bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of the Placental Cytokine-Chemokine Balance on Regulation of Cell-Cell Contact-Induced Human Immunodeficiency Virus Type 1 Translocation across a Trophoblastic Barrier In Vitro
Authors: Derrien Muriel , Faye Albert , Dolcini Guillermina , Chaouat Gérard , Barré-Sinoussi Françoise , Menu Elisabeth 
Published: September 2005

ABSTRACTCells constituting the placental barrier secrete soluble factors that may participate in controlling human immunodeficiency virus type 1 (HIV-1) transmission from the mother to the fetus. In this study, we asked whether placental soluble factors (PSF) could limit cell-cell contact inducing HIV-1 production that occurs after inoculation of HIV-1-infected peripheral blood mononuclear cells (HIV-1+PBMCs) onto trophoblast-derived BeWo cells grown as tight and polarized barriers in a two-chamber system. The activity of recombinant chemokines and cytokines expressed by placental tissue and of factors secreted by either early or term placentae of HIV-1-negative women, was analyzed. We identified chemokines (RANTES and MIP-1β) and cytokines (tumor necrosis factor alpha and interleukin-8) that decreased and increased, respectively, viral production in trophoblast barrier cells inoculated with HIV-1+PBMCs. Unexpectedly, factors secreted by either early or term placentae of HIV-1-negative women enhanced viral production. Nevertheless, the same PSF did not favor infection of trophoblastic barriers with cell-free HIV-1 and strongly reduced viral production in PBMCs infected with cell-free HIV-1. Moreover, PSF contained chemokines (RANTES and MIP-1β) and a cytokine, leukemia inhibitory factor, exhibiting a strong anti-HIV-1 activity in our model of cell-to-cell infection. Together these data suggested that at the maternal interface the global activity of PSF is related to the synergistic action of several soluble factors with a balance in favor of an enhancing activity on the passage of viruses across the trophoblast barrier. This could explain the presence of viral sequences in trophoblasts in all placentae of HIV-1-infected women.
Replication of Minute Virus of Mice DNA Is Critically Dependent on Accumulated Levels of NS2
Authors: Choi Eun-Young , Newman Ann E. , Burger Lisa , Pintel David 
Published: September 2005

ABSTRACTFollowing transfection of murine fibroblasts, the lymphotropic strain of minute virus of mice (MVMi) does not efficiently produce progeny single-strand DNA (ssDNA). However, changing a single nucleotide in the MVMi 3′ splice site to that found in the fibrotropic strain MVMp enabled full DNA replication and production of ssDNA. This change enhanced excision of the large intron and the production of NS2, likely by improving interaction, in fibroblasts with the branch point-binding U2 snRNA. One function of NS2 involves interaction with the nuclear export protein Crm1. The defect in production of MVMi ssDNA in fibroblasts can also be overcome by introducing a mutation in MVMi NS2 that enhances its interaction with Crm1. Although MVMi contains a 3′ splice site that performs poorly in fibroblasts, MVMi generated at least as much R2 and NS2 in murine lymphocytes as did MVMp in fibroblasts. Therefore, it appears that MVMp has acquired a mutation that improves the excision of the large intron, as it adapted to fibroblasts to accommodate the need for NS2 for replication in these cells, and that the ratio of NS1 to NS2 may play a larger role in the host range of MVM than previously appreciated.
Identification of Complement Regulatory Domains in Vaccinia Virus Complement Control Protein
Authors: Mullick Jayati , Bernet John , Panse Yogesh , Hallihosur Sharanabasava , Singh Akhilesh K. , Sahu Arvind 
Published: September 2005

ABSTRACTVaccinia virus encodes a homolog of the human complement regulators named vaccinia virus complement control protein (VCP). It is composed of four contiguous complement control protein (CCP) domains. Previously, VCP has been shown to bind to C3b and C4b and to inactivate the classical and alternative pathway C3 convertases by accelerating the decay of the classical pathway C3 convertase and (to a limited extent) the alternative pathway C3 convertase, as well as by supporting the factor I-mediated inactivation of C3b and C4b (the subunits of C3 convertases). In this study, we have mapped the CCP domains of VCP important for its cofactor activities, decay-accelerating activities, and binding to the target proteins by utilizing a series of deletion mutants. Our data indicate the following. (i) CCPs 1 to 3 are essential for cofactor activity for C3b and C4b; however, CCP 4 also contributes to the optimal activity. (ii) CCPs 1 to 2 are enough to mediate the classical pathway decay-accelerating activity but show very minimal activity, and all the four CCPs are necessary for its efficient activity. (iii) CCPs 2 to 4 mediate the alternative pathway decay-accelerating activity. (iv) CCPs 1 to 3 are required for binding to C3b and C4b, but the presence of CCP 4 enhances the affinity for both the target proteins. These results together demonstrate that the entire length of the protein is required for VCP's various functional activities and suggests why the four-domain structure of viral CCP is conserved in poxviruses.
The Amino Terminus of Epstein-Barr Virus Glycoprotein gH Is Important for Fusion with Epithelial and B Cells
Authors: Omerović Jasmina , Lev Lori , Longnecker Richard 
Published: September 2005

ABSTRACT
Epstein-Barr virus (EBV) infects B lymphocytes and epithelial cells. While the glycoproteins required for entry into these two cell types differ, the gH/gL glycoprotein complex is essential for entry into both epithelial and B cells. Analysis of gH protein sequences from three gammaherpesviruses (EBV, marmoset, and rhesus) revealed a potential coiled-coil domain in the N terminus. Four leucines located in this region in EBV gH were replaced by alanines by site-directed mutagenesis and analyzed for cell-cell membrane fusion with B cells and epithelial cells. Reduction in fusion activity was observed for mutants containing L65A and/or L69A mutations, while substitutions in L55 and L74 enhanced the fusion activity of the mutant gH/gL complexes with both cell types. All of the mutants displayed levels of cell surface expression similar to those of wild-type gH and interacted with gL and gp42. The observation that a conservative mutation of leucine to alanine in the N terminus of EBV gH results in fusion-defective mutant gH/gL complexes is striking and points to an important role for this region in EBV-mediated membrane fusion with B lymphocytes and epithelial cells.
Stem-Loop IV in the 5′ Untranslated Region Is a
cis
-Acting Element in Bovine Coronavirus Defective Interfering RNA Replication
Authors: Raman Sharmila , Brian David A. 
Published: September 2005

ABSTRACT

The 210-nucleotide (nt) 5′ untranslated region (UTR) in the positive-strand bovine coronavirus (BCoV) genome is predicted to contain four higher-order structures identified as stem-loops I to IV, which may function as
cis
-acting elements in genomic RNA replication. Here, we describe evidence that stem-loop IV, a bulged stem-loop mapping at nt 186 through 215, (i) is phylogenetically conserved among group 2 coronaviruses and may have a homolog in groups 1 and 3, (ii) exists as a higher-order structure on the basis of enzyme probing, (iii) is required as a higher-order element for replication of a BCoV defective interfering (DI) RNA in the positive but not the negative strand, and (iv) as a higher-order structure in wild-type (wt) and mutant molecules that replicate, specifically binds six cellular proteins in the molecular mass range of 25 to 58 kDa as determined by electrophoretic mobility shift and UV cross-linking assays; binding to viral proteins was not detected. Interestingly, the predicted stem-loop IV homolog in the severe acute respiratory syndrome (SARS) coronavirus appears to be group 1-like in that it is in part duplicated with a group 1-like conserved loop sequence and is not group 2-like, as would be expected by the SARS coronavirus group 2-like 3′ UTR structure. These results together indicate that stem-loop IV in the BCoV 5′ UTR is a
cis
-acting element for DI RNA replication and that it might function through interactions with cellular proteins. It is postulated that stem-loop IV functions similarly in the virus genome.
Impact of Human Immunodeficiency Virus Type 1 gp41 Amino Acid Substitutions Selected during Enfuvirtide Treatment on gp41 Binding and Antiviral Potency of Enfuvirtide In Vitro
Authors: Mink M. , Mosier S. M. , Janumpalli S. , Davison D. , Jin L. , Melby T. , Sista P. , Erickson J. , Lambert D. , Stanfield-Oakley S. A. , Salgo M. , Cammack N. , Matthews T. , Greenberg M. L. 
Published: September 2005

ABSTRACTEnfuvirtide (ENF), a novel human immunodeficiency virus type 1 (HIV-1) fusion inhibitor, has potent antiviral activity against HIV-1 both in vitro and in vivo. Resistance to ENF observed after in vitro passaging was associated with changes in a three-amino-acid (aa) motif, GIV, at positions 36 to 38 of gp41. Patients with ongoing viral replication while receiving ENF during clinical trials acquired substitutions within gp41 aa 36 to 45 in the first heptad repeat (HR-1) of gp41 in both population-based plasma virus sequences and proviral DNA sequences from isolates showing reduced susceptibilities to ENF. To investigate their impact on ENF susceptibility, substitutions were introduced into a modified pNL4-3 strain by site-directed mutagenesis, and the susceptibilities of mutant viruses and patient-derived isolates to ENF were tested. In general, susceptibility decreases for single substitutions were lower than those for double substitutions, and the levels of ENF resistance seen for clinical isolates were higher than those observed for the site-directed mutant viruses. The mechanism of ENF resistance was explored for a subset of the substitutions by expressing them in the context of a maltose binding protein chimera containing a portion of the gp41 ectodomain and measuring their binding affinity to fluorescein-labeled ENF. Changes in binding affinity for the mutant gp41 fusion proteins correlated with the ENF susceptibilities of viruses containing the same substitutions. The combined results support the key role of gp41 aa 36 to 45 in the development of resistance to ENF and illustrate that additional envelope regions contribute to the ENF susceptibility of fusion inhibitor-naïve viruses and resistance to ENF.
N-Terminal Gag Domain Required for Foamy Virus Particle Assembly and Export
Authors: Cartellieri Marc , Herchenröder Ottmar , Rudolph Wolfram , Heinkelein Martin , Lindemann Dirk , Zentgraf Hanswalter , Rethwilm Axel 
Published: September 2005

ABSTRACT

Among the
Retroviridae
, foamy viruses (FVs) exhibit an unusual way of particle assembly and a highly specific incorporation of envelope protein into progeny virions. We have analyzed deletions and point mutants of the prototypic FV
gag
gene for capsid assembly and egress, envelope protein incorporation, infectivity, and ultrastructure. Deletions introduced at the 3′ end of
gag
revealed the first 297 amino acids (aa) to be sufficient for specific Env incorporation and export of particulate material. Deletions introduced at the 5′ end showed the region between aa 6 and 200 to be dispensable for virus capsid assembly but required for the incorporation of Env and particle egress. Point mutations were introduced in the 5′ region of
gag
to target residues conserved among FVs from different species. Alanine substitutions of residues in a region between aa 40 and 60 resulted in severe alterations in particle morphology. Furthermore, at position 50, this region harbors the conserved arginine that is presumably at the center of a signal sequence directing FV Gag proteins to a cytoplasmic assembly site.
Comprehensive Bioinformatic Analysis of the Specificity of Human Immunodeficiency Virus Type 1 Protease
Authors: You Liwen , Garwicz Daniel , Rögnvaldsson Thorsteinn 
Published: September 2005

ABSTRACT
Rapidly developing viral resistance to licensed human immunodeficiency virus type 1 (HIV-1) protease inhibitors is an increasing problem in the treatment of HIV-infected individuals and AIDS patients. A rational design of more effective protease inhibitors and discovery of potential biological substrates for the HIV-1 protease require accurate models for protease cleavage specificity. In this study, several popular bioinformatic machine learning methods, including support vector machines and artificial neural networks, were used to analyze the specificity of the HIV-1 protease. A new, extensive data set (746 peptides that have been experimentally tested for cleavage by the HIV-1 protease) was compiled, and the data were used to construct different classifiers that predicted whether the protease would cleave a given peptide substrate or not. The best predictor was a nonlinear predictor using two physicochemical parameters (hydrophobicity, or alternatively polarity, and size) for the amino acids, indicating that these properties are the key features recognized by the HIV-1 protease. The present in silico study provides new and important insights into the workings of the HIV-1 protease at the molecular level, supporting the recent hypothesis that the protease primarily recognizes a conformation rather than a specific amino acid sequence. Furthermore, we demonstrate that the presence of 1 to 2 lysine residues near the cleavage site of octameric peptide substrates seems to prevent cleavage efficiently, suggesting that this positively charged amino acid plays an important role in hindering the activity of the HIV-1 protease.
Envelope Protein Requirements for the Assembly of Infectious Virions of Porcine Reproductive and Respiratory Syndrome Virus
Authors: Wissink E. H. J. , Kroese M. V. , van Wijk H. A. R. , Rijsewijk F. A. M. , Meulenberg J. J. M. , Rottier P. J. M. 
Published: September 2005

ABSTRACT

Virions of porcine reproductive and respiratory syndrome virus (PRRSV) contain six membrane proteins: the major proteins GP
5
and M and the minor proteins GP
2a
, E, GP
3
, and GP
4
. Here, we studied the envelope protein requirements for PRRSV particle formation and infectivity using full-length cDNA clones in which the genes encoding the membrane proteins were disrupted by site-directed mutagenesis. By transfection of RNAs transcribed from these cDNAs into BHK-21 cells and analysis of the culture medium using ultracentrifugation, radioimmunoprecipitation, and real-time reverse transcription-PCR, we observed that the production of viral particles is dependent on both major envelope proteins; no particles were released when either the GP
5
or the M protein was absent. In contrast, particle production was not dependent on the minor envelope proteins. Remarkably, in the absence of any one of the latter proteins, the incorporation of all other minor envelope proteins was affected, indicating that these proteins interact with each other and are assembled into virions as a multimeric complex. Independent evidence for such complexes was obtained by coexpression of the minor envelope proteins in BHK-21 cells using a Semliki Forest virus expression system. By analyzing the maturation of their N-linked oligosaccharides, we found that the glycoproteins were each retained in the endoplasmic reticulum unless expressed together, in which case they were collectively transported through the Golgi complex to the plasma membrane and were even detected in the extracellular medium. As the PRRSV particles lacking the minor envelope proteins are not infectious, we hypothesize that the virion surface structures formed by these proteins function in viral entry by mediating receptor binding and/or virus-cell fusion.
Formation of Vesicular Stomatitis Virus Pseudotypes Bearing Surface Proteins of Hepatitis B Virus
Authors: Saha Manujendra N. , Tanaka Atsushi , Jinno-Oue Atsushi , Shimizu Nobuaki , Tamura Kazushi , Shinagawa Masahiko , Chiba Joe , Hoshino Hiroo 
Published: September 2005

ABSTRACTIt has been difficult to propagate and titrate hepatitis B virus (HBV) in tissue culture. We examined whether vesicular stomatitis virus (VSV) pseudotypes bearing HBV surface (HBs) proteins infectious for human cell lines could be prepared. For this, expression plasmids for three surface proteins, L, M, and S, of HBV were made. 293T cells were then transfected with these plasmids either individually or in different combinations. 293T cells expressing HBs proteins were infected with VSVΔG*-G, a recombinant VSV expressing green fluorescent protein (GFP), to make VSV pseudotypes. Culture supernatants together with cells were harvested and sonicated for a short time. The infectivities of freshly harvested supernatants were determined by quantifying the number of cells expressing GFP after neutralization with anti-VSV serum and mouse monoclonal antibodies (MAbs) against HBs protein. Among 14 cell lines tested for susceptibility to HBV pseudotype samples, HepG2, JHH-7, and 293T cells were judged to be the most susceptible. Namely, the infectious units (IU) of the culture supernatant samples neutralized with anti-VSV in the absence and presence of anti-HBs S MAbs and titrated on HepG2 cells ranged from 1,000 to 4,000 IU/ml and 200 to 400 IU/ml, respectively, suggesting the presence of VSVΔG*(HBV) pseudotypes. This infectivity was inhibited by treatment with lactoferrin or dextran sulfate. Pretreatment of the cells with trypsin or tunicamycin inhibited plating of the pseudotype samples. The HBV pseudotypes can be used to analyze early steps of HBV infection, including the entry mechanism of HBV.
Human Immunodeficiency Virus Type 1 gp120 and Other Activation Stimuli Are Highly Effective in Triggering Alpha Interferon and CC Chemokine Production in Circulating Plasmacytoid but Not Myeloid Dendritic Cells
Authors: Del Cornò Manuela , Gauzzi Maria Cristina , Penna Giuseppe , Belardelli Filippo , Adorini Luciano , Gessani Sandra 
Published: September 2005

ABSTRACT

Exposure to aldrithiol-2-inactivated human immunodeficiency virus type 1 or gp120, but not gp41, triggered alpha interferon (IFN-α), CC chemokine ligand 2 (CCL2), CCL3, and CCL4 production in human plasmacytoid dendritic cells (DCs) but not in myeloid DCs (M-DCs) or monocyte-derived DCs from the same donors. The nonresponsiveness of M-DCs for IFN-α/β production was a general feature specific to these cells, as they also failed to produce it in response to inactivated influenza virus, poly(I-C), lipopolysaccharide,
Staphylococcus aureus
Cowans I, or CD40L. The different capacities of circulating DC subsets to produce immune mediators in response to most stimuli argue for a different role for these cells in the regulation of innate immunity to pathogens.
Diabetic heart disease
Authors: Marwick T H 
Published: September 2005

Abstract
Diabetes mellitus is responsible for a spectrum of cardiovascular disease. The best known complications arise from endothelial dysfunction, oxidation, inflammation, and vascular remodelling and contribute to atherogenesis. However, the effects on the heart also relate to concurrent hypertensive heart disease, as well as direct effects of diabetes on the myocardium. Diabetic heart disease, defined as myocardial disease in patients with diabetes that cannot be ascribed to hypertension, coronary artery disease, or other known cardiac disease, is reviewed.
Generalized Hough Modes: The Structure of Damped Global-Scale Waves Propagating on a Mean Flow with Horizontal and Vertical Shear
Authors: Ortland David A. 
Published: September 2005

Abstract
The technique of classical tidal theory in which linear disturbances to a background flow at rest are expanded in terms of Hough modes is generalized for damped disturbances to a general zonal mean state under the assumption that the vertical scale of the background flow is longer than the vertical scale of the disturbance. Generalized Hough modes provide an alternative to the concept of mode coupling between classical modes as a means of describing how the mean flow and damping affect the wave structure. Generalized modes take into account the horizontal shear of the mean flow and damping at lowest order. Effects of vertical shear in the mean flow only arise as first-order corrections, and hence generalized modes provide exact modal solutions to the linearized primitive equations when the mean flow only varies with latitude.
A Study of the Global Structure of the Migrating Diurnal Tide Using Generalized Hough Modes
Authors: Ortland David A. 
Published: September 2005

Abstract
The theory of generalized Hough modes developed in a companion paper is applied here to investigate the structure of the migrating diurnal tide in the mesosphere and lower thermosphere. A series of simple examples illustrate how equatorial and midlatitude jets affect the horizontal structure and vertical wavelength of the tidal modes. Complex damping coefficients are used to model the effects of diffusion and gravity wave forcing acting on the tide. It is shown that the imaginary part of the damping coefficient can have significant effects that cannot be adequately represented by real damping coefficients alone. An exact solution of the linearized equations obtained with realistic mean flow and diffusion values representing solstice conditions is compared to the approximate generalized Hough mode solution. It is found that excellent agreement is obtained when expanding to first order, where the corrections at this order account for the observed hemispheric asymmetry in tidal winds during solstice. It is concluded that the asymmetry arises as the result of strong vertical shear in the mean winds that result from the reversal of the sign of the summer and winter jets in the upper mesosphere.