bluuebunny/crossref_metadata_2025_split huggingface dataset:
Loss of N-Linked Glycosylation from the Hemagglutinin- Neuraminidase Protein Alters Virulence of Newcastle Disease Virus
Authors: Panda Aruna , Elankumaran Subbiah , Krishnamurthy Sateesh , Huang Zhuhui , Samal Siba K. 
Published: April 2004

ABSTRACT
The hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) is an important determinant of its virulence. We investigated the role of each of the four functional N-linked glycosylation sites (G1 to G4) of the HN glycoprotein of NDV on its pathogenicity. The N-linked glycosylation sites G1 to G4 at residues 119, 341, 433, and 481, respectively, of a moderately pathogenic NDV strain Beaudette C (BC) were eliminated individually by site-directed mutagenesis on a full-length cDNA clone of BC. A double mutant (G12) was also created by eliminating the first and second glycosylation sites at residues 119 and 341, respectively. Infectious virus was recovered from each of the cDNA clones of the HN glycoprotein mutants, employing a reverse genetics technique. There was a greater delay in the replication of G4 and G12 mutant viruses than in the parental virus. Loss of glycosylation does not affect the receptor recognition by HN glycoprotein of NDV. The neuraminidase activity of G4 and G12 mutant viruses and the fusogenicity of the G4 mutant virus were significantly lower than those of the parental virus. The fusogenicity of the double mutant virus (G12) was significantly higher than that of the parental virus. Cell surface expression of the G4 virus HN was significantly lower than that of the parental virus. The antigenic reactivities of the mutants to a panel of monoclonal antibodies against the HN protein indicated that removal of glycosylation from the HN protein increased (G1, G3, and G12) or decreased (G2 and G4) the formation of antigenic sites, depending on their location. In standard tests to assess virulence in chickens, all of the glycosylation mutants were less virulent than the parental BC virus, but the G4 and G12 mutants were the least virulent.
Use of gHgL for Attachment of Epstein-Barr Virus to Epithelial Cells Compromises Infection
Authors: Borza Corina M. , Morgan Andrew J. , Turk Susan M. , Hutt-Fletcher Lindsey M. 
Published: April 2004

ABSTRACTEpstein-Barr virus (EBV) is a lymphotropic herpesvirus. However, access to B lymphocytes during primary infection may be facilitated by replication in mucosal epithelial cells. Attachment and penetration of EBV into these two cell types are fundamentally different. Both the distribution of receptors and the cellular origin of the virus impact the efficiency of infection. Epithelial cells potentially offer a wide range of receptors with which virus can interact. We report here on analyses of epithelial cells expressing different combinations of receptors. We find that the stoichiometry of the virus glycoprotein complex that includes gHgL and gp42 affects the use of gHgL not just for entry into epithelial cells but also for attachment. Penetration can be mediated efficiently with either a coreceptor for gp42 or gHgL, but the use of gHgL for attachment as well as penetration greatly compromises its ability to mediate entry.
Requirement for Integrase during Reverse Transcription of Human Immunodeficiency Virus Type 1 and the Effect of Cysteine Mutations of Integrase on Its Interactions with Reverse Transcriptase
Authors: Zhu Kai , Dobard Charles , Chow Samson A. 
Published: April 2004

ABSTRACT

Retroviral integrase catalyzes the essential step of integrating a double-stranded DNA copy of the viral genome into a host cell chromosome. Mutational studies have revealed that integrase is involved in additional steps of viral replication, but the mechanism for the pleiotropic effect is not well characterized. Since Cys residues generally play crucial roles in protein structure and function, we introduced Cys-to-Ser substitutions at positions 56, 65, and 130 of human immunodeficiency virus type 1 (HIV-1) integrase to determine their effects on integration activity and viral replication. None of the substitutions significantly affected the enzymatic activities in vitro. When introduced into the NL4-3 molecular clone of HIV-1, mutant viruses encoding Cys mutations at positions 56 and 65 of integrase replicated similarly to the wild-type virus in CD4
+
-T-cell lines, whereas the C130S-containing virus was noninfectious. The entry and postintegration steps of the viral life cycle for all mutant viruses were normal, and all had particle-associated reverse transcriptase (RT) activity. However, early reverse-transcribed DNA products were absent in the lysate of cells infected with the C130S mutant virus, indicating that the mutation abolished the ability of the virus to initiate endogenous reverse transcription. Coimmunoprecipitation using purified integrase and RT showed that the C-terminal domain of wild-type HIV-1 integrase interacted with RT. The interaction between integrase and RT was not affected in the presence of a reducing or alkylating agent, suggesting that the interaction did not involve a disulfide linkage. The C130S substitution within the core region may disrupt the protein recognition interface of the C-terminal domain and abolish its ability to interact with RT. Our results indicate that integrase plays an important role during the reverse-transcription step of the viral life cycle, possibly through physical interactions with RT.
Identification of Unique Hepatitis C Virus Quasispecies in the Central Nervous System and Comparative Analysis of Internal Translational Efficiency of Brain, Liver, and Serum Variants
Authors: Forton Daniel M. , Karayiannis Peter , Mahmud Nadiya , Taylor-Robinson Simon D. , Thomas Howard C. 
Published: April 2004

ABSTRACT

Reports of cerebral dysfunction in chronic hepatitis C virus (HCV) infection have led to the suggestion that HCV may infect the central nervous system (CNS). We used reverse transcription-PCR, cloning, and sequencing to define quasispecies for the HCV internal ribosomal entry site (IRES) and hypervariable region 1 (HVR1) in autopsy-derived brain, liver, lymph node, and serum samples. There was evidence of tissue compartmentalization of sequences in the brain in two patients, with between 24 and 55% of brain-derived IRES sequences absent from the serum, and significant phylogenetic and phenetic clustering of the brain and lymph node HVR1 sequences. The IRES initiates cap-independent translation of the viral polyprotein. Two unique brain-derived IRES mutations (C
204
→A and G
243
→A), which have previously been associated with lymphoid replication and altered translational efficiency in cell culture, were found in one patient. We used a dicistronic reporter vector to test whether brain-derived variants showed altered IRES-mediated translational efficiency, which might favor CNS infection. The translational efficiencies of the brain-derived IRES sequences were generally reduced compared to those of the master serum and liver sequences in rabbit reticulocyte cell lysates and two human cell lines, HuH7 (liver) and CHME3 (microglial). The C
204
→A and G
243
→A mutations showed preserved translational efficiency in HuH7 cells but reduced efficiency in CHME3 cells. Our data provide evidence that the CNS is a site of HCV replication, consistent with the recent demonstration of negative-strand HCV RNA in brain, and suggest that IRES polymorphisms may be important as a viral strategy of reduced translation to favor latency in the CNS.
CD4+T Cells from CD4C/HIVNefTransgenic Mice Show Enhanced Activation In Vivo with Impaired Proliferation In Vitro but Are Dispensable for the Development of a Severe AIDS-Like Organ Disease
Authors: Weng Xiaoduan , Priceputu Elena , Chrobak Pavel , Poudrier Johanne , Kay Denis G. , Hanna Zaher , Mak Tak W. , Jolicoeur Paul 
Published: April 2004

ABSTRACTThe cellular and molecular mechanisms of dysfunction and depletion of CD4+T lymphocytes over the course of human immunodeficiency virus type 1 (HIV-1) infection are still incompletely understood, but chronic immune activation is thought to play an important role in disease progression. We studied CD4+T-cell biology in CD4C/HIV transgenic (Tg) mice, in which Nef expression is sufficient to induce a severe AIDS-like disease including a preferential decrease of CD4+T cells. We show here that Nef-expressing Tg CD4+T cells exhibit an activated/memory-like phenotype which appears to be independent of antigenic stimulation, as documented in experiments involving breeding with AD10 TcR Tg mice. In addition, in vivo bromodeoxyuridine incorporation showed that a larger proportion of Tg than non-Tg CD4+T cells entered the S phase. However, in vitro, Tg CD4+T cells were found to have a very limited capacity to divide in response to stimulation with anti-CD3 and anti-CD28 or in allogeneic mixed leukocyte reactions. Interestingly, despite these observations, the deletion of Tg CD4+T cells had little impact on the development of other AIDS-like organ phenotypes. Thus, the Nef-induced chronic activation of CD4+T cells may exhaust the T-cell pool and may contribute to the thymic atrophy and the low number of CD4+T cells observed in these Tg mice.
CD8+-Cell-Mediated Suppression of Virulent Simian Immunodeficiency Virus during Tenofovir Treatment
Authors: Van Rompay Koen K. A. , Singh Raman P. , Pahar Bapi , Sodora Donald L. , Wingfield Casey , Lawson Jonathan R. , Marthas Marta L. , Bischofberger Norbert 
Published: April 2004

ABSTRACTThe ability of tenofovir to suppress viremia in simian immunodeficiency virus (SIV)-infected macaques for years despite the presence of virulent viral mutants with reduced in vitro susceptibility is unprecedented in this animal model. In vivo cell depletion experiments demonstrate that tenofovir's ability to suppress viremia during acute and chronic infection is significantly dependent on the presence of CD8+lymphocytes. Continuous tenofovir treatment was required to maintain low viremia. Although it is unclear whether this immune-mediated suppression of viremia is linked to tenofovir's direct antiviral efficacy or is due to independent immunomodulatory effects, these studies prove the concept that antiviral immune responses can play a crucial role in suppressing viremia during anti-human immunodeficiency virus drug therapy.
The Herpes Simplex Virus Type 1 UL20 Protein Modulates Membrane Fusion Events during Cytoplasmic Virion Morphogenesis and Virus-Induced Cell Fusion
Authors: Foster Timothy P. , Melancon Jeffrey M. , Baines Joel D. , Kousoulas Konstantin G. 
Published: April 2004

ABSTRACT
The herpes simplex virus type 1 (HSV-1) UL20 protein is an important determinant for virion morphogenesis and virus-induced cell fusion. A precise deletion of the UL20 gene in the HSV-1 KOS strain was constructed without affecting the adjacent UL20.5 gene. The resultant KOS/UL20-null virus produced small plaques of 8 to 15 cells in Vero cells while it produced wild-type plaques on the complementing cell line G5. Electron microscopic examination of infected cells revealed that the KOS/UL20-null virions predominantly accumulated capsids in the cytoplasm while a small percentage of virions were found as enveloped virions within cytoplasmic vacuoles. Recently, it was shown that UL20 expression was necessary and sufficient for cell surface expression of gK (T. P. Foster, X. Alvarez, and K. G. Kousoulas, J. Virol. 77:499-510, 2003). Therefore, we investigated the effect of UL20 on virus-induced cell fusion caused by syncytial mutations in gB and gK by constructing recombinant viruses containing the gBsyn3 or gKsyn1 mutations in a UL20-null genetic background. Both recombinant viruses failed to cause virus-induced cell fusion in Vero cells while they readily caused fusion of UL20-null complementing G5 cells. Ultrastructural examination of UL20-null viruses carrying the gBsyn3 or gKsyn1 mutation revealed a similar distribution of virions as the KOS/UL20-null virus. However, cytoplasmic vacuoles contained aberrant virions having multiple capsids within a single envelope. These multicapsid virions may have been formed either by fusion of viral envelopes or by the concurrent reenvelopment of multiple capsids. These results suggest that the UL20 protein regulates membrane fusion phenomena involved in virion morphogenesis and virus-induced cell fusion.
Human Immunodeficiency Virus Type 1 Envelope Glycoproteins That Lack Cytoplasmic Domain Cysteines: Impact on Association with Membrane Lipid Rafts and Incorporation onto Budding Virus Particles
Authors: Bhattacharya Jayanta , Peters Paul J. , Clapham Paul R. 
Published: April 2004

ABSTRACTThe human immunodeficiency virus type 1 (HIV-1) envelope comprises a surface gp120 and a transmembrane gp41. The cytoplasmic domain of gp41 contains cysteine residues (C764 and C837) which are targets for palmitoylation and were reported to be required for envelope association with lipid rafts and assembly on budding virions (I. Rousso, M. B. Mixon, B. K. Chen, and P. S. Kim, Proc. Natl. Acad. Sci. USA97:13523-13525, 2000). Several infectious HIV-1 clones contain envelopes that have no gp41 cytoplasmic cysteines. Since no other gp41 amino acid is a target for palmitoylation, these clones imply that palmitoylation is not essential for envelope trafficking and assembly. Here, we show that HIV-1 envelope mutants that lack gp41 cytoplasmic cysteines are excluded from light lipid rafts. Envelopes that contained residues with bulky hydrophobic side chains instead of cysteines retained their association with heavy rafts and were nearly fully functional for incorporation into virions and infectivity. Substitution of cysteines with alanines or serines eliminated raft association and more severely reduced envelope incorporation onto virions and their infectivity. Nevertheless, the A764/A837 mutant envelope retained nearly 40% infectivity compared to the wild type, even though this envelope was excluded from lipid rafts. Our results demonstrate that gp41 cytoplasmic cysteines that are targets for palmitoylation and are required for envelope trafficking to classical lipid rafts are not essential for HIV-1 replication.
Classical Swine Fever Virus Glycoprotein E
rns
Is an Endoribonuclease with an Unusual Base Specificity
Authors: Hausmann Yvonne , Roman-Sosa Gleyder , Thiel Heinz-Jürgen , Rümenapf Till 
Published: April 2004

ABSTRACT

The glycoprotein E
rns
of pestiviruses is a virion-associated and -secreted RNase that is involved in virulence. The requirements at the cleavage site in heteropolymeric RNA substrates were studied for E
rns
. Limited digestion of heteropolymeric RNA substrates indicated a cleavage 5′ of uridine residues irrespective of the preceding nucleotide (Np/U). To further study specificity radiolabeled RNA, molecules of 45 to 56 nucleotides in length were synthesized that contained no or a single Np/U cleavage site. Cleavage was only observed in substrates containing an ApU, CpU, GpU, or UpU dinucleotide and occurred in two steps, an initial NpU-specific and a consecutive unspecific degradation. The NpU-specific cleavage was resistant to 7 M urea while the second-order cleavage was sensitive to denaturation. Kinetic analyses revealed that E
rns
is a highly active endoribonuclease (k
cat
/

K
m

= 2 × 10
6
to 10 × 10
6
M
−1
s
−1
) with a strong affinity to NpU containing single-stranded RNA substrates (

K
m

= 85 to 260 nM).
The Development of the P.E.T.Scale for the Measurement of Physical and Emotional Tormenting Against Animals in Adolescents
Authors: Baldry Anna 
Published: April 2004

AbstractThe Physical and Emotional Tormenting Against Animals Scale (P.E.T.) is a new self-administered scale to measure physical and emotional abuse against animals among adolescents. This study is a first attempt to establish the reliability and validity of this newly developed scale with a non-clinical sample of 1396 Italian adolescents, aged 11-17 years.The scale measures different dimensions of animal abuse, ranging from mild to more severe: bothering, tormenting, hitting, harming, and being cruel to an animal. The scale measures the prevalence and frequency of directed and witnessed abuse against animals. Principal components analysis suggested a two factor solution, with factors labeled "direct" and "indirect" animal abuse; internal consistency was good for each factor.The direct animal abuse factor was significantly correlated with the Child Behavior Checklist's single item assessing engagement in cruelty against animals. These findings suggest that the PET scale has potential as an instrument for the measurement of animal abuse. Future studies of the PET scale's psychometric properties, and cross-validation on new populations, are needed.
Momentaufnahmen photoangeregter Moleküle in fehlgeordneten Medien mit gepulster Synchrotron‐Röntgenstrahlung
Authors: Chen Lin X. 
Published: April 2004

AbstractAn jeder photochemischen Reaktion sind photoangeregte Moleküle beteiligt. Die Kenntnis ihrer Strukturen in fehlgeordneten Medien, in denen die meisten photochemischen Reaktionen ablaufen, ist Voraussetzung für das Verständnis der Photochemie. Über diese Strukturen war lange aber nur wenig bekannt, weil geeignete Röntgenquellen fehlten. Dank der heute verfügbaren gepulsten Röntgenquellen können die Strukturen von Molekülen in kurzlebigen angeregten Zuständen in fehlgeordneten Medien mit Laserpump‐Röntgenanalyse‐Techniken in Synchrotrons der dritten Generation mit Zeitauflösungen von 30–100 ps untersucht werden. Diese Studien liefern wertvolle Informationen über die strukturellen Ursachen molekularer Eigenschaften in angeregten Zuständen. Mit derzeit in Bau befindlichen Röntgeneinrichtungen könnte die Zeitauflösung bei der Strukturbestimmung angeregter Zustände sogar in den Femtosekundenbereich gedrückt werden. Damit wären “molekulare Filme” von Bindungsbrüchen und ‐bildungen oder der Schwingungsrelaxation möglich.
Nanolithography and Nanochemistry: Probe‐Related Patterning Techniques and Chemical Modification for Nanometer‐Sized Devices
Authors: Wouters Daan , Schubert Ulrich S. 
Published: April 2004

AbstractThe size regime for devices produced by photolithographic techniques is limited. Therefore, other patterning techniques have been intensively studied to create smaller structures. Scanning‐probe‐based patterning techniques, such as dip‐pen lithography, local force‐induced patterning, and local‐probe oxidation‐based techniques are highly promising because of their relative ease and widespread availability. The latter of these is especially interesting because of the possibility of producing nanopatterns for a broad range of chemical and physical modification and functionalization processes; both the production of nanometer‐sized electronic devices and the formation of devices involving (bio)molecular recognition and sensor applications is possible. This Review highlights the development of various scanning probe systems and the possibilities of local oxidation methods, as well as giving an overview of state‐of‐the‐art nanometer‐sized devices, and a view of future development.
Effect of processing method on surface and weathering characteristics of wood–flour/HDPE composites
Authors: Stark Nicole M. , Matuana Laurent M. , Clemons Craig M. 
Published: April 2004

AbstractWood–plastic lumber is promoted as a low‐maintenance high‐durability product. When exposed to accelerated weathering, however, wood–plastic composites may experience a color change and/or loss in mechanical properties. Different methods of manufacturing wood–plastic composites lead to different surface characteristics, which can influence weathering. In this study, 50% wood–flour‐filled high‐density polyethylene (HDPE) composite samples were injection molded, extruded, or extruded and then planed, to remove the manufacturing surface characteristics. Fourier transform infrared spectroscopy was used to chemically show the difference in surface components. The samples were weathered in a xenon‐arc weathering apparatus for 1000, 2000, and 3000 h and analyzed for color fade and loss of flexural modulus of elasticity and strength. Final color (lightness) after weathering was not dependent on the manufacturing method. However, the manufacturing method was related to mechanical property loss caused by weathering. Composites with more wood component at the surface (i.e., planed samples) experienced a larger percentage of total loss in flexural modulus of elasticity and strength after weathering. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1021–1030, 2004
Antimicrobial finishing of wool fabrics using quaternary ammonium salts
Authors: Zhu Ping , Sun Gang 
Published: April 2004

AbstractDurable antimicrobial wool fabrics were prepared by using a simple chemical finishing process. Carboxylate groups in wool protein were employed to form ionic interactions with cationic antimicrobial agents, such as cetylpyridinium chloride (CPC) and other quaternary ammonium salts, under the isoelectric point of wool protein, and such interactions were proven effective. The uptakes of the agents were dependent on their chemical structures, pH values of treatment solutions, concentration of the agents, and treatment temperature. The ionic interactions between the agents and the protein could survive repeated laundering, with CPC showing the best durability among three tested quaternary ammonium salts. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1037–1041, 2004
Tubular‐Shaped Stoichiometric Chrysotile Nanocrystals
Authors: Falini Giuseppe , Foresti Elisabetta , Gazzano Massimo , Gualtieri Alessandro F. , Leoni Matteo , Lesci Isidoro G. , Roveri Norberto 
Published: April 2004

AbstractStoichiometric chrysotile tubular nanocrystals have been synthesized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular interactions between chrysotile, the most utilized asbestos, and biological systems. Chrysotile nanocrystals have been synthesized under controlled hydrothermal conditions, and have been characterized by chemical, morphological, structural, spectroscopic and microcalorimetric analyses. They show a constant “cylinder‐in‐cylinder” morphology constituted by two or three concentric subunits. Each single nanocrystal has a tubular shape of about 49±1 nm in outer maximum diameter, and a hollow core of about 7±1 nm. Structural investigation carried out on an X‐ray powder pattern allowed to improve the structural model proposed for chrysotile mineral samples. Synthetic chrysotile crystallizes in the monoclinic Cc space group with a=0.5340(1) nm, b=0.9241(1) nm, and c=1.4689(2) nm, β=93.66(3)°.
Fluidisches Bussystem für die chemische Verfahrenstechnik und für die Produktion von Feinchemikalien
Authors: Müller A. , Cominos V. , Hessel V. , Horn B. , Schürer J. , Ziogas A. , Jähnisch K. , Hillmann V. , Großer V. , Jam K. A. , Bazzanella A. , Rinke G. , Kraut M. 
Published: April 2004

AbstractNo abstracts.