bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relative Sensitivity of Hepatitis B Virus and Other Hepatotropic Viruses to the Antiviral Effects of Cytokines
Authors: McClary Heike , Koch Rick , Chisari Francis V. , Guidotti Luca G. 
Published: July 2002

ABSTRACTWe have previously shown that hepatitis B virus (HBV) replication is inhibited noncytopathically in the livers of transgenic mice following injection of HBV-specific cytotoxic T lymphocytes (CTLs) or infection with unrelated hepatotropic viruses, including lymphocytic choriomeningitis virus (LCMV) and adenovirus. These effects are mediated by gamma interferon (IFNγ), tumor necrosis factor alpha (TNFα), and IFNα/β. In the present study, we crossed HBV transgenic mice with mice genetically deficient for IFNγ (IFNγKO), the TNFα receptor (TNFαRKO), or the IFNα/β receptor (IFNα/βRKO) in order to determine the relative contribution of each cytokine to the antiviral effects observed in each of these systems. Interestingly, we showed that HBV replicates in unmanipulated IFNγKO and IFNα/βRKO mice at levels higher than those observed in control mice, implying that baseline levels of these cytokines control HBV replication in the absence of inflammation. We also showed that IFNγ mediates most of the antiviral effect of the CTLs while IFNα/β is primarily responsible for the early inhibitory effect of LCMV and adenovirus on HBV replication. In addition, we showed that the hepatic induction of IFNα/β observed after injection of poly(I · C) is sufficient to inhibit HBV replication and that a similar antiviral effect is achieved by systemic administration of very high doses of IFNα. We also compared the relative sensitivity of LCMV and adenovirus to control by IFNγ, TNFα, or IFNα/β in these animals. Importantly, IFNα/βRKO mice, and to a lesser extent IFNγKO mice, showed higher hepatic levels of LCMV RNA and adenovirus DNA and RNA than control mice, underscoring the importance of both interferons in controlling these other viral infections as well.
Recombinant Adeno-Associated Virus Expressing Human Papillomavirus Type 16 E7 Peptide DNA Fused with Heat Shock Protein DNA as a Potential Vaccine for Cervical Cancer
Authors: Liu Dai-Wei , Tsao Yeou-Ping , Kung John T. , Ding Yu-An , Sytwu Huey-Kang , Xiao Xiao , Chen Show-Li 
Published: July 2002

ABSTRACTIn this study, we explore a potential vaccine for human papillomavirus (HPV)-induced tumors, using heat shock protein as an adjuvant, a peptide vaccine for safety, and adeno-associated virus (AAV) as a gene delivery vector. The tumor vaccine was devised by constructing a chimeric gene which contained HPV type 16 E7 cytotoxic T-lymphocyte (CTL) epitope DNA (M. C. Feltkamp, H. L. Smits, M. P. Vierboom, R. P. Minnaar, B. M. de Jongh, J. W. Drijfhout, J. ter Schegget, C. J. Melief, and W. M. Kast, Eur. J. Immunol. 23:2242–2249, 1993) fused with the heat shock protein gene as a tumor vaccine delivered via AAV. Our results demonstrate that this vaccine can eliminate tumor cells in syngeneic animals and induce CD4- and CD8-dependent CTL activity in vitro. Moreover, studies with knockout mice with distinct T-cell deficiencies confirm that CTL-induced tumor protection is CD4 and CD8 dependent. Taken together, the evidence indicates that this chimeric gene delivered by AAV has potential as a cervical cancer vaccine.
Feline Immunodeficiency Virus Cell Entry
Authors: Frey Susan C. S. , Hoover Edward A. , Mullins James I. 
Published: July 2002

ABSTRACT
The process of feline immunodeficiency virus (FIV) cell entry was examined using assays for virus replication intermediates. FIV subtype B was found to utilize the chemokine receptor CXCR4, but not CCR5, as a cellular receptor. Zidovudine blocked formation of late viral replication products most effectively, including circular DNA genome intermediates. Our findings extend the role of CXCR4 as a primary receptor for CD4-independent cell entry by FIV.
Potential Sources of the 1995 Venezuelan Equine Encephalitis Subtype IC Epidemic
Authors: Brault Aaron C. , Powers Ann M. , Medina Gladys , Wang Eryu , Kang Wenli , Salas Rosa Alba , De Siger Julieta , Weaver Scott C. 
Published: July 2002

ABSTRACT
Venezuelan equine encephalitis viruses (VEEV) belonging to subtype IC have caused three (1962–1964, 1992–1993 and 1995) major equine epizootics and epidemics. Previous sequence analyses of a portion of the envelope glycoprotein gene demonstrated a high degree of conservation among isolates from the 1962–1964 and the 1995 outbreaks, as well as a 1983 interepizootic mosquito isolate from Panaquire, Venezuela. However, unlike subtype IAB VEEV that were used to prepare inactivated vaccines that probably initiated several outbreaks, subtype IC viruses have not been used for vaccine production and their conservation cannot be explained in this way. To characterize further subtype IC VEEV conservation and to evaluate potential sources of the 1995 outbreak, we sequenced the complete genomes of three isolates from the 1962–1964 outbreak, the 1983 Panaquire interepizootic isolate, and two isolates from 1995. The sequence of the Panaquire isolate, and that of virus isolated from a mouse brain antigen prepared from subtype IC strain P676 and used in the same laboratory, suggested that the Panaquire isolate represents a laboratory contaminant. Some authentic epizootic IC strains isolated 32 years apart showed a greater degree of sequence identity than did isolates from the same (1962–1964 or 1995) outbreak. If these viruses were circulating and replicating between 1964 and 1995, their rate of sequence evolution was at least 10-fold lower than that estimated during outbreaks or that of closely related enzootic VEEV strains that circulate continuously. Current understanding of alphavirus evolution is inconsistent with this conservation. This subtype IC VEEV conservation, combined with phylogenetic relationships, suggests the possibility that the 1995 outbreak was initiated by a laboratory strain.
The Hemagglutinin of Canine Distemper Virus Determines Tropism and Cytopathogenicity
Authors: von Messling Veronika , Zimmer Gert , Herrler Georg , Haas Ludwig , Cattaneo Roberto 
Published: July 2002

ABSTRACT

Canine distemper virus (CDV) and measles virus (MV) cause severe illnesses in their respective hosts. The viruses display a characteristic cytopathic effect by forming syncytia in susceptible cells. For CDV, the proficiency of syncytium formation varies among different strains and correlates with the degree of viral attenuation. In this study, we examined the determinants for the differential fusogenicity of the wild-type CDV isolate 5804Han89 (CDV
5804
), the small- and large-plaque-forming variants of the CDV vaccine strain Onderstepoort (CDV
OS
and CDV
OL
, respectively), and the MV vaccine strain Edmonston B (MV
Edm
). The cotransfection of different combinations of fusion (F) and hemagglutinin (H) genes in Vero cells indicated that the H protein is the main determinant of fusion efficiency. To verify the significance of this observation in the viral context, a reverse genetic system to generate recombinant CDVs was established. This system is based on a plasmid containing the full-length antigenomic sequence of CDV
OS
. The coding regions of the H proteins of all CDV strains and MV
Edm
were introduced into the CDV and MV genetic backgrounds, and recombinant viruses rCDV-H
5804
, rCDV-H
OL
, rCDV-H
Edm
, rMV-H
5804
, rMV-H
OL
, and rMV-H
OS
were recovered. Thus, the H proteins of the two morbilliviruses are interchangeable and fully functional in a heterologous complex. This is in contrast with the glycoproteins of other members of the family
Paramyxoviridae
, which do not function efficiently with heterologous partners. The fusogenicity, growth characteristics, and tropism of the recombinant viruses were examined and compared with those of the parental strains. All these characteristics were found to be predominantly mediated by the H protein regardless of the viral backbone used.
Activity of the Hepatitis A Virus IRES Requires Association between the Cap-Binding Translation Initiation Factor (eIF4E) and eIF4G
Authors: Ali Iraj K. , McKendrick Linda , Morley Simon J. , Jackson Richard J. 
Published: July 2002

ABSTRACT

The question of whether translation initiation factor eIF4E and the complete eIF4G polypeptide are required for initiation dependent on the IRES (internal ribosome entry site) of hepatitis A virus (HAV) has been examined using in vitro translation in standard and eIF4G-depleted rabbit reticulocyte lysates. In agreement with previous publications, the HAV IRES is unique among all picornavirus IRESs in that it was inhibited if translation initiation factor eIF4G was cleaved by foot-and-mouth disease L-proteases. In addition, the HAV IRES was inhibited by addition of eIF4E-binding protein 1, which binds tightly to eIF4E and sequesters it, thus preventing its association with eIF4G. The HAV IRES was also inhibited by addition of m
7
GpppG cap analogue, irrespective of whether the RNA tested was capped or not. Thus, initiation on the HAV IRES requires that eIF4E be associated with eIF4G and that the cap-binding pocket of eIF4E be empty and unoccupied. This suggests two alternative models: (i) initiation requires a direct interaction between an internal site in the IRES and eIF4E/4G, an interaction which involves the cap-binding pocket of eIF4E in addition to any direct eIF4G-RNA interactions; or (ii) it requires eIF4G in a particular conformation which can be attained only if eIF4E is bound to it, with the cap-binding pocket of the eIF4E unoccupied.
High Resistance of Human Parainfluenza Type 2 Virus Protein-Expressing Cells to the Antiviral and Anti-Cell Proliferative Activities of Alpha/Beta Interferons: Cysteine-Rich V-Specific Domain Is Required for High Resistance to the Interferons
Authors: Nishio Machiko , Tsurudome Masato , Ito Morihiro , Kawano Mitsuo , Komada Hiroshi , Ito Yasuhiko 
Published: July 2002

ABSTRACTHuman parainfluenza type 2 virus (hPIV-2)-infected HeLa (HeLa-CA) cells and hPIV-2 V-expressing HeLa (HeLa-V) cells show high resistance to alpha/beta interferons (IFN-α/β) irrespective of whether vesicular stomatitis virus or Sindbis virus is used as a challenge virus. When Sindbis virus is used, these cells show high susceptibility to human IFN-γ. Furthermore, the multiplication of HeLa-V cells is not inhibited by IFN-α/β. HeLa cells expressing the N-terminally truncated V protein show resistance to IFN-α/β, showing that the IFN resistance determinant maps to the cysteine-rich V-specific domain. A complete defect of Stat2 is found in HeLa-CA and HeLa-V cells, whereas the levels of Stat1 expression are not significantly different among HeLa, HeLa-CA, HeLa-P, and HeLa-V cells, indicating that IFN-α/β resistance of HeLa-CA and HeLa-V cells is due to a defect of Stat2. HeLa-SV41V cells show high resistance to all IFNs, and no expression of Stat1 can be detected. Stat2 mRNA is fully detected in HeLa-V cells. Stat2 was scarcely pulse-labeled in the HeLa-V cells, indicating that synthesis of Stat2 is suppressed or Stat2 is very rapidly degraded in HeLa-V cells. The V protein suppresses the in vitro translation of Stat2 mRNA more extensively than that of Stat1 mRNA. An extremely small amount of Stat2 can be detected in HeLa-V cells treated with proteasome inhibitors. The half-life of Stat2 is approximately 3.5 and 2 h in uninfected and hPIV-2-infected HeLa cells, respectively. This study shows that synthesis of Stat2 may be suppressed and Stat2 degradation is also enhanced in hPIV-2-infected HeLa and HeLa-V cells.
Genome Sequence of Bovine Herpesvirus 4, a Bovine
Rhadinovirus,
and Identification of an Origin of DNA Replication
Authors: Zimmermann Wolfgang , Broll Hermann , Ehlers Bernhard , Buhk Hans-Jörg , Rosenthal André , Goltz Michael 
Published: July 2002

ABSTRACT

Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus of cattle. The complete long unique coding region (LUR) of BoHV-4 strain 66-p-347 was determined by a shotgun approach. Together with the previously published noncoding terminal repeats, the entire genome sequence of BoHV-4 is now available. The LUR consists of 108,873 bp with an overall G+C content of 41.4%. At least 79 open reading frames (ORFs) are present in this coding region, 17 of them unique to BoHV-4. In contrast to herpesvirus saimiri and human herpesvirus 8, BoHV-4 has a reduced set of ORFs homologous to cellular genes. Gene arrangement as well as phylogenetic analysis confirmed that BoHV-4 is a member of the genus
Rhadinovirus
. In addition, an origin of replication (
ori
) in the genome of BoHV-4 was identified by
Dpn
I assays. A minimum of 1.69 kbp located between ORFs 69 and 71 was sufficient to act as a
cis
signal for replication.
Yellow Fever Virus Encephalitis: Properties of the Brain-Associated T-Cell Response during Virus Clearance in Normal and Gamma Interferon-Deficient Mice and Requirement for CD4+Lymphocytes
Authors: Liu Ting , Chambers Thomas J. 
Published: July 2002

ABSTRACTViral encephalitis caused by neuroadapted yellow fever 17D virus (PYF) was studied in parental and gamma interferon (IFN-γ)-deficient (IFN-γ knockout [GKO]) C57BL/6 mice. The T-cell responses which enter the brain during acute fatal encephalitis of nonimmunized mice, as well as nonfatal encephalitis of immunized mice, were characterized for relative proportions of CD4+and CD8+cells, their proliferative responses, and antigen-specific expression of cytokines during stimulation in vitro. Unimmunized mice accumulated only low levels of T cells within the brain during fatal disease, whereas the brains of immunized mice contained higher levels of both T-cell subsets in response to challenge, with CD8+cells increased relative to the CD4+subset. The presence of T cells correlated with the time at which virus was cleared from the central nervous system in both parental and GKO mice. Lymphocytes isolated from the brains of challenged immunized mice failed to proliferate in vitro in response to T-cell mitogens or viral antigens; however, IFN-γ, interleukin 4 (IL-4), and, to a lesser extent, IL-2 were detectable after stimulation. The levels of IFN-γ, but not IL-2 or IL-4, were augmented in response to viral antigen, and this specificity was detectable in the CD4+compartment. When tested for the ability to survive both immunization and challenge with PYF virus, GKO and CD8 knockout mice did not differ from parental mice (80 to 85% survival), although GKO mice exhibited a defect in virus clearance. In contrast, CD4 knockout and Igh-6 mice were unable to resist challenge. The data implicate antibody in conjunction with CD4+lymphocytes bearing a Th1 phenotype as the critical factors involved in virus clearance in this model.
Human Immunodeficiency Virus Type 1 Induces Expression of Complement Factors in Human Astrocytes
Authors: Speth Cornelia , Stöckl Gabriele , Mohsenipour Iradji , Würzner Reinhard , Stoiber Heribert , Lass-Flörl Cornelia , Dierich Manfred P. 
Published: July 2002

ABSTRACTSince the brain is separated from the blood immune system by a tight barrier, the brain-resident complement system may represent a central player in the immune defense of this compartment against human immunodeficiency virus (HIV). Chronic complement activation, however, may participate in HIV-associated neurodegeneration. Since the level of complement factors in the cerebrospinal fluid is known to be elevated in AIDS-associated neurological disorders, we evaluated the effect of HIV type 1 (HIV-1) on the complement synthesis of brain astrocytes. Incubation of different astrocytic cell lines and primary astrocytes with HIV-1 induced a marked upregulation of the expression of the complement factors C2 and C3. The synthesis of other secreted or membrane-bound complement proteins was not found to be altered. The enhancement of C3 production was measured both on the mRNA level and as secreted protein in the culture supernatants. HIV-1 laboratory strains as well as primary isolates were capable of inducing C3 production with varied effectiveness. The usage of viral coreceptors by HIV-1 was proved to be a prerequisite for the upregulation of C3 synthesis, which was modulated by the simultaneous addition of cytokines. The C3 protein which is secreted after incubation of the cells with HIV was shown to be biologically active as it can participate in the complement cascade.
GRP78, a Coreceptor for Coxsackievirus A9, Interacts with Major Histocompatibility Complex Class I Molecules Which Mediate Virus Internalization
Authors: Triantafilou Kathy , Fradelizi Didier , Wilson Keith , Triantafilou Martha 
Published: July 2002

ABSTRACTIt is becoming apparent that over the years cell infection by virus seems to have evolved into a multistep process in which many viruses employ distinct cell surface molecules for their attachment and cell entry. In this study the attachment and entry pathway of coxsackievirus A9 (CAV-9), a member of thePicornaviridaefamily, was investigated. It has been known that, although integrin αvβ3 is utilized as a receptor, its presence alone is insufficient for CAV-9 infection and that CAV-9 also requires a 70-kDa major histocompatibility complex class I (MHC-I)-associated protein (MAP-70) as a coreceptor molecule. We document by protein isolation and peptide sequencing that the 70-kDa protein is GRP78, a member of the heat shock protein 70 family of stress proteins. Furthermore we show by using fluorescence resonance energy transfer (FRET) that GRP78 is also expressed on the cell surface and associates with MHC-I molecules. In addition CAV-9 infection of permissive cells requires GRP78 and also MHC-I molecules, which are essential for virus internalization. The identification of GRP78 as a coreceptor for CAV-9 and the revelation of GRP78 and MHC-I associations have provided new insights into the life cycle of CAV-9, which utilizes integrin αvβ3 and GRP78 as receptor molecules whereas MHC-I molecules serve as the internalization pathway of this virus to mammalian cells.
Membrane Recognition by Vesicular Stomatitis Virus Involves Enthalpy-Driven Protein-Lipid Interactions
Authors: Carneiro Fabiana A. , Bianconi M. Lucia , Weissmüller Gilberto , Stauffer Fausto , Da Poian Andrea T. 
Published: July 2002

ABSTRACT
Vesicular stomatitis virus (VSV) infection depends on the fusion of viral and cellular membranes, which is mediated by virus spike glycoprotein G at the acidic environment of the endosomal compartment. VSV G protein does not contain a hydrophobic amino acid sequence similar to the fusion peptides found among other viral glycoproteins, suggesting that membrane recognition occurs through an alternative mechanism. Here we studied the interaction between VSV G protein and liposomes of different phospholipid composition by force spectroscopy, isothermal titration calorimetry (ITC), and fluorescence spectroscopy. Force spectroscopy experiments revealed the requirement for negatively charged phospholipids for VSV binding to membranes, suggesting that this interaction is electrostatic in nature. In addition, ITC experiments showed that VSV binding to liposomes is an enthalpically driven process. Fluorescence data also showed the lack of VSV interaction with the vesicles as well as inhibition of VSV-induced membrane fusion at high ionic strength. Intrinsic fluorescence measurements showed that the extent of G protein conformational changes depends on the presence of phosphatidylserine (PS) on the target membrane. Although the increase in PS content did not change the binding profile, the rate of the fusion reaction was remarkably increased when the PS content was increased from 25 to 75%. On the basis of these data, we suggest that G protein binding to the target membrane essentially depends on electrostatic interactions, probably between positive charges on the protein surface and negatively charged phospholipids in the cellular membrane. In addition, the fusion is exothermic, indicating no entropic constraints to this process.
Respiratory Syncytial Virus (RSV) Nonstructural (NS) Proteins as Host Range Determinants: a Chimeric Bovine RSV with NS Genes from Human RSV Is Attenuated in Interferon-Competent Bovine Cells
Authors: Bossert Birgit , Conzelmann Karl-Klaus 
Published: July 2002

ABSTRACTBovine respiratory syncytial virus (BRSV) escapes from cellular responses to alpha/beta interferon (IFN-α/β) by a concerted action of the two viral nonstructural proteins, NS1 and NS2. Here we show that the NS proteins of human RSV (HRSV) are also able to counteract IFN responses and that they have the capacity to protect replication of an unrelated rhabdovirus. Even combinations of BRSV and HRSV NS proteins showed a protective activity, suggesting common mechanisms and cellular targets of HRSV and BRSV NS proteins. Although able to cooperate, NS proteins from BRSV and HRSV showed differential protection capacity in cells from different hosts. A chimeric BRSV with HRSV NS genes (BRSV h1/2) was severely attenuated in bovine IFN competent MDBK and Klu cells, whereas it replicated like BRSV in IFN-incompetent Vero cells or in IFN-competent human HEp-2 cells. After challenge with exogenous IFN-α, BRSV h1/2 was better protected than wild-type BRSV in human HEp-2 cells. In contrast, in cells of bovine origin, BRSV h1/2 was much less resistant to exogenous IFN than wild-type BRSV. These data demonstrate that RSV NS1 and NS2 proteins are major determinants of host range. The differential IFN escape capacity of RSV NS proteins in cells from different hosts provides a basis for rational development of attenuated live RSV vaccines.
Reactions of Carbonyl Compounds in Basic Solutions. Part 34. The Mechanism of the Base-Catalysed Ring Fission of 2,3-Diphenylcycloprop-2-en-1-one
Authors: Bowden Keith , Burgess Emma J. 
Published: July 2002

The rate coefficients for the base-catalysed ring fission of a series of 2-phenyl-3-(2-, 3- or 4-substituted phenyl)cycloprop-2-en-1-ones to give the corresponding (E)-2,3-diphenylacrylic acids have been determined in water at 30.0 °C, as well as for the unsubstituted compound at 40.0, 50.0 and 60.0 °C. The effects of meta- and para-substituents on the rates have been correlated using the Hammett equation to give a reaction constant, ρ, equal to ca 1.2 at 30 °C. For the unsubstituted compound, the activation parameters have been calculated and the kinetic solvent isotope effect has been studied. The effects of ortho-substituents on the rates appear to be mainly polar, rather than steric, in origin. The evidence indicates a mechanistic pathway which proceeds by addition of hydroxide anion to the ketone, which is rate-determining. The adduct suffers ring fission to give the final product via a carbanionic intermediate.