bluuebunny/crossref_metadata_2025_split huggingface dataset:
Importance of the N-Distal AP-2 Binding Element in Nef for Simian Immunodeficiency Virus Replication and Pathogenicity in Rhesus Macaques
Authors: Brenner Matthias , Münch Jan , Schindler Michael , Wildum Steffen , Stolte Nicole , Stahl-Hennig Christiane , Fuchs Dietmar , Mätz-Rensing Kerstin , Franz Monika , Heeney Jonathan , Ten Haaft Peter , Swigut Tomek , Hrecka Katarzyna , Skowronski Jacek , Kirchhoff Frank 
Published: April 2006

ABSTRACTPoint mutations in SIVmac239 Nef disrupting CD4 downmodulation and enhancement of virion infectivity attenuate viral replication in acutely infected rhesus macaques, but changes selected later in infection fully restore Nef function (A. J. Iafrate et al., J. Virol. 74:9836-9844, 2000). To further evaluate the relevance of these Nef functions for viral persistence and disease progression, we analyzed an SIVmac239 Nef mutant containing a deletion of amino acids Q64 to N67 (Δ64-67Nef). This mutation inactivates the N-distal AP-2 clathrin adaptor binding element and disrupts the abilities of Nef to downregulate CD4, CD28 and CXCR4 and to stimulate viral replication in vitro. However, it does not impair the downmodulation of CD3 and class I major histocompatibility complex (MHC-I) or MHC-II and the upregulation of the MHC-II-associated invariant chain, and it has only a moderate effect on the enhancement of virion infectivity. Replication of the Δ64-67Nef variant in acutely infected macaques was intermediate between grosslynef-deleted and wild-type SIVmac239. Subsequently, three of six macaques developed moderate to high viral loads and developed disease, whereas the remaining animals efficiently controlled SIV replication and showed a more attenuated clinical course of infection. Sequence analysis revealed that the deletion innefwas not repaired in any of these animals. However, some changes that slightly enhanced the ability of Nef to downmodulate CD4 and moderately increased Nef-mediated enhancement of viral replication and infectivity in vitro were observed in macaques developing high viral loads. Our results imply that both the Nef functions that were disrupted by the Δ64-67 mutation and the activities that remained intact contribute to viral pathogenicity.
Junctional Adhesion Molecule 1 Is a Functional Receptor for Feline Calicivirus
Authors: Makino Akiko , Shimojima Masayuki , Miyazawa Takayuki , Kato Kentaro , Tohya Yukinobu , Akashi Hiroomi 
Published: April 2006

ABSTRACTThe life cycle of calicivirus is not fully understood because most of the viruses cannot be propagated in tissue culture cells. We studied the mechanism of calicivirus entry into cells using feline calicivirus (FCV), a cultivable calicivirus. From the cDNA library of Crandell-Rees feline kidney (CRFK) cells, feline junctional adhesion molecule 1 (JAM-1), an immunoglobulin-like protein present in tight junctions, was identified as a cellular-binding molecule of the FCV F4 strain, a prototype strain in Japan. Feline JAM-1 expression in nonpermissive hamster lung cells led to binding and infection by F4 and all other strains tested. An anti-feline JAM-1 antibody reduced the binding of FCV to permissive CRFK cells and strongly suppressed the cytopathic effect (CPE) and FCV progeny production in infected cells. Some strains of FCV, such as F4 and F25, have the ability to replicate in Vero cells. We found that regardless of replication ability, FCV bound to Vero and 293T cells via simian and human JAM-1, respectively. In Vero cells, an anti-human JAM-1 antibody inhibited binding, CPE, and progeny production by F4 and F25. In addition, feline JAM-1 expression permitted FCV infection in 293T cells. Taken together, our results demonstrate that feline JAM-1 is a functional receptor for FCV, simian JAM-1 also functions as a receptor for some strains of FCV, and the interaction between FCV and JAM-1 molecules may be a determinant of viral tropism. This is the first report concerning a functional receptor for the viruses in the familyCaliciviridae.
DNA Binding Activity of the Herpes Simplex Virus Type 1 Origin Binding Protein, UL9, Can Be Modulated by Sequences in the N Terminus: Correlation between Transdominance and DNA Binding
Authors: Chattopadhyay Soma , Weller Sandra K. 
Published: April 2006

ABSTRACT
UL9, the origin binding protein of herpes simplex virus type 1, is a member of the SF2 family of helicases. Cotransfection of cells with infectious viral DNA and plasmids expressing either full-length UL9 or the C-terminal DNA binding domain alone results in the drastic inhibition of plaque formation which can be partially relieved by an insertion mutant lacking DNA binding activity. In this work, C-terminally truncated mutants which terminate at or near residue 359 were shown to potentiate plaque formation, while other C-terminal truncations were inhibitory. Thus, residues in the N-terminal region appear to regulate the inhibitory properties of UL9. To identify which residues were involved in this regulation, a series of N-terminally truncated mutants were constructed which contain the DNA binding domain and various N-terminal extensions. Mutants whose N terminus is either at residue 494 or 535 were able to bind the origin efficiently and were inhibitory to plaque formation, whereas constructs whose N terminus is at residue 304 or 394 were defective in origin binding activity and were able to relieve inhibition. Since UL9 is required for viral infection at early but not late times and is inhibitory to infection when overexpressed, we propose that the DNA binding activities of UL9 are regulated during infection. For infection to proceed, UL9 may need to switch from a DNA binding to a non-DNA binding mode, and we suggest that sequences residing in the N terminus play a role in this switch.
Lambda Interferon (IFN-λ), a Type III IFN, Is Induced by Viruses and IFNs and Displays Potent Antiviral Activity against Select Virus Infections In Vivo
Authors: Ank Nina , West Hans , Bartholdy Christina , Eriksson Kristina , Thomsen Allan R. , Paludan Søren R. 
Published: April 2006

ABSTRACTType III interferons (IFNs) (interleukin-28/29 or lambda interferon [IFN-λ]) are cytokines with IFN-like activities. Here we show that several classes of viruses induce expression of IFN-λ1 and -λ2/3 in similar patterns. The IFN-λs were—unlike alpha/beta interferon (IFN-α/β)—induced directly by stimulation with IFN-α or -λ, thus identifying type III IFNs as IFN-stimulated genes. In vitro assays revealed that IFN-λs have appreciable antiviral activity against encephalomyocarditis virus (EMCV) but limited activity against herpes simplex virus type 2 (HSV-2), whereas IFN-α potently restricted both viruses. Using three murine models for generalized virus infections, we found that while recombinant IFN-α reduced the viral load after infection with EMCV, lymphocytic choriomeningitis virus (LCMV), and HSV-2, treatment with recombinant IFN-λ in vivo did not affect viral load after infection with EMCV or LCMV but did reduce the hepatic viral titer of HSV-2. In a model for a localized HSV-2 infection, we further found that IFN-λ completely blocked virus replication in the vaginal mucosa and totally prevented development of disease, in contrast to IFN-α, which had a more modest antiviral activity. Finally, pretreatment with IFN-λ enhanced the levels of IFN-γ in serum after HSV-2 infection. Thus, type III IFNs are expressed in response to most viruses and display potent antiviral activity in vivo against select viruses. The discrepancy between the observed antiviral activity in vitro and in vivo may suggest that IFN-λ exerts a significant portion of its antiviral activity in vivo via stimulation of the immune system rather than through induction of the antiviral state.
Diverse Effects of Cyclosporine on Hepatitis C Virus Strain Replication
Authors: Ishii Naoto , Watashi Koichi , Hishiki Takayuki , Goto Kaku , Inoue Daisuke , Hijikata Makoto , Wakita Takaji , Kato Nobuyuki , Shimotohno Kunitada 
Published: April 2006

ABSTRACT
Recently, a production system for infectious particles of hepatitis C virus (HCV) utilizing the genotype 2a JFH1 strain has been developed. This strain has a high capacity for replication in the cells. Cyclosporine (CsA) has a suppressive effect on HCV replication. In this report, we characterize the anti-HCV effect of CsA. We observe that the presence of viral structural proteins does not influence the anti-HCV activity of CsA. Among HCV strains, the replication of genotype 1b replicons was strongly suppressed by treatment with CsA. In contrast, JFH1 replication was less sensitive to CsA and its analog, NIM811. Replication of JFH1 did not require the cellular replication cofactor, cyclophilin B (CyPB). CyPB stimulated the RNA binding activity of NS5B in the genotype 1b replicon but not the genotype 2a JFH1 strain. These findings provide an insight into the mechanisms of diversity governing virus-cell interactions and in the sensitivity of these strains to antiviral agents.
Differential Chemokine Expression following Respiratory Virus Infection Reflects Th1- or Th2-Biased Immunopathology
Authors: Culley Fiona J. , Pennycook Alasdair M. J. , Tregoning John S. , Hussell Tracy , Openshaw Peter J. M. 
Published: April 2006

ABSTRACTRespiratory syncytial virus (RSV) is a major viral pathogen of infants that also reinfects adults. During RSV infection, inflammatory host cell recruitment to the lung plays a central role in determining disease outcome. Chemokines mediate cell recruitment to sites of inflammation and are influenced by, and influence, the production of cytokines. We therefore compared chemokine production in a mouse model of immunopathogenic RSV infection in which either Th1 or Th2 immunopathology is induced by prior sensitization to individual RSV proteins. Chemokine expression profiles were profoundly affected by the nature of the pulmonary immunopathology: “Th2” immunopathology in BALB/c mice was associated with increased and prolonged expression of CCL2 (MCP-1), CXCL10 (IP-10), and CCL11 (eotaxin) starting within 24 h of challenge. C57BL/6 mice with “Th2” pathology (enabled by a deficiency of CD8+cells) also showed increased CCL2 production. No differences in chemokine receptor expression were detected. Chemokine blockers may therefore be of use for children with bronchiolitis.
Cellular Stress Rather than Stage of the Cell Cycle Enhances the Replication and Plating Efficiencies of Herpes Simplex Virus Type 1 ICP0
−
Viruses
Authors: Bringhurst Ryan M. , Schaffer Priscilla A. 
Published: April 2006

ABSTRACT

This lab reported previously that the plating efficiency of a herpes simplex virus type 1 ICP0-null mutant was enhanced upon release from an isoleucine block which synchronizes cells to G
1
phase (W. Cai and P. A. Schaffer, J. Virol. 65:4078-4090, 1991). Peak plating efficiency occurred as cells cycled out of G
1
and into S phase, suggesting that the enhanced plating efficiency was due to cellular activities present in late G
1
/early S phase. We have found, however, that the enhanced plating efficiency did not occur when cells were synchronized by alternative methods. We now report that the plating efficiency of ICP0
−
viruses is not enhanced at a particular stage of the cell cycle but rather is enhanced by specific cellular stresses. Both the plating and replication efficiencies of ICP0
−
viruses were enhanced as much as 25-fold to levels similar to that of wild-type virus when monolayers were heat shocked prior to infection. In addition to heat shock, UV-C irradiation but not cold shock of monolayers prior to infection resulted in enhanced plating efficiency. We further report that the effect of cellular stress is transient and that cell density rather than age of the monolayers is the primary determinant of ICP0
−
virus plating efficiency. As both cell stress and ICP0 are required for efficient reactivation from latency, the identification of cellular activities that complement ICP0
−
viruses may lead to the identification of cellular activities that are important for reactivation from neuronal latency.
Sendai Virus Infection Induces Efficient Adaptive Immunity Independently of Type I Interferons
Authors: López Carolina B. , Yount Jacob S. , Hermesh Tamar , Moran Thomas M. 
Published: April 2006

ABSTRACTAdaptive immunity in response to virus infection involves the generation of Th1 cells, cytotoxic T cells, and antibodies. This type of immune response is crucial for the clearance of virus infection and for long-term protection against reinfection. Type I interferons (IFNs), the primary innate cytokines that control virus growth and spreading, can influence various aspects of adaptive immunity. The development of antiviral immunity depends on many viral and cellular factors, and the extent to which type I IFNs contribute to the generation of adaptive immunity in response to a viral infection is controversial. Using two strains (Cantell and 52) of the murine respiratory Sendai virus (SeV) with differential abilities to induce type I IFN production from infected cells, together with type I IFN receptor-deficient mice, we examined the role of type I IFNs in the generation of adaptive immunity. Our results show that type I IFNs facilitate virus clearance and enhance the migration and maturation of dendritic cells after SeV infection in vivo; however, soon after infection, mice clear the virus from their lungs and efficiently generate cytotoxic T cells independently of type I IFN signaling. Furthermore, animals that are unresponsive to type I IFN develop long-term anti-SeV immunity, including CD8+T cells and antibodies. Significantly, this memory response is able to protect mice against challenge with a lethal dose of virus. In conclusion, our results show that primary and secondary anti-SeV adaptive immunities are developed normally in the absence of type I IFN responsiveness.
Prion Infection of Oral and Nasal Mucosa
Authors: DeJoia Crista , Moreaux Brian , O'Connell Kimberly , Bessen Richard A. 
Published: April 2006

ABSTRACTCentrifugal spread of the prion agent to peripheral tissues is postulated to occur by axonal transport along nerve fibers. This study investigated the distribution of the pathological isoform of the protein (PrPSc) in the tongues and nasal cavities of hamsters following intracerebral inoculation of the HY strain of the transmissible mink encephalopathy (TME) agent. We report that PrPScdeposition was found in the lamina propria, taste buds, and stratified squamous epithelium of fungiform papillae in the tongue, as well as in skeletal muscle cells. Using laser scanning confocal microscopy, PrPScwas localized to nerve fibers in each of these structures in the tongue, neuroepithelial taste cells of the taste bud, and, possibly, epithelial cells. This PrPScdistribution was consistent with a spread of HY TME agent along both somatosensory and gustatory cranial nerves to the tongue and suggests subsequent synaptic spread to taste cells and epithelial cells via peripheral synapses. In the nasal cavity, PrPScaccumulation was found in the olfactory and vomeronasal epithelium, where its location was consistent with a distribution in cell bodies and apical dendrites of the sensory neurons. Prion spread to these sites is consistent with transport via the olfactory nerve fibers that descend from the olfactory bulb. Our data suggest that epithelial cells, neuroepithelial taste cells, or olfactory sensory neurons at chemosensory mucosal surfaces, which undergo normal turnover, infected with the prion agent could be shed and play a role in the horizontal transmission of animal prion diseases.
Retrovirus-Induced Oxidative Stress with Neuroimmunodegeneration Is Suppressed by Antioxidant Treatment with a Refined Monosodium α-Luminol (Galavit)
Authors: Jiang Yuhong , Scofield Virginia L. , Yan Mingshan , Qiang Wenan , Liu Na , Reid Amy J. , Lynn William S. , Wong Paul K. Y. 
Published: April 2006

ABSTRACT

Oxidative stress is involved in many human neuroimmunodegenerative diseases, including human immunodeficiency virus disease/AIDS. The retrovirus
ts
1, a mutant of Moloney murine leukemia virus, causes oxidative stress and progressive neuro- and immunopathology in mice infected soon after birth. These pathological changes include spongiform neurodegeneration, astrogliosis, thymic atrophy, and T-cell depletion. Astrocytes and thymocytes are directly infected and killed by
ts
1. Neurons are not infected, but they also die, most likely as an indirect result of local glial infection. Cytopathic effects of
ts
1 infection in cultured astrocytes are associated with accumulation of the viral envelope precursor protein gPr80

env

in the endoplasmic reticulum (ER), which triggers ER stress and oxidative stress. We have reported (i) that activation of the Nrf2 transcription factor and upregulation of antioxidative defenses occurs in astrocytes infected with
ts
1 in vitro and (ii) that some
ts
1-infected astrocytes survive infection by mobilization of these pathways. Here, we show that treatment with a refined monosodium α-luminol (Galavit; GVT) suppresses oxidative stress and Nrf2 activation in cultured
ts
1-infected astrocytes. GVT treatment also inhibits the development of spongiform encephalopathy and gliosis in the central nervous system (CNS) in
ts
1-infected mice, preserves normal cytoarchitecture in the thymus, and delays paralysis, thymic atrophy, wasting, and death. GVT treatment of infected mice reduces
ts
1-induced oxidative stress, cell death, and pathogenesis in both the CNS and thymus of treated animals. These studies suggest that oxidative stress mediates
ts
1-induced neurodegeneration and T-cell loss.
Hexamethylbisacetamide Remodels the Human Immunodeficiency Virus Type 1 (HIV-1) Promoter and Induces Tat-Independent HIV-1 Expression but Blunts Cell Activation
Authors: Klichko Vladimir , Archin Nancy , Kaur Rupinderjeet , Lehrman Ginger , Margolis David 
Published: April 2006

ABSTRACT
Hexamethylbisacetamide (HMBA) induces human immunodeficiency virus type 1 (HIV-1) gene expression in latently infected T-cell and monocytoid cell lines. We find that HMBA activation of viral expression is Tat independent but, like Tat, increases the efficiency of elongation of the HIV-1 promoter (long terminal repeat [LTR]) transcripts. Further, exposure to HMBA induces chromatin remodeling at nucleosome 1 (Nuc-1) near the start site of LTR transcription but does so without increasing histone acetylation or altering histone methylation near Nuc-1. Of note, despite enhanced proviral expression, HMBA suppressed HIV infection ex vivo in primary blood mononuclear cell (PBMC) cultures. Treatment with HMBA did not alter expression of the HIV coreceptors, CCR5 and CXCR4, in PBMCs but down-regulated CD4. Finally, HMBA interferes with cell proliferation and activation; it suppressed expression of Ki67 and CD25 and in PBMCs exposed to mitogen. As HMBA has been tested in oncology trials, its unusual properties make it a useful reagent for future studies of HIV promoter regulation and a novel prototype molecule for therapeutics that abort the latent proviral state of chronic HIV infection.
E2 Proteins from High- and Low-Risk Human Papillomavirus Types Differ in Their Ability To Bind p53 and Induce Apoptotic Cell Death
Authors: Parish Joanna L. , Kowalczyk Anna , Chen Hsin-Tien , Roeder Geraldine E. , Sessions Richard , Buckle Malcolm , Gaston Kevin 
Published: April 2006

ABSTRACT
The E2 proteins from oncogenic (high-risk) human papillomaviruses (HPVs) can induce apoptotic cell death in both HPV-transformed and non-HPV-transformed cells. Here we show that the E2 proteins from HPV type 6 (HPV6) and HPV11, two nononcogenic (low-risk) HPV types, fail to induce apoptosis. Unlike the high-risk HPV16 E2 protein, these low-risk E2 proteins fail to bind p53 and fail to induce p53-dependent transcription activation. Interestingly, neither the ability of p53 to activate transcription nor the ability of p53 to bind DNA, are required for HPV16 E2-induced apoptosis in non-HPV-transformed cells. However, mutations that reduce the binding of the HPV16 E2 protein to p53 inhibit E2-induced apoptosis in non-HPV-transformed cells. In contrast, the interaction between HPV16 E2 and p53 is not required for this E2 protein to induce apoptosis in HPV-transformed cells. Thus, our data suggest that this high-risk HPV E2 protein induces apoptosis via two pathways. One pathway involves the binding of E2 to p53 and can operate in both HPV-transformed and non-HPV-transformed cells. The second pathway requires the binding of E2 to the viral genome and can only operate in HPV-transformed cells.
Human Cytomegalovirus Infection Elicits a Glycoprotein M (gM)/gN-Specific Virus-Neutralizing Antibody Response
Authors: Shimamura Masako , Mach Michael , Britt William J. 
Published: April 2006

ABSTRACT
Human cytomegalovirus (HCMV) is a ubiquitous human pathogen that infects 40 to 90% of adult human populations. HCMV infections are often asymptomatic in healthy individuals but can cause severe organ and life-threatening disease in immunocompromised patients. The antiviral antibody response to HCMV infection is complex and is known to include virus-neutralizing antibody production against surface glycoproteins encoded by HCMV. We have investigated the human antibody response to a complex of HCMV surface glycoproteins composed of glycoprotein M (gM)/gN, the gene products of the UL100 and UL73 open reading frames. Mouse monoclonal antibodies generated against gM/gN have previously been shown to neutralize HCMV infection of human fibroblasts in vitro. To determine whether human antibodies reactive with the gM/gN complex possess virus-neutralizing properties, we isolated human antibodies reactive with gM/gN from pooled human HCMV hyperimmune globulin by affinity purification using recombinant gM/gN. The affinity-purified human anti-gM/gN antibodies reacted specifically by immunofluorescence with HCMV-infected human fibroblasts and with cells transiently expressing gM/gN, but not with cells transfected with plasmids encoding other immunogenic HCMV proteins. The anti-gM/gN antibodies also reacted specifically only with gM/gN in immunoblot assays using lysates of transfected cells expressing specific HCMV proteins. Last, human anti-gM/gN antibodies efficiently neutralized infectious HCMV in vitro with a capacity comparable to that of human anti-gB antibodies. These data indicated that gM/gN can elicit a virus-neutralizing antibody response in humans infected with HCMV and therefore should be considered a potential candidate for inclusion in prophylactic CMV vaccines.
Linkage of Reduced Receptor Affinity and Superinfection to Pathogenesis ofTR1.3 Murine Leukemia Virus
Authors: Murphy Samuel L. , Chung-Landers Maeran , Honczarenko Marek , Gaulton Glen N. 
Published: April 2006

ABSTRACTTR1.3 is a Friend murine leukemia virus (MLV) that induces selective syncytium induction (SI) of brain capillary endothelial cells (BCEC), intracerebral hemorrhage, and death. Syncytium induction by TR1.3 has been mapped to a single tryptophan-to-glycine conversion at position 102 of the envelope glycoprotein (Env102). The mechanism of SI by TR1.3 was examined here in comparison to the non-syncytium-inducing, nonpathogenic MLV FB29, which displays an identical BCEC tropism. Envelope protein expression and stability on both infected cells and viral particles were not statistically different for TR1.3 and FB29. However, affinity measurements derived using purified envelope receptor binding domain (RBD) revealed a reduction of >1 log in theKDof TR1.3 RBD relative to FB29 RBD. Whole-virus particles pseudotyped with TR1.3 Env similarly displayed a markedly reduced binding avidity compared to FB29-pseudotyped viral particles. Lastly, decreased receptor affinity of TR1.3 Env correlated with the failure to block superinfection following acute and chronic infection by TR1.3. These results definitively show that acquisition of a SI phenotype can be directly linked to amino acid changes in retroviral Env that decrease receptor affinity, thereby emphasizing the importance of events downstream of receptor binding in the cell fusion process and pathology.