bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Approach for Detection of Hepatitis E Virus Infection in German Blood Donors
Authors: Vollmer Tanja , Diekmann Juergen , Johne Reimar , Eberhardt Matthias , Knabbe Cornelius , Dreier Jens 
Published: June 2012

ABSTRACT
The risk of transfusion-transmitted hepatitis E virus (HEV) infections by contaminated blood products remains unknown. In the present study, we evaluated and compared different nucleic acid amplification technique (NAT) methods for the detection of HEV in blood components. Minipools of a total of 16,125 individual blood donors were screened for the presence of HEV RNA using the highly sensitive RealStar HEV RT-PCR kit, revealing a minimum detection limit of 4.66 IU/ml. Thirteen donors were HEV RNA positive (0.08%), and of these donors, only three already showed reactive IgM antibody titers. The detected HEV strains all belonged to genotype 3 and were most closely related to German HEV strains from wild boars and pigs as well as from human hepatitis E cases. Furthermore, HEV RNA and HEV-specific IgM and IgG titers were determined in 136 blood donors with elevated alanine aminotransferase (ALT) levels and in 200 donors without pathological findings. HEV RNA was not detectable, but 8.08% (elevated ALT) and 0.5% (nonelevated ALT) of donors showed reactive HEV IgM titers. The overall seroprevalence rate of HEV IgG amounted to 5.94% (elevated ALT, 5.88%; nonelevated ALT, 6.0%). The clinical relevance of transfusion-associated hepatitis E infection still requires further investigation. However, in connection with raising concerns regarding blood safety, our NAT method provides a sensitive possibility for HEV testing.
Cell Culture-Adaptive Mutations Promote Viral Protein-Protein Interactions and Morphogenesis of Infectious Hepatitis C Virus
Authors: Jiang Jieyun , Luo Guangxiang 
Published: June 2012

ABSTRACT
Recent genetic studies suggested that viral nonstructural (NS) proteins play important roles in morphogenesis of flaviviruses, particularly hepatitis C virus (HCV). Adaptive and compensatory mutations occurring in different NS proteins were demonstrated to promote HCV production in cell culture. However, the underlying molecular mechanism of NS proteins in HCV morphogenesis is poorly understood. We have isolated a cell culture-adapted HCV of genotype 2a (JFH1) which grew to an infectious titer 3 orders of magnitude higher than that of wild-type virus. Sequence analysis identified a total of 16 amino acid mutations in core (C), E1, NS2, NS3, NS5A, and NS5B, with the majority of mutations clustered in NS5A. Reverse genetic analysis of these mutations individually or in different combinations demonstrated that amino acid mutations in NS2 and NS5A markedly enhanced HCV production. Additionally, mutations in C, E1, NS3, and NS5B synergistically promoted HCV production in the background of NS2 and NS5A mutations. Adaptive mutations in NS5A domains I, II, and III independently enhanced HCV production, suggesting that all three domains of NS5A are important for HCV morphogenesis. More importantly, adaptive mutations greatly enhanced physical interactions among HCV structural and NS proteins, as determined by studies with coimmunoprecipitation and mammalian two-hybrid assays. Collectively, these findings demonstrate that adaptive mutations can enhance specific protein-protein interactions among viral structural and NS proteins and therefore promote the assembly of infectious HCV particles.
Transport to Late Endosomes Is Required for Efficient Reovirus Infection
Authors: Mainou Bernardo A. , Dermody Terence S. 
Published: June 2012

ABSTRACT
Rab GTPases play an essential role in vesicular transport by coordinating the movement of various types of cargo from one cellular compartment to another. Individual Rab GTPases are distributed to specific organelles and thus serve as markers for discrete types of endocytic vesicles. Mammalian reovirus binds to cell surface glycans and junctional adhesion molecule-A (JAM-A) and enters cells by receptor-mediated endocytosis in a process dependent on β1 integrin. Within organelles of the endocytic compartment, reovirus undergoes stepwise disassembly catalyzed by cathepsin proteases, which allows the disassembly intermediate to penetrate endosomal membranes and release the transcriptionally active viral core into the cytoplasm. The pathway used by reovirus to traverse the endocytic compartment is largely unknown. In this study, we found that reovirus particles traffic through early, late, and recycling endosomes during cell entry. After attachment to the cell surface, reovirus particles and JAM-A codistribute into each of these compartments. Transfection of cells with constitutively active and dominant-negative Rab GTPases that affect early and late endosome biogenesis and maturation influenced reovirus infectivity. In contrast, reovirus infectivity was not altered in cells expressing mutant Rab GTPases that affect recycling endosomes. Thus, reovirus virions localize to early, late, and recycling endosomes during entry into host cells, but only those that traverse early and late endosomes yield a productive infection.
ORF7 of Varicella-Zoster Virus Is a Neurotropic Factor
Authors: Selariu Anca , Cheng Tong , Tang Qiyi , Silver Benjamin , Yang Lianwei , Liu Che , Ye Xiangzhong , Markus Amos , Goldstein Ronald S. , Cruz-Cosme Ruth S. , Lin Yanzhen , Wen Lanling , Qian Hongliu , Han Jinle , Dulal Kalpana , Huang Ying , Li Yimin , Xia Ningshao , Zhu Hua 
Published: June 2012

ABSTRACT

Varicella-zoster virus (VZV) is the causative agent of chickenpox and herpes zoster (shingles). After the primary infection, the virus remains latent in sensory ganglia and reactivates upon weakening of the cellular immune system due to various conditions, erupting from sensory neurons and infecting the corresponding skin tissue. The current varicella vaccine is highly attenuated in the skin and yet retains its neurovirulence and may reactivate and damage sensory neurons. The factors involved in neuronal invasion and establishment of latency are still elusive. Previously, we constructed a library of whole-gene deletion mutants carrying a bacterial artificial chromosome sequence and a luciferase marker in order to perform a comprehensive VZV genome functional analysis. Here, screening of dispensable gene deletion mutants in differentiated neuronal cells led to the identification of ORF7 as the first known, likely a main, VZV neurotropic factor. ORF7 is a virion component localized to the Golgi compartment in infected cells, whose deletion causes loss of polykaryon formation in epithelial cell culture. Interestingly, ORF7 deletion completely abolishes viral spread in human nervous tissue
ex vivo
and in an
in vivo
mouse model. This finding adds to our previous report that ORF7 is also a skin-tropic factor. The results of our investigation will not only lead to a better understanding of VZV neurotropism but could also contribute to the development of a neuroattenuated vaccine candidate against shingles or a vector for delivery of other antigens.
Kaposi's Sarcoma-Associated Herpesvirus ORF54/dUTPase Downregulates a Ligand for the NK Activating Receptor NKp44
Authors: Madrid Alexis Spain , Ganem Don 
Published: June 2012

ABSTRACTKaposi's sarcoma-associated herpesvirus (KSHV) establishes long-term latent infection in humans and can cause cancers in endothelial and B cells. A functioning immune system is vital for restricting viral proliferation and preventing KSHV-dependent neoplasms. While natural killer (NK) lymphocytes are known to target virus-infected cells for destruction, their importance in the anti-KSHV immune response is not currently understood. Activating receptors on NK cells recognize ligands on target cells, including the uncharacterized ligand(s) for NKp44, termed NKp44L. Here we demonstrate that several NK ligands are affected when KSHV-infected cells are induced to enter the lytic program. We performed a screen of most of the known KSHV genes and found that the product of the ORF54 gene could downregulate NKp44L. The ORF54-encoded protein is a dUTPase; however, dUTPase activity is neither necessary nor sufficient for the downregulation of NKp44L. In addition, we find that ORF54 can also target proteins of the cytokine receptor family and the mechanism of downregulation involves perturbation of membrane protein trafficking. The ORF54-related proteins of other human herpesviruses do not possess this activity, suggesting that the KSHV homolog has evolved a novel immunoregulatory function and that the NKp44-NKp44L signaling pathway contributes to antiviral immunity.
Infectious Endogenous Retroviruses in Cats and Emergence of Recombinant Viruses
Authors: Anai Yukari , Ochi Haruyo , Watanabe Shinya , Nakagawa So , Kawamura Maki , Gojobori Takashi , Nishigaki Kazuo 
Published: June 2012

ABSTRACT

Endogenous retroviruses (ERVs) comprise a significant percentage of the mammalian genome, and it is poorly understood whether they will remain as inactive genomes or emerge as infectious retroviruses. Although several types of ERVs are present in domestic cats, infectious ERVs have not been demonstrated. Here, we report a previously uncharacterized class of endogenous gammaretroviruses, termed ERV-DCs, that is present and hereditary in the domestic cat genome. We have characterized a subset of ERV-DC proviral clones, which are numbered according to their genomic insertions. One of these, ERV-DC10, located in the q12-q21 region on chromosome C1, is an infectious gammaretrovirus capable of infecting a broad range of cells, including human. Our studies indicate that ERV-DC10 entered the genome of domestic cats in the recent past and appeared to translocate to or reintegrate at a distinct locus as infectious ERV-DC18. Insertional polymorphism analysis revealed that 92 of 244 domestic cats had ERV-DC10 on a homozygous or heterozygous locus. ERV-DC-like sequences were found in primate and rodent genomes, suggesting that these ERVs, and recombinant viruses such as RD-114 and BaEV, originated from an ancestor of ERV-DC. We also found that a novel recombinant virus, feline leukemia virus subgroup D (FeLV-D), was generated by ERV-DC
env
transduction into feline leukemia virus in domestic cats. Our results indicate that ERV-DCs behave as donors and/or acceptors in the generation of infectious, recombinant viruses. The presence of such infectious endogenous retroviruses, which could be harmful or beneficial to the host, may affect veterinary medicine and public health.
Structure and Receptor Complexes of the Hemagglutinin from a Highly Pathogenic H7N7 Influenza Virus
Authors: Yang Hua , Carney Paul J. , Donis Ruben O. , Stevens James 
Published: June 2012

ABSTRACT
Recurrence of highly pathogenic avian influenza (HPAI) virus subtype H7 in poultry continues to be a public health concern. In 2003, an HPAI H7N7 outbreak in the Netherlands infected 89 people in close contact with affected poultry and resulted in one fatal case. In previous studies, the virus isolated from this fatal case, A/Netherlands/219/2003 (NL219) caused a lethal infection in mouse models and had increased replication efficiency and a broader tissue distribution than nonlethal isolates from the same outbreak. A mutation which introduces a potential glycosylation site at Asn123 in the NL219 hemagglutinin was postulated to contribute to the pathogenic properties of this virus. To study this further, we have expressed the NL219 hemagglutinin in a baculovirus expression system and performed a structural analysis of the hemagglutinin in complex with avian and human receptor analogs. Glycan microarray and kinetic analysis were performed to compare the receptor binding profile of the wild-type recombinant NL219 HA to a variant with a threonine-to-alanine mutation at position 125, resulting in loss of the glycosylation site at Asn123. The results suggest that the additional glycosylation sequon increases binding affinity to avian-type α2-3-linked sialosides rather than switching to a human-like receptor specificity and highlight the mechanistic diversity of these pathogens, which calls attention to the need for further studies to fully understand the unique properties of these viruses.
Antibody-Dependent Cellular Cytotoxicity against Primary HIV-Infected CD4+T Cells Is Directly Associated with the Magnitude of Surface IgG Binding
Authors: Smalls-Mantey Adjoa , Doria-Rose Nicole , Klein Rachel , Patamawenu Andy , Migueles Stephen A. , Ko Sung-Youl , Hallahan Claire W. , Wong Hing , Liu Bai , You Lijing , Scheid Johannes , Kappes John C. , Ochsenbauer Christina , Nabel Gary J. , Mascola John R. , Connors Mark 
Published: June 2012

ABSTRACTAntibody (Ab)-dependent cellular cytotoxicity (ADCC) is thought to potentially play a role in vaccine-induced protection from HIV-1. The characteristics of such antibodies remain incompletely understood. Furthermore, correlates between ADCC and HIV-1 immune status are not clearly defined. We screened the sera of 20 HIV-1-positive (HIV-1+) patients for ADCC. Normal human peripheral blood mononuclear cells were used to derive HIV-infected CD4+T cell targets and autologous, freshly isolated, natural killer (NK) cells in a novel assay that measures granzyme B (GrB) and HIV-1-infected CD4+T cell elimination (ICE) by flow cytometry. We observed that complex sera mediated greater levels of ADCC than anti-HIV-1 envelope glycoprotein (Env)-specific monoclonal antibodies and serum-mediated ADCC correlated with the amount of IgG and IgG1 bound to HIV-1-infected CD4+T cells. No correlation between ADCC and viral load, CD4+T cell count, or neutralization of HIV-1SF162or other primary viral isolates was detected. Sera pooled from clade B HIV-1+individuals exhibited breadth in killing targets infected with HIV-1 from clades A/E, B, and C. Taken together, these data suggest that the total amount of IgG bound to an HIV-1-infected cell is an important determinant of ADCC and that polyvalent antigen-specific Abs are required for a robust ADCC response. In addition, Abs elicited by a vaccine formulated with immunogens from a single clade may generate a protective ADCC responsein vivoagainst a variety of HIV-1 species. Increased understanding of the parameters that dictate ADCC against HIV-1-infected cells will inform efforts to stimulate ADCC activity and improve its potency in vaccinees.
Identification of a Novel Antiviral Inhibitor of the Flavivirus Guanylyltransferase Enzyme
Authors: Stahla-Beek Hillary J. , April Daniel G. , Saeedi Bejan J. , Hannah Amanda M. , Keenan Susan M. , Geiss Brian J. 
Published: June 2012

ABSTRACT

Arthropod-borne flavivirus infection causes serious morbidity and mortality worldwide, but there are currently no effective antiflaviviral chemotherapeutics available for human use. Therefore, it is critical that new therapeutics against virus-specific targets be developed. To identify new compounds that may be used as broadly active flavivirus therapeutics, we have performed a high-throughput screening of 235,456 commercially available compounds for small-molecule inhibitors of the dengue virus NS5 RNA capping enzyme. We identified a family of compounds, the 2-thioxothiazolidin-4-ones, that show potent biochemical inhibition of capping enzyme GTP binding and guanylyltransferase function. During the course of structure-activity relationship analysis, a molecule within this family, (E)-{3-[5-(4-
tert
-butylbenzylidene)-4-oxo-2-thioxo-1,3-thiazolidin-3-yl]propanoic acid} (BG-323), was found to possess significant antiviral activity in a dengue virus subgenomic replicon assay. Further testing of BG-323 demonstrated that this molecule is able to reduce the replication of infectious West Nile virus and yellow fever virus in cell culture with low toxicity. The results of this study describe the first inhibitor that targets the GTP-binding/guanylyltransferase activity of the flavivirus RNA capping enzyme.
Interactions between Proteins Encoded within the Human Cytomegalovirus
UL133-UL138
Locus
Authors: Petrucelli Alex , Umashankar Mahadevaiah , Zagallo Patricia , Rak Michael , Goodrum Felicia 
Published: June 2012

ABSTRACT

We previously described a novel genetic locus within the UL
b
′ region of the human cytomegalovirus (HCMV) genome that, while dispensable for replication in fibroblasts, suppresses replication in hematopoietic progenitors and augments replication in endothelial cells. This locus, referred to as the
UL133-UL138
locus, encodes four proteins, pUL133, pUL135, pUL136, and pUL138. In this work, we have mapped the interactions among these proteins. An analysis of all pairwise interactions during transient expression revealed a robust interaction between pUL133 and pUL138. Potential interactions between pUL136 and both pUL133 and pUL138 were also revealed. In addition, each of the
UL133-UL138
locus proteins self-associated, suggesting a potential to form higher-order homomeric complexes. As both pUL133 and pUL138 function in promoting viral latency in CD34
+
hematopoietic progenitor cells (HPCs) infected
in vitro
, we further focused on this interaction. pUL133 and pUL138 are the predominant complex detected when all proteins are expressed together and require no other proteins in the locus for their association. During infection, the interaction between pUL133 and pUL138 or pUL136 can be detected. A recombinant virus that fails to express both pUL133 and pUL138 exhibited a latency phenotype similar to that of viruses that fail to express either pUL133 or pUL138, indicating that these proteins function cooperatively in latency and do not have independent functions that additively contribute to HCMV latency. These studies identify protein interactions among proteins encoded by the
UL133-UL138
locus and demonstrate an important interaction impacting the outcome of HCMV infection.
Identification of Novel T Cell Factor 4 (TCF-4) Binding Sites on the HIV Long Terminal Repeat Which Associate with TCF-4, β-Catenin, and SMAR1 To Repress HIV Transcription
Authors: Henderson Lisa J. , Narasipura Srinivas D. , Adarichev Vyacheslav , Kashanchi Fatah , Al-Harthi Lena 
Published: June 2012

ABSTRACT
Molecular regulation of HIV transcription is a multifaceted process dictated in part by the abundance of cellular transcription factors that induce or repress HIV promoter activity. β-Catenin partners with members of the T cell factor (TCF)/LEF transcription factors to regulate gene expression. The interaction between β-catenin and TCF-4 is linked to inhibition of HIV replication in multiple cell types, including lymphocytes and astrocytes. Here, we evaluated the molecular mechanism by which β-catenin/TCF-4 repress HIV replication. We identified for the first time multiple TCF-4 binding sites at −336, −143, +66, and +186 relative to the transcription initiation site on the HIV long terminal repeat (LTR). Two of the sites (−143 and +66) were present in approximately 1/3 of 500 HIV-1 isolates examined. Although all four sites could bind to TCF-4, the strongest association occurred at −143. Deletion and/or mutation of −143, in conjunction with β-catenin or TCF-4 knockdown in cells stably expressing an LTR reporter construct, enhanced basal HIV promoter activity by 5-fold but had no effect on Tat-mediated transactivation of the HIV LTR. We also found that TCF-4, β-catenin, and the nuclear matrix binding protein SMAR1 tether at the −143-nucleotide (nt) site on the HIV LTR to inhibit HIV promoter activity. Collectively, these data indicate that TCF-4 and β-catenin at −143 associate with SMAR1, which likely pulls the HIV DNA segment into the nuclear matrix and away from transcriptional machinery, leading to repression of basal HIV LTR transcription. These studies point to novel avenues for regulation of HIV replication by manipulation of β-catenin signaling within cells.
Revisiting the Clinal Concept of Evolution and Dispersal for the Tick-Borne Flaviviruses by Using Phylogenetic and Biogeographic Analyses
Authors: Heinze D. M. , Gould E. A. , Forrester N. L. 
Published: June 2012

ABSTRACTTick-borne flaviviruses (TBF) are widely dispersed across Africa, Europe, Asia, Oceania, and North America, and some present a significant threat to human health. Seminal studies on tick-borne encephalitis viruses (TBEV), based on partial envelope gene sequences, predicted a westward clinal pattern of evolution and dispersal across northern Eurasia, terminating in the British Isles. We tested this hypothesis using all available full-length open reading frame (ORF) TBF sequences. Phylogenetic analysis was consistent with current reports. However, linear and nonlinear regression analysis of genetic versus geographic distance combined with BEAST analysis identified two separate clines, suggesting that TBEV spread both east and west from a central point. In addition, BEAST analysis suggested that TBF emerged and dispersed more than 16,000 years ago, significantly earlier than previously predicted. Thus, climatic and ecological changes may have played a greater role in TBF dispersal than humans.
Potential of decaying wood to restore root-available base cations in depleted forest soils
Authors: Shortle Walter C. , Smith Kevin T. , Jellison Jody , Schilling Jonathan S. 
Published: June 2012

The depletion of root-available Ca in northern forest soils exposed to decades of increased acid deposition adversely affects forest health and productivity. Laboratory studies indicated the potential of wood-decay fungi to restore lost Ca. This study presents changes in concentration of Ca, Mg, and K in sapwood of red spruce ( Picea rubens Sarg.), red maple ( Acer rubrum L.), eastern hemlock ( Tsuga canadensis (L.) Carrière), and paper birch ( Betula papyrifera Marshall) during the decay process at two experimental forests for 12 years and to compare concentrations of exchangeable Ca, Mg, and Al in decayed wood residues at 10 and 12 years with those in the forest floor. Significant loss of mass indicated by decreasing wood density occurred after 2–8 years in conifers and after only 2 years in hardwoods. A significant gain in wood K was observed at 2 years followed by a significant loss at 8 years. A negligible gain in Ca concentration occurred at 2 years and a substantial gain at 8 years. Observed changes in Mg concentration were variable. No significant difference in exchangeable Ca concentration was observed between decayed wood residue of spruce and maple and the forest floor. However, decayed wood residue had a much lower Al concentration and molar Al/Ca ratio, a condition characteristic of sites with high root-available Ca.
Response of different white fir geographic provenances to Trichosporium symbioticum inoculation in California
Authors: Otrosina William J. , Zarnoch Stanley J. 
Published: June 2012

We inoculated the fir engraver ( Scolytus ventralis LeConte) associated fungus Trichosporium symbioticum Wright onto 56 white fir ( Abies concolor (Gordon & Glend.) Lindl. ex Hildebr.) trees planted in a common garden study near Camino, California, that represented five geographic provenances of this species. The objective was to determine if there is a differential lesion length response of white fir provenances with respect to provenance. We found a significant (P < 0.019) difference between the provenances from Arizona and those of eastern Nevada origins 28 days after inoculation. There was a significant interaction between the two T. symbioticum isolates and season of inoculation. Fall inoculations tended to have smaller lesions than those in the spring but this varied by isolate in that the one from eastern Nevada tended to produce longer lesions in the spring (P = 0.0001) whereas the isolate from the Camino plantation did not differ between spring and fall (P = 1.000). There is evidence for genetic variability relative to white fir provenance lesion length in response to T. symbioticum inoculation, and in future studies, isolate variability should also be taken into account.