bluuebunny/crossref_metadata_2025 huggingface dataset:
A Poxvirus Host Range Protein, CP77, Binds to a Cellular Protein, HMG20A, and Regulates Its Dissociation from the Vaccinia Virus Genome in CHO-K1 Cells
Authors: Hsiao Jye-Chian , Chao Chien-Chiang , Young Ming-Jer , Chang Yu-Tai , Cho Er-Chieh , Chang Wen
Published: July 2006

Vaccinia virus does not grow in Chinese hamster ovary (CHO-K1) cells in the absence of a viral host range factor, cowpox protein CP77. In this study, CP77 was fused to the C terminus of green fluorescence protein (GFP-CP77) and a series of nested deletion mutants of GFP-CP77 was constructed for insertion into a vaccinia virus host range mutant, VV-hr, and expressed from a viral early promoter. Deletion mapping analyses demonstrated that the N-terminal 352 amino acids of CP77 were sufficient to support vaccinia virus growth in CHO-K1 cells, whereas the C-terminal residues 353 to 668 were dispensable. In yeast two-hybrid analyses, CP77 bound to a cellular protein, HMG20A, and GST pulldown analyses showed that residues 1 to 234 of CP77 were sufficient for this interaction. After VV-hr virus infection of CHO-K1 cells, HMG20A was translocated from the nucleus to viral factories and bound to the viral genome via the HMG box region. In control VV-hr-infected CHO-K1 cells, binding of HMG20A to the viral genome persisted from 2 to 8 h postinfection (h p.i.); in contrast, when CP77 was expressed, the association of HMG20A with viral genome was transient, with little HMG20A remaining bound at 8 h p.i. This indicates that dissociation of HMG20A from viral factories correlates well with CP77 host range activity in CHO-K1 cells. Finally, in cells expressing a CP77 deletion protein (amino acids 277 to 668) or a ΔANK5 mutant that did not support vaccinia virus growth and did not contain the HMG20A binding site, HMG20A remained bound to viral DNA, demonstrating that the binding of CP77 to HMG20A is essential for its host range function. In summary, our data revealed that a novel cellular protein, HMG20A, the dissociation of which from viral DNA is regulated by CP77, providing the first cellular target regulated by viral host range CP77 protein.
Reduction of Human T-Cell Leukemia Virus Type 1 (HTLV-1) Proviral Loads in Rats Orally Infected with HTLV-1 by Reimmunization with HTLV-1-Infected Cells
Authors: Komori Kazuya , Hasegawa Atsuhiko , Kurihara Kiyoshi , Honda Takayuki , Yokozeki Hiroo , Masuda Takao , Kannagi Mari
Published: July 2006

Human T-cell leukemia virus type 1 (HTLV-1) persistently infects humans, and the proviral loads that persist in vivo vary widely among individuals. Elevation in the proviral load is associated with serious HTLV-1-mediated diseases, such as adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. However, it remains controversial whether HTLV-1-specific T-cell immunity can control HTLV-1 in vivo. We previously reported that orally HTLV-1-infected rats showed insufficient HTLV-1-specific T-cell immunity that coincided with elevated levels of the HTLV-1 proviral load. In the present study, we found that individual HTLV-1 proviral loads established in low-responding hosts could be reduced by the restoration of HTLV-1-specific T-cell responses. Despite the T-cell unresponsiveness for HTLV-1 in orally infected rats, an allogeneic mixed lymphocyte reaction in the splenocytes and a contact hypersensitivity response in the skin of these rats were comparable with those of naive rats. HTLV-1-specific T-cell response in orally HTLV-1-infected rats could be restored by subcutaneous reimmunization with mitomycin C (MMC)-treated syngeneic HTLV-1-transformed cells. The reimmunized rats exhibited lower proviral loads than untreated orally infected rats. We also confirmed that the proviral loads in orally infected rats decreased after reimmunization in the same hosts. Similar T-cell immune conversion could be reproduced in orally HTLV-1-infected rats by subcutaneous inoculation with MMC-treated primary T cells from syngeneic orally HTLV-1-infected rats. The present results indicate that, although HTLV-1-specific T-cell unresponsiveness is an underlying risk factor for the propagation of HTLV-1-infected cells in vivo, the risk may potentially be reduced by reimmunization, for which autologous HTLV-1-infected cells are a candidate immunogen.
C-Terminal Arginine Cluster Is Essential for Receptor Binding of Norovirus Capsid Protein
Authors: Tan Ming , Meller Jarek , Jiang Xi
Published: July 2006

Noroviruses are the major viral pathogens of epidemic acute gastroenteritis affecting people worldwide. They have been found to recognize human histo-blood group antigens as receptors. The P domain of norovirus capsid protein was found to be responsible for binding to viral receptors, and the recombinant P protein forms P dimers and P particles in vitro. In this study, we demonstrate that a highly conserved arginine (R) cluster at the C terminus of the P domain is critical for receptor binding and P particle formation of the P proteins. Deletions of the R cluster abolished these functions. Replacement of the R cluster with histidines (another positively charged amino acid) resulted in low efficiency of receptor binding and P particle formation, while replacement with alanines led to loss of both functions completely. The R cluster also contains a highly conserved trypsin digestion site. A treatment of capsid protein or P domain mutants from both genogroup I (Norwalk virus) and genogroup II (VA387) noroviruses with trypsin resulted in a removal of the R cluster and the S domain, leaving a P polypeptide of 31.3 kDa (Norwalk virus) or 34.3 kDa (VA387), similar to the soluble P protein found in vivo. Our findings imply that the proteolytic process could be a necessary step for norovirus replication in the host.
Newcastle Disease Virus Exerts Oncolysis by both Intrinsic and Extrinsic Caspase-Dependent Pathways of Cell Death
Authors: Elankumaran Subbiah , Rockemann Daniel , Samal Siba K.
Published: July 2006

Newcastle disease virus (NDV), an avian paramyxovirus, is tumor selective and intrinsically oncolytic. Here, we present evidence that genetically modified, recombinant NDV strains are cytotoxic to human tumor cell lines of ecto-, endo-, and mesodermal origin. We show that cytotoxicity against tumor cells is due to multiple caspase-dependent pathways of apoptosis independent of interferon signaling competence. The signaling pathways of NDV-induced, cancer cell-selective apoptosis are not well understood. We demonstrate that NDV triggers apoptosis by activating the mitochondrial/intrinsic pathway and that it acts independently of the death receptor/extrinsic pathway. Caspase-8-methylated SH-SY5Y neuroblastoma cells are as sensitive to NDV as other caspase-8-competent cells. This demonstrates that NDV is likely to act primarily through the mitochondrial death pathway. NDV infection results in the loss of mitochondrial membrane potential and the subsequent release of the mitochondrial protein cytochromec, but the second mitochondrion-derived activator of caspase (Smac/DIABLO) is not released. In addition, we describe early activation of caspase-9 and caspase-3. In contrast, cleavage of caspase-8, which is predominantly activated by the death receptor pathway, is a TNF-related, apoptosis-inducing ligand (TRAIL)-induced late event in NDV-mediated apoptosis of tumor cells. Our data, therefore, indicate that the death signal(s) generated by NDV in tumor cells ultimately converges at the mitochondria and that it acts independently of the death receptor pathway. Our cytotoxicity studies demonstrate that recombinant NDV could be developed as a cancer virotherapy agent, either alone or in combination with therapeutic transgenes. We have also shown that trackable oncolytic NDV could be developed without any reduction in oncolytic efficacy.
Promoter Activation by the Varicella-Zoster Virus Major Transactivator IE62 and the Cellular Transcription Factor USF
Authors: Yang Min , Peng Hua , Hay John , Ruyechan William T.
Published: July 2006

The varicella-zoster virus major transactivator, IE62, can activate expression from homologous and heterologous promoters. High levels of IE62-mediated activation appear to involve synergy with cellular transcription factors. The work presented here focuses on functional interactions of IE62 with the ubiquitously expressed cellular factor USF. We have found that USF can synergize with IE62 to a similar extent on model minimal promoters and the complex native ORF28/29 regulatory element, neither of which contains a consensus IE62 binding site. Using Gal4 fusion constructs, we have found that the activation domain of USF1 is necessary and sufficient for synergistic activation with IE62. We have mapped the regions of USF and IE62 required for direct physical interaction. Deletion of the required region within IE62 does not ablate synergistic activation but does influence its efficiency depending on promoter architecture. Both proteins stabilize/increase binding of TATA binding protein/TFIID to promoter elements. These findings suggest a novel mechanism for the observed synergistic activation which requires neither site-specific IE62 binding to the promoter nor a direct physical interaction with USF.
Identification of a Naturally Occurring Recombinant Genotype 2/6 Hepatitis C Virus
Authors: Noppornpanth Suwanna , Lien Truong Xuan , Poovorawan Yong , Smits Saskia L. , Osterhaus Albert D. M. E. , Haagmans Bart L.
Published: July 2006

Hepatitis C viruses (HCVs) display a high level of sequence diversity and are currently classified into six genotypes and an increasing number of subtypes. Most likely, this heterogeneity is caused by genetic drift; evidence for recombination is scarce. To study the molecular heterogeneity of HCV in Vietnam, we analyzed 58 HCV RNA-positive sera from Vietnamese blood donors by sequence analysis of the CORE and NS5B regions. Phylogenetic analyses revealed the presence of genotype 1 (38%), genotype 2 (10.3%), and genotype 6 viruses (51.7%). All samples showed concordant results except for two (D3 and D54). Sample D54 was a mixed infection of genotype 2i and 6h viruses. Whole-genome analysis and bootscan analysis of sample D3, on the other hand, revealed a recombinant virus with genotype 2i and genotype 6p sequences at the 5′ and 3′ ends, respectively. The crossover point was located between nucleotide positions 3405 to 3464 (numbering according to prototype strain HCV-H, M67463) at the NS2/NS3 junction. The identification of this naturally occurring recombinant virus strengthens the concept that recombination may play a role in HCV epidemiology and evolution. Furthermore, the location of the recombination breakpoint may be relevant for constructing infectious chimeric viruses.
Functional Genomic Analysis of Herpes Simplex Virus Type 1 Counteraction of the Host Innate Response
Authors: Pasieka Tracy Jo , Baas Tracey , Carter Victoria S. , Proll Sean C. , Katze Michael G. , Leib David A.
Published: July 2006

Herpes simplex virus type 1 (HSV-1) mutants lacking the ICP34.5 gene are severely attenuated in mouse models and have a significant growth defect in confluent mouse embryo fibroblasts. Previously, ICP34.5 was demonstrated to have a crucial role in evading the innate immune response to infection by mediating the dephosphorylation of eIF2α, a translation initiation factor phosphorylated by PKR during the antiviral response. To further understand the role of ICP34.5 in evasion of the antiviral response, we used transcriptional profiling to examine host cell gene expression in both wild-type and ICP34.5-null virus-infected mouse embryo fibroblasts over a time course of infection. Our study revealed that cells responded to infection within 3 h through PKR-dependent eIF2α phosphorylation and that the majority of up-regulated genes at 3 h postinfection were involved in the antiviral response. HSV-1 counters this response through early expression of ICP34.5 and dephosphorylation of eIF2α. By 12 h postinfection, the differences between the number and functional classification of genes differentially up- and down-regulated between wild-type and ICP34.5-null virus-infected cells were maximal. Specifically, in wild-type virus-infected cells, the majority of changed genes were involved in metabolic and biosynthetic processes, while in ICP34.5-null virus-infected cells, mostly antiviral genes were up-regulated. Further, ICP34.5-null virus-infected cells produced greater amounts of beta interferon than wild-type virus-infected cells. These results indicate that ICP34.5 expression and function at early times postinfection have a pivotal role in the ability of HSV-1 to gain control of the host cell and maintain an environment for successful viral replication.
The NS5A Protein of Bovine Viral Diarrhea Virus Contains an Essential Zinc-Binding Site Similar to That of the Hepatitis C Virus NS5A Protein
Authors: Tellinghuisen Timothy L. , Paulson Matthew S. , Rice Charles M.
Published: July 2006

The recent demonstration that the NS5A protein of hepatitis C virus (HCV) contains an unconventional zinc-binding site with the format Cx
17
CxCx
20
C and the presence of a similar sequence element in the NS5A proteins of members of the
Pestivirus
genus has led to the hypothesis that the NS5A protein of the pestivirus bovine viral diarrhea virus (BVDV) is a zinc-binding protein. A method for the expression and partial purification of BVDV NS5A was developed, and the partially purified protein was analyzed for zinc content by atomic absorption spectroscopy. BVDV NS5A was found to coordinate a single zinc atom per protein molecule. Mutation of any of the four cysteines of the predicted zinc-binding motif eliminated zinc coordination. Furthermore, analysis of mutations at these cysteine residues in the context of a BVDV replicon system indicated that these residues were absolutely essential for RNA replication. The recently determined crystal structure of the N-terminal zinc-binding domain of the HCV NS5A protein, combined with secondary structure predictions of the region surrounding the mapped BVDV zinc-binding region, indicates that the BVDV zinc-binding motif fits the general template Cx
22
CxCx
24
C and likely comprises a three-stranded antiparallel β-sheet fold. These data highlight the similarities between the
Hepacivirus
and
Pestivirus
NS5A proteins and suggest that both proteins perform a not-yet-defined function in RNA replication that requires coordination of a single zinc atom.
Severe Acute Respiratory Syndrome Coronavirus 7a Accessory Protein Is a Viral Structural Protein
Authors: Huang Cheng , Ito Naoto , Tseng Chien-Te K. , Makino Shinji
Published: July 2006

Severe acute respiratory syndrome coronavirus (SCoV) 7a protein is one of the viral accessory proteins. In expressing cells, 7a protein exhibits a variety of biological activities, including induction of apoptosis, activation of the mitogen-activated protein kinase signaling pathway, inhibition of host protein translation, and suppression of cell growth progression. Analysis of SCoV particles that were purified by either sucrose gradient equilibrium centrifugation or a virus capture assay, in which intact SCoV particles were specifically immunoprecipitated by anti-S protein monoclonal antibody, demonstrated that 7a protein was associated with purified SCoV particles. Coexpression of 7a protein with SCoV S, M, N, and E proteins resulted in production of virus-like particles (VLPs) carrying 7a protein, while 7a protein was not released from cells expressing 7a protein alone. Although interaction between 7a protein and another SCoV accessory protein, 3a, has been reported, 3a protein was dispensable for assembly of 7a protein into VLPs. S protein was not required for the 7a protein incorporation into VLPs, and yet 7a protein interacted with S protein in coexpressing cells. These data established that, in addition to 3a protein, 7a protein was a SCoV accessory protein identified as a SCoV structural protein.
Ribosomal Protein S6 Associates with Alphavirus Nonstructural Protein 2 and Mediates Expression from Alphavirus Messages
Authors: Montgomery Stephanie A. , Berglund Peter , Beard Clayton W. , Johnston Robert E.
Published: July 2006

Although alphaviruses dramatically alter cellular function within hours of infection, interactions between alphaviruses and specific host cellular proteins are poorly understood. Although the alphavirus nonstructural protein 2 (nsP2) is an essential component of the viral replication complex, it also has critical auxiliary functions that determine the outcome of infection in the host. To gain a better understanding of nsP2 function, we sought to identify cellular proteins with which Venezuelan equine encephalitis virus nsP2 interacted. We demonstrate here that nsP2 associates with ribosomal protein S6 (RpS6) and that nsP2 is present in the ribosome-containing fractions of a polysome gradient, suggesting that nsP2 associates with RpS6 in the context of the whole ribosome. This result was noteworthy, since viral replicase proteins have seldom been described in direct association with components of the ribosome. The association of RpS6 with nsP2 was detected throughout the course of infection, and neither the synthesis of the viral structural proteins nor the presence of the other nonstructural proteins was required for RpS6 interaction with nsP2. nsP1 also was associated with RpS6, but other nonstructural proteins were not. RpS6 phosphorylation was dramatically diminished within hours after infection with alphaviruses. Furthermore, a reduction in the level of RpS6 protein expression led to diminished expression from alphavirus subgenomic messages, whereas no dramatic diminution in cellular translation was observed. Taken together, these data suggest that alphaviruses alter the ribosome during infection and that this alteration may contribute to differential translation of host and viral messages.
H7N3 Avian Influenza Virus Found in a South American Wild Duck Is Related to the Chilean 2002 Poultry Outbreak, Contains Genes from Equine and North American Wild Bird Lineages, and Is Adapted to Domestic Turkeys
Authors: Spackman Erica , McCracken Kevin G. , Winker Kevin , Swayne David E.
Published: July 2006

An H7N3 avian influenza virus (AIV) was isolated from a Cinnamon Teal (
Anas cyanoptera
) (A/CinnamonTeal/Bolivia/4537/01) during a survey of wild waterfowl in Bolivia in 2001. The NA and M genes had the greatest identity with North American wild bird isolates, the NS was most closely related to an equine virus, and the remaining genes were most closely related to isolates from an outbreak of H7N3 in commercial poultry in Chile in 2002. The HA protein cleavage site and the results of pathogenesis studies in chickens were consistent with a low-pathogenicity virus, and the infective dose was 10
5
times higher for chickens than turkeys.
A Common Mechanism for Cytoplasmic Dynein-Dependent Microtubule Binding Shared among Adeno-Associated Virus and Adenovirus Serotypes
Authors: Kelkar Samir , De Bishnu P. , Gao Guangping , Wilson James M. , Crystal Ronald G. , Leopold Philip L.
Published: July 2006

During infection, adenovirus-associated virus (AAV) undergoes microtubule-dependent retrograde transport as part of a program of vectorial transport of viral genome to the nucleus. A microtubule binding assay was used to evaluate the hypothesis that cytoplasmic dynein mediates AAV interaction with microtubules. Binding of AAV serotype 2 (AAV2) was enhanced in a nucleotide-dependent manner by the presence of total cellular microtubule-associated proteins (MAPs) but not cytoplasmic dynein-depleted MAPs. Excess AAV2 capsid protein prevented microtubule binding by AAV serotypes 2, 5, and rh.10, as well as adenovirus serotype 5, indicating that similar binding sites are used by these viruses.
Integration of Human Immunodeficiency Virus Type 1 in Untreated Infection Occurs Preferentially within Genes
Authors: Liu Hongbing , Dow Eugene C. , Arora Reetakshi , Kimata Jason T. , Bull Lara M. , Arduino Roberto C. , Rice Andrew P.
Published: July 2006

Previous analyses of human immunodeficiency virus type 1 (HIV-1) integration sites generated in infections in vitro or in patients in whom viral replication was repressed by antiviral therapy have demonstrated a preference for integration within protein-coding genes. We analyzed integration sites in peripheral blood mononuclear cells (PBMCs), spleen, lymph node, and cerebral cortex from patients with untreated HIV-1 infections. The great majority of integration sites in each tissue were within genes. Statistical analyses of the frequencies of integration in genes in PBMCs and lymph tissue demonstrated a strong preference for integration within genes. Although the sample size for brain tissue was too small to demonstrate a clear statistical preference for integration in genes, four of the five integration sites identified in brain were within genes. Taken together, our data indicate that HIV-1 preferentially integrates within genes during untreated infection.
Structural Determinants of Chemokine Binding by an Ectromelia Virus-Encoded Decoy Receptor
Authors: Arnold Phoebe L. , Fremont Daved H.
Published: July 2006

The EVM1 protein encoded byEctromelia virusis a member of a highly conserved family of poxvirus chemokine binding proteins that interfere with host immune surveillance processes. EVM1 is abundantly expressed early during mousepox infection and is able to selectively bind CC chemokines and inhibit their interactions with host receptors. Here, we characterize the interaction between EVM1 and the human and murine chemokines CCL3 (MIP-1α), CCL2 (MCP-1), and CCL5 (RANTES). Each of these CC chemokines binds EVM1 with 1:1 stoichiometry and equilibrium dissociation constants ranging from 29 pM to 20 nM. The interactions are characterized by rapid-association kinetics between acidic EVM1 and generally basic chemokines with half-lives enduring up to 30 min. The 2.6-Å crystal structure of EVM1 reveals a globular β sandwich with a large, sequence-conserved surface patch encircled by acidic residues on one face of the protein. To determine whether this conserved cluster of residues is involved in chemokine engagement, a structure-based mutational analysis of EVM1 was employed. Mapping of the mutational results onto the surface of EVM1 reveals that a cluster of five residues (I173, S171, S134, N136, and Y69) emanating from one β sheet is critical for CCL2 and CCL3 sequestration. Additionally, we find that the extended β2-β4 loop flanking this conserved cluster is also essential for high-affinity, lasting interactions with chemokines. This analysis provides insight into the mechanism of CC-chemokine inhibition employed by the poxvirus family of chemokine decoy receptors.
Genomic Sites of Human Immunodeficiency Virus Type 2 (HIV-2) Integration: Similarities to HIV-1 In Vitro and Possible Differences In Vivo
Authors: MacNeil Adam , Sankalé Jean-Louis , Meloni Seema Thakore , Sarr Abdoulaye Dieng , Mboup Souleymane , Kanki Phyllis
Published: July 2006

Retroviruses have distinct preferences in integration site selection in the host cell genome during in vitro infection, with human immunodeficiency virus type 1 (HIV-1) integration strongly favoring transcriptional units. Additionally, studies with HIV-1 have shown that the genomic site of proviral integration may impact viral replication, with integration in heterochromatin associated with a block in viral transcription. HIV-2 is less pathogenic than HIV-1 and is believed to have a lower replication rate in vivo. Although differences in integration site selection between HIV-2 and HIV-1 could potentially explain the attenuated pathogenicity of HIV-2, no studies have characterized integration site selection by HIV-2. In this study, we mapped 202 HIV-2 integration sites during in vitro infection of peripheral blood mononuclear cells with a primary HIV-2 isolate. In addition, we assayed for in vivo proviral integration within heterochromatin in 21 HIV-1-infected subjects and 23 HIV-2-infected subjects, using an alphoid repeat PCR assay. During in vitro infection, HIV-2 displayed integration site preferences similar to those previously reported for HIV-1. Notably, 82% of HIV-2 integrations mapped to Refseq genes, and integration strongly favored regions of the genome with high gene density and high GC content. Though rare, the proportion of HIV-2 subjects with evidence of proviral integration within heterochromatin in vivo was higher than that of HIV-1-infected subjects. It is therefore possible that integration site selection may play a role in the differences in HIV-1 and HIV-2 in vivo pathogenesis.
Ancient Origin and Molecular Features of the Novel Human T-Lymphotropic Virus Type 3 Revealed by Complete Genome Analysis
Authors: Switzer William M. , Qari Shoukat H. , Wolfe Nathan D. , Burke Donald S. , Folks Thomas M. , Heneine Walid
Published: July 2006

Human T-lymphotropic virus type 3 (HTLV-3) is a new virus recently identified in two primate hunters in Central Africa. Limited sequence analysis shows that HTLV-3 is distinct from HTLV-1 and HTLV-2 but is genetically similar to simian T-lymphotropic virus type 3 (STLV-3). We report here the first complete HTLV-3 sequence obtained by PCR-based genome walking using uncultured peripheral blood lymphocytes from an HTLV-3-infected person. The HTLV-3(2026ND) genome is 8,917 bp long and is genetically equidistant from HTLV-1 and HTLV-2, sharing about 62% identity. Phylogenetic analysis of all gene regions confirms this relationship and shows that HTLV-3 falls within the diversity of STLV-3, suggesting a primate origin. However, HTLV-3(2026ND) is unique, sharing only 87% to 92% sequence identity with STLV-3. SimPlot and phylogenetic analysis did not reveal any evidence of genetic recombination with either HTLV-1, HTLV-2, or STLV-3. Molecular dating estimates that the ancestor of HTLV-3 is as old as HTLV-1 and HTLV-2, with an inferred divergence time of 36,087 to 54,067 years ago. HTLV-3 has a prototypic genomic structure, with all enzymatic, regulatory, and structural proteins preserved. Like STLV-3, HTLV-3 is missing a third 21-bp transcription element found in the long terminal repeats of HTLV-1 and HTLV-2 but instead contains a unique activator protein-1 transcription factor upstream of the 21-bp repeat elements. A PDZ motif, like that in HTLV-1, which is important for cellular signal transduction and transformation, is present in the C terminus of the HTLV-3 Tax protein. A basic leucine zipper region located in the antisense strand of HTLV-1, believed to play a role in viral replication and oncogenesis, was also found in the complementary strand of HTLV-3. The ancient origin of HTLV-3, the broad distribution of STLV-3 in Africa, and the propensity of STLVs to cross species into humans all suggest that HTLV-3 may be prevalent and support the need for expanded surveillance for this virus.
Prevalence and Genetic Diversity of Coronaviruses in Bats from China
Authors: Tang X. C. , Zhang J. X. , Zhang S. Y. , Wang P. , Fan X. H. , Li L. F. , Li G. , Dong B. Q. , Liu W. , Cheung C. L. , Xu K. M. , Song W. J. , Vijaykrishna D. , Poon L. L. M. , Peiris J. S. M. , Smith G. J. D. , Chen H. , Guan Y.
Published: July 2006

Coronaviruses can infect a variety of animals including poultry, livestock, and humans and are currently classified into three groups. The interspecies transmissions of coronaviruses between different hosts form a complex ecosystem of which little is known. The outbreak of severe acute respiratory syndrome (SARS) and the recent identification of new coronaviruses have highlighted the necessity for further investigation of coronavirus ecology, in particular the role of bats and other wild animals. In this study, we sampled bat populations in 15 provinces of China and reveal that approximately 6.5% of the bats, from diverse species distributed throughout the region, harbor coronaviruses. Full genomes of four coronavirues from bats were sequenced and analyzed. Phylogenetic analyses of the spike, envelope, membrane, and nucleoprotein structural proteins and the two conserved replicase domains, putative RNA-dependent RNA polymerase and RNA helicase, revealed that bat coronaviruses cluster in three different groups: group 1, another group that includes all SARS and SARS-like coronaviruses (putative group 4), and an independent bat coronavirus group (putative group 5). Further genetic analyses showed that different species of bats maintain coronaviruses from different groups and that a single bat species from different geographic locations supports similar coronaviruses. Thus, the findings of this study suggest that bats may play an integral role in the ecology and evolution of coronaviruses.
Mapping the Domains of CD134 as a Functional Receptor for Feline Immunodeficiency Virus
Authors: Willett Brian J. , McMonagle Elizabeth L. , Bonci Francesca , Pistello Mauro , Hosie Margaret J.
Published: July 2006

The feline homologue of CD134 is the primary binding receptor for feline immunodeficiency virus (FIV), targeting the virus preferentially to activated CD4
+
helper T cells. However, strains of FIV differ in utilization of CD134; the prototypic strain PPR requires a minimal determinant in the first cysteine-rich domain (CRD1) of feline CD134 to confer near-optimal receptor function, while strains such as GL8 require additional determinants in the CD134 CRD2. We map this determinant to a loop in CRD2 governing the interaction between the receptor and its ligand; the amino acid substitutions S78N-S79Y-K80E restored full viral receptor activity to the CDR2 of human CD134 in the context of feline CD134, with tyrosine-79 appearing to be the critical residue for restoration of receptor function.
Cytomegalovirus Encodes a Positive Regulator of Antigen Presentation
Authors: Holtappels Rafaela , Gillert-Marien Dorothea , Thomas Doris , Podlech Jürgen , Deegen Petra , Herter Sylvia , Oehrlein-Karpi Silke A. , Strand Dennis , Wagner Markus , Reddehase Matthias J.
Published: July 2006

Murine cytomegalovirus encodes three regulators of antigen presentation to antiviral CD8 T cells. According to current paradigms, all three regulators are committed to the inhibition of the presentation of antigenic peptides. Whereas m152/gp40 catalyzes the retention of peptide-loaded major histocompatibility complex (MHC) class I molecules in a
cis
-Golgi compartment, m06/gp48 binds stably to class I molecules and directs them into the cellular cargo-sorting pathway of lysosomal degradation. Regulator m04/gp34 also binds stably to class I molecules, but unlike m152 and m06, it does not downmodulate MHC class I cell surface expression. It has entered the literature as a direct inhibitor of T-cell recognition of the MHC-peptide complex at the cell surface. In this work, we have studied the presentation of antigenic viral peptides in cells infected with a comprehensive set of mutant viruses expressing the three regulators separately as well as in all possible combinations. The results redefine m04 as a positive regulator dedicated to the facilitation of antigen presentation. When expressed alone, it did not inhibit T-cell recognition, and when expressed in the presence of m152, it restored antigen presentation by antagonizing the inhibitory function of m152. Its intrinsic positive function, however, was antagonized and even slightly overcompensated for by the negative regulator m06. In an adoptive cell transfer model, the opposing forces of the three regulators were found to govern immune surveillance in the infected host. While negative regulators, also known as immunoevasins, are common, the existence of a positive regulator is without precedent and indicates an intriguing genetic potential of this virus to influence antigen presentation.
Human Cytomegalovirus Subverts the Functions of Monocytes, Impairing Chemokine-Mediated Migration and Leukocyte Recruitment
Authors: Frascaroli Giada , Varani Stefania , Moepps Barbara , Sinzger Christian , Landini Maria Paola , Mertens Thomas
Published: July 2006

Despite their role in innate and adaptive immunity, during human cytomegalovirus (HCMV) infection, monocytes are considered to be an important target of infection, a site of latency, and vehicles for virus dissemination. Since chemokine receptors play crucial roles in monocyte activation and trafficking, we investigated the effects of HCMV on their expression and function. By using endotheliotropic strains of HCMV, we obtained high rates (roughly 50%) of in vitro-infected monocytes but only restricted viral gene expression. At 24 h after infection, while the chemokine receptors CX3CR and CCR7 were unaffected, CCR1, CCR2, CCR5, and CXCR4 were downmodulated on the cell surface and retained intracellularly. Structural components of the viral particles, but not viral gene expression or soluble factors released from infected cells, accounted for the changed localization of the receptor molecules and for the block of chemokine-driven migration. HCMV-infected monocytes indeed became unresponsive to inflammatory and homeostatic chemokines, although the basal cell motility and responsiveness toN-formyl-Met-Leu-Phe were unaffected or slightly increased. The production of inflammatory mediators responsible for the recruitment of other immune cells was also hampered by HCMV. Whereas endothelial and fibroblast cells infected by HCMV efficiently recruited leukocytes, infected monocytes were unable to recruit lymphocytes, monocytes, and neutrophils. Our data further highlight the complex level of interference exerted by HCMV on the host immune system.
Cyclosporine Increases Human Immunodeficiency Virus Type 1 Vector Transduction of Primary Mouse Cells
Authors: Noser Josh A. , Towers Greg J. , Sakuma Ryuta , Dumont Jean-Maurice , Collins Mary K. L. , Ikeda Yasuhiro
Published: July 2006

Murine primary cells are poorly permissive to human immunodeficiency virus type 1 (HIV-1) vector infection. Retroviral infectivity is influenced by dominant inhibitors such as TRIM5α. Sensitivity to TRIM5α is altered by interactions between cyclophilin A and the HIV-1 capsid. Here we demonstrate that competitive inhibitors of cyclophilins, cyclosporine or the related Debio-025, stimulate HIV-1 vector transduction of primary murine cells, including bone marrow and macrophages, up to 20-fold. Unexpectedly, the infectivity of an HIV-1 mutant or a simian lentivirus that does not recruit cyclophilin A is also stimulated by these drugs. We propose that cyclosporine and related compounds will be useful tools for experimental infection of murine primary cells. It is possible that HIV-1 infection of murine cells is inhibited by dominant factors related to immunophilins.
Influenza Virus Receptor Specificity and Cell Tropism in Mouse and Human Airway Epithelial Cells
Authors: Ibricevic Aida , Pekosz Andrew , Walter Michael J. , Newby Celeste , Battaile John T. , Brown Earl G. , Holtzman Michael J. , Brody Steven L.
Published: July 2006

Recent human infections caused by the highly pathogenic avian influenza virus H5N1 strains emphasize an urgent need for assessment of factors that allow viral transmission, replication, and intra-airway spread. Important determinants for virus infection are epithelial cell receptors identified as glycans terminated by an α2,3-linked sialic acid (SA) that preferentially bind avian strains and glycans terminated by an α2,6-linked SA that bind human strains. The mouse is often used as a model for study of influenza viruses, including recent avian strains; however, the selectivity for infection of specific respiratory cell populations is not well described, and any relationship between receptors in the mouse and human lungs is incompletely understood. Here, using in vitro human and mouse airway epithelial cell models and in vivo mouse infection, we found that the α2,3-linked SA receptor was expressed in ciliated airway and type II alveolar epithelial cells and was targeted for cell-specific infection in both species. The α2,6-linked SA receptor was not expressed in the mouse, a factor that may contribute to the inability of some human strains to efficiently infect the mouse lung. In human airway epithelial cells, α2,6-linked SA was expressed and functional in both ciliated and goblet cells, providing expanded cellular tropism. Differences in receptor and cell-specific expression in these species suggest that differentiated human airway epithelial cell cultures may be superior for evaluation of some human strains, while the mouse can provide a model for studying avian strains that preferentially bind only the α2,3-linked SA receptor.
Rinderpest Virus Blocks Type I and Type II Interferon Action: Role of Structural and Nonstructural Proteins
Authors: Nanda Sambit K. , Baron Michael D.
Published: July 2006

Rinderpest virus
(RPV) is a paramyxovirus closely related to the human pathogen
Measles virus
. It causes severe disease in cattle, buffalo, and some wild animals; although it can infect humans, it does not cause disease. Here, we demonstrate that RPV blocks the action of both type I (α) and type II (γ) interferons (IFNs) by blocking the phosphorylation and nuclear translocation of STAT1 and STAT2 and that this block is not related to species specificity. In addition, both wild-type virulent and vaccine strains of the virus blocked IFN action. Unlike the case with some other paramyxoviruses, neither STAT1 nor STAT2 is degraded upon virus infection. STAT1 is bound by both the viral structural protein P, and thereby recruited to concentrations of viral protein in the cell, and the nonstructural protein V. Although both P and V proteins bind to STAT1 and can block IFN action when expressed in transfected cells, the IFN antagonist activity of the P protein is weaker than that of the V protein. The viral C protein also seems to weakly block IFN-induced activation of STAT1 in transfection experiments. However, studies with knockout viruses showed that the viral V protein appears to be the dominant inhibitor of IFN signaling in the context of virus infection, since prevention of viral V expression restored the IFN sensitivity of infected cells. Although a change in the distribution pattern of STAT2 was observed in virus-infected cells, STAT2 was not bound by any viral protein.
Apoptin Nucleocytoplasmic Shuttling Is Required for Cell Type-Specific Localization, Apoptosis, and Recruitment of the Anaphase-Promoting Complex/Cyclosome to PML Bodies
Authors: Heilman Destin W. , Teodoro Jose G. , Green Michael R.
Published: July 2006

The chicken anemia virus protein Apoptin selectively induces apoptosis in transformed cells while leaving normal cells intact. This selectivity is thought to be largely due to cell type-specific localization: Apoptin is cytoplasmic in primary cells and nuclear in transformed cells. The basis of Apoptin cell type-specific localization and activity remains to be determined. Here we show that Apoptin is a nucleocytoplasmic shuttling protein whose localization is mediated by an N-terminal nuclear export signal (NES) and a C-terminal nuclear localization signal (NLS). Both signals are required for cell type-specific localization, since Apoptin fragments containing either the NES or the NLS fail to differentially localize in transformed and primary cells. Significantly, cell type-specific localization can be conferred in
trans
by coexpression of the two separate fragments, which interact through an Apoptin multimerization domain. We have previously shown that Apoptin interacts with the APC1 subunit of the anaphase-promoting complex/cyclosome (APC/C), resulting in G
2
/M cell cycle arrest and apoptosis in transformed cells. We found that the nucleocytoplasmic shuttling activity is critical for efficient APC1 association and induction of apoptosis in transformed cells. Interestingly, both Apoptin multimerization and APC1 interaction are mediated by domains that overlap with the NES and NLS sequences, respectively. Apoptin expression in transformed cells induces the formation of PML nuclear bodies and recruits APC/C to these subnuclear structures. Our results reveal a mechanism for the selective killing of transformed cells by Apoptin.
New N4-Hydroxycytidine Derivatives: Synthesis and Antiviral Activity
Authors: Ivanov Maksim A. , Antonova Elena V. , Maksimov Aleksey V. , Pigusova Lyudmila K. , Belanov Evgenii F. , Aleksandrova Lyudmila A.
Published: July 2006

Two series of N4-hydroxycytidine derivatives were synthesized and evaluated as potential antipox virus agents. Acylation of N4-hydroxycytidine (1) with an excess of acyl chloride or imidazolide yielded the corresponding N4-(acyloxy) derivatives. 5'-Phosphonates of 1 were prepared by the reaction of cytidine 5'-phosphonates with aqueous hydroxylamine hydrochloride (pH 6.0). Nucleoside 1 and its N4-(acyloxy) derivatives inhibited replication of pox viruses in cell cultures, N4-(pivaloyloxy)- and N4-(benzoyloxy)cytidines being the most potent. The synthesized 5'-phosphonates were more cytotoxic than the parent nucleoside.
Pax-5 immunoexpression in various types of benign and malignant tumours: a high-throughput tissue microarray analysis
Authors: Mhawech-Fauceglia Paulette , Saxena Rhakee , Zhang Shaozeng , Terracciano Luigi , Sauter Guido , Chadhuri Arundhuti , Herrmann Francois R , Penetrante Remedios
Published: July 2006

Background:Pax-5 belongs to thePaxgene family transcription factors that play an important role in organogenesis and in B cell ontogeny. It is expressed in B cell non-Hodgkin’s lymphoma (B-NHL), Hodgkin’s lymphoma (HL) and neuroendocrine carcinomas. However, its expression in other tumour types is not fully explored.

Aims and methods:To determine Pax-5 expression in other tumour types, immunohistochemistry was performed on 3758 benign and malignant tumours using multiple tumour microarrays, as well as on whole sections.

Results:Pax-5 was expressed in 108/118 (91.5%) B-NHLs, in 60/70 (85.7%) HLs and in 0/7 T cell lymphomas. In addition, Pax-5 was seen in 24/34 (70.6%) Merkel cell carcinomas, 42/53 (79.2%) small cell carcinomas, 1/164 (0.6%) breast carcinomas, 2/204 (1%) endometrial adenocarcinomas and 1/452 (0.2%) urothelial carcinoma of the bladder.

Conclusion:Despite its expression in a small subset of malignancies of epithelial origin, Pax-5 is still a good and reliable immunomarker in diagnosing B-NHL, HL and neuroendocrine carcinomas.
CHIRAL AND UA(1) PHASE TRANSITIONS IN π0, η AND η′ MESONS
Authors: SEN SURAJIT , BAGCHI B.
Published: July 2006

We have generalized the Pisarsky–Wilczek model of studying the UA(1) phase transition in π0, η and η′ system by incorporating the chiral phase transition. The mass-squared matrix of the neutral pseudoscalar mesons is revisited explicitly from the chiral effective action which necessitates the mixing among the unmixed states to get the physical states. The derivation of the mass spectra of the neutral pseudoscalar mesons shows that apart from their masses, the mixing angles also become temperature dependent. Based on the dilute instanton gas approximation we show that, the UA(1) phase transition along with the chiral phase transition plays an important role in the process of hadronization of the quark–gluon plasma with the quarks of three flavors.
OBSERVABILITY OF THE SZ EFFECT MAP'S NON-GAUSSIAN FEATURES
Authors: CAO LIANG , CHU YAO-QUAN
Published: July 2006

We study the high order cross-correlation between the WMAP map and 2MASS galaxy distribution in order to detect the non-Gaussian behaviors of the SZ effect on the CMB fluctuations induced by 2MASS. The 2MASS distribution is significantly non-Gaussian, which is characterized by the fourth order correlations in DWT representation. With an unbiased mock sample we show, if the CMB data contains the information of 2MASS hot gas caused SZ effect, the non-Gaussianity of the cross-correlations between the CMB and 2MASS is observable with the fourth order statistics on scales of clusters. We compared this result with the cross-correlation between the observed WMAP data and 2MASS, finding similar non-Gaussianity to the mock SZ samples. It strongly evidences the existence and observability of the SZ signal in the WMAP data caused by the 2MASS clusters.
THE EINSTEIN–HILBERT LAGRANGIAN DENSITY IN A TWO-DIMENSIONAL SPACETIME IS AN EXACT DIFFERENTIAL
Authors: DA ROCHA ROLDÃO , RODRIGUES WALDYR A.
Published: July 2006

Recently Kiriushcheva and Kuzmin1 claimed to have shown that the Einstein–Hilbert Lagrangian density cannot be written in any coordinate gauge as an exact differential in a two-dimensional spacetime. Since this is contrary to other statements on the subject found in the literature, as e.g., by Deser,2 Deser and Jackiw,3 Jackiw4 and Grumiller, Kummer and Vassilevich5 it is necessary to decide who has reason. This is done in this paper in a very simply way using the Clifford bundle formalism.
ADDING OPEN STRING MODES TO THE GAUGE/GRAVITY CORRESPONDENCE
Authors: RAMALLO ALFONSO V.
Published: July 2006

We review some recent results on the extension of the gauge/gravity correspondence to include matter in the fundamental representation by adding D-branes to the supergravity backgrounds. Working in the quenched approximation, in which the D-branes are considered as probes, we show how to compute the meson spectrum for a general case of brane intersections which are dual to supersymmetric gauge theories with matter supermultiplets in several dimensions.
CHARGED AXIALLY SYMMETRIC SOLUTION, ENERGY AND ANGULAR MOMENTUM IN TETRAD THEORY OF GRAVITATION
Authors: NASHED GAMAL G. L.
Published: July 2006

Charged axially symmetric solution of the coupled gravitational and electromagnetic fields in the tetrad theory of gravitation is derived. The metric associated with this solution is an axially symmetric metric which is characterized by three parameters "the gravitational mass M, the charge parameter Q and the rotation parameter a." The parallel vector fields and the electromagnetic vector potential are axially symmetric. We calculate the total exterior energy. The energy–momentum complex given by Møller in the framework of the Weitzenböck geometry "characterized by vanishing the curvature tensor constructed from the connection of this geometry" has been used. This energy–momentum complex is considered as a better definition for calculation of energy and momentum than those of general relativity theory. The energy contained in a sphere is found to be consistent with pervious results which is shared by its interior and exterior. Switching off the charge parameter, one finds that no energy is shared by the exterior of the charged axially symmetric solution. The components of the momentum density are also calculated and used to evaluate the angular momentum distribution. We found no angular momentum contributes to the exterior of the charged axially symmetric solution if zero charge parameter is used.
TIMELIKE AND SPACELIKE MATTER INHERITANCE VECTORS IN SPECIFIC FORMS OF ENERGY–MOMENTUM TENSOR
Authors: SHARIF M. , SHEIKH UMBER
Published: July 2006

This paper is devoted to the investigation of the consequences of timelike and spacelike matter inheritance vectors in specific forms of energy–momentum tensor, i.e. for string cosmology (string cloud and string fluid) and perfect fluid. Necessary and sufficient conditions are developed for a space–time with string cosmology and perfect fluid to admit a timelike matter inheritance vector, parallel to ua and spacelike matter inheritance vector, parallel to xa. We compare the outcome with the conditions of conformal Killing vectors. This comparison provides us the conditions for the existence of matter inheritance vector when it is also a conformal Killing vector. Finally, we discuss these results for the existence of matter inheritance vector in the special cases of the above mentioned space–times.