bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural Requirements for gp80 Independence of Human Herpesvirus 8 Interleukin-6 (vIL-6) and Evidence for gp80 Stabilization of gp130 Signaling Complexes Inducedby vIL-6
Authors: Chen Daming , Nicholas John 
Published: September 2006

ABSTRACT

Human herpesvirus 8 interleukin-6 (vIL-6) displays 25% amino acid identity
with human IL-6 (hIL-6) and shares an overall four-helix-bundle
structure and gp130-mediated STAT/mitogen-activated protein kinase
signaling with its cellular counterpart. However, vIL-6 is distinct in
that it can signal through gp130 alone, in the absence of the
nonsignaling gp80 α-subunit of the IL-6 receptor. To
investigate the structural requirements for gp80 independence of vIL-6,
a series of expression vectors encoding vIL-6/hIL-6 chimeric and
site-mutated IL-6 proteins was generated. The replacement of hIL-6
residues with three vIL-6-specific tryptophans implicated in gp80
independence from crystallographic studies or the A and C helices
containing these residues did not confer gp80 independence to hIL-6.
The N- and C-terminal regions of vIL-6 could be substituted with hIL-6
sequences with the retention of gp80-independent signaling, but
substitutions of other regions of vIL-6 (helix A, A/B loop, helix B,
helix C, and proximal half of helix D) with equivalent sequences of
hIL-6 abolished gp80 independence. Interestingly, the B helix of vIL-6
was absolutely required for gp80 independence, despite the fact that
this region contains no receptor-binding residues. Point mutational
analysis of helix C, which contains residues involved in physical and
functional interactions with gp130 domains 2 and 3 (cytokine-binding
homology region), identified a variant, VI
120
EE, that was
able to signal and dimerize gp130 only in the presence of gp80. gp80
was also found to stabilize gp130:g130 dimers induced by a distal D
helix variant of vIL-6 that was nonetheless able to signal
independently of gp80. Together, our data reveal the crucial importance
of overall vIL-6 structure and conformation for gp80-independent
signaling and provide functional and physical evidence of the
stabilization of vIL-6-induced gp130 signaling complexes by
gp80.
The 37/67-Kilodalton Laminin Receptor Is a Receptor for Adeno-Associated Virus Serotypes 8, 2, 3, and 9
Authors: Akache Bassel , Grimm Dirk , Pandey Kusum , Yant Stephen R. , Xu Hui , Kay Mark A. 
Published: September 2006

ABSTRACT
Adeno-associated virus serotype 8 (AAV8) is currently emerging as a powerful gene transfer vector, owing to its capability to efficiently transduce many different tissues in vivo. While this is believed to be in part due to its ability to uncoat more readily than other AAV serotypes such as AAV2, understanding all the processes behind AAV8 transduction is important for its application and optimal use in human gene therapy. Here, we provide the first report of a cellular receptor for AAV8, the 37/67-kDa laminin receptor (LamR). We document binding of LamR to AAV8 capsid proteins and intact virions in vitro and demonstrate its contribution to AAV8 transduction of cultured cells and mouse liver in vivo. We also show that LamR plays a role in transduction by three other closely related serotypes (AAV2, -3, and -9). Sequence and deletion analysis allowed us to map LamR binding to two protein subdomains predicted to be exposed on the AAV capsid exterior. Use of LamR, which is constitutively expressed in many clinically relevant tissues and is overexpressed in numerous cancers, provides a molecular explanation for AAV8's broad tissue tropism. Along with its robust transduction efficiency, our findings support the continued development of AAV8-based vectors for clinical applications in humans, especially for tumor gene therapy.
Cross-Protection against Marburg Virus Strains by Using a Live, Attenuated Recombinant Vaccine
Authors: Daddario-DiCaprio Kathleen M. , Geisbert Thomas W. , Geisbert Joan B. , Ströher Ute , Hensley Lisa E. , Grolla Allen , Fritz Elizabeth A. , Feldmann Friederike , Feldmann Heinz , Jones Steven M. 
Published: September 2006

ABSTRACT
Marburg virus (MARV) has been associated with sporadic episodes of hemorrhagic fever, including a recent highly publicized outbreak in Angola that produced severe disease and significant mortality in infected patients. MARV is also considered to have potential as a biological weapon. Recently, we reported the development of a promising attenuated, replication-competent vaccine against MARV based on recombinant vesicular stomatitis virus (VSV) expressing the glycoprotein of the Musoke strain of MARV (VSVΔG/MARVGP-Musoke). We used this vaccine to demonstrate complete protection of cynomolgus monkeys against a homologous MARV challenge. While these results are highly encouraging, an effective vaccine would need to confer protection against all relevant strains of MARV. Here, we evaluated the protective efficacy of the VSVΔG/MARVGP-Musoke vaccine against two heterologous MARV strains, the seemingly more pathogenic Angola strain and the more distantly related Ravn strain. In this study, seven cynomolgus monkeys were vaccinated with the VSVΔG/MARVGP-Musoke vector. Three of these animals were challenged with the Angola strain, three with the Ravn strain, and a single animal with the Musoke strain of MARV. Two animals served as controls and were each injected with a nonspecific VSV vector; these controls were challenged with the Angola and Ravn strains, respectively. Both controls succumbed to challenge by day 8. However, none of the specifically vaccinated animals showed any evidence of illness either from the vaccination or from the MARV challenges and all of these animals survived. These data suggest that the VSVΔG/MARVGP-Musoke vaccine should be sufficient to protect against all known MARV strains.
Peripheral Blood B-Cell Death Compensates for Excessive Proliferation in Lymphoid Tissues and Maintains Homeostasis in Bovine Leukemia Virus-InfectedSheep
Authors: Debacq Christophe , Gillet Nicolas , Asquith Becca , Sanchez-Alcaraz Maria Teresa , Florins Arnaud , Boxus Mathieu , Schwartz-Cornil Isabelle , Bonneau Michel , Jean Geneviève , Kerkhofs Pierre , Hay Jack , Théwis André , Kettmann Richard , Willems Luc 
Published: September 2006

ABSTRACTThe size of a lymphocyte population is primarily determined by a dynamic equilibrium between cell proliferation and death. Hence, lymphocyte recirculation between the peripheral blood and lymphoid tissues is a key determinant in the maintenance of cell homeostasis. Insights into these mechanisms can be gathered from large-animal models, where lymphatic cannulation from individual lymph nodes is possible. In this study, we assessed in vivo lymphocyte trafficking in bovine leukemia virus (BLV)-infected sheep. With a carboxyfluorescein diacetate succinimidyl ester labeling technique, we demonstrate that the dynamics of lymphocyte recirculation is unaltered but that accelerated proliferation in the lymphoid tissues is compensated for by increased death in the peripheral blood cell population. Lymphocyte homeostasis is thus maintained by biphasic kinetics in two distinct tissues, emphasizing a very dynamic process during BLV infection.
Mapping and Functional Role of the Self-Association Domain of Vesicular Stomatitis Virus Phosphoprotein
Authors: Chen Mingzhou , Ogino Tomoaki , Banerjee Amiya K. 
Published: September 2006

ABSTRACT
The phosphoprotein (P protein) of vesicular stomatitis virus (VSV) is an essential subunit of the viral RNA-dependent RNA polymerase complex and plays a central role in viral transcription and replication. Using both the yeast two-hybrid system and coimmunoprecipitation assays, we confirmed the self-association of the P protein of Indiana serotype (Pind) and heterotypic interaction between Pind and the P protein of New Jersey serotype (Pnj). Furthermore, by using various truncation and deletion mutants of Pind, the self-association domain of the Pind protein was mapped to amino acids 161 to 210 within the hinge region. The self-association domain of Pind protein is not required for its binding to nucleocapsid and large proteins. We further demonstrated that the self-association domain of Pind protein is essential for VSV transcription in a minireplicon system and that a synthetic peptide spanning amino acids 191 to 210 in the self-association domain of Pind protein strongly inhibited the transcription of the VSV genome in vitro in a dose-dependent manner. These results indicated that the self-association domain of Pind protein plays a critical role in VSV transcription.
Human ESCRT-II Complex and Its Role in Human Immunodeficiency Virus Type 1 Release
Authors: Langelier Charles , von Schwedler Uta K. , Fisher Robert D. , De Domenico Ivana , White Paul L. , Hill Christopher P. , Kaplan Jerry , Ward Diane , Sundquist Wesley I. 
Published: September 2006

ABSTRACT

The budding of many enveloped RNA viruses, including human immunodeficiency virus type 1 (HIV-1), requires some of the same cellular machinery as vesicle formation at the multivesicular body (MVB). In
Saccharomyces cerevisiae
, the ESCRT-II complex performs a central role in MVB protein sorting and vesicle formation, as it is recruited by the upstream ESCRT-I complex and nucleates assembly of the downstream ESCRT-III complex. Here, we report that the three subunits of human ESCRT-II, EAP20, EAP30, and EAP45, have a number of properties in common with their yeast orthologs. Specifically, EAP45 bound ubiquitin via its N-terminal GRAM-like ubiquitin-binding in EAP45 (GLUE) domain, both EAP45 and EAP30 bound the C-terminal domain of TSG101/ESCRT-I, and EAP20 bound the N-terminal half of CHMP6/ESCRT-III. Consistent with its expected role in MVB vesicle formation, (i) human ESCRT-II localized to endosomal membranes in a VPS4-dependent fashion and (ii) depletion of EAP20/ESCRT-II and CHMP6/ESCRT-III inhibited lysosomal targeting and downregulation of the epidermal growth factor receptor, albeit to a lesser extent than depletion of TSG101/ESCRT-I. Nevertheless, HIV-1 release and infectivity were not reduced by efficient small interfering RNA depletion of EAP20/ESCRT-II or CHMP6/ESCRT-III. These observations indicate that there are probably multiple pathways for protein sorting/MVB vesicle formation in human cells and that HIV-1 does not utilize an ESCRT-II-dependent pathway to leave the cell.
Site-Directed Antibodies against the Stem Region Reveal Low pH-Induced Conformational Changes of the Semliki Forest Virus Fusion Protein
Authors: Liao Maofu , Kielian Margaret 
Published: September 2006

ABSTRACT
The E1 envelope protein of the alphavirus Semliki Forest virus (SFV) is a class II fusion protein that mediates low pH-triggered membrane fusion during virus infection. Like other class I and class II fusion proteins, during fusion E1 inserts into the target membrane and rearranges to form a trimeric hairpin structure. The postfusion structures of the alphavirus and flavivirus fusion proteins suggest that the “stem” region connecting the fusion protein domain III to the transmembrane domain interacts along the trimer core during the low pH-induced conformational change. However, the location of the E1 stem in the SFV particle and its rearrangement and functional importance during fusion are not known. We developed site-directed polyclonal antibodies to the N- or C-terminal regions of the SFV E1 stem and used them to study the stem during fusion. The E1 stem was hidden on neutral pH virus but became accessible after low pH-triggered dissociation of the E2/E1 heterodimer. The stem packed onto the trimer core in the postfusion conformation and became inaccessible to antibody binding. Generation of the E1 homotrimer on fusion-incompetent membranes identified an intermediate conformation in which domain III had folded back but stem packing was incomplete. Our data suggest that E1 hairpin formation occurs by the sequential packing of domain III and the stem onto the trimer core and indicate a tight correlation between stem packing and membrane merger.
Brd4 Is Required for E2-Mediated Transcriptional Activation but Not Genome Partitioning of All Papillomaviruses
Authors: McPhillips M. G. , Oliveira J. G. , Spindler J. E. , Mitra R. , McBride A. A. 
Published: September 2006

ABSTRACT
Bromodomain protein 4 (Brd4) has been identified as the cellular binding target through which the E2 protein of bovine papillomavirus type 1 links the viral genome to mitotic chromosomes. This tethering ensures retention and efficient partitioning of genomes to daughter cells following cell division. E2 is also a regulator of viral gene expression and a replication factor, in association with the viral E1 protein. In this study, we show that E2 proteins from a wide range of papillomaviruses interact with Brd4, albeit with variations in efficiency. Moreover, disruption of the E2-Brd4 interaction abrogates the transactivation function of E2, indicating that Brd4 is required for E2-mediated transactivation of all papillomaviruses. However, the interaction of E2 and Brd4 is not required for genome partitioning of all papillomaviruses since a number of papillomavirus E2 proteins associate with mitotic chromosomes independently of Brd4 binding. Furthermore, mutations in E2 that disrupt the interaction with Brd4 do not affect the ability of these E2s to associate with chromosomes. Thus, while all papillomaviruses attach their genomes to cellular chromosomes to facilitate genome segregation, they target different cellular binding partners. In summary, the E2 proteins from many papillomaviruses, including the clinically important alpha genus human papillomaviruses, interact with Brd4 to mediate transcriptional activation function but not all depend on this interaction to efficiently associate with mitotic chromosomes.
Proteolytic Activation of Influenza Viruses by Serine Proteases TMPRSS2 and HAT from Human Airway Epithelium
Authors: Böttcher Eva , Matrosovich Tatyana , Beyerle Michaela , Klenk Hans-Dieter , Garten Wolfgang , Matrosovich Mikhail 
Published: September 2006

ABSTRACT
Host cell proteases that cleave the hemagglutinin (HA) of influenza viruses in the human respiratory tract are still not identified. Here we cloned two human type II transmembrane serine proteases with known airway localization, TMPRSS2 and HAT, into mammalian expression vector. Cotransfection of mammalian cells with plasmids encoding HA and either protease resulted in HA cleavage in situ. Transient expression of either protease in MDCK cells enabled multicycle replication of influenza viruses in these cells in the absence of exogenous trypsin. These data suggest that TMPRSS2 and HAT are candidates for proteolytic activation of influenza viruses in vivo.
Herpes Simplex Virus ICP27 Is Required for Virus-Induced Stabilization of the ARE-Containing IEX-1 mRNA Encoded by the Human IER3 Gene
Authors: Corcoran Jennifer A. , Hsu Wei-Li , Smiley James R. 
Published: September 2006

ABSTRACT
Herpes simplex virus (HSV) stifles cellular gene expression during productive infection of permissive cells, thereby diminishing host responses to infection. Host shutoff is achieved largely through the complementary actions of two viral proteins, ICP27 and virion host shutoff (vhs), that inhibit cellular mRNA biogenesis and trigger global mRNA decay, respectively. Although most cellular mRNAs are thus depleted, some instead increase in abundance after infection; perhaps surprisingly, some of these contain AU-rich instability elements (AREs) in their 3′-untranslated regions. ARE-containing mRNAs normally undergo rapid decay; however, their stability can increase in response to signals such as cytokines and virus infection that activate the p38/MK2 mitogen-activated protein kinase (MAPK) pathway. We and others have shown that HSV infection stabilizes the ARE mRNA encoding the stress-inducible IEX-1 mRNA, and a previous report from another laboratory has suggested vhs is responsible for this effect. However, we now report that ICP27 is essential for IEX-1 mRNA stabilization whereas vhs plays little if any role. A recent report has documented that ICP27 activates the p38 MAPK pathway, and we detected a strong correlation between this activity and stabilization of IEX-1 mRNA by using a panel of HSV type 1 (HSV-1) isolates bearing an array of previously characterized ICP27 mutations. Furthermore, IEX-1 mRNA stabilization was abrogated by the p38 inhibitor SB203580. Taken together, these data indicate that the HSV-1 immediate-early protein ICP27 alters turnover of the ARE-containing message IEX-1 by activating p38. As many ARE mRNAs encode proinflammatory cytokines or other immediate-early response proteins, some of which may limit viral replication, it will be of great interest to determine if ICP27 mediates stabilization of many or all ARE-containing mRNAs.
Induction of Cell-Cell Fusion from Without by Human Herpesvirus 6B
Authors: Pedersen Simon Metz , Øster Bodil , Bundgaard Bettina , Höllsberg Per 
Published: September 2006

ABSTRACT
Human herpesvirus (HHV) 6A induce fusion from without (FFWO), whereas HHV-6B is believed to be ineffective in this process. Here, we demonstrate that HHV-6B induces rapid fusion in both epithelial cells and lymphocytes. The fusion was identified 1 h postinfection, could be inhibited by antibodies to HHV-6B gH and to the cellular receptor CD46, and was dependent on virus titer but independent of de novo protein synthesis and UV inactivation of the virus. Comparisons indicate that HHV-6A is only 10-fold more effective in inducing FFWO than HHV-6B. These data demonstrate that HHV-6B can induce FFWO in epithelial cells and lymphocytes.
Plasmin/plasminogen is essential for the healing of tympanic membrane perforations
Authors: Li Jinan , Eriksson Per-Olof , Hansson Annika , Hellström Sten , Ny Tor 
Published: September 2006

SummaryPlasminogen has been proposed to play an important role in different tissue remodeling processes such as wound healing and tissue regeneration after injuries. The healing of tympanic membrane perforations is a well-organized chain of inflammatory events, with an initial invasion of inflammatory cells followed by reparative and restoration phases. Here we show that the healing of tympanic membrane perforations is completely arrested in plasminogen-deficient mice, with no signs of any healing even 143 days after perforation. Inflammatory cells were recruited to the wounded area, but there were no signs of tissue debridement. In addition, removal of fibrin, keratinocyte migration and in-growth of connective tissue were impaired. This contrasts with skin wound healing, where studies have shown that, although the healing process is delayed, it reaches completion in all plasminogen-deficient mice. Our finding that keratinocyte migration and re-epithelialization were completely arrested in plasminogen-deficient mice indicates that plasminogen/plasmin plays a more profound role in the healing of tympanic membrane perforations than in the healing of other epithelial wounds.
A direct thrombin inhibitor studied by dynamic whole blood clot formation
Authors: Ingerslev Jørgen , Sørensen Benny 
Published: September 2006

SummaryDirect thrombin inhibitors have proven efficacious in prevention of venous thromboembolism. Bleeding complications are rare, but in case of acute serious bleeding, an effective and instant haemostatic intervention may be required. In the present study it was demonstrated that the direct thrombin inhibitor melagatran induces dose-dependent abnormalities in whole blood (WB) clotting profiles as recorded bya recently described modified thrombelastographic model, and that rFVIIa or APCC are capable of improving the haemostatic capacity. Experiments were performed using WB from 30 healthy males. In-vitro titration experiments (n=10) with addition of melagatran to WB corresponding to plasma concentrations ranging from 0 to 5.0 µM (12 steps) showed a dose-dependent prolongation of the clot initiation and characteristic decrease of the maximum rate of clot propagation. In-vitro intervention studies (n=20) were completed with four different concentrations of melagatran as well as addition of four different levels of rFVIIa or APCC. At all tested concentrations of melagatran, rFVIIa significantly shortened the melagatran-induced prolonged clot initiation but induced only minor improvements of the reduced clot propagation. In contrast, APCC significantly and dose-dependently shortened the clot initiation and accelerated the clot propagation. In conclusion, our thrombelastographic model appears useful for evaluating the effect of direct thrombin inhibitors on dynamic WB clot formation and rFVIIa, but especially APCC significantly improved theWB clot formation. The pronounced stabilizing effect of APCC may be caused by its content of prothrombin and activated coagulation factors.
Increased red blood cell aggregation in patients with idiopathic intracranial hypertension
Authors: Kesler Anat , Yatziv Yossi , Shapira Itzhak , Ben Assayag Einor , Berliner Shlomo 
Published: September 2006

SummaryIt was the objective of this study to explore the possibility that the aggregation of red blood cells is enhanced in individuals with increased intracranial hypertension (IIH). This is a prospective cross sectional examination in a cohort of patients with IIH and matched controls.The aggregation of red blood cells in the peripheral venous blood was determined by using a slide test and image analysis.We have presently included a group of 33 women with IIH and the same number of women matched for age, body mass index, vascular risk factors and medications. A significant (p=0.038) increment in fibrinogen concentrations was noted in the patients (341 ± 60.8 mg/dl) as opposed to the controls 307.9 ± 64.8).The same stands for the aggregation of red blood cells (aggregation parameter of 8.7 ± 4.9 in patients vs.5.9 ± 3.2 in the controls, p=0.001).We noted an increment in the aggregation of red blood cells in the peripheral blood of 33 women with IIH as opposed to matched controls. Being associated with capillary slow flow,these findings might be relevant to the ethiopathogenesis of this disease.
Elevated complement C3 is associated with early restenosis after eversion carotid endarterectomy
Authors: Széplaki Gábor , Varga Lilian , Laki Judit , Doása Edit , Madsen Hans , Prohászka Zoltán , Szabó Attila , Acsády György , Selmeci László , Garred Peter , Entz László , Füst George 
Published: September 2006

SummaryEarly restenosis following carotid endarterectomy (CEA) is an inflammatory process leading to myointimal hyperplasia of smooth muscle cells. The risk for restenosis is increased in homozygous carriers of the normal (A) allele of mannose-binding lectin (MBL2) gene. Our objective was to study the associ-ations of C3 and as control three non-complement acute-phase reactants (APRs) (C-reactive protein, haptoglobin and α2HS-glycoprotein) with early restenosis following CEA.We also considered, whether MBL2 genotype relates to C3 levels and to the risk of restenosis. Concentrations of the APRs were determined by radial immunodiffusion or immunoturbidimetric methods in 64 patients who underwent eversion CEA and were followed up with carotid duplex scan (CDS) examinations for at least one year. MBL2 genotypes were determined by a PCR-SSP method. C3 levels increased during the follow-up and correlated with the percentage of restenosis detected by CDS at 14 months postsurgery, in MBL2 A/A allele carriers. Patients with high C3 levels had nearly five-fold higher odds for the presence of significant restenosis (>50% reduction in diameter) even after adjusting for MBL2 genotype, age and gender. By contrast, no such associations were detected between the non-complement APRs and early restenosis. C3 is associated with and might have a direct role in the development of an early restenosis following CEA, which is partially related to an intact MBL lectin pathway, thus determining C3 levels might have clinical importance. On the other hand, our results indicate that the regulation of C3 differs from non-complement APRs.