bluuebunny/crossref_metadata_2025_split huggingface dataset:
CD40 Engagement on Dendritic Cells, but Not on B or T Cells, Is Required for Long-Term Control of Murine Gammaherpesvirus 68
Authors: Giannoni Francesca , Shea Ashley , Inglis Chandra , Lee Lian Ni , Sarawar Sally R. 
Published: September 2008

ABSTRACTCD4 T cells are not essential for primary clearance of replicating murine gammaherpesvirus 68 (MHV-68) but are required for effective long-term control. The virus reactivates in the lungs of major histocompatibility complex class II-deficient (CII−/−) mice that lack functional CD4 T cells. CD40 ligand (CD40L) is upregulated on activated CD4 T cells, and it is thought that CD40-CD40L interactions are an important component of CD4 T-cell help. Our previous studies have shown that agonistic antibodies to CD40 can substitute for CD4 T-cell function in the long-term control of MHV-68. In the present study, we sought to identify the CD40-positive cell type mediating this effect. To address this question, we adoptively transferred MHV-68 peptide-pulsed CII−/−dendritic cells (DC) that had been treated with an agonistic antibody to CD40 into MHV-68-infected CII−/−recipients. Viral reactivation was significantly lower in mice injected with anti-CD40-treated DC than in those injected with control DC or in mice that did not receive any DC. However, in similar experiments with B cells, anti-CD40 treatment had no effect. We also investigated the requirement for CD40 expression on T cells by adoptive transfer of T cells from CD40+/+or CD40−/−mice into T-cell-deficient recipients that were subsequently infected with MHV-68. The results showed that CD40 expression on T cells is not necessary for preventing viral reactivation. Taken together, our data suggest that CD40 engagement on DC, but not on T or B cells, is essential for effective long-term control of MHV-68.
Mutation of Mapped TIA-1/TIAR Binding Sites in the 3′ Terminal Stem-Loop of West Nile Virus Minus-Strand RNA in an Infectious Clone Negatively Affects Genomic RNA Amplification
Authors: Emara Mohamed M. , Liu Hsuan , Davis William G. , Brinton Margo A. 
Published: September 2008

ABSTRACTPrevious data showed that the cellular proteins TIA-1 and TIAR bound specifically to the West Nile virus 3′ minus-strand stem-loop [WNV3′(−)SL] RNA (37) and colocalized with flavivirus replication complexes in WNV- and dengue virus-infected cells (21). In the present study, the sites on the WNV3′(−)SL RNA required for efficient in vitro T-cell intracellular antigen-related (TIAR) and T-cell intracellular antigen-1 (TIA-1) protein binding were mapped to short AU sequences (UAAUU) located in two internal loops of the WNV3′(−)SL RNA structure. Infectious clone RNAs with all or most of the binding site nucleotides in one of the 3′ (−)SL loops deleted or substituted did not produce detectable virus after transfection or subsequent passage. With one exception, deletion/mutation of a single terminal nucleotide in one of the binding sequences had little effect on the efficiency of protein binding or virus production, but mutation of a nucleotide in the middle of a binding sequence reduced both the in vitro protein binding efficiency and virus production. Plaque size, intracellular genomic RNA levels, and virus production progressively decreased with decreasing in vitro TIAR/TIA-1 binding activity, but the translation efficiency of the various mutant RNAs was similar to that of the parental RNA. Several of the mutant RNAs that inefficiently interacted with TIAR/TIA-1 in vitro rapidly reverted in vivo, indicating that they could replicate at a low level and suggesting that an interaction between TIAR/TIA-1 and the viral 3′(−)SL RNA is not required for initial low-level symmetric RNA replication but instead facilitates the subsequent asymmetric amplification of genome RNA from the minus-strand template.
Mode of Transmission Affects the Sensitivity of Human Immunodeficiency Virus Type 1 to Restriction by Rhesus TRIM5α
Authors: Richardson Max W. , Carroll Richard G. , Stremlau Matthew , Korokhov Nikolay , Humeau Laurent M. , Silvestri Guido , Sodroski Joseph , Riley James L. 
Published: September 2008

ABSTRACTRhesus TRIM5α (rhTRIM5α), but not human TRIM5α (huTRIM5α), potently inhibits human immunodeficiency virus (HIV) infection and is thus a potentially valuable therapeutic tool. Primary human CD4 T cells engineered to express rhTRIM5α were highly resistant to cell-free HIV type 1 (HIV-1) infection. However, when cocultured with unmodified T cells, rhTRIM5α-expressing cells became highly permissive to HIV-1 infection. Physical separation of rhTRIM5α-expressing cells and unmodified cells revealed that rhTRIM5α efficiently restricts cell-free but not cell-associated HIV transmission. Furthermore, we observed that HIV-infected human cells could infect rhesus CD4 T cells by cell-to-cell contact, but the infection was self-limiting. Subsequently, we noted that a spreading infection ensued when HIV-1-infected rhTRIM5α-expressing human cells were cultured with huTRIM5α- but not rhTRIM5α-expressing cells. Our results suggest that cell-associated HIV transmission in humans is blocked only when both donor and recipient cells express rhTRIM5α. These studies further define the role of rhTRIM5α in cell-free and cell-associated HIV transmission and delineate the utility of rhTRIM5α in anti-HIV therapy.
Glutamine Deprivation Causes Enhanced Plating Efficiency of a Herpes Simplex Virus Type 1 ICP0-Null Mutant
Authors: Bringhurst Ryan M. , Dominguez Antonia A. , Schaffer Priscilla A. 
Published: September 2008

ABSTRACT

Isoleucine deprivation of cellular monolayers prior to infection has been reported to result in partial complementation of a herpes simplex virus type 1 (HSV-1) ICP0 null (ICP0
−
) mutant. We now report that glutamine deprivation alone is able to enhance the plating efficiency of an ICP0
−
virus and that isoleucine deprivation has little or no effect. Because a low glutamine level is associated with stress and because stress is known to induce reactivation, low levels of glutamine may be relevant to the reactivation of HSV-1 from latency. Additionally, we demonstrate that arginine and methionine deprivation result in partial complementation of the ICP0
−
virus.
Transactivation, Dimerization, and DNA-Binding Activity of White Spot Syndrome Virus Immediate-Early Protein IE1
Authors: Liu Wang-Jing , Chang Yun-Shiang , Wang Hao-Ching , Leu Jiann-Horng , Kou Guang-Hsiung , Lo Chu-Fang 
Published: September 2008

ABSTRACT

Immediate-early proteins from many viruses function as transcriptional regulators and exhibit transactivation activity, DNA binding activity, and dimerization. In this study, we investigated these characteristics in white spot syndrome virus (WSSV) immediate-early protein 1 (IE1) and attempted to map the corresponding functional domains. Transactivation was investigated by transiently expressing a protein consisting of the DNA binding domain of the yeast transactivator GAL4 fused to full-length IE1. This GAL4-IE1 fusion protein successfully activated the
Autographa californica
multicapsid nucleopolyhedrovirus
p35
basal promoter when five copies of the GAL4 DNA binding site were inserted upstream of the TATA box. A deletion series of GAL4-IE1 fusion proteins suggested that the transactivation domain of WSSV IE1 was carried within its first 80 amino acids. A point mutation assay further showed that all 12 of the acidic residues in this highly acidic domain were important for IE1's transactivation activity. DNA binding activity was confirmed by an electrophoresis mobility shift assay using a probe with
32
P-labeled random oligonucleotides. The DNA binding region of WSSV IE1 was located in its C-terminal end (amino acids 81 to 224), but mutation of a putative zinc finger motif in this C-terminal region suggested that this motif was not directly involved in the DNA binding activity. A homotypic interaction between IE1 molecules was demonstrated by glutathione
S
-transferase pull-down assay and a coimmunoprecipitation analysis. A glutaraldehyde cross-linking experiment and gel filtration analysis showed that this self-interaction led to the formation of stable IE1 dimers.
The Interferon Antagonist ML Protein of Thogoto Virus Targets General Transcription Factor IIB
Authors: Vogt Carola , Preuss Ellen , Mayer Daniel , Weber Friedemann , Schwemmle Martin , Kochs Georg 
Published: September 2008

ABSTRACT
The ML protein of Thogoto virus, a tick-transmitted orthomyxovirus, is a splice variant of the viral matrix protein and antagonizes the induction of antiviral type I interferon (IFN). Here we identified the general RNA polymerase II transcription factor IIB (TFIIB) as an ML-interacting protein. Overexpression of TFIIB neutralized the inhibitory effect of ML on IRF3-mediated promoter activation. Moreover, a recombinant virus expressing a mutant ML protein unable to bind TFIIB was severely impaired in its ability to suppress IFN induction. We concluded that TFIIB binding is required for the IFN antagonist effect exerted by ML. We further demonstrate that the ML-TFIIB interaction has surprisingly little impact on gene expression in general, while a strong negative effect is observed for IRF3- and NF-κB-regulated promoters.
Eastern and Venezuelan Equine Encephalitis Viruses Differ in Their Ability To Infect Dendritic Cells and Macrophages: Impact of Altered Cell Tropism on Pathogenesis
Authors: Gardner Christina L. , Burke Crystal W. , Tesfay Mulu Z. , Glass Pamela J. , Klimstra William B. , Ryman Kate D. 
Published: September 2008

ABSTRACT
Eastern and Venezuelan equine encephalitis viruses (EEEV and VEEV, respectively) cause severe morbidity and mortality in equines and humans. Like other mosquito-borne viruses, VEEV infects dendritic cells (DCs) and macrophages in lymphoid tissues, fueling a serum viremia and facilitating neuroinvasion. In contrast, EEEV replicates poorly in lymphoid tissues, preferentially infecting osteoblasts. Here, we demonstrate that infectivity of EEEV for myeloid lineage cells including DCs and macrophages was dramatically reduced compared to that of VEEV, whereas both viruses replicated efficiently in mesenchymal lineage cells such as osteoblasts and fibroblasts. We determined that EEEV infection of myeloid lineage cells was restricted after attachment, entry, and uncoating of the genome. Using replicon particles and translation reporter RNAs, we found that translation of incoming EEEV genomes was almost completely inhibited in myeloid, but not mesenchymal, lineage cells. Alpha/beta interferon (IFN-α/β) responses did not mediate the restriction, as infectivity was not restored in the absence of double-stranded RNA-dependent protein kinase, RNase L, or IFN-α/β receptor-mediated signaling. We confirmed these observations in vivo, demonstrating that EEEV is compromised in its ability to replicate within lymphoid tissues, whereas VEEV does so efficiently. The altered tropism of EEEV correlated with an almost complete avoidance of serum IFN-α/β induction in vivo, which may allow EEEV to evade the host's innate immune responses and thereby enhance neurovirulence. Taken together, our data indicate that inhibition of genome translation restricts EEEV infectivity for myeloid but not mesenchymal lineage cells in vitro and in vivo. In this regard, the tropisms of EEEV and VEEV differ dramatically, likely contributing to observed differences in disease etiology.
Integration of Rous Sarcoma Virus DNA: a CA Dinucleotide Is Not Required for Integration of the U3 End of Viral DNA
Authors: Oh Jangsuk , Chang Kevin W. , Hughes Stephen H. 
Published: September 2008

ABSTRACT
The two ends of RSV linear DNA are independently inserted into host DNA by integrase in vivo. We previously showed that the range of U3 sequences that are acceptable substrates for integrase appeared to be greater than the range of acceptable U5 sequences in vivo. We have done additional experiments to determine which U3 sequences are good integrase substrates. On the U3 end, there does not appear to be a stringent requirement for the canonical CA, integrase can efficiently remove three nucleotides, and six nucleotides are sufficient to allow integration with reasonable, albeit reduced, efficiency.
Artificial MicroRNAs Highly Accessible to Targets Confer Efficient Virus Resistance in Plants
Authors: Duan Cheng-Guo , Wang Chun-Han , Fang Rong-Xiang , Guo Hui-Shan 
Published: September 2008

ABSTRACT

Short-hairpin RNAs based on microRNA (miRNA) precursors to express the artificial miRNAs (amiRNAs) can specifically induce gene silencing and confer virus resistance in plants. The efficacy of RNA silencing depends not only on the nature of amiRNAs but also on the local structures of the target mRNAs. However, the lack of tools to accurately and reliably predict secondary structures within long RNAs makes it very hard to predict the secondary structures of a viral genome RNA in the natural infection conditions in vivo. In this study, we used an experimental approach to dissect how the endogenous silencing machinery acts on the 3′ untranslated region (UTR) of the
Cucumber mosaic virus
(CMV) genome. Transiently expressed 3′UTR RNAs were degraded by site-specific cleavage. By comparing the natural cleavage hotspots within the 3′UTR of the CMV-infected wild-type
Arabidopsis
to those of the triple
dcl2/3/4
mutant, we acquired true small RNA programmed RNA-induced silencing complex (siRISC)-mediated cleavage sites to design valid amiRNAs. We showed that the tRNA-like structure within the 3′UTR impeded target site access and restricted amiRNA-RISC-mediated cleavage of the target viral RNA. Moreover, target recognition in the less-structured area also influenced siRISC catalysis, thereby conferring different degrees of resistance to CMV infection. Transgenic plants expressing the designed amiRNAs that target the putative RISC accessible target sites conferred high resistance to the CMV challenge from both CMV subgroup strains. Our work suggests that the experimental approach is credible for studying the course of RISC target recognition to engineer effective gene silencing and virus resistance in plants by amiRNAs.
Methods for Sampling of Airborne Viruses
Authors: Verreault Daniel , Moineau Sylvain , Duchaine Caroline 
Published: September 2008

SUMMARYTo better understand the underlying mechanisms of aerovirology, accurate sampling of airborne viruses is fundamental. The sampling instruments commonly used in aerobiology have also been used to recover viruses suspended in the air. We reviewed over 100 papers to evaluate the methods currently used for viral aerosol sampling. Differentiating infections caused by direct contact from those caused by airborne dissemination can be a very demanding task given the wide variety of sources of viral aerosols. While epidemiological data can help to determine the source of the contamination, direct data obtained from air samples can provide very useful information for risk assessment purposes. Many types of samplers have been used over the years, including liquid impingers, solid impactors, filters, electrostatic precipitators, and many others. The efficiencies of these samplers depend on a variety of environmental and methodological factors that can affect the integrity of the virus structure. The aerodynamic size distribution of the aerosol also has a direct effect on sampler efficiency. Viral aerosols can be studied under controlled laboratory conditions, using biological or nonbiological tracers and surrogate viruses, which are also discussed in this review. Lastly, general recommendations are made regarding future studies on the sampling of airborne viruses.
Getting a Handle on the Role of Coenzyme M in Alkene Metabolism
Authors: Krishnakumar Arathi M. , Sliwa Darius , Endrizzi James A. , Boyd Eric S. , Ensign Scott A. , Peters John W. 
Published: September 2008

SUMMARY

Coenzyme M (2-mercaptoethanesulfonate; CoM) is one of several atypical cofactors discovered in methanogenic archaea which participate in the biological reduction of CO
2
to methane. Elegantly simple, CoM, so named for its role as a methyl carrier in all methanogenic archaea, is the smallest known organic cofactor. It was thought that this cofactor was used exclusively in methanogenesis until it was recently discovered that CoM is a key cofactor in the pathway of propylene metabolism in the gram-negative soil microorganism
Xanthobacter autotrophicus
Py2. A four-step pathway requiring CoM converts propylene and CO
2
to acetoacetate, which feeds into central metabolism. In this process, CoM is used to activate and convert highly electrophilic epoxypropane, formed from propylene epoxidation, into a nucleophilic species that undergoes carboxylation. The unique properties of CoM provide a chemical handle for orienting compounds for site-specific redox chemistry and stereospecific catalysis. The three-dimensional structures of several of the enzymes in the pathway of propylene metabolism in defined states have been determined, providing significant insights into both the enzyme mechanisms and the role of CoM in this pathway. These studies provide the structural basis for understanding the efficacy of CoM as a handle to direct organic substrate transformations at the active sites of enzymes.
Convergence of Molecular, Modeling, and Systems Approaches for an Understanding of the
Escherichia coli
Heat Shock Response
Authors: Guisbert Eric , Yura Takashi , Rhodius Virgil A. , Gross Carol A. 
Published: September 2008

SUMMARY

The heat shock response (HSR) is a homeostatic response that maintains the proper protein-folding environment in the cell. This response is universal, and many of its components are well conserved from bacteria to humans. In this review, we focus on the regulation of one of the most well-characterized HSRs, that of
Escherichia coli
. We show that even for this simple model organism, we still do not fully understand the central component of heat shock regulation, a chaperone-mediated negative feedback loop. In addition, we review other components that contribute to the regulation of the HSR in
E. coli
and discuss how these additional components contribute to regulation. Finally, we discuss recent genomic experiments that reveal additional functional aspects of the HSR.
Progress in Metabolic Engineering of
Saccharomyces cerevisiae
Authors: Nevoigt Elke 
Published: September 2008

SUMMARY

The traditional use of the yeast
Saccharomyces cerevisiae
in alcoholic fermentation has, over time, resulted in substantial accumulated knowledge concerning genetics, physiology, and biochemistry as well as genetic engineering and fermentation technologies.
S. cerevisiae
has become a platform organism for developing metabolic engineering strategies, methods, and tools. The current review discusses the relevance of several engineering strategies, such as rational and inverse metabolic engineering, evolutionary engineering, and global transcription machinery engineering, in yeast strain improvement. It also summarizes existing tools for fine-tuning and regulating enzyme activities and thus metabolic pathways. Recent examples of yeast metabolic engineering for food, beverage, and industrial biotechnology (bioethanol and bulk and fine chemicals) follow.
S. cerevisiae
currently enjoys increasing popularity as a production organism in industrial (“white”) biotechnology due to its inherent tolerance of low pH values and high ethanol and inhibitor concentrations and its ability to grow anaerobically. Attention is paid to utilizing lignocellulosic biomass as a potential substrate.
Candida albicansCell Wall Proteins
Authors: Chaffin W. LaJean 
Published: September 2008

SUMMARYThe Candida albicans cell wall maintains the structural integrity of the organism in addtion to providing a physical contact interface with the environment. The major components of the cell wall are fibrillar polysaccharides and proteins. The proteins of the cell wall are the focus of this review. Three classes of proteins are present in the candidal cell wall. One group of proteins attach to the cell wall via a glycophosphatidylinositol remnant or by an alkali-labile linkage. A second group of proteins with N-terminal signal sequences but no covalent attachment sequences are secreted by the classical secretory pathway. These proteins may end up in the cell wall or in the extracellular space. The third group of proteins lack a secretory signal, and the pathway(s) by which they become associated with the surface is unknown. Potential constituents of the first two classes have been predicted from analysis of genome sequences. Experimental analyses have identified members of all three classes. Some members of each class selected for consideration of confirmed or proposed function, phenotypic analysis of a mutant, and regulation by growth conditions and transcription factors are discussed in more detail.
Characterization and chromosomal organization of satellite DNA sequences inPicea abies
Authors: Sarri V. , Minelli S. , Panara F. , Morgante M. , Jurman I. , Zuccolo A. , Cionini P. G. 
Published: September 2008

Three clones containing satellite DNA sequences were selected from a randomly sheared genomic DNA library of Picea abies (clones PAF1, PAG004P22F (2F), and PAG004E03C (3C)). PAF1 contained 7 repeats that were 37–55 bp in length and had 68.9%–91.9% nucleotide sequence similarity. Two 2F repeats were 305–306 bp in length and had 83% sequence similarity. Two 3C repeats were 193–226 bp in length and had a sequence similarity of 78.6%. The copy number per 1C DNA of PAF1, 2F, and 3C repeats was 2.7 × 106, 2.9 × 105, and 2.9 × 104, respectively. In situ hybridization showed centromeric localization of these sequences in two chromosome pairs with PAF1, all pairs but one with 2F, and three pairs with 3C. Moreover, PAF1 sequences hybridized at secondary constrictions in six pairs, while 2F-related sequences were found at these chromosome regions only in four pairs. These hybridization patterns allow all chromosome pairs to be distinguished. PAF1-related repeats were contained in the intergenic spacer (IGS) of ribosomal cistrons in all six nucleolar organizers of the complement, while sequences related to 2F were found on only one side of the rDNA arrays in four pairs, showing structural diversity between rDNA regions of different chromosomes.
Allopolyploid speciation of the Mexican tetraploid potato species Solanum stoloniferum and S. hjertingii revealed by genomic in situ hybridization
Authors: Pendinen Galina , Gavrilenko Tatjana , Jiang Jiming , Spooner David M. 
Published: September 2008

Thirty-six percent of the wild potato ( Solanum L. section Petota Dumort.) species are polyploid, and about half of the polyploids are tetraploid species (2n = 4x = 48). Determination of the type of polyploidy and development of the genome concept for members of section Petota traditionally has been based on the analysis of chromosome pairing in species and their hybrids and, most recently, DNA sequence phylogenetics. Based on these data, the genome designation AABB was proposed for Mexican tetraploid species of series Longipedicellata Buk. We investigated this hypothesis with genomic in situ hybridization (GISH) for both representatives of the series, S. stoloniferum Schltdl. and S. hjertingii Hawkes. GISH analysis supports an AABB genome constitution for these species, with S. verrucosum Schltdl. (or its progenitor) supported as the A genome donor and another North or Central American diploid species (S. cardiophyllum Lindl., S. ehrenbergii (Bitter) Rydb., or S. jamesii Torrey) as the B genome donor. GISH analysis of chromosome pairing of S. stoloniferum also confirms the strict allopolyploid nature of this species. In addition, fluorescence in situ hybridization data suggest that 45S rDNA regions of the two genomes of S. stoloniferum were changed during coevolution of A and B genomes of this allotetraploid species.