bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional Surfaces of the Human Immunodeficiency Virus Type 1 Capsid Protein
Authors: von Schwedler Uta K. , Stray Kirsten M. , Garrus Jennifer E. , Sundquist Wesley I. 
Published: April 2003

ABSTRACT
The human immunodeficiency virus type 1 initially assembles and buds as an immature particle that is organized by the viral Gag polyprotein. Gag is then proteolyzed to produce the smaller capsid protein CA, which forms the central conical capsid that surrounds the RNA genome in the mature, infectious virus. To define CA surfaces that function at different stages of the viral life cycle, a total of 48 different alanine-scanning surface mutations in CA were tested for their effects on Gag protein expression, processing, particle production and morphology, capsid assembly, and infectivity. The 27 detrimental mutations fall into three classes: 13 mutations significantly diminished or altered particle production, 9 mutations failed to assemble normal capsids, and 5 mutations supported normal viral assembly but were nevertheless reduced more than 20-fold in infectivity. The locations of the assembly-defective mutations implicate three different CA surfaces in immature particle assembly: one surface encompasses helices 4 to 6 in the CA N-terminal domain (NTD), a second surrounds the crystallographically defined CA dimer interface in the C-terminal domain (CTD), and a third surrounds the loop preceding helix 8 at the base of the CTD. Mature capsid formation required a distinct surface encompassing helices 1 to 3 in the NTD, in good agreement with a recent structural model for the viral capsid. Finally, the identification of replication-defective mutants with normal viral assembly phenotypes indicates that CA also performs important nonstructural functions at early stages of the viral life cycle.
A Long Terminal Repeat-Containing Retrotransposon of
Schizosaccharomyces pombe
Expresses a Gag-Like Protein That Assembles into Virus-Like Particles Which Mediate Reverse Transcription
Authors: Teysset Laure , Dang Van-Dinh , Kim Min Kyung , Levin Henry L. 
Published: April 2003

ABSTRACT

The Tf1 element of
Schizosaccharomyces pombe
is a long terminal repeat-containing retrotransposon that encodes functional protease, reverse transcriptase, and integrase proteins. Although these proteins are known to be necessary for protein processing, reverse transcription, and integration, respectively, the function of the protein thought to be Gag has not been determined. We present here the first electron microscopy of Tf1 particles. We tested whether the putative Gag of Tf1 was required for particle formation, packaging of RNA, and reverse transcription. We generated deletions of 10 amino acids in each of the four hydrophilic domains of the protein and found that all four mutations reduced transposition activity. The N-terminal deletion removed a nuclear localization signal and inhibited nuclear import of the transposon. The two mutations in the center of Gag destabilized the protein and resulted in no virus-like particles. The C-terminal deletion caused a defect in RNA packaging and, as a result, low levels of cDNA. The electron microscopy of cells expressing a truncated Tf1 showed that Gag alone was sufficient for the formation of virus-like particles. Taken together, these results indicate that Tf1 encodes a Gag protein that is a functional equivalent of the Gag proteins of retroviruses.
Human Papillomavirus Type 16 E7 Peptide-Directed CD8+T Cells from Patients with Cervical Cancer Are Cross-Reactive with the Coronavirus NS2 Protein
Authors: Nilges Katja , Höhn Hanni , Pilch Henryk , Neukirch Claudia , Freitag Kirsten , Talbot P. J. , Maeurer Markus J. 
Published: April 2003

ABSTRACTHuman papillomavirus type 16 (HPV16) E6 and E7 oncoproteins are required for cellular transformation and represent candidate targets for HPV-specific and major histocompatibility complex class I-restricted CD8+-T-cell responses in patients with cervical cancer. Recent evidence suggests that cross-reactivity represents the inherent nature of the T-cell repertoire. We identified HLA-A2 binding HPV16 E7 variant peptides from human, bacterial, or viral origin which are able to drive CD8+-T-cell responses directed against wild-type HPV16 E7 amino acid 11 to 19/20 (E711-19/20) epitope YMLDLQPET(T) in vitro. CD8+T cells reacting to the HLA-A2-presented peptide from HPV16 E711-19(20)recognized also the HLA-A2 binding peptide TMLDIQPED (amino acids 52 to 60) from the human coronavirus OC43 NS2 gene product. Establishment of coronavirus NS2-specific, HLA-A2-restricted CD8+-T-cell clones and ex vivo analysis of HPV16 E7 specific T cells obtained by HLA-A2 tetramer-guided sorting from PBL or tumor-infiltrating lymphocytes obtained from patients with cervical cancer showed that cross-reactivity with HPV16 E711-19(20)and coronavirus NS252-60represents a common feature of this antiviral immune response defined by cytokine production. Zero of 10 patients with carcinoma in situ neoplasia and 3 of 18 patients with cervical cancer showed ≥0.1% HPV16 E7-reactive T cells in CD8+peripheral blood lymphocytes. In vivo priming with HPV16 was confirmed in patients with cervical cancer or preinvasive HPV16-positive lesions using HLA-A2 tetramer complexes loaded with the E6-derived epitope KLPQLCTEL. In contrast, we could not detect E6-reactive T cells in healthy individuals. These data imply that the measurement of the HPV16 E711-19(20)CD8+-T-cell response may reflect cross-reactivity with a common pathogen and that variant peptides may be employed to drive an effective cellular immune response against HPV.
Crystal Structure of Swine Vesicular Disease Virus and Implications for Host Adaptation
Authors: Fry Elizabeth E. , Knowles Nick J. , Newman John W. I. , Wilsden Ginette , Rao Zihe , King Andrew M. Q. , Stuart David I. 
Published: April 2003

ABSTRACT

Swine vesicular disease virus
(SVDV) is an
Enterovirus
of the family
Picornaviridae
that causes symptoms indistinguishable from those of foot-and-mouth disease virus. Phylogenetic studies suggest that it is a recently evolved genetic sublineage of the important human pathogen coxsackievirus B5 (CBV5), and in agreement with this, it has been shown to utilize the coxsackie and adenovirus receptor (CAR) for cell entry. The 3.0-Å crystal structure of strain UK/27/72 SVDV (highly virulent) reveals the expected similarity in core structure to those of other picornaviruses, showing most similarity to the closest available structure to CBV5, that of coxsackievirus B3 (CBV3). Features that help to cement together and rigidify the protein subunits are extended in this virus, perhaps explaining its extreme tolerance of environmental factors. Using the large number of capsid sequences available for both SVDV and CBV5, we have mapped the amino acid substitutions that may have occurred during the supposed adaptation of SVDV to a new host onto the structure of SVDV and a model of the SVDV/CAR complex generated by reference to the cryo-electron microscopy-visualized complex of CBV3 and CAR. The changes fall into three clusters as follows: one lines the fivefold pore, a second maps to the CAR-binding site and partially overlaps the site for decay accelerating factor (DAF) to bind to echovirus 7 (ECHO7), and the third lies close to the fivefold axis, where the low-density lipoprotein receptor binds to the minor group of rhinoviruses. Later changes in SVDV (post-1971) map to the first two clusters and may, by optimizing recognition of a pig CAR and/or DAF homologue, have improved the adaptation of the virus to pigs.
Interleukin-1 Inhibits Hepatitis C Virus Subgenomic RNA Replication by Activation of Extracellular Regulated Kinase Pathway
Authors: Zhu Haizhen , Liu Chen 
Published: April 2003

ABSTRACT
Interleukin-1 (IL-1) plays an important role in the inflammatory process. Some studies have demonstrated that IL-1 production was impaired in patients with chronic infections of hepatitis C virus (HCV), implying that IL-1 may play a role in viral clearance. Using an HCV subgenomic replicon cell line, we demonstrate that IL-1 can effectively inhibit HCV subgenomic RNA replication and viral protein expression, suggesting that IL-1 has direct antiviral activity. The inhibitory effect is associated with the extracellular regulatory kinase (ERK) activation. In addition, we also show that IL-1 can induce one of the interferon-stimulated genes (ISGs), 1-8U, which exhibits antiviral activity. However, it has no effect on the other ISG, 6-16, suggesting that IL-1 induces novel antiviral pathways within a cell.
Hepatitis B Virus-Mediated Changes of Apolipoprotein mRNA Abundance in Cultured Hepatoma Cells
Authors: Norton Pamela A. , Gong Qiaoke , Mehta Anand S. , Lu Xuanyong , Block Timothy M. 
Published: April 2003

ABSTRACT
An inverse correlation between hepatitis B virus (HBV) and steady-state levels of apolipoprotein AI and CIII mRNAs was observed in two hepatoma cell lines. Analysis of a third line containing an inducible viral genome implicated viral pregenomic RNA in apolipoprotein mRNA reduction. We conclude that HBV alters infected cells despite the absence of overt cytopathogenicity.
Activation of PKR by Bunyamwera Virus Is Independent of the Viral Interferon Antagonist NSs
Authors: Streitenfeld Hein , Boyd Amanda , Fazakerley John K. , Bridgen Anne , Elliott Richard M. , Weber Friedemann 
Published: April 2003

ABSTRACT

Double-stranded RNA (dsRNA) is a by-product of viral RNA polymerase activity, and its recognition is one mechanism by which the innate immune system is activated. Cellular responses to dsRNA include induction of alpha/beta interferon (IFN) synthesis and activation of the enzyme PKR, which exerts its antiviral effect by phosphorylating the eukaryotic initiation factor eIF-2 alpha, thereby inhibiting translation. We have recently identified the nonstructural protein NSs of
Bunyamwera virus
(BUNV), the prototype of the family
Bunyaviridae
, as a virulence factor that blocks the induction of IFN by dsRNA. Here, we investigated the potential of NSs to inhibit PKR. We show that wild-type (wt) BUNV that expresses NSs triggered PKR-dependent phosphorylation of eIF-2 alpha to levels similar to those of a recombinant virus that does not express NSs (BUNdelNSs virus). Furthermore, the sensitivity of viruses in cell culture to IFN was independent of PKR and was not determined by NSs. PKR knockout mice, however, succumbed to infection approximately 1 day earlier than wt mice or mice deficient in expression of RNase L, another dsRNA-activated antiviral enzyme. Our data indicate that (i) bunyaviruses activate PKR, but are only marginally sensitive to its antiviral effect, and (ii) NSs is different from other IFN antagonists, since it inhibits dsRNA-dependent IFN induction but has no effect on the dsRNA-activated PKR and RNase L systems.
Characterization of the DNA-Binding Properties of the Origin-Binding Domain of Simian Virus 40 Large T Antigen by Fluorescence Anisotropy
Authors: Titolo S. , Welchner E. , White P. W. , Archambault J. 
Published: April 2003

ABSTRACT
The affinity of the origin-binding domain (OBD) of simian virus 40 large T antigen for its cognate origin was measured at equilibrium using a DNA binding assay based on fluorescence anisotropy. At a near-physiological concentration of salt, the affinities of the OBD for site II and the core origin were 31 and 50 nM, respectively. Binding to any of the four 5′-GAGGC-3′ binding sites in site II was only slightly weaker, between 57 and 150 nM. Although the OBD was shown previously to assemble as a dimer on two binding sites spaced by 7 bp, we found that increasing the distance between both binding sites by 1 to 3 bp had little effect on affinity. Similar results were obtained for full-length T antigen in absence of nucleotide. Addition of ADP-Mg, which promotes hexamerization of T antigen, greatly increased the affinity of full-length T antigen for the core origin and for nonspecific DNA. The implications of these findings for the assembly of T antigen at the origin and its transition to a non-specific DNA helicase are discussed.
The Cell-Rounding Activity of the Vesicular Stomatitis Virus Matrix Protein Is due to the Induction of Cell Death
Authors: Kopecky Sarah A. , Lyles Douglas S. 
Published: April 2003

ABSTRACTThe matrix (M) protein of vesicular stomatitis virus (VSV) expressed in the absence of other viral components causes many of the cytopathic effects of VSV, including an inhibition of host gene expression and the induction of cell rounding. It was recently shown that M protein also induces apoptosis in the absence of other viral components. This raises the possibility that the activation of apoptotic pathways causes the inhibition of host gene expression and cell rounding by M protein. To test this hypothesis, host gene expression and cell rounding were analyzed after the transfection of M mRNA into HeLa cells stably overexpressing Bcl-2 (HeLa-Bcl-2 cells). We have shown previously that Bcl-2 inhibits M-protein-induced apoptosis. Here, we show that activation of the apoptotic pathways downstream of Bcl-2 is not required for the inhibition of host gene expression by M protein. In contrast, overexpression of Bcl-2 inhibited cell rounding induced by M protein, indicating that apoptotic pathways downstream of Bcl-2 are required for the cell-rounding activities of M protein.
Itchy, a Nedd4 Ubiquitin Ligase, Downregulates Latent Membrane Protein 2A Activity in B-Cell Signaling
Authors: Ikeda Akiko , Caldwell Robert G. , Longnecker Richard , Ikeda Masato 
Published: April 2003

ABSTRACT

Nedd4 family ubiquitin protein ligases (E3s) specifically associate with latent membrane protein 2A (LMP2A) of Epstein-Barr virus. Our previous studies analyzing LMP2A function in vitro have suggested that Nedd4 family E3s regulate LMP2A function. To determine the role of Nedd4 family E3s in LMP2A B-cell signaling, LMP2A transgenic (LMP2A
+
) mice were crossed with mice with the Itch-deficient (Itch
−/−
) background. Itchy, a mouse homologue of human AIP4, is a Nedd4 family E3 and is also the most abundant Nedd4 family E3 found in LMP2A affinity precipitates from B cells. There were significantly fewer B-cell receptor-positive B cells in spleen and bone marrow B cells in LMP2A
+
Itch
−/−
mice than in LMP2A
+
mice. In addition, LMP2A
+
Itch
−/−
bone marrow B cells formed larger colonies in cultures treated with interleukin-7 (IL-7) than control bone marrow B cells did. Finally, there was a dramatic increase in tyrosine phosphorylation of LMP2A and Syk in IL-7-cultured LMP2A
+
Itch
−/−
B cells. These results indicate that Nedd4 family E3s, in particular Itchy, downmodulate LMP2A activity in B-cell signaling.
Sphingosine Kinase-Dependent Migration of Immature Dendritic Cells in Response to Neurotoxic Prion Protein Fragment
Authors: Kaneider Nicole C. , Kaser Arthur , Dunzendorfer Stefan , Tilg Herbert , Wiedermann Christian J. 
Published: April 2003

ABSTRACTThe concept that circulating dendritic cells mediate neuroinvasion in transmissible spongiform encephalopathies received strong support from recent observations that prion protein is expressed in myeloid dendritic cells. We observed that prion protein fragment 106-126 is a chemoattractant for monocyte-derived immature but not mature dendritic cells. Signaling events in chemotaxis involved enzymes downstream of Gqprotein and were inhibited by blockade of sphingosine kinase, suggesting transactivation of sphingosine-1-phosphate-dependent cell motility by prion protein.
Evolutionary Indicators of Human Immunodeficiency Virus Type 1 Reservoirs and Compartments
Authors: Nickle David C. , Jensen Mark A. , Shriner Daniel , Brodie Scott J. , Frenkel Lisa M. , Mittler John E. , Mullins James I. 
Published: April 2003

ABSTRACT
In vivo virologic compartments are cell types or tissues between which there is a restriction of virus flow, while virologic reservoirs are cell types or tissues in which there is a relative restriction of replication. The distinction between reservoirs and compartments is important because therapies that would be effective against a reservoir may not be effective against viruses produced by a given compartment, and vice versa. For example, the use of cytokines to “flush out” long-lived infected cells in patients on highly active antiretroviral therapy (T. W. Chun, D. Engel, M. M. Berrey, T. Shea, L. Corey, and A. S. Fauci, Proc. Natl. Acad. Sci. USA 95:8869-8873, 1998) may be successful for a latent reservoir but may not impact a compartment in which virus continues to replicate because of poor drug penetration. Here, we suggest phylogenetic criteria to illustrate, define, and differentiate between reservoirs and compartments. We then apply these criteria to the analysis of simulated and actual human immunodeficiency virus type 1 sequence data sets. We report that existing statistical methods work quite well at detecting viral compartments, and we learn from simulations that viral divergence from a calculated most recent common ancestor is a strong predictor of viral reservoirs.
Association Between Complement Factor H and Proteoglycans in Early Human Coronary Atherosclerotic Lesions
Authors: Oksjoki Riina , Jarva Hanna , Kovanen Petri T. , Laine Petri , Meri Seppo , Pentikäinen Markku O. 
Published: April 2003

Objective—Complement activation has been suggested to play a role in atherogenesis. To study the regulation of complement activation in human coronary atherosclerotic lesions, we examined the spatial relationships between the major complement inhibitor, factor H, and the complement activation products C3d and C5b-9.Methods and Results—In early lesions (American Heart Association types II and III), factor H was immunohistochemically found in the superficial proteoglycan-rich layer in association with numerous macrophages and C3d, whereas C5b-9 was found deeper in the intima, where factor H was virtually absent. In vitro experiments involving surface plasmon resonance and affinity chromatography analyses demonstrated that isolated human arterial proteoglycans bind factor H, and functional complement assays showed that glycosaminoglycans inhibit the complement activation induced by modified low density lipoprotein or by a foreign surface.Conclusions—The present observations raise the possibility that proteoglycans, because of their ability to bind the major complement inhibitor factor H, may inhibit complement activation in the superficial layer of the arterial intima. In contrast, deeper in the intima, where factor H and proteoglycans are absent, complement may be activated and proceed to C5b-9. Thus, the superficial and the deep layers of the human coronary artery appear to differ in their ability to regulate complement activation.
Oncostatin M, an Interleukin-6 Family Cytokine, Upregulates Matrix Metalloproteinase-9 Through the Mitogen-Activated Protein Kinase Kinase-Extracellular Signal-Regulated Kinase Pathway in Cultured Smooth Muscle Cells
Authors: Nagata Tsuyoshi , Kai Hisashi , Shibata Rei , Koga Mitsuhisa , Yoshimura Akihiko , Imaizumi Tsutomu 
Published: April 2003

Objectives—Matrix metalloproteinase (MMP)-9 is implicated in extracellular matrix (ECM) degradation of atherosclerotic lesions. Oncostatin M (OSM) regulates ECM metabolism in various kinds of cells. Thus, we sought to investigate whether OSM regulates MMP-9 expression in cultured rat aortic smooth muscle cells (SMCs) and, if so, to determine the signaling pathway for MMP-9 induction by OSM.Methods and Results—Competitive reverse transcriptase polymerase chain reaction showed that OSM upregulated MMP-9 mRNA expression, peaking at 4 hours and returning to unstimulated levels by 24 hours. Gelatin zymography revealed that MMP-9 activity was increased in the conditioned medium after the 24-hour OSM treatment. Immunoblot analysis demonstrated that OSM transiently induced extracellular signal-regulated kinase (ERK)1/2 and STAT3 phosphorylations with a peak at 15 and 5 minutes, respectively. A MEK1 inhibitor, PD98059, not only blocked ERK1/2 phosphorylation but also abolished the OSM-induced MMP-9 upregulation, whereas the MMP-9 induction was not affected by overexpressing dominant-negative STAT3. In addition, OSM slightly upregulated MMP-2 and downregulated tissue inhibitors of MMP-1 and -3 through different mechanisms from that in case of MMP-9.Conclusions—OSM upregulates MMP-9 expression in SMCs through the MEK-ERK but not STAT3 pathway.
Enzymatically Modified LDL Induces Cathepsin H in Human Monocytes
Authors: Han Shan-Rui , Momeni Arash , Strach Katharina , Suriyaphol Prapat , Fenske Dominic , Paprotka Kerstin , Hashimoto Shin Ichi , Torzewski Michael , Bhakdi Sucharit , Husmann Matthias 
Published: April 2003

Objective—Modification with proteases and cholesterylesterase transforms LDL to a moiety that resembles lipoproteins isolated from atherosclerotic lesions and possesses atherogenic properties. To identify changes in monocyte-derived foam cells laden with enzymatically modified LDL (E-LDL), we compared patterns of the most abundant transcripts in these cells after incubation with LDL or E-LDL.Methods and Results—Serial analyses of gene expression (SAGE) libraries were constructed from human monocytes after treatment with LDL or E-LDL. Several tags were differentially expressed in LDL-treated versus E-LDL–treated cells, whereby marked selective induction by E-LDL of cathepsin H was conspicuous. We show that cathepsin H is expressed in atherosclerotic lesions in colocalization with E-LDL. Furthermore, we demonstrate that LDL modified with cathepsin H and cholesterylesterase can confer onto LDL the capacity to induce macrophage foam cell formation and to induce cathepsin H.Conclusions—Cathepsin H could contribute to the transformation of LDL to an atherogenic moiety; the process might involve a self-sustaining amplifying circle.
Hematopoietic stem cell transplantation: contrasting the outcome of transplantations from HLA-identical siblings, partially HLA-mismatched related donors, and HLA-matched unrelated donors
Authors: Ottinger Hellmut D. , Ferencik Stanislav , Beelen Dietrich W. , Lindemann Monika , Peceny Rudolf , Elmaagacli Ahmed H. , Hüsing Johannes , Grosse-Wilde Hans 
Published: April 2003

Abstract
Allogeneic hematopoietic stem cell transplantation (HSCT) is a proven curative therapy for many hematologic malignancies. HSCT from HLA-identical sibling donors (ISDs) is still the golden standard. For the remaining 70% of the patients lacking an ISD, alternative (partially) HLA-matched family donors (MFDs) and HLA-matched unrelated donors (MUDs) are now widely accepted. However, it is presently unclear whether outcome after HSCT from an MFD or an MUD is superior. Thus, the classical clinical end points after HSCT from an ISD (n = 138), MFD (n = 86), and MUD (n = 101) were compared by means of univariate and multivariate statistical analyses. MFD transplantations with HLA class II (DRB1 ± DQB1) mismatches in graft-versus-host (GVH) direction showed an increased risk of grades II to IV graft-versus-host disease, and MFD transplantations with more than a single HLA class I (A ± B ± C) mismatch in host-versus-graft (HVG) direction were associated with a higher risk of graft failure. However, no significant difference in overall survival was detectable among the 3 study groups after adjustment for the main predictors of transplantation outcome. Thus, for patients lacking an ISD, an already identified MFD with an HLA-DRB1 ± DQB1 mismatch in GVH or a combined HLA-A ± B ± C mismatch in HVG direction should be accepted only in clinically urgent settings that leave no time to identify an MUD.