bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cross-Reactive, Cell-Mediated Immunity and Protection of Chickens from Lethal H5N1 Influenza Virus Infection in Hong Kong Poultry Markets
Authors: Seo Sang Heui , Webster Robert G. 
Published: July 2002

ABSTRACTIn 1997, avian H5N1 influenza virus transmitted from chickens to humans resulted in 18 confirmed infections. Despite harboring lethal H5N1 influenza viruses, most chickens in the Hong Kong poultry markets showed no disease signs. At this time, H9N2 influenza viruses were cocirculating in the markets. We investigated the role of H9N2 influenza viruses in protecting chickens from lethal H5N1 influenza virus infections. Sera from chickens infected with an H9N2 influenza virus did not cross-react with an H5N1 influenza virus in neutralization or hemagglutination inhibition assays. Most chickens primed with an H9N2 influenza virus 3 to 70 days earlier survived the lethal challenge of an H5N1 influenza virus, but infected birds shed H5N1 influenza virus in their feces. Adoptive transfer of T lymphocytes or CD8+T cells from inbred chickens (B2/B2) infected with an H9N2 influenza virus to naive inbred chickens (B2/B2) protected them from lethal H5N1 influenza virus. In vitro cytotoxicity assays showed that T lymphocytes or CD8+T cells from chickens infected with an H9N2 influenza virus recognized target cells infected with either an H5N1 or H9N2 influenza virus in a dose-dependent manner. Our findings indicate that cross-reactive cellular immunity induced by H9N2 influenza viruses protected chickens from lethal infection with H5N1 influenza viruses in the Hong Kong markets in 1997 but permitted virus shedding in the feces. Our findings are the first to suggest that cross-reactive cellular immunity can change the outcome of avian influenza virus infection in birds in live markets and create a situation for the perpetuation of H5N1 influenza viruses.
Antibody Binding and Neutralization of Primary and T-Cell Line-Adapted Isolates of Human Immunodeficiency Virus Type 1
Authors: York Joanne , Follis Kathryn E. , Trahey Meg , Nyambi Phillipe N. , Zolla-Pazner Susan , Nunberg Jack H. 
Published: July 2002

ABSTRACTThe relative resistance of human immunodeficiency virus type 1 (HIV-1) primary isolates (PIs) to neutralization by a wide range of antibodies remains a theoretical and practical barrier to the development of an effective HIV vaccine. One model to account for the differential neutralization sensitivity between Pls and laboratory (or T-cell line-adapted [TCLA]) strains of HIV suggests that the envelope protein (Env) complex is made more accessible to antibody binding as a consequence of adaptation to growth in established cell lines. Here, we revisit this question using genetically related PI and TCLA viruses and molecularly clonedenvgenes. By using complementary techniques of flow cytometry and virion binding assays, we show that monoclonal antibodies targeting the V3 loop, CD4-binding site, CD4-induced determinant of gp120, or the ectodomain of gp41 bind equally well to PI and TCLA Env complexes, despite large differences in neutralization outcome. The data suggest that the differential neutralization sensitivity of PI and TCLA viruses may derive not from differences in the initial antibody binding event but rather from differences in the subsequent functioning of the PI and TCLA Envs during virus entry. An understanding of these as yet undefined differences may enhance our ability to generate broadly neutralizing HIV vaccine immunogens.
Lentivirus Vector-Mediated Hematopoietic Stem Cell Gene Transfer of Common Gamma-Chain Cytokine Receptor in Rhesus Macaques
Authors: An Dong Sung , Kung Sam K. P. , Bonifacino Aylin , Wersto Robert P. , Metzger Mark E. , Agricola Brian A. , Mao Si Hua , Chen Irvin S. Y. , Donahue Robert E. 
Published: July 2002

ABSTRACT

Nonhuman primate model systems of autologous CD34
+
cell transplant are the most effective means to assess the safety and capabilities of lentivirus vectors. Toward this end, we tested the efficiency of marking, gene expression, and transplant of bone marrow and peripheral blood CD34
+
cells using a self-inactivating lentivirus vector (CS-Rh-MLV-E) bearing an internal murine leukemia virus long terminal repeat derived from a murine retrovirus adapted to replicate in rhesus macaques. In vitro cytokine stimulation was not required to achieve efficient transduction of CD34
+
cells resulting in marking and gene expression of the reporter gene encoding enhanced green fluorescent protein (EGFP) following transplant of the CD34
+
cells. Monkeys transplanted with mobilized peripheral blood CD34
+
cells resulted in EGFP expression in 1 to 10% of multilineage peripheral blood cells, including red blood cells and platelets, stable for 15 months to date. The relative level of gene expression utilizing this vector is 2- to 10-fold greater than that utilizing a non-self-inactivating lentivirus vector bearing the cytomegalovirus immediate-early promoter. In contrast, in animals transplanted with autologous bone marrow CD34
+
cells, multilineage EGFP expression was evident initially but diminished over time. We further tested our lentivirus vector system by demonstrating gene transfer of the human common gamma-chain cytokine receptor gene (γ
c
), deficient in X-linked SCID patients and recently successfully used to treat disease. Marking was 0.42 and .001 HIV-1 vector DNA copy per 100 cells in two animals. To date, all EGFP- and γ
c
-transplanted animals are healthy. This system may prove useful for expression of therapeutic genes in human hematopoietic cells.
Genetic Analysis of a Poliovirus/Hepatitis C Virus Chimera: New Structure for Domain II of the Internal Ribosomal Entry Site of Hepatitis C Virus
Authors: Zhao Wei Dong , Wimmer Eckard 
Published: July 2002

ABSTRACT

Internal ribosomal entry sites (IRESs) of certain plus-strand RNA viruses direct cap-independent initiation of protein synthesis both in vitro and in vivo, as can be shown with artificial dicistronic mRNAs or with chimeric viral genomes in which IRES elements were exchanged from one virus to another. Whereas IRESs of picornaviruses can be readily analyzed in the context of their cognate genome by genetics, the IRES of hepatitis C virus (HCV), a
Hepacivirus
belonging to
Flaviviridae
, cannot as yet be subjected to such analyses because of difficulties in propagating HCV in tissue culture or in experimental animals. This enigma has been overcome by constructing a poliovirus (PV) whose translation is controled by the HCV IRES. Within the PV/HCV chimera, the HCV IRES has been subjected to systematic 5′ deletion analyses to yield a virus (P/H710-d40) whose replication kinetics match that of the parental poliovirus type 1 (Mahoney). Genetic analyses of the HCV IRES in P/H710-d40 have confirmed that the 5′ border maps to domain II, thereby supporting the validity of the experimental approach applied here. Additional genetic experiments have provided evidence for a novel structural region within domain II. Arguments that the phenotypes observed with the mutant chimera relate solely to impaired genome replication rather than deficiencies in translation have been dispelled by constructing novel dicistronic poliovirus replicons with the gene order [PV]cloverleaf-[HCV]IRES-Δcore-
R-Luc
-[PV]IRES-
F-Luc
-P2,3-3′NTR, which have allowed the measurement of HCV IRES-dependent translation independently from the replication of the replicon RNA.
Human Immunodeficiency Virus Type 1 Particles Pseudotyped with Envelope Proteins That Fuse at Low pH No Longer Require Nef for Optimal Infectivity
Authors: Chazal Nathalie , Singer Gregory , Aiken Christopher , Hammarskjöld Marie-Louise , Rekosh David 
Published: July 2002

ABSTRACT
We have investigated the effects of Nef on infectivity in the context of various viral envelope proteins. These experiments were performed with a minimal vector system where Nef is the only accessory protein present. Our results support the hypothesis that the route of entry influences the ability of Nef to enhance human immunodeficiency virus (HIV) infectivity. We show that HIV particles pseudotyped with Ebola virus glycoprotein or vesicular stomatitis virus glycoprotein (VSV-G), which fuse at low pH, do not require Nef for optimal infectivity. In contrast, Nef significantly enhances the infectivity of virus particles that contain envelope proteins that fuse at neutral pH (CCR5-dependent HIV Env, CXCR4-dependent HIV Env, or amphotropic murine leukemia virus Env). In addition, our results demonstrate that virus particles containing mixed CXCR4-dependent HIV and VSV-G envelope proteins show a conditional requirement for Nef for optimal infectivity, depending on which protein is allowed to facilitate entry.
Inhibition of Host Transcription by Vesicular Stomatitis Virus Involves a Novel Mechanism That Is Independent of Phosphorylation of TATA-Binding Protein (TBP) or Association of TBP with TBP-Associated Factor Subunits
Authors: Yuan Hang , Puckett Shelby , Lyles Douglas S. 
Published: July 2002

ABSTRACT
The matrix (M) protein of vesicular stomatitis virus (VSV) is a potent inhibitor in vivo of transcription by all three host RNA polymerases (RNAP). In the case of host RNA polymerase II (RNAPII), the inhibition is due to lack of activity of the TATA-binding protein (TBP), which is a subunit of the basal transcription factor TFIID. Despite the potency of M protein-induced inhibition in vivo, experiments presented here show that M protein cannot directly inactivate TFIID in vitro. Addition of M protein to nuclear extracts from uninfected cells did not inhibit transcription activity, indicating that the inhibition is indirect and is mediated through host factors. The host factors that are known to regulate TBP activity include phosphorylation by host kinases and association with different TBP-associated factor (TAF) subunits. However, TBP in VSV-infected cells was found to be assembled normally with its TAF subunits, as shown by ion exchange high-pressure liquid chromatography and sedimentation velocity analysis. A normal pattern of phosphorylation of TBP in VSV-infected cells was also observed by pH gradient gel electrophoresis. Collectively, these data indicate that M protein inactivates TBP activity in RNAPII-dependent transcription by a novel mechanism, since the known mechanisms for regulating TBP activity cannot account for the inhibition.
Association of Herpes Simplex Virus Type 1 ICP8 and ICP27 Proteins with Cellular RNA Polymerase II Holoenzyme
Authors: Zhou Changhong , Knipe David M. 
Published: July 2002

ABSTRACT

Herpes simplex virus 1 (HSV-1) infection causes the shutoff of host gene transcription and the induction of a transcriptional program of viral gene expression. Cellular RNA polymerase II is responsible for transcription of all the viral genes, but several viral proteins stimulate viral gene transcription. ICP4 is required for all delayed-early and late gene transcription, ICP0 stimulates transcription of viral genes, and ICP27 stimulates expression of some early genes and transcription of at least some late viral genes. The early DNA-binding protein, ICP8, also stimulates late gene transcription. We therefore investigated which HSV proteins interact with RNA polymerase II. Using immunoprecipitation and Western blotting methods, we observed the coprecipitation of ICP27 and ICP8 with RNA polymerase II holoenzyme. The association of ICP27 with RNA polymerase II was detectable as early as 3 h postinfection, while ICP8 association became evident by 5 h postinfection, and the association of both was independent of viral DNA synthesis. Infections with
ICP27
gene mutant viruses revealed that ICP27 is required for the association of ICP8 with RNA polymerase II, while studies with
ICP8
gene deletion mutants showed no apparent role for ICP8 in the association of ICP27 with RNA polymerase II. The association of ICP27 and ICP8 with RNA polymerase II holoenzyme appeared to be independent of nucleic acids. We hypothesize that the interaction of ICP27 with RNA polymerase II holoenzyme reflects its role in stimulating early and late gene expression and/or its role in inhibiting host transcription and that the interaction of ICP8 with RNA polymerase II holoenzyme reflects its role in stimulating late gene transcription.
A Variable Region 3 (V3) Mutation Determines a Global Neutralization Phenotype and CD4-Independent Infectivity of a Human Immunodeficiency Virus Type 1 Envelope Associated with a Broadly Cross-Reactive, Primary Virus-Neutralizing Antibody Response
Authors: Zhang Peng Fei , Bouma Peter , Park Eun Ju , Margolick Joseph B. , Robinson James E. , Zolla-Pazner Susan , Flora Michael N. , Quinnan Gerald V. 
Published: July 2002

ABSTRACTThe human serum human immunodeficiency virus type 1 (HIV-1)-neutralizing serum 2 (HNS2) neutralizes many primary isolates of different clades of HIV-1, and virus expressing envelope from the same donor, clone R2, is neutralized cross-reactively by HIV-immune human sera. The basis for this cross-reactivity was investigated. It was found that a rare mutation in the proximal limb of variable region 3 (V3), 313-4 PM, caused virus pseudotyped with the R2 envelope to be highly sensitive to neutralization by monoclonal antibodies (MAbs) directed against conformation-sensitive epitopes at the tip of the V3 loop, such as 19b, and moderately sensitive to MAbs against CD4 binding site (CD4bs) and CD4-induced (CD4i) epitopes, soluble CD4 (sCD4), and HNS2. In addition, introduction of this sequence by mutagenesis caused enhanced sensitivity to neutralization by 19b, anti-CD4i MAb, and HNS2 in three other primary HIV-1 envelopes and by anti-CD4bs MAb and sCD4 in one of the three. The 313-4 PM sequence also conferred increased infectivity for CD4+CCR5+cells and the ability to infect CCR5+cells upon all of these four and two of these four HIV-1 envelopes, respectively. Neutralization of R2 by HNS2 was substantially inhibited by the cyclized R2 V3 35-mer synthetic peptide. Similarly, the peptide also had some lesser efficacy in blocking neutralization of R2 by other sera or of neutralization of other primary viruses by HNS2. Together, these results indicate that the unusual V3 mutation in the R2 clone accounts for its uncommon neutralization sensitivity phenotype and its capacity to mediate CD4-independent infection, both of which could relate to immunogenicity and the neutralizing activity of HNS2. This is also the first primary HIV-1 isolate envelope glycoprotein found to be competent for CD4-independent infection.
RelB Nuclear Translocation Mediated by C-Terminal Activator Regions of Epstein-Barr Virus-Encoded Latent Membrane Protein 1 and Its Effect on Antigen-Presenting Function in B Cells
Authors: Pai Saparna , O'Sullivan Brendan J. , Cooper Leanne , Thomas Ranjeny , Khanna Rajiv 
Published: July 2002

ABSTRACT
Previous studies have shown that Epstein-Barr virus-encoded latent membrane protein 1 (LMP1) is uniquely able to up-regulate the expression of the peptide transporters (referred to as TAP-1 and TAP-2) and major histocompatibility complex (MHC) class I in Burkitt's lymphoma (BL) cell lines. This up-regulation is often accompanied by a restoration of antigen-presenting function as measured by the ability of these cells to present endogenously expressed viral antigen to cytotoxic T lymphocytes. Here we show that the expression of LMP1 resulted in up-regulation and nuclear translocation of RelB that were coincident with increased expression of MHC class I in BL cells. Deletion of the C-terminal activator regions (CTARs) of LMP1 significantly impaired the abilities of LMP1 to translocate RelB into the nucleus and to up-regulate the expression of antigen-processing genes. Further analysis with single-point mutations within the CTARs confirmed that the residues critical for NF-κB activation directly contribute to antigen-processing function regulation in BL cells. This LMP1-mediated effect was blocked following expression of either dominant negative IκBα S32/36A, an NF-κB inhibitor, or antisense RelB. These observations indicate that upregulation of antigen-presenting function in B cells mediated by LMP1 is signaled through the NF-κB subunit RelB. The data provide a mechanism by which LMP1 modulates immunogenicity of Epstein-Barr virus-infected normal and malignant cells.
Expression of Herpes Simplex Virus ICP0 Inhibits the Induction of Interferon-Stimulated Genes by Viral Infection
Authors: Eidson Kasey M. , Hobbs William E. , Manning Brian J. , Carlson Paul , DeLuca Neal A. 
Published: July 2002

ABSTRACTThe herpes simplex virus type 1 (HSV-1) mutantd109 does not express any of the immediate-early (IE) proteins and persists in cells for a prolonged length of time. As has been shown by Nicholl et al. (J. Gen. Virol. 81:2215-2218, 2000) and Mossman et al. (J. Virol. 75:750-758, 2001) using other mutants defective for IE gene expression, infection withd109 induced the expression of a number of interferon-stimulated genes. Induction of these genes was significantly greater at multiplicities of infection (MOI) of 10 PFU/cell or greater, and the resulting antiviral effect was only seen at MOIs greater than 10 PFU/cell. Using mutants defective for sets of IE genes established that the lack of ICP0 expression was necessary for high levels of interferon-stimulated gene expression in HEL cells. The induction of interferon-stimulated genes byd109 could also be inhibited by infection with an E1−:E3−:E4− adenovirus expressing levels of ICP0 that are comparable to those expressed within the first hour of wild-type virus infection. Lastly, the addition of the proteasome inhibitor MG132 to cells infected with a mutant that expresses ICP0,d106, also resulted in the induction of interferon-stimulated genes. Thus, ICP0 may function through the proteasome very early in HSV infection to inhibit a cellular antiviral response induced by the virion.
Distinct Roles of Adenovirus Vector-Transduced Dendritic Cells, Myoblasts, and Endothelial Cells in Mediating an Immune Response against a Transgene Product
Authors: Mercier Stéphanie , Gahéry-Segard Hanne , Monteil Martine , Lengagne Renée , Guillet Jean-Gérard , Eloit Marc , Denesvre Caroline 
Published: July 2002

ABSTRACTAdenovirus-mediated gene delivery via the intramuscular route efficiently promotes an immune response against the transgene product. In this study, a recombinant adenovirus vector encoding β-galactosidase (AdβGal) was used to transduce dendritic cells (DC), which are antigen-presenting cells, as well as myoblasts and endothelial cells (EC), neither of which present antigens. C57BL/6 mice received a single intramuscular injection of AdβGal-transduced DC, EC, or myoblasts and were then monitored for anti-β-galactosidase (anti-β-Gal) antibody production, induction of gamma interferon-secreting CD8+T cells, and protection against melanoma tumor cells expressing β-Gal. While all transduced cell types were able to elicit an antibody response against the transgene product, the specific isotypes were distinct, with exclusive production of immunoglobulin G2a (IgG2a) antibodies following injection of transduced DC and EC versus equivalent IgG1 and IgG2a responses in mice inoculated with transduced myoblasts. Transduced DC induced a strong ex vivo CD8+T-cell response at a level of 50% of the specific response obtained with the AdβGal control. In contrast, this response was 6- to 10-fold-lower in animals injected with transduced myoblasts and EC. Accordingly, only animals injected with transduced DC were protected against a β-Gal tumor challenge. Thus, in order to induce a strong and protective immune response to an adenovirus-encoded transgene product, it is necessary to transduce cells of dendritic lineage. Importantly, it will be advantageous to block the transduction of DC for adenovirus-based gene therapy strategies.
Amperometric Enzyme Electrodes for Substrates of Immobilized Pyranose Oxidase
Authors: Petřivalský Marek , Skládal Petr , Macholán Lumír , Volc Jindřich 
Published: July 2002

Two kinds of biosensors for the determination of pyranose oxidase substrates were developed, based on the detection of evolving hydrogen peroxide on a platinum or platinized graphite electrode at +650 or +400 mV, respectively. The membranes consisted of enzyme immobilized by covalent bonds on nylon net and were stable for 8 months of dry storage at 4 °C. In addition to D-glucose, low concentrations of D-xylose, D-galactose and L-sorbose can also be measured with the biosensor. The shift of the optimum pH of the immobilized enzyme to the alkaline region (8.0 - 9.5) is convenient for the borate buffer medium which extends the linear concentration region of the biosensor to 15 mmol l-1 for D-galactose, 30 mmol l-1 for D-xylose and 30 mmol l-1 for maltose. L-Sorbose provides no response up to a concentration of 10 mmol l-1 in 0.05 M borate and up to a concentration of 30 mmol l-1 in 0.2 M borate at pH 9.2. Interfering D-glucose was eliminated up to 2.5 mmol l-1 by means of an enzyme pre-membrane with immobilized hexokinase. The effect of ascorbate was eliminated, up to 75 mmol l-1, by using a cellulose acetate electrostatic barrier. D-Galactose, however, decreases the sensor response to D-glucose.
Continuous Precipitation of Lead Iodide
Authors: Žáček Stanislav , Nývlt Jaroslav 
Published: July 2002

Lead iodide was precipitated from aqueous solutions of 0.015 - 0.1 M Pb(NO3)2 and 0.03 - 0.2 M KI in the equimolar ratio using a laboratory model of a stirred continuous crystallizer at 22 °C. After reaching the steady state, the PbI2 crystal size distribution was measured sedimentometrically and the crystallization kinetics was evaluated based on the mean particle size. Both the linear crystal growth rate and the nucleation rate depend on the specific output of the crystallizer. The system crystallization constant either points to a significant effect of secondary nucleation by the mechanism of contact of the crystals with the stirrer blade, or depends on the concentrations of the components added due to the micromixing mechanism.
Hyperhomocysteinaemia and MTHFR C677T gene polymorphism in renal transplant recipients
Authors: Szabó A J , Tulassay T , Melegh B , Szabó T , Szabó A , Vannay Á , Fekete A , Süveges Z , Reusz G S 
Published: July 2002

AIMTo study the effect of folate treatment on hyperhomocysteinaemia and the effect of 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism on total homocysteine and folate concentrations after renal transplantation.METHODSA total of 30 transplanted children and adolescents were investigated for total homocysteine and folate serum concentrations before and after folate treatment, as well as for the presence of the MTHFR C677T polymorphism.RESULTSThe allele frequency of C677T polymorphism in the MTHFR gene in the study population (0.33) was not different to that in controls (0.38). Before folate treatment the homocysteine concentration was raised in all groups; following folate supplementation it was significantly decreased in the CC and CT groups, but not in the TT group. In patients with CC genotype, serum homocysteine correlated with serum creatinine and cholesterol, and time since transplantation before treatment.CONCLUSIONFolate supplementation appears to be an effective strategy to normalise total homocysteine concentration in renal transplanted children and adolescents.