bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunization of Macaques with Single-Cycle Simian Immunodeficiency Virus (SIV) Stimulates Diverse Virus-Specific Immune Responses and Reduces Viral Loads after Challenge with SIVmac239
Authors: Evans David T. , Bricker Jennifer E. , Sanford Hannah B. , Lang Sabine , Carville Angela , Richardson Barbra A. , Piatak Michael , Lifson Jeffrey D. , Mansfield Keith G. , Desrosiers Ronald C. 
Published: May 2005

ABSTRACTGenetically engineered simian immunodeficiency viruses (SIV) that is limited to a single cycle of infection was evaluated as a nonreplicating AIDS vaccine approach for rhesus macaques. Four Mamu-A*01+macaques were inoculated intravenously with three concentrated doses of single-cycle SIV (scSIV). Each dose consisted of a mixture of approximately equivalent amounts of scSIV strains expressing the SIVmac239 and SIVmac316 envelope glycoproteins with mutations innefthat prevent major histocompatibility complex (MHC) class I downregulation. Viral loads in plasma peaked between 104and 105RNA copies/ml on day 4 after the first inoculation and then steadily declined to undetectable levels over the next 4 weeks. SIV Gag-specific T-cell responses were detected in peripheral blood by MHC class I tetramer staining (peak, 0.07 to 0.2% CD8+T cells at week 2) and gamma interferon (IFN-γ) enzyme-linked immunospot (ELISPOT) assays (peak, 50 to 250 spot forming cells/106peripheral blood mononuclear cell at week 3). Following the second and third inoculations at weeks 8 and 33, respectively, viral loads in plasma peaked between 102and 104RNA copies/ml on day 2 and were cleared over a 1-week period. T-cell-proliferative responses and antibodies to SIV were also observed after the second inoculation. Six weeks after the third dose, each animal was challenged intravenously with SIVmac239. All four animals became infected. However, three of the four scSIV-immunized animals exhibited 1 to 3 log reductions in acute-phase plasma viral loads relative to two Mamu-A*01+control animals. Additionally, two of these animals were able to contain their viral loads below 2,000 RNA copies/ml as late as 35 weeks into the chronic phase of infection. Given the extraordinary difficulty in protecting against SIVmac239, these results are encouraging and support further evaluation of lentiviruses that are limited to a single cycle of infection as a preclinical AIDS vaccine approach.
[
18
F]FHPG Positron Emission Tomography for Detection of Herpes Simplex Virus (HSV) in Experimental HSV Encephalitis
Authors: Buursma A. R. , de Vries E. F. J. , Garssen J. , Kegler D. , van Waarde A. , Schirm J. , Hospers G. A. P. , Mulder N. H. , Vaalburg W. , Klein H. C. 
Published: May 2005

ABSTRACT

Herpes simplex virus type 1 (HSV-1) is one of the most common causes of sporadic encephalitis. The initial clinical course of HSV encephalitis (HSE) is highly variable, and the infection may be rapidly fatal. For effective treatment with antiviral medication, an early diagnosis of HSE is crucial. Subtle brain infections with HSV may be causally related to neuropsychiatric disorders such as Alzheimer's dementia. We investigated the feasibility of a noninvasive positron emission tomography (PET) imaging technique using [
18
F]FHPG as a tracer for the detection of HSE. For this purpose, rats received HSV-1 (infected group) or phosphate-buffered saline (control group) by intranasal application, and dynamic PET scans were acquired. In addition, the distribution of tracer accumulation in specific brain areas was studied with phosphor storage imaging. The PET images revealed that the overall brain uptake of [
18
F]FHPG was significantly higher for the infected group than for control animals. Phosphor storage images showed an enhanced accumulation of [
18
F]FHPG in regions known to be affected after intranasal infection with HSV. High-performance liquid chromatography metabolite analysis showed phosphorylated metabolites of [
18
F]FHPG in infected brains, proving that the increased [
18
F]FHPG uptake in infected brains was due to HSV thymidine kinase-mediated trapping. Freeze lesion experiments showed that damage to the blood-brain barrier could in principle induce elevated [
18
F]FHPG uptake, but this nonspecific tracer uptake could easily be discriminated from HSE-derived uptake by differences in the tracer kinetics. Our results show that [
18
F]FHPG PET is a promising tool for the detection of HSV encephalitis.
Induction of T-Cell Immunity to Antiretroviral Drug-Resistant Human Immunodeficiency Virus Type 1
Authors: Stratov Ivan , Dale C. Jane , Chea Socheata , McCluskey James , Kent Stephen J. 
Published: May 2005

ABSTRACTAntiretroviral drug-resistant human immunodeficiency virus type 1 (HIV-1) is a major, growing, public health problem. Immune responses targeting epitopes spanning drug resistance sites could ameliorate development of drug resistance. We studied 25 individuals harboring multidrug-resistant HIV-1 for T-cell immunity to HIV-1 proteins and peptides spanning all common drug resistance mutations. CD8 T cells targeting epitopes spanning drug-induced mutations were detected but only in the 3 individuals with robust HIV-specific T-cell activity. Novel CD8 T-cell responses were detected against the common L63P and L10I protease inhibitor fitness mutations. Induction of T-cell immunity to drug-resistant variants was demonstrated in simian human immunodeficiency virus-infected macaques, where both CD8 and CD4 T-cell immune responses to reverse transcriptase and protease antiretroviral mutations were elicited using a novel peptide-based immunotherapy. T-cell responses to antiretroviral resistance mutations were strongest in the most immunocompetent animals. This study suggests feasible strategies to further evaluate the potential of limiting antiretroviral drug resistance through induction of T-cell immunity.
Identification of a Cell Population That Produces Alpha/Beta Interferon In Vitro and In Vivo in Response to Noncytopathic Bovine Viral Diarrhea Virus
Authors: Brackenbury L. S. , Carr B. V. , Stamataki Z. , Prentice H. , Lefevre E. A. , Howard C. J. , Charleston B. 
Published: May 2005

ABSTRACTIn vitro infection of bovine cells of many origins with the cytopathogenic bovine viral diarrhea virus (cpBVDV) results in the induction of alpha/beta interferon (IFN-α/β), whereas noncytopathogenic BVDV (ncpBVDV) isolates have been shown not to induce IFN-α/β in vitro. Similarly, cpBVDV induces IFN-α/β in the early bovine fetus, but ncpBVDV does not. However, acute infection of naïve cattle with ncpBVDV results in IFN-α/β production. In this study, we identified and characterized a minor population of cells, present in lymph nodes that produce IFN-α in response to ncpBVDV. These cells expressed the myeloid markers CD14, CD11b, and CD172a but did not express CD4 and CD45RB. We also established that these cells produced IFN-α in the absence of detectable productive infection.
The Structure of the Poliovirus 135S Cell Entry Intermediate at 10-Angstrom Resolution Reveals the Location of an Externalized Polypeptide That Binds to Membranes
Authors: Bubeck Doryen , Filman David J. , Cheng Naiqian , Steven Alasdair C. , Hogle James M. , Belnap David M. 
Published: May 2005

ABSTRACT
Poliovirus provides a well-characterized system for understanding how nonenveloped viruses enter and infect cells. Upon binding its receptor, poliovirus undergoes an irreversible conformational change to the 135S cell entry intermediate. This transition involves shifts of the capsid protein β barrels, accompanied by the externalization of VP4 and the N terminus of VP1. Both polypeptides associate with membranes and are postulated to facilitate entry by forming a translocation pore for the viral RNA. We have calculated cryo-electron microscopic reconstructions of 135S particles that permit accurate placement of the β barrels, loops, and terminal extensions of the capsid proteins. The reconstructions and resulting models indicate that each N terminus of VP1 exits the capsid though an opening in the interface between VP1 and VP3 at the base of the canyon that surrounds the fivefold axis. Comparison with reconstructions of 135S particles in which the first 31 residues of VP1 were proteolytically removed revealed that the externalized N terminus is located near the tips of propeller-like features surrounding the threefold axes rather than at the fivefold axes, as had been proposed in previous models. These observations have forced a reexamination of current models for the role of the 135S particle in transmembrane pore formation and suggest testable alternatives.
Single Point Mutations in the Zinc Finger Motifs of the Human Immunodeficiency Virus Type 1 Nucleocapsid Alter RNA Binding Specificities of the Gag Protein and Enhance Packaging and Infectivity
Authors: Mark-Danieli Michal , Laham Nihay , Kenan-Eichler Michal , Castiel Asher , Melamed Daniel , Landau Meytal , Bouvier Nicole M. , Evans Matthew J. , Bacharach Eran 
Published: May 2005

ABSTRACT
A specific interaction between the nucleocapsid (NC) domain of the Gag polyprotein and the RNA encapsidation signal (Ψ) is required for preferential incorporation of the retroviral genomic RNA into the assembled virion. Using the yeast three-hybrid system, we developed a genetic screen to detect human immunodeficiency virus type 1 (HIV-1) Gag mutants with altered RNA binding specificities. Specifically, we randomly mutated full-length HIV-1 Gag or its NC portion and screened the mutants for an increase in affinity for the Harvey murine sarcoma virus encapsidation signal. These screens identified several NC zinc finger mutants with altered RNA binding specificities. Furthermore, additional zinc finger mutants that also demonstrated this phenotype were made by site-directed mutagenesis. The majority of these mutants were able to produce normal virion-like particles; however, when tested in a single-cycle infection assay, some of the mutants demonstrated higher transduction efficiencies than that of wild-type Gag. In particular, the N17K mutant showed a seven- to ninefold increase in transduction, which correlated with enhanced vector RNA packaging. This mutant also packaged larger amounts of foreign RNA. Our results emphasize the importance of the NC zinc fingers, and not other Gag sequences, in achieving specificity in the genome encapsidation process. In addition, the described mutations may contribute to our understanding of HIV diversity resulting from recombination events between copackaged viral genomes and foreign RNA.
Indoleamine 2,3-Dioxygenase Mediates Cell Type-Specific Anti-Measles Virus Activity of Gamma Interferon
Authors: Obojes Karola , Andres Oliver , Kim Kwang Sik , Däubener Walter , Schneider-Schaulies Jürgen 
Published: May 2005

ABSTRACTGamma interferon (IFN-γ) has been shown to be increased in sera from patients with acute measles and after vaccination, to exhibit protective functions in brains of patients with subacute sclerosing panencephalitis, and to mediate a noncytolytic clearance of measles virus (MV) from rodent brains. In order to reveal a possible intracellular antiviral activity in the absence of antigen presentation and cytotoxic T cells, we investigated IFN-γ-induced effects on MV replication in various tissue culture cells. While attenuated MV strains are more sensitive to IFN-α/β than are wild-type strains, IFN-γ inhibits the replication of all MV strains in epithelial, endothelial, and astroglial cells, but not in lymphoid and neuronal cell lines. The antiviral activity induced by IFN-γ correlates with the induction of indoleamine 2,3-dioxygenase (IDO), an enzyme of the tryptophan degradation pathway known to mediate antiviral as well as antibacterial and antiparasitic effects. The IFN-γ-induced antiviral activity can be overcome by the addition of excess amounts ofl-tryptophan, which indicates a specific role of IDO in the anti-MV activity. Our data suggest that the IFN-γ-induced enzyme IDO plays an important antiviral role in MV infections of epithelial, endothelial, and astroglial cells.
Resistance of Human Immunodeficiency Virus Type 1 to the High-Mannose Binding Agents Cyanovirin N and Concanavalin A
Authors: Witvrouw Myriam , Fikkert Valery , Hantson Anke , Pannecouque Christophe , O'Keefe Barry R. , McMahon James , Stamatatos Leonidas , de Clercq Erik , Bolmstedt Anders 
Published: May 2005

ABSTRACT

Due to the biological significance of the carbohydrate component of the human immunodeficiency virus type 1 (HIV-1) glycoproteins in viral pathogenesis, the glycosylation step constitutes an attractive target for anti-HIV therapy. Cyanovirin N (CV-N), which specifically targets the high-mannose (HM) glycans on gp120, has been identified as a potent HIV-1 entry inhibitor. Concanavalin A (ConA) represents another mannose-binding lectin, although it has a lower specificity for HM glycans than that of CV-N. For the present study, we selected CV-N- and ConA-resistant HIV-1 strains in the presence of CV-N and ConA, respectively. Both resistant strains exhibited a variety of mutations eliminating N-linked glycans within gp120. Strains resistant to CV-N or ConA displayed high levels of cross-resistance towards one another. The N-glycan at position 302 was eliminated in both of the lectin-resistant strains. However, the elimination of this glycan alone by site-directed mutagenesis was not sufficient to render HIV-1 resistant to CV-N or ConA, suggesting that HIV-1 needs to mutate several N-glycans to become resistant to these lectins. Both strains also demonstrated clear cross-resistance towards the carbohydrate-dependent monoclonal antibody 2G12. In contrast, the selected strains did not show a reduced susceptibility towards the nonlectin entry inhibitors AMD3100 and enfuvirtide or towards reverse transcriptase or protease inhibitors. Recombination of the mutated
gp160
genes of the strains resistant to CV-N or ConA into a wild-type background fully reproduced the (cross-)resistance profiles of the originally selected strains, pointing to the impact of the N-glycan mutations on the phenotypic resistance profiles of both selected strains.
Systematic Identification of Antiprion Drugs by High-Throughput Screening Based on Scanning for Intensely Fluorescent Targets
Authors: Bertsch Uwe , Winklhofer Konstanze F. , Hirschberger Thomas , Bieschke Jan , Weber Petra , Hartl F. Ulrich , Tavan Paul , Tatzelt Jörg , Kretzschmar Hans A. , Giese Armin 
Published: May 2005

ABSTRACTConformational changes and aggregation of specific proteins are hallmarks of a number of diseases, like Alzheimer's disease, Parkinson's disease, and prion diseases. In the case of prion diseases, the prion protein (PrP), a neuronal glycoprotein, undergoes a conformational change from the normal, mainly alpha-helical conformation to a disease-associated, mainly beta-sheeted scrapie isoform (PrPSc), which forms amyloid aggregates. This conversion, which is crucial for disease progression, depends on direct PrPC/PrPScinteraction. We developed a high-throughput assay based on scanning for intensely fluorescent targets (SIFT) for the identification of drugs which interfere with this interaction at the molecular level. Screening of a library of 10,000 drug-like compounds yielded 256 primary hits, 80 of which were confirmed by dose response curves with half-maximal inhibitory effects ranging from 0.3 to 60 μM. Among these, six compounds displayed an inhibitory effect on PrPScpropagation in scrapie-infected N2a cells. Four of these candidate drugs share anN′-benzylidene-benzohydrazide core structure. Thus, the combination of high-throughput in vitro assay with the established cell culture system provides a rapid and efficient method to identify new antiprion drugs, which corroborates that interaction of PrPCand PrPScis a crucial molecular step in the propagation of prions. Moreover, SIFT-based screening may facilitate the search for drugs against other diseases linked to protein aggregation.
Interaction between the Human Cytomegalovirus UL82 Gene Product (pp71) and hDaxx Regulates Immediate-Early Gene Expression and Viral Replication
Authors: Cantrell Stacy R. , Bresnahan Wade A. 
Published: May 2005

ABSTRACT
The human cytomegalovirus UL82-encoded pp71 protein is required for efficient virus replication and immediate-early gene expression when cells are infected at a low multiplicity. Functions attributed to pp71 include the ability to enhance the infectivity of viral DNA, bind to and target hypophosphorylated Rb family member proteins for degradation, drive quiescent cells into the cell cycle, and bind to the cellular protein hDaxx. Using UL82 mutant viruses, we demonstrate that the LXCXD motif within pp71 is not necessary for efficient virus replication in fibroblasts, suggesting that pp71's ability to degrade hypophosphorylated Rb family members and induce quiescent cells into the cell cycle is not responsible for the growth defect associated with a UL82 deletion mutant. However, UL82 mutants that cannot bind to hDaxx are unable to induce immediate-early gene expression and are severely attenuated for viral replication. These results indicate that the interaction between the human cytomegalovirus UL82 gene product (pp71) and hDaxx regulates immediate-early gene expression and viral replication.
Allosteric Effects of Ligands and Mutations on Poliovirus RNA-Dependent RNA Polymerase
Authors: Boerner Joanna E. , Lyle John M. , Daijogo Sarah , Semler Bert L. , Schultz Stephen C. , Kirkegaard Karla , Richards Oliver C. 
Published: May 2005

ABSTRACT
Protein priming of viral RNA synthesis plays an essential role in the replication of picornavirus RNA. Both poliovirus and coxsackievirus encode a small polypeptide, VPg, which serves as a primer for addition of the first nucleotide during synthesis of both positive and negative strands. This study examined the effects on the VPg uridylylation reaction of the RNA template sequence, the origin of VPg (coxsackievirus or poliovirus), the origin of 3D polymerase (coxsackievirus or poliovirus), the presence and origin of interacting protein 3CD, and the introduction of mutations at specific regions in the poliovirus 3D polymerase. Substantial effects associated with VPg origin were traced to differences in VPg-polymerase interactions. The effects of 3CD proteins and mutations at polymerase-polymerase intermolecular Interface I were most consistent with allosteric effects on the catalytic 3D polymerase molecule. In conclusion, the efficiency and specificity of VPg uridylylation by picornavirus polymerases is greatly influenced by allosteric effects of ligand binding that are likely to be relevant during the viral replicative cycle.
Plant Virus-Derived Small Interfering RNAs Originate Predominantly from Highly Structured Single-Stranded Viral RNAs
Authors: Molnár Attila , Csorba Tibor , Lakatos Lóránt , Várallyay Éva , Lacomme Christophe , Burgyán József 
Published: May 2005

ABSTRACTRNA silencing is conserved in a broad range of eukaryotes and includes the phenomena of RNA interference in animals and posttranscriptional gene silencing (PTGS) in plants. In plants, PTGS acts as an antiviral system; a successful virus infection requires suppression or evasion of the induced silencing response. Small interfering RNAs (siRNAs) accumulate in plants infected with positive-strand RNA viruses and provide specificity to this RNA-mediated defense. We present here the results of a survey of virus-specific siRNAs characterized by a sequence analysis of siRNAs from plants infected withCymbidium ringspot tombusvirus(CymRSV). CymRSV siRNA sequences have a nonrandom distribution along the length of the viral genome, suggesting that there are hot spots for virus-derived siRNA generation. CymRSV siRNAs bound to the CymRSV p19 suppressor protein have the same asymmetry in strand polarity as the sequenced siRNAs and are imperfect double-stranded RNA duplexes. Moreover, an analysis of siRNAs derived from two other nonrelated positive-strand RNA viruses showed that they displayed the same asymmetry as CymRSV siRNAs. Finally, we show thatTobacco mosaic virus(TMV) carrying a short inverted repeat of the phytoene desaturase (PDS) gene triggered more accumulation ofPDSsiRNAs than the corresponding antisensePDSsequence. Taken together, these results suggest that virus-derived siRNAs originate predominantly by direct DICER cleavage of imperfect duplexes in the most folded regions of the positive strand of the viral RNA.
Stringent Requirement for the C Protein of Wild-Type Measles Virus for Growth both In Vitro and in Macaques
Authors: Takeuchi Kaoru , Takeda Makoto , Miyajima Naoko , Ami Yasushi , Nagata Noriyo , Suzaki Yuriko , Shahnewaz Jamila , Kadota Shin-ichi , Nagata Kyosuke 
Published: May 2005

ABSTRACT

The P gene of measles virus (MV) encodes the P protein and three accessory proteins (C, V, and R). However, the role of these accessory proteins in the natural course of MV infection remains unclear. For this study, we generated a recombinant wild-type MV lacking the C protein, called wtMV(C−), by using a reverse genetics system (M. Takeda, K. Takeuchi, N. Miyajima, F. Kobune, Y. Ami, N. Nagata, Y. Suzaki, Y. Nagai, and M. Tashiro, J. Virol.
74:
6643-6647). When 293 cells expressing the MV receptor SLAM (293/hSLAM) were infected with wtMV(C−) or parental wild-type MV (wtMV), the growth of wtMV(C−) was restricted, particularly during late stages. Enhanced green fluorescent protein-expressing wtMV(C−) consistently induced late-stage cell rounding and cell death in the presence of a fusion-inhibiting peptide, suggesting that the C protein can prevent cell death and is required for long-term MV infection. Neutralizing antibodies against alpha/beta interferon did not restore the growth restriction of wtMV(C−) in 293/hSLAM cells. When cynomolgus monkeys were infected with wtMV(C−) or wtMV, the number of MV-infected cells in the thymus was >1,000-fold smaller for wtMV(C−) than for wtMV. Immunohistochemical analyses showed strong expression of an MV antigen in the spleen, lymph nodes, tonsils, and larynx of a cynomolgus monkey infected with wtMV but dramatically reduced expression in the same tissues in a cynomolgus monkey infected with wtMV(C−). These data indicate that the MV C protein is necessary for efficient MV replication both in vitro and in cynomolgus monkeys.
Modified Vaccinia Virus Ankara Protects Macaques against Respiratory Challenge with Monkeypox Virus
Authors: Stittelaar Koert J. , van Amerongen Geert , Kondova Ivanela , Kuiken Thijs , van Lavieren Rob F. , Pistoor Frank H. M. , Niesters Hubert G. M. , van Doornum Gerard , van der Zeijst Ben A. M. , Mateo Luis , Chaplin Paul J. , Osterhaus Albert D. M. E. 
Published: May 2005

ABSTRACT
The use of classical smallpox vaccines based on vaccinia virus (VV) is associated with severe complications in both naïve and immune individuals. Modified vaccinia virus Ankara (MVA), a highly attenuated replication-deficient strain of VV, has been proven to be safe in humans and immunocompromised animals, and its efficacy against smallpox is currently being addressed. Here we directly compare the efficacies of MVA alone and in combination with classical VV-based vaccines in a cynomolgus macaque monkeypox model. The MVA-based smallpox vaccine protected macaques against a lethal respiratory challenge with monkeypox virus and is therefore an important candidate for the protection of humans against smallpox.