bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molluscum Contagiosum Virus Interleukin-18 (IL-18) Binding Protein Is Secreted as a Full-Length Form That Binds Cell Surface Glycosaminoglycans through the C-Terminal Tail and a Furin-Cleaved Form with Only the IL-18 Binding Domain
Authors: Xiang Yan , Moss Bernard 
Published: January 2003

ABSTRACT

Some poxviruses and their mammalian hosts encode homologous proteins that bind interleukin-18 (IL-18) with high affinity and inhibit IL-18-mediated immune responses. MC54L, the IL-18 binding protein of the human poxvirus that causes molluscum contagiosum, is unique in having a C-terminal tail of nearly 100 amino acids that is dispensable for IL-18 binding. When recombinant MC54L was expressed and purified via a C-terminal six-histidine tag, a shorter fragment was detected in addition to the full-length protein. This C-terminal fragment resulted from the cleavage of MC54L by cellular furin, as it was greatly diminished when furin was specifically inhibited or when a furin-deficient cell line was used for expression. Furthermore, the N- and C-terminal fragments of MC54L were generated by cleavage of the recombinant protein with furin in vitro. The furin cleavage site was mapped within a 32-amino-acid segment that is C terminal to the IL-18 binding domain. Full-length MC54L, but not the N-terminal IL-18 binding fragment, bound to cells and to purified heparin and other glycosaminoglycans that are commonly found on the cell surface and in the extracellular matrix. MC54L bound to heparin with a nanomolar

K
d

and could simultaneously bind to IL-18. Their different glycosaminoglycan and cell binding properties may allow the long and short forms of MC54L to inactivate IL-18 near the site of infection and at more distal locations, respectively.
Developing Novel Oncolytic Adenoviruses through Bioselection
Authors: Yan Wen , Kitzes Galila , Dormishian Farid , Hawkins Lynda , Sampson-Johannes Adam , Watanabe Josh , Holt Jenny , Lee Vivian , Dubensky Thomas , Fattaey Ali , Hermiston Terry , Balmain Allan , Shen Yuqiao 
Published: January 2003

ABSTRACT
Mutants of human adenovirus 5 (Ad5) with enhanced oncolytic activity were isolated by using a procedure termed bioselection. Two mutants, ONYX-201 and ONYX-203, were plaque purified from a pool of randomly mutagenized Ad5 that was repeatedly passaged in the human colorectal cancer cell line HT29, and they were subsequently characterized. ONYX-201 and ONYX-203 replicated more rapidly in HT29 cells than wild-type Ad5, and they lysed HT29 cells up to 1,000-fold more efficiently. The difference was most profound when cells were infected at a relatively low multiplicity of infection, presumably due to the compounding effects of multiple rounds of infection. This enhanced cytolytic activity was observed not only in HT29 cells but also in many other human cancer cell lines tested. In contrast, the cytotoxicity of the bioselected mutants in a number of normal primary human cells was similar to that of wild-type Ad5, thus enhancing the therapeutic index (cytotoxicity in tumor cells versus that in normal cells) of these oncolytic agents. Both ONYX-201 and -203 contain seven single-base-pair mutations when compared with Ad5, four of which were common between ONYX-201 and -203. The mutation at nucleotide 8350, shared by both mutant viruses, was shown to be essential for the observed phenotypes. This mutation was mapped to the i-leader region of the major late transcription unit, resulting in the truncation of 21 amino acids from the C terminus of the i-leader protein. This work demonstrates that bioselection is a powerful tool for developing novel tumor-selective oncolytic viruses. Other potential applications of this technology are discussed.
E1A Sensitizes Cells to Tumor Necrosis Factor Alpha by Downregulating c-FLIPS
Authors: Perez Denise , White Eileen 
Published: January 2003

ABSTRACTTumor necrosis factor alpha (TNF-α) activates both apoptosis and NF-κB-dependent survival pathways, the former of which requires inhibition of gene expression to be manifested.c-FLIPis a TNF-α-induced gene that inhibits caspase-8 activation during TNF-α signaling. Adenovirus infection and E1A expression sensitize cells to TNF-α by allowing apoptosis in the absence of inhibitors of gene expression, suggesting that it may be disabling a survival signaling pathway. E1A promoted TNF-α-mediated activation of caspase-8, suggesting that sensitivity was occurring at the level of the death-inducing signaling complex. Furthermore, E1A expression downregulated c-FLIPSexpression and prevented its induction by TNF-α. c-FLIPSand viral FLIP expression rescued E1A-mediated sensitization to TNF-α by restoring the resistance of caspase-8 to activation, thereby preventing cell death. E1A inhibited TNF-α-dependent induction of c-FLIPSmRNA and stimulated ubiquitination- and proteasome-dependent degradation of c-FLIPSprotein. Since elevated c-FLIP levels confer resistance to apoptosis and promote tumorigenicity, interference with its induction by NF-κB and stimulation of its destruction in the proteasome may provide novel therapeutic approaches for facilitating the elimination of apoptosis-refractory tumor cells.
Early Induction and Maintenance of Env-Specific T-Helper Cells following Human Immunodeficiency Virus Type 1 Infection
Authors: Malhotra Uma , Holte Sarah , Zhu Tuofu , Delpit Elizabeth , Huntsberry Claire , Sette Alessandro , Shankarappa Raj , Maenza Janine , Corey Lawrence , McElrath M. Juliana 
Published: January 2003

ABSTRACTMounting evidence points to a role for CD4+T-helper (Th) cell activities in controlling human immunodeficiency virus type 1 (HIV-1) infection. To determine the induction and evolution of Th responses following acute infection, we prospectively analyzed Env- and Gag-specific Th responses longitudinally for 92 patients with acute (n= 28) or early (n= 64) HIV-1 infection (median, 55 days postinfection [DPI]). The probability of detecting HIV-1-specific lymphoproliferative responses was remarkably low, and when present, the responses were more likely to be Gag specific than Env specific (16 versus 5%). Env-specific responses were significantly more common in patients presenting at <30 DPI than in those presenting at 30 to 365 DPI (21 versus 0.5%,P= 0.001). By contrast, Gag-specific responses occurred with similar frequencies among subjects presenting at <30 DPI and 30 to 365 DPI (13 versus 17%,P= 0.6). After treatment, and regardless of the duration of infection before therapy, Gag-specific Th responses predominated. Furthermore, some acutely infected subjects lost detectable Env-specific Th proliferative responses, which failed to reemerge upon treatment. Detailed analysis for one such subject revealed Env-specific lymphoproliferation at 11 DPI but no detectable Env-specific lymphoproliferation or ex vivo gamma interferon (IFN-γ) secretion at multiple subsequent time points. Env-specific CD4+T-cell clones from 11 DPI recognized six epitopes in both conserved and variable regions within gp120 and gp41, exhibited major histocompatibility complex-restricted cytotoxicity, and secreted high levels of antiviral cytokines. T-cell receptor clonal transcript analyses and autologous virus sequencing revealed that Th cells induced during acute infection were maintained and there were no Th escape mutations. Subsequent analysis for this subject and six of seven others revealed detectable IFN-γ-secreting cells, but only following in vitro gp160 stimulation. In summary, we conclude that Env-specific Th responses are elicited very early in acute infection and may precede Gag-specific responses. The inability to detect Env-specific Th responses over time and despite antiretroviral therapy may reflect low frequencies and impaired proliferative capacity, and viral escape is not necessary for this to occur.
Herpes Simplex Virus gE/gI Expressed in Epithelial Cells Interferes with Cell-to-Cell Spread
Authors: Collins Wendy J. , Johnson David C. 
Published: January 2003

ABSTRACT
The herpes simplex virus (HSV) glycoprotein heterodimer gE/gI plays an important role in virus cell-to-cell spread in epithelial and neuronal tissues. In an analogous fashion, gE/gI promotes virus spread between certain cell types in culture, e.g., keratinocytes and epithelial cells, cells that are polarized or that form extensive cell junctions. One mechanism by which gE/gI facilitates cell-to-cell spread involves selective sorting of nascent virions to cell junctions, a process that requires the cytoplasmic domain of gE. However, the large extracellular domains of gE/gI also appear to be involved in cell-to-cell spread. Here, we show that coexpression of a truncated form of gE and gI in a human keratinocyte line, HaCaT cells, decreased the spread of HSV between cells. This truncated gE/gI was found extensively at cell junctions. Expression of wild-type gE/gI that accumulates at intracellular sites, in the trans-Golgi network, did not reduce cell-to-cell spread. There was no obvious reduction in production of infectious HSV in cells expressing gE/gI, and virus particles accumulated at cell junctions, not at intracellular sites. Expression of HSV gD, which is known to bind virus receptors, also blocked cell-to-cell spread. Therefore, like gD, gE/gI appears to be able to interact with cellular components of cell junctions, gE/gI receptors which can promote HSV cell-to-cell spread.
PrP Polymorphisms Tightly Control Sheep Prion Replication in Cultured Cells
Authors: Sabuncu Elifsu , Petit Stéphanie , Le Dur Annick , Lan Lai Thanh , Vilotte Jean-Luc , Laude Hubert , Vilette Didier 
Published: January 2003

ABSTRACTPrion diseases are fatal neurodegenerative disorders of animals and humans that are characterized by the conversion of the host-encoded prion protein (PrP) to an abnormal isoform. In several species, including humans, polymorphisms in the gene encoding the PrP protein tightly control susceptibility of individuals toward this disease. In the present study we show that Rov cells expressing an ovine PrP allele (VRQPrP) associated with high susceptibility of sheep to scrapie were very sensitive to sheep prion transmission and replicated the agent to high titers. In contrast, we did not find any evidence of infection when Rov cells expressed similar levels of a PrP variant (ARRPrP) linked to resistance. Our data provide the first direct evidence that natural PrP polymorphisms may affect prion susceptibility by controlling prion replication at the cell level. The study of how PrP polymorphisms influence the genetic control of prion propagation in cultured Rov cells may help elucidate basic mechanisms of prion replication.
Amino Acid Substitutions in VP2 Residues Contacting Sialic Acid in Low-Neurovirulence BeAn Virus Dramatically Reduce Viral Binding and Spread of Infection
Authors: Kumar A. S. Manoj , Kallio Patricia , Luo Ming , Lipton Howard L. 
Published: January 2003

ABSTRACTTheiler's murine encephalomyelitis viruses (TMEV) consist of two groups, the high- and low-neurovirulence groups, based on lethality in intracerebrally inoculated mice. Low-neurovirulence TMEV result in a persistent central nervous system infection in mice, leading to an inflammatory demyelinating pathology and disease. Low- but not high-neurovirulence strains use sialic acid as an attachment factor. The recent resolution of the crystal structure of the low-neurovirulence DA virus in complex with the sialic acid mimic sialyllactose demonstrated that four capsid residues make contact with sialic acid through noncovalent hydrogen bonds. To systematically test the importance of these sialic acid-binding residues in viral entry and infection, we mutated three VP2 puff B amino acids proposed to make contact with sialic acid and analyzed the consequences of each amino acid substitution on viral entry and spread. The fourth residue is in the VP3-VP1 cleavage dipeptide and could not be mutated. Our data suggest that residues Q2161 and G2174 are directly involved in BeAn virus attachment to sialic acid and that substitutions of these two residues result in the loss of or reduced viral binding and hemagglutination and in the inability to spread among BHK-21 cells. In addition, a gain of function-revertant virus was recovered with the Q2161A mutation after prolonged passage in cells.
The Interaction between the Major Capsid Protein and the Smallest Capsid Protein of Human Cytomegalovirus Is Dependent on Two Linear Sequences in the Smallest Capsid Protein
Authors: Lai Lilin , Britt William J. 
Published: January 2003

ABSTRACT
The assembly of human cytomegalovirus (HCMV) with recombinant systems has not been accomplished. An understanding of specific interactions between individual capsid proteins could point to unique characteristics of the assembly process of HCMV capsids. Similar to its herpes simplex virus counterpart, VP26 (UL35), the HCMV smallest capsid protein (SCP; UL48/49) decorates hexons in the mature capsid. In contrast to VP26, the HCMV SCP is essential for virus assembly. In this study we have shown that the major capsid protein (MCP) and the SCP interact in the cytoplasm of transfected cells and can be coprecipitated from insect cells expressing the MCP and the SCP. Using a two-hybrid reporter assay, we demonstrated that two linear sequences within the SCP are sufficient for SCP and MCP interactions.
Expression of the Major Histocompatibility Complex Class I Molecule Mamu-A*01 Is Associated with Control of Simian Immunodeficiency Virus SIVmac239 Replication
Authors: Mothé Bianca R. , Weinfurter Jason , Wang Chenxi , Rehrauer William , Wilson Nancy , Allen Todd M. , Allison David B. , Watkins David I. 
Published: January 2003

ABSTRACTSeveral HLA alleles are associated with attenuated human immunodeficiency virus disease progression. We explored the relationship between the expression of particular major histocompatibility complex (MHC) class I alleles and viremia in simian immunodeficiency virus SIVmac239-infected macaques. Of the common MHC class I alleles, animals that expressed Mamu-A*01 exhibited the best control of viral replication.
Adeno-Associated Virus Type 2-Mediated Gene Transfer: Role of Cellular T-Cell Protein Tyrosine Phosphatase in Transgene Expression in Established Cell Lines In Vitro and Transgenic Mice In Vivo
Authors: Qing Keyun , Li Weiming , Zhong Li , Tan Mengqun , Hansen Jonathan , Weigel-Kelley Kirsten A. , Chen Linyuan , Yoder Mervin C. , Srivastava Arun 
Published: January 2003

ABSTRACT
The use of adeno-associated virus type 2 (AAV) vectors has gained attention as a potentially useful alternative to the more commonly used retrovirus and adenovirus vectors for human gene therapy. However, the transduction efficiency of AAV vectors varies greatly in different cells and tissues in vitro and in vivo. We have documented that a cellular protein that binds the immunosuppressant drug FK506, termed the FK506-binding protein (FKBP52), interacts with the single-stranded D sequence within the AAV inverted terminal repeats, inhibits viral second-strand DNA synthesis, and consequently limits high-efficiency transgene expression (K. Qing, J. Hansen, K. A. Weigel-Kelley, M. Tan, S. Zhou, and A. Srivastava, J. Virol., 75: 8968-8976, 2001). FKBP52 can be phosphorylated at both tyrosine and serine/threonine residues, but only the phosphorylated forms of FKBP52 interact with the D sequence. Furthermore, the tyrosine-phosphorylated FKBP52 inhibits AAV second-strand DNA synthesis by greater than 90%, and the serine/threonine-phosphorylated FKBP52 causes ∼40% inhibition, whereas the dephosphorylated FKBP52 has no effect on AAV second-strand DNA synthesis. In the present study, we have identified that the tyrosine-phosphorylated form of FKBP52 is a substrate for the cellular T-cell protein tyrosine phosphatase (TC-PTP). Deliberate overexpression of the murine wild-type (wt) TC-PTP gene, but not that of a cysteine-to-serine (C-S) mutant, caused tyrosine dephosphorylation of FKBP52, leading to efficient viral second-strand DNA synthesis and resulting in a significant increase in AAV-mediated transduction efficiency in HeLa cells in vitro. Both wt and C-S mutant TC-PTP expression cassettes were also used to generate transgenic mice. Primitive hematopoietic stem/progenitor cells from wt TC-PTP-transgenic mice, but not from C-S mutant TC-PTP-transgenic mice, could be successfully transduced by recombinant AAV vectors. These studies corroborate the fact that tyrosine phosphorylation of the cellular FKBP52 protein strongly influences AAV transduction efficiency, which may have important implications in the optimal use of AAV vectors in human gene therapy.
Targeted Retroviral Infection of Tumor Cells by Receptor Cooperation
Authors: Martin Francisco , Chowdhury Simon , Neil Stuart J. , Chester Kerry A. , Cosset Francois-Loic , Collins Mary K. 
Published: January 2003

ABSTRACT
Retroviruses expressing two different receptor-binding domains linked by proline-rich spacers infect only cells expressing both retroviral receptors (Valsesia-Wittman et al., EMBO J. 6:1214-1223, 1997). Here we apply this receptor cooperation strategy to target human tumor cells by linking single-chain antibodies recognizing tumor antigens via proline-rich spacers to the 4070A murine leukemia virus surface protein.
Identification of a TAP-Independent, Immunoproteasome-Dependent CD8+T-Cell Epitope in Epstein-Barr Virus Latent Membrane Protein 2
Authors: Lautscham Georg , Haigh Tracey , Mayrhofer Sabine , Taylor Graham , Croom-Carter Debbie , Leese Alison , Gadola Stephan , Cerundolo Vincenzo , Rickinson Alan , Blake Neil 
Published: January 2003

ABSTRACTWe have identified an HLA-A2-restricted CD8+T-cell epitope, FLYALALLL, in the Epstein-Barr virus (EBV) latent membrane protein 2 (LMP2), an important target antigen in the context of EBV-associated malignancies. This epitope is TAP independent, like other hydrophobic LMP2-derived epitopes, but uniquely is dependent upon the immunoproteasome for its generation.
Human Immunodeficiency Virus Type 1 Attachment, Coreceptor, and Fusion Inhibitors Are Active against both Direct andtransInfection of Primary Cells
Authors: Ketas Thomas J. , Frank Ines , Klasse Per Johan , Sullivan Brian M. , Gardner Jason P. , Spenlehauer Catherine , Nesin Mirjana , Olson William C. , Moore John P. , Pope Melissa 
Published: January 2003

ABSTRACTInhibitors of human immunodeficiency virus type 1 attachment (CD4-immunoglobulin G subclass 2), CCR5 usage (PRO 140), and fusion (T-20) were tested on diverse primary cell types that represent the major targets both for infection in vivo and for the inhibition oftransinfection of target cells by virus bound to dendritic cells. Although minor cell-type-dependent differences in potency were observed, each inhibitor was active on each cell type andtransinfection was similarly vulnerable to inhibition at each stage of the fusion cascade.
Characterization of Tissue Tropism Determinants of Adeno-Associated Virus Type 1
Authors: Hauck Bernd , Xiao Weidong 
Published: January 2003

ABSTRACT

Muscle is an attractive target for gene delivery because of its mass and because vectors can be delivered in a noninvasive fashion. Adeno-associated virus (AAV) has been shown to be effective for muscle-targeted gene transfer. Recent progress in characterization of AAV serotype 1 (AAV1) and AAV6 demonstrated that these two AAV serotypes are far more efficient in transducing muscle than is the traditionally used AAV2. Since all
cis
elements are identical in these vectors, the potential determinants for their differences in transducing muscle appear to be located within the AAV capsid proteins. In the present study, a series of AAV capsid mutants were generated to identify the major regions affecting AAV transduction efficiency in muscle. Replacement of amino acids 350 to 736 of AAV2 VP1 with the corresponding amino acids from VP1 of AAV1 resulted in a hybrid vector that behaved very similarly to AAV1 in vitro and in vivo in muscle. Characterization of additional mutants carrying smaller regions of the AAV1 VP1 amino acid sequence in the AAV2 capsid protein suggested that amino acids 350 to 430 of VP1 function as a major tissue tropism determinant. Further analysis showed that the heparin binding domain and the major antigenic determinants in the AAV capsid region were not necessary for the efficiency of AAV1 transduction of muscle.
Kinetics of Virus-Specific CD8+-T-Cell Expansion and Trafficking following Central Nervous System Infection
Authors: Marten Norman W. , Stohlman Stephen A. , Zhou Jiehao , Bergmann Cornelia C. 
Published: January 2003

ABSTRACTCD8+T cells control acute infection of the central nervous system (CNS) by neurotropic mouse hepatitis virus but do not suffice to achieve sterile immunity. To determine the lag between T-cell priming and optimal activity within the CNS, the accumulation of virus-specific CD8+T cells in the CNS relative to that in peripheral lymphoid organs was assessed by using gamma interferon-specific ELISPOT assays and class I tetramer staining. Virus-specific CD8+T cells were first detected in the cervical lymph nodes. Expansion in the spleen was delayed and less pronounced but also preceded accumulation in the CNS. The data further suggest peripheral acquisition of cytolytic function, thus enhancing CD8+-T-cell effector function upon cognate antigen recognition in the CNS.
The Latency-Associated Nuclear Antigen of Kaposi's Sarcoma-Associated Herpesvirus Permits Replication of Terminal Repeat-Containing Plasmids
Authors: Grundhoff Adam , Ganem Don 
Published: January 2003

ABSTRACT
The latency-associated nuclear antigen (LANA) of Kaposi's sarcoma-associated herpesvirus can associate with mitotic chromosomes and promote latent episome maintenance and segregation. Here we report that LANA also mediates the replication of plasmid DNAs bearing viral terminal repeats. The predicted secondary structure of LANA's C terminus reveals striking similarity to the known structure of the DNA-binding domain of Epstein-Barr virus EBNA1, despite the absence of primary sequence homology between these proteins, suggesting conservation of the key mechanistic features of latent gammaherpesvirus DNA replication.
Molecular Chaperone GRP78/BiP Interacts with the Large Surface Protein of Hepatitis B Virus In Vitro and In Vivo
Authors: Cho Dae-Yeon , Yang Gi-Hyeok , Ryu Chun Jeih , Hong Hyo Jeong 
Published: January 2003

ABSTRACT
The proper folding and assembly of viral envelope proteins are mediated by host chaperones. In this study, we demonstrated that an endoplasmic reticulum luminal chaperone GRP78/BiP bound specifically to the pre-S1 domain of the L protein in vitro and in vivo where complete viral particles were secreted, suggesting that GRP78/BiP plays an essential role in the proper folding of the L protein and/or assembly of viral envelope proteins.
Molecular Characterization of Bovine Enteric Caliciviruses: a Distinct Third Genogroup of Noroviruses (Norwalk-Like Viruses) Unlikely To Be of Risk to Humans
Authors: Oliver S. L. , Dastjerdi A. M. , Wong S. , El-Attar L. , Gallimore C. , Brown D. W. G. , Green J. , Bridger J. C. 
Published: January 2003

ABSTRACTBovine enteric caliciviruses (BoCVs) have been classified in theNorovirus(Norwalk-like virus) genus of theCaliciviridae,raising questions about zoonotic transmission and an animal reservoir for the human Norwalk-like viruses (NLVs), an important cause of nonbacterial gastroenteritis in humans. We examined the genetic relationship of human NLVs to BoCVs that were identified by using reverse transcription-PCR with primer pairs originally designed to detect human NLVs. Polymerase, capsid, and open reading frame 3 (ORF3) gene sequence analyses of BoCVs that were identified from 1976 to 2000 from throughout the United Kingdom showed that BoCVs formed a distinct third genogroup of closely related viruses distinct from the human genogroup I and II NLVs. Evidence was not obtained to support the concept that BoCVs are circulating in humans and pose a threat to human health.