediated through the interaction of both proteins with pU
L
28. The data also suggest that one function of pU
L
33 is to optimize the pU
L
15/pU
L
28 interaction.
Vaccine-Induced Cellular Immune Responses Reduce Plasma Viral Concentrations after Repeated Low-Dose Challenge with Pathogenic Simian Immunodeficiency Virus SIVmac239
Authors: Wilson Nancy A. , Reed Jason , Napoe Gnankang S. , Piaskowski Shari , Szymanski Andy , Furlott Jessica , Gonzalez Edna J. , Yant Levi J. , Maness Nicholas J. , May Gemma E. , Soma Taeko , Reynolds Matthew R. , Rakasz Eva , Rudersdorf Richard , McDermott Adrian B. , O'Connor David H. , Friedrich Thomas C. , Allison David B. , Patki Amit , Picker Louis J. , Burton Dennis R. , Lin Jing , Huang Lingyi , Patel Deepa , Heindecker Gwendolyn , Fan Jiang , Citron Michael , Horton Melanie , Wang Fubao , Liang Xiaoping , Shiver John W. , Casimiro Danilo R. , Watkins David I. 
Published: May 2006

ABSTRACTThe goal of an AIDS vaccine regimen designed to induce cellular immune responses should be to reduce the viral set point and preserve memory CD4 lymphocytes. Here we investigated whether vaccine-induced cellular immunity in the absence of any Env-specific antibodies can control viral replication following multiple low-dose challenges with the highly pathogenic SIVmac239 isolate. EightMamu-A*01-positive Indian rhesus macaques were vaccinated with simian immunodeficiency virus (SIV)gag,tat,rev, andnefusing a DNA prime-adenovirus boost strategy. Peak viremia (P= 0.007) and the chronic phase set point (P= 0.0192) were significantly decreased in the vaccinated cohort, out to 1 year postinfection. Loss of CD4+memory populations was also ameliorated in vaccinated animals. Interestingly, only one of the eight vaccinees developed Env-specific neutralizing antibodies after infection. The control observed was significantly improved over that observed in animals vaccinated with SIVgagonly. Vaccine-induced cellular immune responses can, therefore, exert a measure of control over replication of the AIDS virus in the complete absence of neutralizing antibody and give us hope that a vaccine designed to induce cellular immune responses might control viral replication.
Crystal Structures of Human Immunodeficiency Virus Type 1 (HIV-1) Neutralizing Antibody 2219 in Complex with Three Different V3 Peptides Reveal a New Binding Mode for HIV-1 Cross-Reactivity
Authors: Stanfield Robyn L. , Gorny Miroslaw K. , Zolla-Pazner Susan , Wilson Ian A. 
Published: May 2006

ABSTRACTHuman monoclonal antibody 2219 is a neutralizing antibody isolated from a human immunodeficiency virus type 1-infected individual. 2219 was originally selected for binding to a V3 fusion protein and can neutralize primary isolates from subtypes B, A, and F. Thus, 2219 represents a cross-reactive, human anti-V3 antibody. Fab 2219 binds to one face of the variable V3 β-hairpin, primarily contacting conserved residues on the N-terminal β-strand of V3, leaving the V3 crown or tip largely accessible. Three V3/2219 complexes reveal the antibody-bound conformations for both the N- and C-terminal regions that flank the V3 crown and illustrate how twisting of the V3 loop alters the relative dispositions and pairing of the amino acids in the adjacent V3 β-strands and how the antibody can accommodate V3 loops with different sequences.
Disruption of Microtubule Organization and Centrosome Function by Expression ofTobacco Mosaic VirusMovement Protein
Authors: Ferralli Jacqueline , Ashby Jamie , Fasler Monika , Boyko Vitaly , Heinlein Manfred 
Published: May 2006

ABSTRACTThe movement protein (MP) ofTobacco mosaic virusmediates the cell-to-cell transport of viral RNA through plasmodesmata, cytoplasmic cell wall channels for direct cell-to-cell communication between adjacent cells. Previous in vivo studies demonstrated that the RNA transport function of the protein correlates with its association with microtubules, although the exact role of microtubules in the movement process remains unknown. Since the binding of MP to microtubules is conserved in transfected mammalian cells, we took advantage of available mammalian cell biology reagents and tools to further address the interaction in flat-growing and transparent COS-7 cells. We demonstrate that neither actin, nor endoplasmic reticulum (ER), nor dynein motor complexes are involved in the apparent alignment of MP with microtubules. Together with results of in vitro coprecipitation experiments, these findings indicate that MP binds microtubules directly. Unlike microtubules associated with neuronal MAP2c, MP-associated microtubules are resistant to disruption by microtubule-disrupting agents or cold, suggesting that MP is a specialized microtubule binding protein that forms unusually stable complexes with microtubules. MP-associated microtubules accumulate ER membranes, which is consistent with a proposed role for MP in the recruitment of membranes in infected plant cells and may suggest that microtubules are involved in this process. The ability of MP to interfere with centrosomal γ-tubulin is independent of microtubule association with MP, does not involve the removal of other tested centrosomal markers, and correlates with inhibition of centrosomal microtubule nucleation activity. These observations suggest that the function of MP in viral movement may involve interaction with the microtubule-nucleating machinery.
High-Molecular-Weight Protein (pUL48) of Human Cytomegalovirus Is a Competent Deubiquitinating Protease: Mutant Viruses Altered in Its Active-Site Cysteine or Histidine Are Viable
Authors: Wang Jianlei , Loveland Amy N. , Kattenhorn Lisa M. , Ploegh Hidde L. , Gibson Wade 
Published: May 2006

ABSTRACT
We show here that the high-molecular-weight protein (HMWP or pUL48; 253 kDa) of human cytomegalovirus (HCMV) is a functionally competent deubiquitinating protease (DUB). By using a suicide substrate probe specific for ubiquitin-binding cysteine proteases (DUB probe) to screen lysates of HCMV-infected cells, we found just one infected-cell-specific DUB. Characteristics of this protein, including its large size, expression at late times of infection, presence in extracellular virus particles, and reactivity with an antiserum to the HMWP, identified it as the HMWP. This was confirmed by constructing mutant viruses with substitutions in two of the putative active-site residues, Cys24Ile and His162Ala. HMWP with these mutations either failed to bind the DUB probe (C24I) or had significantly reduced reactivity with it (H162A). More compellingly, the deubiquitinating activity detected in wild-type virus particles was completely abolished in both the C24I and H162A mutants, thereby directly linking HMWP with deubiquitinating enzyme activity. Mutations in these active-site residues were not lethal to virus replication but slowed production of infectious virus relative to wild type and mutations of other conserved residues. Initial studies, by electron microscopy, of cells infected with the mutants revealed no obvious differences at late times of replication in the general appearance of the cells or in the distribution, relative numbers, or appearance of virus particles in the cytoplasm or nucleus.
Endosomal Proteolysis by Cathepsins Is Necessary for Murine Coronavirus Mouse Hepatitis Virus Type 2 Spike-Mediated Entry
Authors: Qiu Zhaozhu , Hingley Susan T. , Simmons Graham , Yu Christopher , Das Sarma Jayasri , Bates Paul , Weiss Susan R. 
Published: May 2006

ABSTRACT
Most strains of murine coronavirus mouse hepatitis virus (MHV) express a cleavable spike glycoprotein that mediates viral entry and pH-independent cell-cell fusion. The MHV type 2 (MHV-2) strain of murine coronavirus differs from other strains in that it expresses an uncleaved spike and cannot induce cell-cell fusion at neutral pH values. We show here that while infection of the prototype MHV-A59 strain is not sensitive to pretreatment with lysosomotropic agents, MHV-2 replication is significantly inhibited by these agents. By use of an A59/MHV-2 chimeric virus, the susceptibility to lysosomotropic agents is mapped to the MHV-2 spike, suggesting a requirement of acidification of endosomes for MHV-2 spike-mediated entry. However, acidification is likely not a direct trigger for MHV-2 spike-mediated membrane fusion, as low-pH treatment is unable to overcome ammonium chloride inhibition, and it also cannot induce cell-cell fusion between MHV-2-infected cells. In contrast, trypsin treatment can both overcome ammonium chloride inhibition and promote cell-cell fusion. Inhibitors of the endosomal cysteine proteases cathepsin B and cathepsin L greatly reduce MHV-2 spike-mediated entry, while they have little effect on A59 entry, suggesting that there is a proteolytic step in MHV-2 entry. Finally, a recombinant virus expressing a cleaved MHV-2 spike has the ability to induce cell-cell fusion at neutral pH values and does not require low pH and endosomal cathepsins during infection. These studies demonstrate that endosomal proteolysis by cathepsins is necessary for MHV-2 spike-mediated entry; this is similar to the entry pathway recently described for severe acute respiratory syndrome coronavirus and indicates that coronaviruses may use multiple pathways for entry.
Rotavirus NSP4 Induces a Novel Vesicular Compartment Regulated by Calcium and Associated with Viroplasms
Authors: Berkova Z. , Crawford S. E. , Trugnan G. , Yoshimori T. , Morris A. P. , Estes M. K. 
Published: May 2006

ABSTRACTRotavirus is a major cause of infantile viral gastroenteritis. Rotavirus nonstructural protein 4 (NSP4) has pleiotropic properties and functions in viral morphogenesis as well as pathogenesis. Recent reports show that the inhibition of NSP4 expression by small interfering RNAs leads to alteration of the production and distribution of other viral proteins and mRNA synthesis, suggesting that NSP4 also affects virus replication by unknown mechanisms. This report describes studies aimed at correlating the localization of intracellular NSP4 in cells with its functions. To be able to follow the localization of NSP4, we fused the C terminus of full-length NSP4 with the enhanced green fluorescent protein (EGFP) and expressed this fusion protein inducibly in a HEK 293-based cell line to avoid possible cytotoxicity. NSP4-EGFP was initially localized in the endoplasmic reticulum (ER) as documented by Endo H-sensitive glycosylation and colocalization with ER marker proteins. Only a small fraction of NSP4-EGFP colocalized with the ER-Golgi intermediate compartment (ERGIC) marker ERGIC-53. NSP4-EGFP did not enter the Golgi apparatus, in agreement with the Endo H sensitivity and a previous report that secretion of an NSP4 cleavage product generated in rotavirus-infected cells is not inhibited by brefeldin A. A significant population of expressed NSP4-EGFP was distributed in novel vesicular structures throughout the cytoplasm, not colocalizing with ER, ERGIC, Golgi, endosomal, or lysosomal markers, thus diverging from known biosynthetic pathways. The appearance of vesicular NSP4-EGFP was dependent on intracellular calcium levels, and vesicular NSP4-EGFP colocalized with the autophagosomal marker LC3. In rotavirus-infected cells, NSP4 colocalized with LC3 in cap-like structures associated with viroplasms, the site of nascent viral RNA replication, suggesting a possible new mechanism for the involvement of NSP4 in virus replication.
Phosphorylation and Function of the Kaposin B Direct Repeats of Kaposi's Sarcoma-Associated Herpesvirus
Authors: McCormick Craig , Ganem Don 
Published: May 2006

ABSTRACT
Kaposi's sarcoma-associated herpesvirus encodes a protein, kaposin B, which is composed of multiple copies of 23-amino-acid direct repeats, termed DR2 and DR1. Kaposin B enhances the release of pathogenetically important proinflammatory cytokines by activating the p38 mitogen-activated protein kinase (MAPK)-MK2 kinase pathway and blocking cytokine mRNA decay. Here, we show that this mRNA stabilization function requires both the DR2 and DR1 elements of kaposin B; a monomeric form of the protein consisting of one copy of each repeat retains function. Furthermore, we show that p38 MAPK is capable of directly phosphorylating kaposin B in vitro and map the site of phosphorylation to a specific serine residue in DR1. Mutational ablation of this serine abolishes phosphorylation of the protein by p38 MAPK but does not affect kaposin B's ability to extend mRNA half-life.
Efficient In Vitro System of Homologous Recombination in Brome Mosaic Bromovirus
Authors: Wierzchoslawski Rafal , Bujarski Jozef J. 
Published: May 2006

ABSTRACT

Recent in vivo studies have revealed that the subgenomic promoter (sgp) in brome mosaic bromovirus (BMV) RNA3 supports frequent homologous recombination events (R. Wierzchoslawski, A. Dzianott, and J. Bujarski, J. Virol.
78:
8552-8564, 2004). In this paper, we describe an sgp-driven in vitro system that supports efficient RNA3 crossovers. A 1:1 mixture of two (−)-sense RNA3 templates was copied with either a BMV replicase (RdRp) preparation or recombinant BMV protein 2a. The BMV replicase enzyme supported a lower recombination frequency than 2a, demonstrating a role of other viral and/or host factors. The described in vitro system will allow us to study the mechanism of homologous RNA recombination.
Identification of a Novel Human Immunodeficiency Virus Type 1 Integrase Interactor, Gemin2, That Facilitates Efficient Viral cDNA Synthesis In Vivo
Authors: Hamamoto Seiji , Nishitsuji Hironori , Amagasa Teruo , Kannagi Mari , Masuda Takao 
Published: May 2006

ABSTRACT
Retroviral integrase (IN) catalyzes the integration of viral cDNA into a host chromosome. Additional roles have been suggested for IN, including uncoating, reverse transcription, and nuclear import of the human immunodeficiency virus type 1 (HIV-1) genome. However, the underlying mechanism is largely unknown. Here, using a yeast two-hybrid system, we identified a survival motor neuron (SMN)-interacting protein 1 (Gemin2) that binds to HIV-1 IN. Reduction of Gemin2 with small interfering RNA duplexes (siGemin2) dramatically reduced HIV-1 infection in human primary monocyte-derived macrophages and also reduced viral cDNA synthesis. In contrast, siGemin2 did not affect HIV-1 expression from the integrated proviral DNA. Although Gemin2 was undetectable in cell-free viral particles, coimmunoprecipitation experiments using FLAG-tagged Gemin2 strongly suggested that Gemin2 interacts with the incoming viral genome through IN. Further experiments reducing SMN or other SMN-interacting proteins suggested that Gemin2 might act on HIV-1 either alone or with unknown proteins to facilitate efficient viral cDNA synthesis soon after infection. Thus, we provide the evidence for a novel host protein that binds to HIV-1 IN and facilitates viral cDNA synthesis and subsequent steps that precede integration in vivo.
Evaluation of the Roles of Specific Regions of the
Cucumber Necrosis Virus
Coat Protein Arm in Particle Accumulation and Fungus Transmission
Authors: Hui Elizabeth , Rochon D'Ann 
Published: May 2006

ABSTRACT

The
Cucumber necrosis virus
(CNV) particle is a T=3 icosahedron composed of 180 identical coat protein (CP) subunits. Each CP subunit includes a 34-amino-acid (aa) arm which connects the RNA binding and shell domains. The arm is comprised of an 18-aa “
β
” region and a 16-aa “ε” region, with the former contributing to a
β
-annular structure involved in particle stability and the latter contributing to quasiequivalence and virion RNA binding. Previous work has shown that specific regions of the CNV capsid play important roles in transmission by zoospores of the fungal vector
Olpidium bornovanus
and that particle expansion is essential for this process. To assess the importance of the two arm regions in particle accumulation, stability, and virus transmission, five CP arm deletion mutants were constructed. Our findings indicate that
β
(−) mutants are capable of producing particles in plants; however, the arm(−) and ε(−) mutants are not. In addition,
β
(−) particles bind zoospores less efficiently than wild-type CNV and are not fungally transmissible.
β
(−) particles are also less thermally stable and disassemble under swelling conditions. Our finding that
β
(−) mutants can accumulate in plants suggests that other features of the virion, such as RNA/CP interactions, may also be important for particle stability.
Dissociation of a MAVS/IPS-1/VISA/Cardif-IKKε Molecular Complex from the Mitochondrial Outer Membrane by Hepatitis C Virus NS3-4A Proteolytic Cleavage
Authors: Lin Rongtuan , Lacoste Judith , Nakhaei Peyman , Sun Qiang , Yang Long , Paz Suzanne , Wilkinson Peter , Julkunen Ilkka , Vitour Damien , Meurs Eliane , Hiscott John 
Published: May 2006

ABSTRACT
Intracellular RNA virus infection is detected by the cytoplasmic RNA helicase RIG-I that plays an essential role in signaling to the host antiviral response. Recently, the adapter molecule that links RIG-I sensing of incoming viral RNA to downstream signaling and gene activation events was characterized by four different groups; MAVS/IPS-1-1/VISA/Cardif contains an amino-terminal CARD domain and a carboxyl-terminal mitochondrial transmembrane sequence that localizes to the mitochondrial membrane. Furthermore, the hepatitis C virus NS3-4A protease complex specifically targets MAVS/IPS-1/VISA/Cardif for cleavage as part of its immune evasion strategy. With a novel search program written in python, we also identified an uncharacterized protein, KIAA1271 (K1271), containing a single CARD-like domain at the N terminus and a Leu-Val-rich C terminus that is identical to that of MAVS/IPS-1/VISA/Cardif. Using a combination of biochemical analysis, subcellular fractionation, and confocal microscopy, we now demonstrate that NS3-4A cleavage of MAVS/IPS-1/VISA/Cardif/K1271 results in its dissociation from the mitochondrial membrane and disrupts signaling to the antiviral immune response. Furthermore, virus-induced IKKε kinase, but not TBK1, colocalized strongly with MAVS at the mitochondrial membrane, and the localization of both molecules was disrupted by NS3-4A expression. Mutation of the critical cysteine 508 to alanine was sufficient to maintain mitochondrial localization of MAVS/IPS-1/VISA/Cardif and IKKε in the presence of NS3-4A. These observations provide an outline of the mechanism by which hepatitis C virus evades the interferon antiviral response.
Erythroblast Transformation by the Friend Spleen Focus-Forming Virus Is Associated with a Block in Erythropoietin-Induced STAT1 Phosphorylation and DNA Binding and Correlates with High Expression of the Hematopoietic Phosphatase SHP-1
Authors: Nishigaki Kazuo , Hanson Charlotte , Ohashi Takashi , Spadaccini Angelo , Ruscetti Sandra 
Published: May 2006

ABSTRACT
Infection of mice with Friend spleen focus-forming virus (SFFV) results in a multistage erythroleukemia. In the first stage, the SFFV envelope glycoprotein interacts with the erythropoietin receptor and a short form of the receptor tyrosine kinase sf-Stk, resulting in constitutive activation of signal transducing molecules and the development of erythropoietin (Epo)-independent erythroid hyperplasia and polycythemia. The second stage results from the outgrowth of a rare virus-infected erythroid cell that expresses nonphysiological levels of the myeloid transcription factor PU.1. These cells exhibit a differentiation block and can be grown as murine erythroleukemia (MEL) cell lines. In this study, we examined SFFV MEL cells to determine whether their transformed phenotype was associated with a block in the activation of any Epo signal-transducing molecules. Our studies indicate that Epo- or SFFV-induced activation of STAT1/3 DNA binding activity is blocked in SFFV MEL cells. The block is at the level of tyrosine phosphorylation of STAT1, although Jak2 phosphorylation is not blocked in these cells. In contrast to Epo, alpha interferon can induce STAT1 phosphorylation and DNA binding in SFFV MEL cells. The SFFV-transformed cells were shown to express elevated levels of the hematopoietic phosphatase SHP-1, and treatment of the cells with a phosphatase inhibitor restored STAT1 tyrosine phosphorylation. MEL cells derived from Friend murine leukemia virus (MuLV) or ME26 MuLV-infected mice, which do not express PU.1, express lower levels of SHP-1 and are not blocked in STAT1/3 DNA-binding activity. Our studies suggest that SFFV-infected erythroid cells become transformed when differentiation signals activated by STAT1/3 are blocked due to high SHP-1 levels induced by inappropriate expression of the PU.1 protein.