bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Extension of the Cytoplasmic Domain of Human Immunodeficiency Type 1 Virus Transmembrane Protein gp41 on Virus Replication
Authors: Chan Woan-Eng , Wang Ya-Lin , Lin Hui-Hua , Chen Steve S.-L. 
Published: April 2004

ABSTRACT

The biological significance of the presence of a long cytoplasmic domain in the envelope (Env) transmembrane protein gp41 of human immunodeficiency virus type 1 (HIV-1) is still not fully understood. Here we examined the effects of cytoplasmic tail elongation on virus replication and characterized the role of the C-terminal cytoplasmic tail in interactions with the Gag protein. Extensions with six and nine His residues but not with fewer than six His residues were found to severely inhibit virus replication through decreased Env electrophoretic mobility and reduced Env incorporation compared to the wild-type virus. These two mutants also exhibited distinct N glycosylation and reduced cell surface expression. An extension of six other residues had no deleterious effect on infectivity, even though some mutants showed reduced Env incorporation into the virus and/or decreased cell surface expression. We further show that these elongated cytoplasmic tails in a format of the glutathione
S
-transferase fusion protein still interacted effectively with the Gag protein. In addition, the immediate C terminus of the cytoplasmic tail was not directly involved in interactions with Gag, but the region containing the last 13 to 43 residues from the C terminus was critical for Env-Gag interactions. Taken together, our results demonstrate that HIV-1 Env can tolerate extension at its C terminus to a certain degree without loss of virus infectivity and Env-Gag interactions. However, extended elongation in the cytoplasmic tail may impair virus infectivity, Env cell surface expression, and Env incorporation into the virus.
The V1/V2 Domain of gp120 Is a Global Regulator of the Sensitivity of Primary Human Immunodeficiency Virus Type 1 Isolates to Neutralization by Antibodies Commonly Induced upon Infection
Authors: Pinter Abraham , Honnen William J. , He Yuxian , Gorny Miroslaw K. , Zolla-Pazner Susan , Kayman Samuel C. 
Published: April 2004

ABSTRACT
A major problem hampering the development of an effective vaccine against human immunodeficiency virus type 1 (HIV-1) is the resistance of many primary viral isolates to antibody-mediated neutralization. To identify factors responsible for this resistance, determinants of the large differences in neutralization sensitivities of HIV-1 pseudotyped with Env proteins derived from two prototypic clade B primary isolates were mapped. SF162 Env pseudotypes were neutralized very potently by a panel of sera from HIV-infected individuals, while JR-FL Env pseudotypes were neutralized by only a small fraction of these sera. This differential sensitivity to neutralization was also observed for a number of monoclonal antibodies (MAbs) directed against sites in the V2, V3, and CD4 binding domains, despite often similar binding affinities of these MAbs towards the two soluble rgp120s. The neutralization phenotypes were switched for chimeric Envs in which the V1/V2 domains of these two sequences were exchanged, indicating that the V1/V2 region regulated the overall neutralization sensitivity of these Envs. These results suggested that the inherent neutralization resistance of JR-FL, and presumably of related primary isolates, is to a great extent mediated by gp120 V1/V2 domain structure rather than by sequence variations at the target sites. Three MAbs (immunoglobulin G-b12, 2G12, and 2F5) previously reported to possess broad neutralizing activity for primary HIV-1 isolates neutralized JR-FL virus at least as well as SF162 virus and were not significantly affected by the V1/V2 domain exchanges. The rare antibodies capable of neutralizing a broad range of primary isolates thus appeared to be targeted to exceptional epitopes that are not sensitive to V1/V2 domain regulation of neutralization sensitivity.
A Mutation in the HLA-B*2705-Restricted NP383-391Epitope Affects the Human Influenza A Virus-Specific Cytotoxic T-Lymphocyte Response In Vitro
Authors: Berkhoff E. G. M. , Boon A. C. M. , Nieuwkoop N. J. , Fouchier R. A. M. , Sintnicolaas K. , Osterhaus A. D. M. E. , Rimmelzwaan G. F. 
Published: April 2004

ABSTRACTViruses can exploit a variety of strategies to evade immune surveillance by cytotoxic T lymphocytes (CTL), including the acquisition of mutations in or adjacent to CTL epitopes. Recently, an amino acid substitution (R384G) in an HLA-B*2705-restricted CTL epitope in the influenza A virus nucleoprotein (nucleoprotein containing residues 383 to 391 [NP383-391]; SRYWAIRTR, whereRis the residue that was mutated) was associated with escape from CTL-mediated immunity. The effect of this mutation on the in vitro influenza A virus-specific CTL response was studied. To this end, two influenza A viruses, one with and one without the NP383-391epitope, were constructed by reverse genetics and designated influenza viruses A/NL/94-384R and A/NL/94-384G, respectively. The absence of the HLA-B*2705-restricted CTL epitope in influenza virus A/NL/94-384G was confirmed by using51Cr release assays with a T-cell clone specific for the NP383-391epitope. In addition, peripheral blood mononuclear cells (PBMC) stimulated with influenza virus A/NL/94-384G failed to recognize HLA-B*2705-positive target cells pulsed with the original NP383-391peptide. The proportion of virus-specific CD8+gamma interferon (IFN-γ)-positive T cells in in vitro-stimulated PBMC was determined by intracellular IFN-γ staining after restimulation with virus-infected autologous B-lymphoblastoid cell lines and C1R cell lines expressing only HLA-B*2705. The proportion of virus-specific CD8+T cells was lower in PBMC stimulated in vitro with influenza virus A/NL/94-384G obtained from several HLA-B*2705-positive donors than in PBMC stimulated with influenza virus A/NL/94-384R. This finding indicated that amino acid variations in CTL epitopes can affect the virus-specific CTL response and that the NP383-391epitope is the most important HLA-B*2705-restricted epitope in the nucleoprotein of influenza A viruses.
Copatching and Lipid Raft Association of Different Viral Glycoproteins Expressed on the Surfaces of Pseudorabies Virus-Infected Cells
Authors: Favoreel Herman W. , Mettenleiter Thomas C. , Nauwynck Hans J. 
Published: April 2004

ABSTRACTPseudorabies virus (PRV) is a swine alphaherpesvirus that is closely related to human herpes simplex virus (HSV). Both PRV and HSV express a variety of viral envelope glycoproteins in the plasma membranes of infected cells. Here we show that at least four major PRV glycoproteins (gB, gC, gD, and gE) in the plasma membrane of infected swine kidney cells and monocytes seem to be linked, since monospecific antibody-induced patching of any one of these proteins results in copatching of the others. Further, for all four PRV glycoproteins, monospecific antibody-induced patches were enriched in GM1, a typical marker of lipid raft microdomains, but were excluded for transferrin receptor, a nonraft marker, suggesting that these viral proteins may associate with lipid rafts. However, only gB and, to a lesser extent, gE were found in lipid raft fractions by using detergent floatation assays, indicating that gC and gD do not show strong lipid raft association. Addition of methyl-β-cyclodextrin (MCD), a cholesterol-depleting agent that is commonly used to disrupt lipid rafts, only slightly reduced copatching efficiency between the different viral proteins, indicating that other factors, perhaps tegument-glycoprotein interactions, may be important for the observed copatching events. On the other hand, MCD strongly reduced polarization of the antibody-induced viral glycoprotein patches to a cap structure, a gE-dependent process that has been described for specific PRV- and HSV-infected cells. Therefore, we hypothesize that efficient gE-mediated capping of antibody-antigen patches may require the lipid raft-associated signal transduction machinery.
The Papillomavirus E7 Oncoprotein Is Ubiquitinated by UbcH7 and Cullin 1- and Skp2-Containing E3 Ligase
Authors: Oh Kwang-Jin , Kalinina Anna , Wang Jing , Nakayama Keiko , Nakayama Keiichi I. , Bagchi Srilata 
Published: April 2004

ABSTRACT

Recurrent infections with high-risk human papillomaviruses (HPVs) are associated with human cervical cancers. All HPV-associated cancer tissues express the viral oncoproteins E6 and E7, which stimulate cell growth. The expression of E7 is crucial for both the initiation and the maintenance of HPV-associated cancer. Recent studies showed that the level of E7 in cancer cells is regulated by ubiquitin-dependent proteolysis through the 26S proteasome. In this study, we characterized the enzymes involved in the ubiquitin-dependent proteolysis of E7. We show that UbcH7, an E2 ubiquitin-conjugating enzyme, is specifically involved in the ubiquitination of E7. Furthermore, we show that E7 interacts with the SCF (Skp-Cullin-F box) ubiquitin ligase complex containing Cullin 1 (Cul1) and Skp2 and can be ubiquitinated by the Cul1-containing ubiquitin ligase in vitro. Coimmunoprecipitation analyses revealed that E7 interacts with Skp2 and Cul1 in vivo. Finally, the half-life of E7 was found to be significantly longer in Skp2
−/−
mouse embryo fibroblasts (MEFs) than in wild-type MEFs. Taken together, these results suggest that the Cul1- and Skp2-containing ubiquitin ligase plays a role in the ubiquitination and proteolysis of E7. In HPV type 16-containing cervical carcinoma cell line Caski, E7 localizes to both the cytoplasm and the nucleus. Brief treatment of Caski cells with MG132 (a proteasome inhibitor) causes the accumulation of E7 in discrete nuclear bodies. These nuclear bodies are detergent insoluble and contain polyubiquitinated E7. We suggest that E7 relocates to specific nuclear bodies for proteolysis in HPV-containing epithelial cells.
Rice Dwarf Phytoreovirus Segment S6-Encoded Nonstructural Protein Has a Cell-to-Cell Movement Function
Authors: Li Yi , Bao Yi M. , Wei Chun H. , Kang Zhen S. , Zhong Yong W. , Mao Peng , Wu Gang , Chen Zhang L. , Schiemann Joachim , Nelson Richard S. 
Published: April 2004

ABSTRACTRice dwarf virus(RDV) is a member of the genusPhytoreovirus, which is composed of viruses with segmented double-stranded RNA genomes. Proteins that support the intercellular movement of these viruses in the host have not been identified. Microprojectile bombardment was used to determine which open reading frames (ORFs) support intercellular movement of a heterologous virus. A plasmid containing an infectious clone ofPotato virus X(PVX) defective in cell-to-cell movement and expressing either β-glucuronidase or green fluorescent protein (GFP) was used for cobombardment with plasmids containing ORFs from RDV gene segments S1 through S12 onto leaves ofNicotiana benthamiana. Cell-to-cell movement of the movement-defective PVX was restored by cobombardment with a plasmid containing S6. In the absence of S6, no other gene segment supported movement. Identical results were obtained withNicotiana tabacum, a host that allows fewer viruses to infect and spread within its tissue. S6 supported the cell-to-cell movement of the movement-defective PVX in sink and source leaves ofN. benthamiana. A mutant S6 lacking the translation start codon did not complement the cell-to-cell movement of the movement-defective PVX. An S6 protein product (Pns6)-enhanced GFP fusion was observed near or within cell walls of epidermal cells fromN. tabacum. By immunocytochemistry, unfused Pns6 was localized to plasmodesmata in rice leaves infected with RDV. S6 thus encodes a protein with characteristics identical to those of other viral proteins required for the cell-to-cell movement of their genome and therefore is likely required for the cell-to-cell movement of RDV.
Characterization of a Subtype D Human Immunodeficiency Virus Type 1 Isolate That Was Obtained from an Untreated Individual and That Is Highly Resistant to Nonnucleoside Reverse Transcriptase Inhibitors
Authors: Gao Yong , Paxinos Ellen , Galovich Justin , Troyer Ryan , Baird Heather , Abreha Measho , Kityo Cissy , Mugyenyi Peter , Petropoulos Christos , Arts Eric J. 
Published: April 2004

ABSTRACT

Human immunodeficiency virus type 1 (HIV-1) isolates derived from HIV-infected, treatment-naive Ugandan infants were propagated and tested for sensitivity to antiretroviral (ARV) drugs. Although most subtype A and D isolates displayed inhibition profiles similar to those of subtype B strains, a subtype D isolate identified as D14-UG displayed high-level resistance to nevirapine in peripheral blood mononuclear cell cultures (>2,000-fold) and in MT4 cell cultures (∼800-fold) but weaker resistance to delavirdine (∼13-fold) and efavirenz (∼8-fold) in MT4 cell cultures. To investigate the possible mechanism for this resistance to nonnucleoside reverse transcriptase (RT) inhibitors (NNRTIs), the RT coding region in
pol
was sequenced and compared to the consensus RT sequence of NNRTI-resistant and NNRTI-sensitive subtype A, B, and D HIV-1 isolates. D14-UG did not contain the classic amino acid substitutions conferring NNRTI resistance (e.g., Y181C, K103N, and G190A) but did have some putative sites associated with drug resistance, I135L, T139V, and V245T. Wild-type and mutated protease-RT genes from D14-UG and an NNRTI-sensitive subtype D isolate from Uganda (D13-UG) were cloned into pNL4-3 to produce recombinant viruses and to determine the effects of the mutations on susceptibility to ARV drugs, specifically, NNRTIs. The results showed that I135L and/or V245T mutations can confer high-level resistance to nevirapine and delavirdine as well as low level cross-resistance to efavirenz. Finally, ex vivo fitness analyses suggested that NNRTI-resistant sites 135L and 245T in wild-type isolate D14-UG may reduce RT fitness but do not have an impact on the fitness of the primary HIV-1 isolate.
Binding and Susceptibility to Postentry Restriction Factors in Monkey Cells Are Specified by Distinct Regions of the Human Immunodeficiency Virus Type 1 Capsid
Authors: Owens Christopher M. , Song Byeongwoon , Perron Michel J. , Yang Peter C. , Stremlau Matthew , Sodroski Joseph 
Published: April 2004

ABSTRACT

In
cells of Old World and some New World monkeys, dominant factors
restrict human immunodeficiency virus type 1 (HIV-1)
infections after virus entry. The simian immunodeficiency virus
SIV
mac
is less susceptible to these restrictions, a property
that is determined largely by the viral capsid protein. For this study,
we altered exposed amino acid residues on the surface of the HIV-1
capsid, changing them to the corresponding residues found on the
SIV
mac
capsid. We identified two distinct pathways of escape
from early, postentry restriction in monkey cells. One set of mutants
that were altered near the base of the cyclophilin A-binding loop of
the N-terminal capsid domain or in the interdomain linker exhibited a
decreased ability to bind the restricting factor(s). Consistent with
the location of this putative factor-binding site, cyclophilin A and
the restricting factor(s) cooperated to achieve the postentry block. A
second set of mutants that were altered in the ridge formed by helices
3 and 6 of the N-terminal capsid domain efficiently bound the
restricting factor(s) but were resistant to the consequences of factor
binding. These results imply that binding of the simian restricting
factor(s) is not sufficient to mediate the postentry block to HIV-1 and
that SIV
mac
capsids escape the block by decreases in both
factor binding and susceptibility to the effects of the
factor(s).
Impact of Mutations in the Coreceptor Binding Site on Human Immunodeficiency Virus Type 1 Fusion, Infection, and Entry Inhibitor Sensitivity
Authors: Reeves Jacqueline D. , Miamidian John L. , Biscone Mark J. , Lee Fang-Hua , Ahmad Navid , Pierson Theodore C. , Doms Robert W. 
Published: April 2004

ABSTRACTAn increasingly large number of antiviral agents that prevent entry of human immunodeficiency virus (HIV) into cells are in preclinical and clinical development. The envelope (Env) protein of HIV is the major viral determinant that affects sensitivity to these compounds. To understand how changes in Env can impact entry inhibitor sensitivity, we introduced six mutations into the conserved coreceptor binding site of the R5 HIV-1 strain YU-2 and measured the effect of these changes on CD4 and coreceptor binding, membrane fusion levels and rates, virus infection, and sensitivity to the fusion inhibitors enfuvirtide (T-20) and T-1249, the CCR5 inhibitor TAK-779, and an antibody to CD4. The mutations had little effect on CD4 binding but reduced CCR5 binding to various extents. In general, reductions in coreceptor binding efficiency resulted in slower fusion kinetics and increased sensitivity to TAK-779 and enfuvirtide. In addition, low CCR5 binding usually reduced overall fusion and infection levels. However, one mutation adjacent to the bridging sheet β21 strand, P438A, had little effect on fusion activity, fusion rate, infectivity, or sensitivity to enfuvirtide or T-1249 despite causing a marked reduction in CCR5 binding and a significant increase in TAK-779 sensitivity. Thus, our findings indicate that changes in the coreceptor binding site of Env can modulate its fusion activity, infectivity, and entry inhibitor sensitivity by multiple mechanisms and suggest that reductions in coreceptor binding do not always result in prolonged fusion kinetics and increased sensitivity to enfuvirtide.
The Human-Animal Bond and Self Psychology: Toward a New Understanding
Authors: Brown Sue-Ellen 
Published: April 2004

AbstractThe purpose of this paper is to introduce and define self psychology and its concepts (self and selfobject) so that they can be applied toward a new understanding of the human-nonhuman animal bond. The paper utilizes selected literature from both self psychology and the human-animal bond fields. The paper contains four primary conclusions: 1. Self psychology provides a unique model for understanding the depth and meaning of human-animal relationships; 2. Companion animals and humans can be equally important in their selfobject roles; 3. Self psychology can offer a model for understanding individual differences in attachment to companion animals; and 4. A future direction includes finding ways to assess self psychology constructs in order to measure the depth and function of the selfobject relationship.
Preparation and Properties of a Structually Novel Heterocyclic Dispiro Compound, 3,10-Dimethyl-3,10-diazadispiro[5.0.5.4]hexadeca-1,4,8,11-tetraene
Authors: Muramatsu Takashi , Toyota Azumao , Adachi Nao 
Published: April 2004

Abstract
The two-electron reduction of 3 with sodium amalgam in degassed acetonitrile affords 4 in quantitative yield. Under deoxygenerated conditions, 4 is stable for a long time at room temperature, but slowly undergoes an opening of the cyclohexane ring skeleton with elimination of methyl groups to yield 5 at about 200 °C. At the same time, a small amount of 6 is obtained by fission of a CC single bond of the cyclohexane ring skeleton with the transfer of hydrogen atom.
Involvement of Monkey Inferior Colliculus in Spatial Hearing
Authors: Zwiers Marcel P. , Versnel Huib , Van Opstal A. John 
Published: April 2004

The midbrain inferior colliculus (IC) is implicated in coding sound location, but evidence from behaving primates is scarce. Here we report single-unit responses to broadband sounds that were systematically varied within the two-dimensional (2D) frontal hemifield, as well as in sound level, while monkeys fixated a central visual target.Results show that IC neurons are broadly tuned to both sound-source azimuth and level in a way that can be approximated by multiplicative, planar modulation of the firing rate of the cell. In addition, a fraction of neurons also responded to elevation. This tuning, however, was more varied: some neurons were sensitive to a specific elevation; others responded to elevation in a monotonic way. Multiple-linear regression parameters varied from cell to cell, but the only topography encountered was a dorsoventral tonotopy.In a second experiment, we presented sounds from straight ahead while monkeys fixated visual targets at different positions. We found that auditory responses in a fraction of IC cells were weakly, but systematically, modulated by 2D eye position. This modulation was absent in the spontaneous firing rates, again suggesting a multiplicative interaction of acoustic and eye-position inputs. Tuning parameters to sound frequency, location, intensity, and eye position were uncorrelated. On the basis of simulations with a simple neural network model, we suggest that the population of IC cells could encode the head-centered 2D sound location and enable a direct transformation of this signal into the eye-centered topographic motor map of the superior colliculus. Both signals are required to generate rapid eye-head orienting movements toward sounds.
Heat transfer in poly(methyl acrylate) by photoacoustic measurements
Authors: Jothi Rajan M. A. , Vivekanandam T. S. , Ramakrishnan S. K. , Ramachandran K. , Umapathy S. 
Published: April 2004

AbstractThe thermal properties (thermal diffusivity, thermal effusivity, thermal conductivity, and specific heat capacity) of poly(methyl acrylate), which was obtained by ultrasonochemical polymerization, were measured experimentally with photoacoustic and other techniques. In addition, the thermal expansion of poly(methyl acrylate) was measured experimentally with an indigenously modified Fizeau's apparatus and is reported here for the first time to an accuracy of 0.05%. The results were compared with the available literature values and examined. Sinclare's apparatus was used to determine the specific heat capacity and matched well with differential scanning calorimetry measurements. The method‐of‐mixtures technique was an alternative method of determining the specific heat capacity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1071–1076, 2004
A new approach for selective surface modification of fluoropolymers by remote plasmas
Authors: Park Y. W. , Inagaki N. 
Published: April 2004

AbstractEthylene‐co‐tetrafluoroethylene (ETFE) and poly (vinylidene fluoride) (PVDF) films were exposed to the remote Ar, H2, and O2 plasmas. The modified polymer surfaces were characterized by X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurement. The plasma exposure led to weight loss and changes in the chemical composition on the polymer surface. Selective surface modification of fluoropolymers introduces various functional groups without altering the bulk properties. The results may be summarized as follows: the remote hydrogen plasma was the most effective in alternation from CF to CH (abstraction of fluorine). On the other hand, the remote oxygen plasma was unfavorable to abstract fluorine atoms, but effective in dehydrogenation (abstraction of hydrogen). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1012–1020, 2004