bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early Spatial and Temporal Events of Human T-Lymphotropic Virus Type 1 Spread following Blood-Borne Transmission in a Rabbit Model of Infection
Authors: Haynes Rashade A. H. , Zimmerman Bevin , Millward Laurie , Ware Evan , Premanandan Christopher , Yu Lianbo , Phipps Andrew J. , Lairmore Michael D. 
Published: March 2010

ABSTRACT

Human T-lymphotropic virus type 1 (HTLV-1) infection causes adult T-cell leukemia/lymphoma (ATL) and is associated with a variety of lymphocyte-mediated disorders. HTLV-1 transmission occurs by transmission of infected cells via breast-feeding by infected mothers, sexual intercourse, and contaminated blood products. The route of exposure and early virus replication events are believed to be key determinants of virus-associated spread, antiviral immune responses, and ultimately disease outcomes. The lack of knowledge of early events of HTLV-1 spread following blood-borne transmission of the virus
in vivo
hinders a more complete understanding of the immunopathogenesis of HTLV-1 infections. Herein, we have used an established animal model of HTLV-1 infection to study early spatial and temporal events of the viral infection. Twelve-week-old rabbits were injected intravenously with cell-associated HTLV-1 (ACH-transformed R49). Blood and tissues were collected at defined intervals throughout the study to test the early spread of the infection. Antibody and hematologic responses were monitored throughout the infection. HTLV-1 intracellular Tax and soluble p19 matrix were tested from
ex vivo
cultured lymphocytes. Proviral copy numbers were measured by real-time PCR from blood and tissue mononuclear leukocytes. Our data indicate that intravenous infection with cell-associated HTLV-1 targets lymphocytes located in both primary lymphoid and gut-associated lymphoid compartments. A transient lymphocytosis that correlated with peak virus detection parameters was observed by 1 week postinfection before returning to baseline levels. Our data support emerging evidence that HTLV-1 promotes lymphocyte proliferation preceding early viral spread in lymphoid compartments to establish and maintain persistent infection.
A Novel Molecular Mechanism of Dual Resistance to Nucleoside and Nonnucleoside Reverse Transcriptase Inhibitors
Authors: Nikolenko Galina N. , Delviks-Frankenberry Krista A. , Pathak Vinay K. 
Published: March 2010

ABSTRACTRecently, mutations in the connection subdomain (CN) and RNase H domain of HIV-1 reverse transcriptase (RT) were observed to exhibit dual resistance to nucleoside and nonnucleoside reverse transcriptase inhibitors (NRTIs and NNRTIs). To elucidate the mechanism by which CN and RH mutations confer resistance to NNRTIs, we hypothesized that these mutations reduce RNase H cleavage and provide more time for the NNRTI to dissociate from the RT, resulting in the resumption of DNA synthesis and enhanced NNRTI resistance. We observed that the effect of the reduction in RNase H cleavage on NNRTI resistance is dependent upon the affinity of each NNRTI to the RT and further influenced by the presence of NNRTI-binding pocket (BP) mutants. D549N, Q475A, and Y501A mutants, which reduce RNase H cleavage, enhance resistance to nevirapine (NVP) and delavirdine (DLV), but not to efavirenz (EFV) and etravirine (ETR), consistent with their increase in affinity for RT. Combining the D549N mutant with NNRTI BP mutants further increases NNRTI resistance from 3- to 30-fold, supporting the role of NNRTI-RT affinity in our NNRTI resistance model. We also demonstrated that CNs from treatment-experienced patients, previously reported to enhance NRTI resistance, also reduce RNase H cleavage and enhance NNRTI resistance in the context of the patient RT pol domain or a wild-type pol domain. Together, these results confirm key predictions of our NNRTI resistance model and provide support for a unifying mechanism by which CN and RH mutations can exhibit dual NRTI and NNRTI resistance.
Identification of Dominant Negative Human Immunodeficiency Virus Type 1 Vif Mutants That Interfere with the Functional Inactivation of APOBEC3G by Virus-Encoded Vif
Authors: Walker Robert C. , Khan Mohammad A. , Kao Sandra , Goila-Gaur Ritu , Miyagi Eri , Strebel Klaus 
Published: March 2010

ABSTRACT
APOBEC3G (A3G) is a host cytidine deaminase that serves as a potent intrinsic inhibitor of retroviral replication. A3G is packaged into human immunodeficiency virus type 1 virions and deaminates deoxycytidine to deoxyuridine on nascent minus-strand retroviral cDNA, leading to hyper-deoxyguanine-to-deoxyadenine mutations on positive-strand cDNA and inhibition of viral replication. The antiviral activity of A3G is suppressed by Vif, a lentiviral accessory protein that prevents encapsidation of A3G. In this study, we identified dominant negative mutants of Vif that interfered with the ability of wild-type Vif to inhibit the encapsidation and antiviral activity of A3G. These mutants were nonfunctional due to mutations in the highly conserved HCCH and/or SOCS box motifs, which are required for assembly of a functional Cul5-E3 ubiquitin ligase complex. Similarly, mutation or deletion of a PPLP motif, which was previously reported to be important for Vif dimerization, induced a dominant negative phenotype. Expression of dominant negative Vif counteracted the Vif-induced reduction of intracellular A3G levels, presumably by preventing Vif-induced A3G degradation. Consequently, dominant negative Vif interfered with wild-type Vif's ability to exclude A3G from viral particles and reduced viral infectivity despite the presence of wild-type Vif. The identification of dominant negative mutants of Vif presents exciting possibilities for the design of novel antiviral strategies.
Jaagsiekte Sheep Retrovirus Transformation in Madin-Darby Canine Kidney Epithelial Cell Three-Dimensional Culture
Authors: Johnson Chassidy , Sanders Kiah , Fan Hung 
Published: March 2010

ABSTRACT

Jaagsiekte sheep retrovirus (JSRV) is the causative agent of a contagious lung cancer in sheep that shares similarities with human bronchioloalveolar carcinoma (BAC). JSRV is unique because the envelope gene (
env
) is the oncogene, as it can transform cells in culture and induce tumors in animals. The phosphatidylinositol 3-kinase (PI3K)-Akt-mTOR and H/N-Ras-MEK-mitogen-activated protein kinase (MAPK) pathways have been shown to be critical for Env transformation. However, the question still remains of how disruption of these pathways relates to tumor formation. To address this, JSRV Env transformation was studied in the context of epithelial structure, using the polarized Madin-Darby canine kidney (MDCK) epithelial cell three-dimensional (3-D) culture system. The results indicated that JSRV Env-transformed MDCK cells were larger and had full or multiple lumens, in contrast to the single lumens observed in controls. The altered phenotype was largely mediated by an increase in proliferation, in addition to overcoming the proliferative suppression signal. JSRV Env was not found to disrupt polarity or tight junctions or to inhibit lumen apoptosis. The PI3K-Akt-mTOR pathway was important for Env transformation in MDCK cells, although the mechanisms of action differed in 3-D and monolayer cultures. PI3K-dependent signaling to mTOR occurred in monolayers, while PI3K-independent signaling to mTOR occurred in 3-D culture. In contrast, the H/N-Ras-MEK-MAPK pathway was found to be inhibitory to transformation in both normal and transformed MDCK cells in 3-D culture. However, in monolayer culture, inhibition of MEK reverted the transformed phenotype, suggesting a different mechanism(s) of action in monolayer versus 3-D culture.
Role of Human Immunodeficiency Virus Type 1 Integrase in Uncoating of the Viral Core
Authors: Briones Marisa S. , Dobard Charles W. , Chow Samson A. 
Published: March 2010

ABSTRACT
After membrane fusion with a target cell, the core of human immunodeficiency virus type 1 (HIV-1) enters into the cytoplasm, where uncoating occurs. The cone-shaped core is composed of the viral capsid protein (CA), which disassembles during uncoating. The underlying factors and mechanisms governing uncoating are poorly understood. Several CA mutations can cause changes in core stability and a block at reverse transcription, demonstrating the requirement for optimal core stability during viral replication. HIV-1 integrase (IN) catalyzes the insertion of the viral cDNA into the host genome, and certain IN mutations are pleiotropic. Similar to some CA mutants, two IN mutants, one with a complete deletion of IN (NL-ΔIN) and the other with a Cys-to-Ser substitution (NL-C130S), were noninfectious, with a replication block at reverse transcription. Compared to the wild type (WT), the cytoplasmic CA levels of the IN mutants in infected cells were reduced, suggesting accelerated uncoating. The role of IN during uncoating was examined by isolating and characterizing cores from NL-ΔIN and NL-C130S. Both IN mutants could form functional cores, but the core yield and stability were decreased. Also, virion incorporation of cyclophilin A (CypA), a cellular peptidyl-prolyl isomerase that binds specifically to CA, was decreased in the IN mutants. Cores isolated from WT virus depleted of CypA had an unstable-core phenotype, confirming a role of CypA in promoting optimal core stability. Taken together, our results indicate that IN is required during uncoating for maintaining CypA-CA interaction, which promotes optimal stability of the viral core.
Autographa californica
Multiple Nucleopolyhedrovirus LEF-2 Is a Capsid Protein Required for Amplification but Not Initiation of Viral DNA Replication
Authors: Wu Carol P. , Huang Yi-Ju , Wang Jen-Yeu , Wu Yueh-Lung , Lo Huei-Ru , Wang Jui-Ching , Chao Yu-Chan 
Published: March 2010

ABSTRACT

The late expression factor 2 gene (
lef-2
) of baculovirus
Autographa californica
multiple nucleopolyhedrovirus (AcMNPV) has been identified as one of the factors essential for origin-dependent DNA replication in transient expression assays and has been shown to be involved in late/very late gene expression. To study the function of
lef-2
in the life cycle of AcMNPV,
lef-2
knockout and repair bacmids were generated by homologous recombination in
Escherichia coli
. Growth curve analysis showed that
lef-2
was essential for virus production. Interestingly, a DNA replication assay indicated that
lef-2
is not required for the initiation of viral DNA replication and that, rather, it is required for the amplification of DNA replication.
lef-2
is also required for the expression of late and very late genes, as the expression of these genes was abolished by
lef-2
deletion. Temporal and spatial distributions of LEF-2 protein in infected cells were also analyzed, and the data showed that LEF-2 protein was localized to the virogenic stroma in the nuclei of the infected cells. Analysis of purified virus particles revealed that LEF-2 is a viral protein component of both budded and occlusion-derived virions, predominantly in the nucleocapsids of the virus particles. This observation suggests that LEF-2 may be required immediately after virus entry into host cells for efficient viral DNA replication.
Intrahost Evolutionary Dynamics of Canine Influenza Virus in Naïve and Partially Immune Dogs
Authors: Hoelzer Karin , Murcia Pablo R. , Baillie Gregory J. , Wood James L. N. , Metzger Stephan M. , Osterrieder Nikolaus , Dubovi Edward J. , Holmes Edward C. , Parrish Colin R. 
Published: March 2010

ABSTRACT
The patterns and dynamics of evolution in acutely infecting viruses within individual hosts are largely unknown. To this end, we investigated the intrahost variation of canine influenza virus (CIV) during the course of experimental infections in naïve and partially immune dogs and in naturally infected dogs. Tracing sequence diversity in the gene encoding domain 1 of the hemagglutinin (HA1) protein over the time course of infection provided information on the patterns and processes of intrahost viral evolution and revealed some of the effects of partial host immunity. Viral populations sampled on any given day were generally characterized by mean pairwise genetic diversities between 0.1 and 0.2% and by mutational spectra that changed considerably on different days. Some observed mutations may have affected antigenicity or host range, including reversions of CIV host-associated mutations. Patterns of sequence diversity differed between naïve and vaccinated dogs, with some presumably antigenic mutations transiently reaching high frequency in the latter. CIV populations are therefore characterized by the rapid generation and clearance of genetic diversity. Potentially advantageous mutations arise readily during the course of single infections and may give rise to antigenic escape or host range variants.
5′ to 3′ mRNA Decay Factors Colocalize with Ty1 Gag and Human APOBEC3G and Promote Ty1 Retrotransposition
Authors: Dutko James A. , Kenny Alison E. , Gamache Eric R. , Curcio M. Joan 
Published: March 2010

ABSTRACTThe genomic RNA of retroviruses and retrovirus-like transposons must be sequestered from the cellular translational machinery so that it can be packaged into viral particles. Eukaryotic mRNA processing bodies (P bodies) play a central role in segregating cellular mRNAs from the translational machinery for storage or decay. In this work, we provide evidence that the RNA of theSaccharomyces cerevisiaeTy1 retrotransposon is packaged into virus-like particles (VLPs) in P bodies. Ty1 RNA is translationally repressed, and Ty1 Gag, the capsid and RNA binding protein, accumulates in discrete cytoplasmic foci, a subset of which localize to P bodies. Human APOBEC3G, a potent Ty1 restriction factor that is packaged into Ty1 VLPs via an interaction with Gag, also localizes to P bodies. The association of APOBEC3G with P bodies does not require Ty1 element expression, suggesting that P-body localization of APOBEC3G and Ty1 Gag precedes VLP assembly. Additionally, we report that two P-body-associated 5′ to 3′ mRNA decay pathways, deadenylation-dependent mRNA decay (DDD) and nonsense-mediated decay (NMD), stimulate Ty1 retrotransposition. The additive contributions of DDD and NMD explain the strong requirement for general 5′ to 3′ mRNA degradation factors Dcp1, Dcp2, and Xrn1 in Ty1 retromobility. 5′ to 3′ decay factors act at a posttranslational step in retrotransposition, and Ty1 RNA packaging into VLPs is abolished in the absence of the 5′ to 3′ exonuclease Xrn1. Together, the results suggest that VLPs assemble in P bodies and that 5′ to 3′ mRNA decay is essential for the packaging of Ty1 RNA in VLPs.
Novel Type II Transmembrane Serine Proteases, MSPL and TMPRSS13, Proteolytically Activate Membrane Fusion Activity of the Hemagglutinin of Highly Pathogenic Avian Influenza Viruses and Induce Their Multicycle Replication
Authors: Okumura Yuushi , Takahashi Etsuhisa , Yano Mihiro , Ohuchi Masanobu , Daidoji Tomo , Nakaya Takaaki , Böttcher Eva , Garten Wolfgang , Klenk Hans-Dieter , Kido Hiroshi 
Published: March 2010

ABSTRACTHost cellular proteases induce influenza virus entry into cells by cleaving the viral surface envelope glycoprotein hemagglutinin (HA). However, details on the cellular proteases involved in this event are not fully available. We report here that ubiquitous type II transmembrane serine proteases, MSPL and its splice variant TMPRSS13, are novel candidates for proteases processing HA proteins of highly pathogenic avian influenza (HPAI) viruses, apart from the previously identified furin and proprotein convertases 5 and 6. HAs from all HPAI virus H5 and H7 strains have one of two cleavage site motifs, theR-X-K/R-R motif withRat position P4 and theK-K/R-K/T-R motif withKat position P4. In studies of synthetic 14-residue HPAI virus HA peptides with these cleavage site motifs, furin preferentially cleaved only HA peptides with theR-K-K-R motif in the presence of calcium and not peptides with the other motif, whereas MSPL and TMPRSS13 cleaved both types of HA peptides (those with theR/K-K-K-R motif) efficiently in the absence of calcium. Full-length recombinant HPAI virus HA with theK-K-K-R cleavage motif exhibited poor susceptibility to cleavage in the absence of MSPL or TMPRSS13 and the presence of furin in infected cells, but it was converted to mature HA subunits in transfected cells expressing MSPL or TMPRSS13, with membrane-fused giant-cell formation. This conversion and membrane fusion were suppressed by inhibitors of MSPL and TMPRSS13. Furthermore, infection with and multiplication of genetically modified live HPAI virus A/Crow/Kyoto/53/2004 (H5N1) with theK-K-K-R cleavage site motif were detected only in MSPL- and TMPRSS13-expressing cells.
Complex Interactions between the Major and Minor Envelope Proteins of Equine Arteritis Virus Determine Its Tropism for Equine CD3+T Lymphocytes and CD14+Monocytes
Authors: Go Yun Young , Zhang Jianqiang , Timoney Peter J. , Cook R. Frank , Horohov David W. , Balasuriya Udeni B. R. 
Published: March 2010

ABSTRACTExtensive cell culture passage of the virulent Bucyrus (VB) strain of equine arteritis virus (EAV) to produce the modified live virus (MLV) vaccine strain has altered its tropism for equine CD3+T lymphocytes and CD14+monocytes. The VB strain primarily infects CD14+monocytes and a small subpopulation of CD3+T lymphocytes (predominantly CD4+T lymphocytes), as determined by dual-color flow cytometry. In contrast, the MLV vaccine strain has a significantly reduced ability to infect CD14+monocytes and has lost its capability to infect CD3+T lymphocytes. Using a panel of five recombinant chimeric viruses, we demonstrated that interactions among the GP2, GP3, GP4, GP5, and M envelope proteins play a major role in determining the CD14+monocyte tropism while the tropism for CD3+T lymphocytes is determined by the GP2, GP4, GP5, and M envelope proteins but not the GP3 protein. The data clearly suggest that there are intricate interactions among these envelope proteins that affect the binding of EAV to different cell receptors on CD3+T lymphocytes and CD14+monocytes. This study shows, for the first time, that CD3+T lymphocytes may play an important role in the pathogenesis of equine viral arteritis when horses are infected with the virulent strains of EAV.
Occupational exposure to asbestos in New South Wales, Australia (1970–1989): development of an asbestos task exposure matrix
Authors: Hyland Rebecca A , Yates Deborah H , Benke Geza , Sim Malcolm , Johnson Anthony R 
Published: March 2010

ObjectivesTo design and construct a standardised tool to provide exposure information associated with commonly used asbestos products and their related tasks in New South Wales (NSW), Australia.MethodsAsbestos dust exposure measurements taken during workplace inspections in the 1970s and 1980s were collected and stored in an exposure database. Measurements were assigned to specific asbestos product and task groups and divided into two sampling periods 1970–1979 and 1980–1989.ResultsA total of 1578 asbestos air measurements collected from WorkCover and Dust Diseases Board company records were entered into a custom built exposure database. An asbestos-specific exposure matrix (ASTEM) was constructed in Microsoft Excel 2000, consisting of 3 axes incorporating 12 tasks, 8 asbestos products and the 2 time periods based on 872 individual measurements extracted from the exposure database. Each matrix cell contains the mean asbestos exposure levels measured in fibres/ml, 5th and 95th percentiles and number of data points in the set.ConclusionAn ASTEM has been developed which provides exposure levels for different task/product combinations. When used in conjunction with a detailed occupational history, it will improve exposure estimates of a worker's cumulative asbestos exposure.
BOCHNER–MARTINELLI FORMULAS ON SINGULAR COMPLEX SPACES
Authors: ANCONA VINCENZO , GAVEAU BERNARD 
Published: March 2010

Let U be a complex space of complex dimension n ≥ 2, P a point of U, π : Ũ → U a modification such that Ũ is nonsingular and D = π-1(P) is a divisor with normal crossings. A Bochner–Martinelli form on U\{P} is a [Formula: see text]-closed differential form ω on Ũ\D, of pure type (n,n - 1), logarithmic along D. Such form detects a cohomology class of H2n - 1(U\{P},ℂ) on the singular space U\{P}. Thanks to a general residue formula we prove that the forms ω give rise to an integral formula of Bochner–Martinelli type for holomorphic functions.If U satisfies the following assumption that {there exists a compact complex space X bimeromorphic to a Kähler manifold, and a closed subspace T ⊂ X, such that X\T = U (an affine, or a quasi-projective variety satisfies the above property), we relate Bochner–Martinelli forms to the mixed Hodge structure carried by H2n-1(U\{P},ℂ). Most of our results hold for complex spaces which are not Stein.
THE PONTRJAGIN–HOPF INVARIANTS FOR SOBOLEV MAPS
Authors: AUCKLY DAVE , KAPITANSKI LEV 
Published: March 2010

Subtle issues arise when extending homotopy invariants to spaces of functions having little regularity, e.g., Sobolev spaces containing discontinuous functions. Sometimes it is not possible to extend the invariant at all, and sometimes, even when the formulas defining the invariants make sense, they may not have expected properties (e.g., there are maps having non-integral degree).In this paper, we define a complete set of homotopy invariants for maps from three-manifolds to the two-sphere and show that these invariants extend to finite Faddeev energy maps and maps in suitable Sobolev spaces. For smooth maps, our description is proved to be equivalent to Pontrjagin's original homotopy classification from the 1930's. We further show that for the finite energy maps the invariants take on exactly the same values as for smooth maps. We include applications to the Faddeev model.The techniques that we use would also apply to many more problems and/or other functionals. We have tried to make the paper accessible to analysts, geometers and mathematical physicists.
On the Fixed-Point Set of a Family of Relatively Nonexpansive and Generalized Nonexpansive Mappings
Authors: Nilsrakoo Weerayuth , Saejung Satit 
Published: March 2010

AbstractWe prove that the set of common fixed points of a given countable family of relatively nonexpansive mappings is identical to the fixed-point set of a single strongly relatively nonexpansive mapping. This answers Kohsaka and Takahashi's question in positive. We also introduce the concept of strongly generalized nonexpansive mappings and prove the analogue version of the result above for Ibaraki-Takahashi's generalized nonexpansive mappings. The duality theorem for two classes of strongly relatively nonexpansive mappings and of strongly generalized nonexpansive mappings is proved.