bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression and Function of Chemokine Receptors on Human Thymocytes: Implications for Infection by Human Immunodeficiency Virus Type 1
Authors: Taylor James R. , Kimbrell Katherine C. , Scoggins Robert , Delaney Marie , Wu Lijun , Camerini David 
Published: July 2002

ABSTRACTThe presence or absence of the receptor CD4 and the coreceptors CCR5 and CXCR4 restrict the cell tropism of human immunodeficiency virus type 1 (HIV-1). Despite the importance of thymic infection by HIV-1, conflicting reports regarding the expression of HIV-1 coreceptors on human thymocytes have not been resolved. We assayed the expression and function of the major HIV-1 coreceptors, CCR5 and CXCR4, as well as CCR4 and CCR7 as controls, on human thymocytes. We detected CCR5 on 2.5% of thymocytes, CXCR4 on 53% of the cells, and CCR4 on 16% and CCR7 on 11% of human thymocytes. Moreover, infection by R5 HIV-1 did not significantly induce expression of CCR5. We found that two widely used anti-CCR5 monoclonal antibodies cross-reacted with CCR8, which may account for discrepancies among published reports of CCR5 expression on primary cells. This cross-reactivity could be eliminated by deletion of amino acids 2 through 4 of CCR8. Chemotaxis assays showed that SDF-1, which binds CXCR4; MDC, which binds CCR4; and ELC, which binds CCR7, mediated significant chemotaxis of thymocytes. In contrast, MIP-1β, whose receptor is CCR5, did not induce significant chemotaxis. Our results indicate that CXCR4, CCR4, CCR7, and their chemokine ligands may be involved in thymocyte migration during development in the thymus. CCR5 and its ligands, however, are likely not involved in these processes. Furthermore, the pattern of CCR5 and CXCR4 expression that we found may explain the greater susceptibility of human thymocytes to infection by HIV-1 isolates capable of using CXCR4 in cell entry compared to those that use only CCR5.
The Synthetic Peptide P-197 Inhibits Human T-Cell Leukemia Virus Type 1 Envelope-Mediated Syncytium Formation by a Mechanism That Is Independent of Hsc70
Authors: Brighty David W. , Jassal Sushma R. 
Published: July 2002

ABSTRACT
Entry of human T-cell leukemia virus type 1 (HTLV-1) into cells is mediated by the viral envelope glycoproteins gp46 and gp21. The gp46 surface glycoprotein binds to a poorly characterized cell surface receptor, thereby promoting the gp21-dependent fusion of the viral and cellular membranes. Interestingly, a synthetic peptide (P-197) simulating amino acids 197 to 216 of gp46 strongly inhibits envelope-dependent membrane fusion with Molt-4 target cells. It has been suggested that this peptide acts by competitively binding to Hsc70, a putative cellular receptor for HTLV-1. We now demonstrate that P-197 inhibits membrane fusion among diverse HTLV-1-permissive target cells. Importantly, most of these cells lack detectable levels of Hsc70, indicating that P-197 inhibits membrane fusion by a mechanism that is Hsc70 independent. We now suggest that competition for primary receptor binding is unlikely to account for the inhibitory activity of P-197. Understanding the mechanism by which P-197 functions may reveal concepts of general relevance to antiretroviral chemotherapy.
Widespread Gene Delivery and Structure-Specific Patterns of Expression in the Brain after Intraventricular Injections of Neonatal Mice with an Adeno-Associated Virus Vector
Authors: Passini Marco A. , Wolfe John H. 
Published: July 2002

ABSTRACT
Developing a system for widespread somatic gene transfer in the central nervous system (CNS) would be beneficial for understanding the global influence of exogenous genes on animal models. We injected an adeno-associated virus serotype 2 (AAV2) vector into the cerebral lateral ventricles at birth and mapped its distribution and transduction pattern from a promoter capable of expression in multiple targets. The injections resulted in structure-specific patterns of expression that were maintained for at least 1 year in most regions, with efficient targeting of some of the major principal neuron layers. The patterns of transduction were explained by circulation of the viral vector in the subarachnoid space via CSF flow, followed by transduction of underlying structures, rather than by progenitor cell infection and subsequent migration. This study demonstrates that gene transfer throughout the CNS can be achieved without germ line transmission and establishes an experimental strategy for introducing genes to somatic cells in a highly predictable manner.
Sorting of Marburg Virus Surface Protein and Virus Release Take Place at Opposite Surfaces of Infected Polarized Epithelial Cells
Authors: Sänger Christian , Mühlberger Elke , Ryabchikova Elena , Kolesnikova Larissa , Klenk Hans-Dieter , Becker Stephan 
Published: July 2002

ABSTRACT
Marburg virus, a filovirus, causes severe hemorrhagic fever with hitherto poorly understood molecular pathogenesis. We have investigated here the vectorial transport of the surface protein GP of Marburg virus in polarized epithelial cells. To this end, we established an MDCKII cell line that was able to express GP permanently (MDCK-GP). The functional integrity of GP expressed in these cells was analyzed using vesicular stomatitis virus pseudotypes. Further experiments revealed that GP is transported in MDCK-GP cells mainly to the apical membrane and is released exclusively into the culture medium facing the apical membrane. When MDCKII cells were infected with Marburg virus, the majority of GP was also transported to the apical membrane, suggesting that the protein contains an autonomous apical transport signal. Release of infectious progeny virions, however, took place exclusively at the basolateral membrane of the cells. Thus, vectorial budding of Marburg virus is presumably determined by factors other than the surface protein.
Protein-DNA Binding and CpG Methylation at Nucleotide Resolution of Latency-Associated Promoters Qp, Cp, and LMP1p of Epstein-Barr Virus
Authors: Salamon Daniel , Takacs Maria , Ujvari Dorina , Uhlig Jörg , Wolf Hans , Minarovits Janos , Niller Hans Helmut 
Published: July 2002

ABSTRACT
Epstein-Barr viral (EBV) latency-associated promoters Qp, Cp, and LMP1p are crucial for the regulated expression of the EBNA and LMP transcripts in dependence of the latency type. By transient transfection and in vitro binding analyses, many promoter elements and transcription factors have previously been shown to be involved in the activities of these promoters. However, the latency promoters have only partially been examined at the nucleotide level in vivo. Therefore, we undertook a comprehensive analysis of in vivo protein binding and CpG methylation patterns at these promoters in five representative cell lines and correlated the results with the known in vitro binding data and activities of these promoters from previous transfection experiments. Promoter activity inversely correlated with the methylation state of promoters, although Qp was a remarkable exception. Novel protein binding data were obtained for all promoters. For Cp, binding correlated well with promoter activity; for LMP1p and Qp, binding patterns looked similar regardless of promoter activity.
Modified FGF4 Signal Peptide Inhibits Entry of Herpes Simplex Virus Type 1
Authors: Bultmann Hermann , Busse James S. , Brandt Curtis R. 
Published: July 2002

ABSTRACTEntry of herpes simplex virus type 1 (HSV-1) into host cells occurs through fusion of the viral envelope with the plasma membrane and involves complex and poorly understood interactions between several viral and cellular proteins. One strategy for dissecting the function of this fusion machine is through the use of specific inhibitors. We identified a peptide with antiviral activity that blocks HSV-1 infection at the entry stage and during cell-to-cell spreading. This peptide (called EB for “entry blocker”) consists of the FGF4 signal sequence with an RRKK tetramer at the amino terminus to improve solubility. The activity of EB depends exclusively but not canonically on the signal sequence. Inhibition of virus entry (hrR3) and plaque formation (KOS) strongly depend on virus concentrations and serum addition, with 50% inhibitory concentrations typically ranging from 1 to 10 μM. Blocking preadsorbed virus requires higher EB concentrations. Cytotoxic effects (trypan blue exclusion) are first noted at 50 μM EB in serum-free medium and at ≥200 μM in the presence of serum. EB does not affect gC-dependent mechanisms of virus attachment and does not block virus attachment at 4°C. Instead, EB directly interacts with virions and inactivates them irreversibly without, however, disrupting their physical integrity as judged by electron microscopy. At subvirucidal concentrations, EB changes the adhesive properties of virions, causing aggregation at high virus concentrations. This peptide may be a useful tool for studying viral entry mechanisms.
Multiple Groups of Novel Retroviral Genomes in Pigs and Related Species
Authors: Patience Clive , Switzer William M. , Takeuchi Yasuhiro , Griffiths David J. , Goward Melanie E. , Heneine Walid , Stoye Jonathan P. , Weiss Robin A. 
Published: July 2002

ABSTRACT

In view of the concern over potential infection hazards in the use of porcine tissues and organs for xenotransplantation to humans, we investigated the diversity of porcine endogenous retrovirus (PERV) genomes in the DNA of domestic pigs and related species. In addition to the three known envelope subgroups of infectious gamma retroviruses (PERV-A, -B, and -C), classed together here as PERV group γ1, four novel groups of gamma retrovirus (γ2 to γ5) and four novel groups of beta retrovirus (β1 to β4) genomes were detected in pig DNA using generic and specific PCR primers. PCR quantification indicated that the retroviral genome copy number in the Landrace × Duroc F
1
hybrid pig ranged from 2 (β2 and γ5) to approximately 50 (γ1). The γ1, γ2, and β4 genomes were transcribed into RNA in adult kidney tissue. Apart from γ1, the retroviral genomes are not known to be infectious, and sequencing of a small number of amplified genome fragments revealed stop codons in putative open reading frames in several cases. Analysis of DNA from wild boar and other species of Old World pigs (
Suidae
) and New World peccaries (
Tayassuidae
) showed that one retrovirus group, β2, was common to all species tested, while the others were present among all Old World species but absent from New World species. The PERV-C subgroup of γ1 genomes segregated among domestic pigs and were absent from two African species (red river hog and warthog). Thus domestic swine and their phylogenetic relatives harbor multiple groups of hitherto undescribed PERV genomes.
Efficient Translation Initiation Is Required for Replication of Bovine Viral Diarrhea Virus Subgenomic Replicons
Authors: Myers Tina M. , Kolupaeva Victoria G. , Mendez Ernesto , Baginski Scott G. , Frolov Ilya , Hellen Christopher U. T. , Rice Charles M. 
Published: July 2002

ABSTRACT

An internal ribosome entry site (IRES) mediates translation initiation of bovine viral diarrhea virus (BVDV) RNA. Studies have suggested that a portion of the N
pro
open reading frame (ORF) is required, although its exact function has not been defined. Here we show that a subgenomic (sg) BVDV RNA in which the NS3 ORF is preceded only by the 5′ nontranslated region did not replicate to detectable levels following transfection. However, RNA synthesis and cytopathic effects were observed following serial passage in the presence of a noncytopathic helper virus. Five sg clones derived from the passaged virus contained an identical, silent substitution near the beginning of the NS3 coding sequence (G400U), as well as additional mutations. Four of the reconstructed mutant RNAs replicated in transfected cells, and in vitro translation showed increased levels of NS3 for the mutant RNAs compared to that of wild-type (wt) MetNS3. To more precisely dissect the role of these mutations, we constructed two sg derivatives: ad3.10, which contains only the G400U mutation, and ad3.7, with silent substitutions designed to minimize RNA secondary structure downstream of the initiator AUG. Both RNAs replicated and were translated in vitro to similar levels. Moreover, ad3.7 and ad3.10, but not wt MetNS3, formed toeprints downstream of the initiator AUG codon in an assay for detecting the binding of 40S ribosomal subunits and 43S ribosomal complexes to the IRES. These results suggest that a lack of stable RNA secondary structure(s), rather than a specific RNA sequence, immediately downstream of the initiator AUG is important for optimal translation initiation of pestivirus RNAs.
Analysis of an
Autographa californica
Multicapsid Nucleopolyhedrovirus
lef-6
-Null Virus: LEF-6 Is Not Essential for Viral Replication but Appears To Accelerate Late Gene Transcription
Authors: Lin Guangyun , Blissard Gary W. 
Published: July 2002

ABSTRACT

The
Autographa californica
multicapsid nucleopolyhedrovirus (Ac
M
NPV)
lef-6
gene was previously shown to be necessary for optimal transcription from an Ac
M
NPV late promoter in transient late expression assays. In the present study, we examined the expression and cellular localization of
lef-6
during the Ac
M
NPV infection cycle and generated a
lef-6
-null virus for studies of the role of
lef-6
in the infection cycle. Transcription of
lef-6
was detected from 4 to 48 h postinfection, and the LEF-6 protein was identified in dense regions of infected cell nuclei, a finding consistent with its potential role as a late transcription factor. To examine
lef-6
in the context of the Ac
M
NPV infection cycle, we deleted the
lef-6
gene from an Ac
M
NPV genome propagated as an infectious BACmid in
Escherichia coli
. Unexpectedly, the resulting Ac
M
NPV
lef-6
-null BACmid (vAc
lef6KO
) was able to propagate in cell culture, although virus yields were substantially reduced. Thus, the
lef-6
gene is not essential for viral replication in Sf9 cells. Two “repair” Ac
M
NPV BACmids (vAc
lef6KO-REP-P
and vAc
lef6KO-REP-ie1P
) were generated by transposition of the
lef-6
gene into the polyhedrin locus of the vAc
lef6KO
BACmid. Virus yields from the two repair viruses were similar to those from wild-type Ac
M
NPV or a control (BACmid-derived) virus. The
lef-6
-null BACmid (vAc
lef6KO
) was further examined to determine whether the deletion of
lef-6
affected DNA replication or late gene transcription in the context of an infection. The
lef-6
deletion did not appear to affect viral DNA replication. Using Northern blot analysis, we found that although early transcription was apparently unaffected, both late and very late transcription were delayed in cells infected with the
lef-6
-null BACmid. This phenotype was rescued in viruses containing the
lef-6
gene reinserted into the
polyhedrin
locus. Thus, the
lef-6
gene was not essential for either viral DNA replication or late gene transcription, but the absence of
lef-6
resulted in a substantial delay in the onset of late transcription. Therefore,
lef-6
appears to accelerate the infection cycle of Ac
M
NPV.
Targeting and Hematopoietic Suppression of Human CD34+Cells by Measles Virus
Authors: Manchester Marianne , Smith Kent A. , Eto Danelle S. , Perkin Hugh B. , Torbett Bruce E. 
Published: July 2002

ABSTRACTThe major cause of mortality in measles is generalized suppression of cell-mediated immunity that persists following virus clearance and results in secondary infections. The mechanisms contributing to this long-term immunosuppression are not clear. Herein we present evidence that measles virus (MV) disrupts hematopoiesis by infecting human CD34+cells and human bone marrow stroma. MV infection does not affect the hematopoietic capability of hematopoietic stem cells (HSCs) directly; rather, the infection impairs the ability of stroma to support development of HSCs. These results suggest that MV-mediated defects in hematopoiesis contribute to the long-term immunosuppression seen in measles.
Determination of a Statistically Valid Neutralization Titer in Plasma That Confers Protection against Simian-Human Immunodeficiency Virus Challenge following Passive Transfer of High-Titered Neutralizing Antibodies
Authors: Nishimura Yoshiaki , Igarashi Tatsuhiko , Haigwood Nancy , Sadjadpour Reza , Plishka Ron J. , Buckler-White Alicia , Shibata Riri , Martin Malcolm A. 
Published: July 2002

ABSTRACT

We previously reported that high-titered neutralizing antibodies directed against the human immunodeficiency virus type 1 (HIV-1) envelope can block the establishment of a simian immunodeficiency virus (SIV)/HIV chimeric virus (SHIV) infection in two monkeys following passive transfer (R. Shibata et al., Nat. Med. 5:204-210, 1999). In the present study, increasing amounts of neutralizing immunoglobulin G (IgG) were administered to 15 pig-tailed macaques in order to obtain a statistically valid protective neutralization endpoint titer in plasma. Using an in vitro assay which measures complete neutralization of the challenge SHIV, we correlated the titers of neutralizing antibodies in plasma at the time of virus inoculation (which ranged from 1:3 to 1:123) with the establishment of infection in virus-challenged animals. Ten of 15 monkeys in the present experiment were virus free as a result of neutralizing IgG administration as monitored by DNA PCR (peripheral blood mononuclear cells and lymph node cells), RNA PCR (plasma), virus isolation, and the transfer of lymph node cell suspensions (10
8
cells) plus 8 ml of whole blood from protected animals to naïve macaques. The titer of neutralizing antibodies in the plasma calculated to protect 99% of virus-challenged monkeys was 1:38.
Pseudorabies Virus UL36 Tegument Protein Physically Interacts with the UL37 Protein
Authors: Klupp Barbara G. , Fuchs Walter , Granzow Harald , Nixdorf Ralf , Mettenleiter Thomas C. 
Published: July 2002

ABSTRACT

The UL36 open reading frame encoding the tegument protein ICP1/2 represents the largest open reading frame in the genome of herpes simplex virus type 1 (HSV-1). Polypeptides homologous to the HSV-1 UL36 protein are present in all subfamilies of
Herpesviridae
. We sequenced the UL36 gene of the alphaherpesvirus pseudorabies virus (PrV) and prepared a monospecific polyclonal rabbit antiserum against a bacterial glutathione
S
-transferase (GST)-UL36 fusion protein for identification of the protein. The antiserum detected a >300-kDa protein in PrV-infected cells and in purified virions. Interestingly, in coprecipitation analyses using radiolabeled infected-cell extracts, the anti-UL36 serum reproducibly coprecipitated the UL37 tegument protein, and antiserum directed against the UL37 protein coprecipitated the UL36 protein. This physical interaction could be verified using yeast two-hybrid analysis which demonstrated that the UL37 protein interacts with a defined region within the amino-terminal part of the UL36 protein. By use of immunogold labeling, capsids which accumulate in the cytoplasm in the absence of the UL37 protein (B. G. Klupp, H. Granzow, E. Mundt, and T. C. Mettenleiter, J. Virol. 75:8927-8936, 2001) as well as wild-type intracytoplasmic and extracellular virions were decorated by the anti-UL36 antiserum, whereas perinuclear primary enveloped virions were not. We postulate that the physical interaction of the UL36 protein, which presumably constitutes the innermost layer of the tegument (Z. Zhou, D. Chen, J. Jakana, F. J. Rixon, and W. Chiu, J. Virol. 73:3210-3218, 1999), with the UL37 protein is an important early step in tegumentation during virion morphogenesis in the cytoplasm.
Role of RNA in Facilitating Gag/Gag-Pol Interaction
Authors: Khorchid Ahmad , Halwani Rabih , Wainberg Mark A. , Kleiman Lawrence 
Published: July 2002

ABSTRACT
We have examined the influence of RNA upon the interaction of Gag-Pol with Gag during human immunodeficiency virus type 1 (HIV-1) assembly. COS7 cells were transfected with protease-negative HIV-1 proviral DNA, and Gag/Gag-Pol complexes were detected by coimmunoprecipitation with anti-integrase. In COS7 cells, Gag/Gag-Pol is found almost entirely in pelletable, membrane-bound complexes. Exposure of cells to 1% Triton X-100 releases Gag/Gag-Pol from bulk membrane, but the complexes remain pelletable. The role of RNA in facilitating the interaction between Gag and Gag-Pol was examined in these bulk membrane-free, pelletable complexes. The specific presence of viral genomic RNA is not required to maintain the Gag/Gag-Pol interaction, but some type of RNA is, since exposure to RNase destabilized the Gag/Gag-Pol complex. When present only in Gag, the nucleocapsid mutation R7R10K11S, which inhibits Gag binding to RNA, inhibits the formation of both Gag and Gag/Gag-Pol complexes. When present only in Gag-Pol, this mutation has no effect upon complex formation. This result indicates that Gag-Pol may not interact directly with RNA but rather requires RNA-facilitated Gag multimerization for its interaction with Gag.
Saturated Solutions of M(NO3)2-H2O-CH3OH (M = Sr, Ba) Systems
Authors: Stoev Mitko D. , Robledo Jóse M. A. 
Published: July 2002

The solubility isotherms of the M(NO3)2 - H2O - CH3OH (M = Sr, Ba) systems at 25 °C have been studied. Crystallization fields of the equilibrium existence of the salts Sr(NO3)2 .4 H2O, Sr(NO3)2 and Ba(NO3)2 have been found. The structures of the saturated solutions on the basis of statistic calculations and IR spectra have been discussed.
Purification and Characterisation of a Vitellogenin Derived Aminopeptidase from Rainbow Trout Eggs
Authors: Kronovetr Jakub , Barthová Jana , Barth Tomislav , Ryšlavá Helena 
Published: July 2002

An aminopeptidase specific for N-terminal alanine was isolated from the rainbow trout (Oncorhynchus mykiss) maturing eggs using a simple procedure. The enzyme is composed of two identical units each of MW 16 000, separable by disulfide reduction. The enzyme has a high content of acid amino acids and its N-terminal sequence is the following 1EVNAVKCSMV10RDTLTTFNNK20KYQIN25. The sequence is identical with that of the rainbow trout vitellogenin precursor beginning with the amino acid in position 1 385. No peptidase activity has been so far observed in proteins derived from this precursor. The enzyme activity is partially blocked by Na4-EDTA but it is not inactivated by 4-(chloromercuri)benzoate, phenylmethanesulfonyl fluoride or pepstatin A.
Synthesis and Crystal Structure Determination of Cyclosporin H
Authors: Jegorov Alexandr , Cvak Ladislav , Husek Aleš , Šimek Petr , Heydová Anna , Ondráček Jan , Pakhomova Svetlana , Hušák Michal , Kratochvíl Bohumil , Sedmera Petr , Havlíček Vladimír 
Published: July 2002

Acid-catalyzed degradation of cyclosporin A was studied in various solvents and products of reaction were monitored by HPLC. Identification of amino acids and their chirality were determined after hydrolysis and derivatization by GC-MS. Cyclosporin H was isolated as the principal product and its structure was determined by X-ray diffraction: Cyclosporin H- diethyl ether-water (1 : 0.5 : 1) crystallizes in the monoclinic space groupI2witha= 12.338(2) Å,b= 18.963(2) Å,c= 34.074(3) Å, β = 96.47(2)°,Z= 4, andV= 7 921.4(17) Å3.