bluuebunny/crossref_metadata_2025_split huggingface dataset:
Opening of Size-Selective Pores in Endosomes during Human Rhinovirus Serotype 2 In Vivo Uncoating Monitored by Single-Organelle Flow Analysis
Authors: Brabec Marianne , Schober Daniela , Wagner Ernst , Bayer Nora , Murphy Robert F. , Blaas Dieter , Fuchs Renate 
Published: December 2004

ABSTRACT
The effect of virus uncoating on endosome integrity during the early steps in viral infection was investigated. Using fluid-phase uptake of 10- and 70-kDa dextrans labeled with a pH-dependent fluorophore (fluorescein isothiocyanate [FITC]) and a pH-independent fluorophore (cyanine 5 [Cy5]), we determined the pHs of labeled compartments in intact HeLa cells by fluorescence-activated cell sorting analysis. Subsequently, the number and pH of fluorescent endosomes in cell homogenates were determined by single-organelle flow analysis. Cointernalization of adenovirus and 70-kDa FITC- and Cy5-labeled dextran (FITC/Cy5-dextran) led to virus-induced endosomal rupture, resulting in the release of the marker from the low-pH environment into the neutral cytosol. Consequently, in the presence of adenovirus, the number of fluorescent endosomes was reduced by 40% compared to that in the control. When human rhinovirus serotype 2 (HRV2) was cointernalized with 10-and 70-kDa FITC/Cy5-dextrans, the 10-kDa dextran was released, whereas the 70-kDa dextran remained within the endosomes, which also maintained their low pH. These data demonstrate that pores are generated in the membrane during HRV2 uncoating and RNA penetration into the cytosol without gross damage of the endosomes; 10-kDa dextran can access the cytosol through these pores. Whereas rhinovirus-mediated pore formation was prevented by the vacuolar ATPase inhibitor bafilomycin A1, adenovirus-mediated endosomal rupture also occurred in the presence of the inhibitor. This finding is in keeping with the low-pH requirement of HRV2 infection; for adenovirus, no pH dependence for endosomal escape was found with this drug.
Natural History of a Recurrent Feline Coronavirus Infection and the Role of Cellular Immunity in Survival and Disease
Authors: de Groot-Mijnes Jolanda D. F. , van Dun Jessica M. , van der Most Robbert G. , de Groot Raoul J. 
Published: December 2004

ABSTRACTWe describe the natural history, viral dynamics, and immunobiology of feline infectious peritonitis (FIP), a highly lethal coronavirus infection. A severe recurrent infection developed, typified by viral persistence and acute lymphopenia, with waves of enhanced viral replication coinciding with fever, weight loss, and depletion of CD4+and CD8+T cells. Our combined observations suggest a model for FIP pathogenesis in which virus-induced T-cell depletion and the antiviral T-cell response are opposing forces and in which the efficacy of early T-cell responses critically determines the outcome of the infection. Rising amounts of viral RNA in the blood, consistently seen in animals with end-stage FIP, indicate that progression to fatal disease is the direct consequence of a loss of immune control, resulting in unchecked viral replication. The pathogenic phenomena described here likely bear relevance to other severe coronavirus infections, in particular severe acute respiratory syndrome, for which multiphasic disease progression and acute T-cell lymphopenia have also been reported. Experimental FIP presents a relevant, safe, and well-defined model to study coronavirus-mediated immunosuppression and should provide an attractive and convenient system for in vivo testing of anticoronaviral drugs.
Diabetes Acceleration or Prevention by a Coxsackievirus B4 Infection: Critical Requirements for both Interleukin-4 and Gamma Interferon
Authors: Serreze David V. , Wasserfall Clive , Ottendorfer Eric W. , Stalvey Michael , Pierce Melissa A. , Gauntt Charles , O'Donnell Brian , Flanagan James B. , Campbell-Thompson Martha , Ellis Tamir M. , Atkinson Mark A. 
Published: December 2004

ABSTRACTType 1 diabetes acceleration in nonobese diabetic (NOD) mice through coxsackievirus B4 (CVB4) infection requires a preexisting critical mass of autoreactive T cells in pancreatic islets, and in the absence of this insulitic threshold, CVB4 infection leads to long-term disease protection. To understand this acceleration and protection process, we challenged 8- and 12-week-old NOD mice containing a disruption in interleukin-4 (IL-4) or gamma interferon (IFN-γ) genes (NOD IL-4−/−and NOD IFN-γ−/−, respectively) with a diabetogenic, pancreatropic Edwards strain of CVB4. The elimination of IL-4 did not alter the rate of insulitis or diabetes development in NOD mice, while the elimination of IFN-γ delayed these events several weeks. CVB4 infection in 8-week-old mice only significantly accelerated the onset of diabetes in a subset of standard, but not IL-4- or IFN-γ-deficient, NOD mice. Long-term diabetes protection was established in standard NOD mice as well as in the NOD IFN-γ−/−mice that did not rapidly develop disease following CVB4 infection at 8 weeks of age. When mice were infected at 12 weeks of age, the onset of diabetes was accelerated in NOD IL-4−/−mice, while neither acceleration nor long-term protection was elicited in NOD IFN-γ−/−mice. No differences were observed in the kinetics of CVB4 clearance in pancreases from NOD, NOD IL-4−/−, and NOD IFN-γ−/−mice. Collectively, these results suggest that at the insulitis threshold at which CVB4 infection can first accelerate the onset of diabetes in NOD mice, IL-4 as well as IFN-γ contributes to this pathogenic process. The protective mechanism against diabetes elicited in NOD mice infected with CVB4 prior to the development of a critical threshold level of insulitis requires neither IL-4 nor IFN-γ.
Genomic Variation of the Fibropapilloma-Associated Marine Turtle Herpesvirus across Seven Geographic Areas and Three Host Species
Authors: Greenblatt Rebecca J. , Quackenbush Sandra L. , Casey Rufina N. , Rovnak Joel , Balazs George H. , Work Thierry M. , Casey James W. , Sutton Claudia A. 
Published: December 2004

ABSTRACT

Fibropapillomatosis (FP) of marine turtles is an emerging neoplastic disease associated with infection by a novel turtle herpesvirus, fibropapilloma-associated turtle herpesvirus (FPTHV). This report presents 23 kb of the genome of an FPTHV infecting a Hawaiian green turtle (
Chelonia mydas
). By sequence homology, the open reading frames in this contig correspond to herpes simplex virus genes U
L
23 through U
L
36. The order, orientation, and homology of these putative genes indicate that FPTHV is a member of the
Alphaherpesvirinae
. The U
L
27-, U
L
30-, and U
L
34-homologous open reading frames from FPTHVs infecting nine FP-affected marine turtles from seven geographic areas and three turtle species (
C. mydas
,
Caretta caretta
, and
Lepidochelys olivacea
) were compared. A high degree of nucleotide sequence conservation was found among these virus variants. However, geographic variations were also found: the FPTHVs examined here form four groups, corresponding to the Atlantic Ocean, West pacific, mid-Pacific, and east Pacific. Our results indicate that FPTHV was established in marine turtle populations prior to the emergence of FP as it is currently known.
Antigenicity and Immunogenicity of a Synthetic Human Immunodeficiency Virus Type 1 Group M Consensus Envelope Glycoprotein
Authors: Gao Feng , Weaver Eric A. , Lu Zhongjing , Li Yingying , Liao Hua-Xin , Ma Benjiang , Alam S. Munir , Scearce Richard M. , Sutherland Laura L. , Yu Jae-Sung , Decker Julie M. , Shaw George M. , Montefiori David C. , Korber Bette T. , Hahn Beatrice H. , Haynes Barton F. 
Published: December 2004

ABSTRACTGenetic variation of human immunodeficiency virus (HIV-1) represents a major obstacle for AIDS vaccine development. To decrease the genetic distances between candidate immunogens and field virus strains, we have designed and synthesized an artificial group M consensusenvgene (CON6 gene) to be equidistant from contemporary HIV-1 subtypes and recombinants. This novel envelope gene expresses a glycoprotein that binds soluble CD4, utilizes CCR5 but not CXCR4 as a coreceptor, and mediates HIV-1 entry. Key linear, conformational, and glycan-dependent monoclonal antibody epitopes are preserved in CON6, and the glycoprotein is recognized equally well by sera from individuals infected with different HIV-1 subtypes. When used as a DNA vaccine followed by a recombinant vaccinia virus boost in BALB/c mice, CON6envgp120 and gp140CF elicited gamma interferon-producing T-cell responses that recognized epitopes within overlapping peptide pools from three HIV-1 Env proteins, CON6, MN (subtype B), and Chn19 (subtype C). Sera from guinea pigs immunized with recombinant CON6 Env gp120 and gp140CF glycoproteins weakly neutralized selected HIV-1 primary isolates. Thus, the computer-generated “consensus”envgenes are capable of expressing envelope glycoproteins that retain the structural, functional, and immunogenic properties of wild-type HIV-1 envelopes.
A Surface Loop of the Potato Leafroll Virus Coat Protein Is Involved in Virion Assembly, Systemic Movement, and Aphid Transmission
Authors: Lee Lawrence , Kaplan Igor B. , Ripoll Daniel R. , Liang Delin , Palukaitis Peter , Gray Stewart M. 
Published: December 2004

ABSTRACTTwo acidic domains of thePotato leafroll virus(PLRV) coat protein, separated by 55 amino acids and predicted to be adjacent surface features on the virion, were the focus of a mutational analysis. Eleven site-directed mutants were generated from a cloned infectious cDNA of PLRV and delivered to plants byAgrobacterium-mediated mechanical inoculation. Alanine substitutions of any of the three amino acids of the sequence EWH (amino acids 170 to 172) or of D177 disrupted the ability of the coat protein to assemble stable particles and the ability of the viral RNA to move systemically in four host plant species. Alanine substitution of E109, D173, or E176 reduced the accumulation of virus in agrobacterium-infiltrated tissues, the efficiency of systemic infection, and the efficiency of aphid transmission relative to wild-type virus, but the mutations did not affect virion stability. A structural model of the PLRV capsid predicted that the amino acids critical for virion assembly were located within a depression at the center of a coat protein trimer. The other amino acids that affected plant infection and/or aphid transmission were predicted to be located around the perimeter of the depression. PLRV virions play key roles in phloem-limited virus movement in plant hosts as well as in transport and persistence in the aphid vectors. These results identified amino acid residues in a surface-oriented loop of the coat protein that are critical for virus assembly and stability, systemic infection of plants, and movement of virus through aphid vectors.
Distinct Subsets of Primary Effusion Lymphoma Can Be Identified Based on Their Cellular Gene Expression Profile and Viral Association
Authors: Fan Wen , Bubman Darya , Chadburn Amy , Harrington William J. , Cesarman Ethel , Knowles Daniel M. 
Published: December 2004

ABSTRACT
Primary effusion lymphomas (PELs) are specifically associated with Kaposi's sarcoma-associated herpesvirus (KSHV) infection and most frequently occur in human immunodeficiency virus (HIV)-positive individuals as lymphomatous effusions in the serous cavities without a detectable solid tumor mass. Most PELs have concomitant Epstein-Barr virus (EBV) infection, suggesting that EBV is an important pathogenetic cofactor, although other as yet unidentified cofactors, such as cellular genetic alterations, are also likely to play a role. Lymphomatous effusions that lack KSHV also occur; these are frequently EBV associated in the setting of HIV infection. Here we used gene expression profile analysis to determine the viral impact on cellular gene expression and the pathogenesis of these lymphomatous effusions. Our results show that many genes, including cell cycle and signal transduction regulators, are differentially expressed between KSHV-positive PELs and KSHV-negative lymphomatous effusions and also between KSHV-positive, EBV-positive and KSHV-positive, EBV-negative PELs. Our results confirm that KSHV plays an important role in the pathogenesis of PELs, as its presence selects for a very distinct cellular gene expression category and a clearly different lymphoma type. Within the KSHV-positive PELs, the effect of EBV is more subtle but nevertheless clear.
Anti-Human Immunodeficiency Virus Type 1 (HIV-1) Antibodies 2F5 and 4E10 Require Surprisingly Few Crucial Residues in the Membrane-Proximal External Region of Glycoprotein gp41 To Neutralize HIV-1
Authors: Zwick Michael B. , Jensen Richard , Church Sarah , Wang Meng , Stiegler Gabriela , Kunert Renate , Katinger Hermann , Burton Dennis R. 
Published: December 2004

ABSTRACT

The conserved membrane-proximal external region (MPER) of human immunodeficiency virus type 1 (HIV-1) gp41 is a target of two broadly neutralizing human monoclonal antibodies, 2F5 and 4E10, and is an important lead for vaccine design. However, immunogens that bear MPER epitopes so far have not elicited neutralizing antibodies in laboratory animals. One explanation is that the immunogens fail to recreate the proper molecular environment in which the epitopes of 2F5 and 4E10 are presented on the virus. To explore this molecular environment, we used alanine-scanning mutagenesis across residues 660 to 680 in the MPER of a pseudotyped variant of HIV-1
JR-FL
, designated HIV-1
JR2
, and examined the ability of 2F5 and 4E10 to neutralize the Ala mutant viruses. The results show that the only changes to produce neutralization resistance to 2F5 occurred in residue D, K, or W of the core epitope (LEL
DKW
ANL). Likewise, 4E10 resistance arose by replacing one of three residues; two (W and F) were in the core epitope, and one (W) was seven residues C-terminal to these two (N
WF
DISNWL
W
). Importantly, no single substitution resulted in resistance of virus to both 2F5 and 4E10. Surprisingly, 8 out of 21 MPER Ala mutants were more sensitive than the parental pseudovirus to 2F5 and/or 4E10. At most, only small differences in neutralization sensitivity to anti-gp120 monoclonal antibody b12 and peptide T20 were observed with the MPER Ala mutant pseudoviruses. These data suggest that MPER substitutions can act locally and enhance the neutralizing activity of antibodies to this region and imply a distinct role of the MPER of gp41 during HIV-1 envelope-mediated fusion. Neutralization experiments showing synergy between and T20 and 4E10 against HIV-1 are also presented. The data presented may aid in the design of antigens that better present the MPER of gp41 to the immune system.
Influenza A Viruses with Mutations in the M1 Helix Six Domain Display a Wide Variety of Morphological Phenotypes
Authors: Burleigh Laura M. , Calder Lesley J. , Skehel John J. , Steinhauer David A. 
Published: December 2004

ABSTRACT
Several functions required for the replication of influenza A viruses have been attributed to the viral matrix protein (M1), and a number of studies have focused on a region of the M1 protein designated “helix six.” This region contains an exposed positively charged stretch of amino acids, including the motif 101-RKLKR-105, which has been identified as a nuclear localization signal, but several studies suggest that this domain is also involved in functions such as binding to the ribonucleoprotein genome segments (RNPs), membrane association, interaction with the viral nuclear export protein, and virus assembly. In order to define M1 functions in more detail, a series of mutants containing alanine substitutions in the helix six region were generated in A/WSN/33 virus. These were analyzed for RNP-binding function, their capacity to incorporate into infectious viruses by using reverse genetics, the replication properties of rescued viruses, and the morphological phenotypes of the mutant virus particles. The most notable effect that was identified concerned single amino acid substitution mutants that caused significant alterations to the morphology of budded viruses. Whereas A/WSN/33 virus generally forms particles that are predominantly spherical, observations made by negative stain electron microscopy showed that several of the mutant virions, such as K95A, K98A, R101A, and K102A, display a wide range of shapes and sizes that varied in a temperature-dependent manner. The K102A mutant is particularly interesting in that it can form extended filamentous particles. These results support the proposition that the helix six domain is involved in the process of virus assembly.
Molecular Determinants for Subcellular Localization of Hepatitis C Virus Core Protein
Authors: Suzuki Ryosuke , Sakamoto Shinichiro , Tsutsumi Takeya , Rikimaru Akiko , Tanaka Keiko , Shimoike Takashi , Moriishi Kohji , Iwasaki Takuya , Mizumoto Kiyohisa , Matsuura Yoshiharu , Miyamura Tatsuo , Suzuki Tetsuro 
Published: December 2004

ABSTRACT
Hepatitis C virus (HCV) core protein is a putative nucleocapsid protein with a number of regulatory functions. In tissue culture cells, HCV core protein is mainly located at the endoplasmic reticulum as well as mitochondria and lipid droplets within the cytoplasm. However, it is also detected in the nucleus in some cells. To elucidate the mechanisms by which cellular trafficking of the protein is controlled, we performed subcellular fractionation experiments and used confocal microscopy to examine the distribution of heterologously expressed fusion proteins involving various deletions and point mutations of the HCV core combined with green fluorescent proteins. We demonstrated that a region spanning amino acids 112 to 152 can mediate association of the core protein not only with the ER but also with the mitochondrial outer membrane. This region contains an 18-amino-acid motif which is predicted to form an amphipathic α-helix structure. With regard to the nuclear targeting of the core protein, we identified a novel bipartite nuclear localization signal, which requires two out of three basic-residue clusters for efficient nuclear translocation, possibly by occupying binding sites on importin-α. Differences in the cellular trafficking of HCV core protein, achieved and maintained by multiple targeting functions as mentioned above, may in part regulate the diverse range of biological roles of the core protein.
Potential Nectin-1 Binding Site on Herpes Simplex Virus Glycoprotein D
Authors: Connolly Sarah A. , Landsburg Daniel J. , Carfi Andrea , Whitbeck J. Charles , Zuo Yi , Wiley Don C. , Cohen Gary H. , Eisenberg Roselyn J. 
Published: December 2004

ABSTRACT
Four glycoproteins (gD, gB, gH, and gL) are essential for herpes simplex virus (HSV) entry into cells. An early step of fusion requires gD to bind one of several receptors, such as nectin-1 or herpesvirus entry mediator (HVEM). We hypothesize that a conformational change in gD occurs upon receptor binding that triggers the other glycoproteins to mediate fusion. Comparison of the crystal structures of gD alone and gD bound to HVEM reveals that upon HVEM binding, the gD N terminus transitions from a flexible stretch of residues to a hairpin loop. To address the contribution of this transition to the ability of gD to trigger fusion, we attempted to “lock” the gD N terminus into a looped conformation by engineering a disulfide bond at its N and C termini. The resulting mutant (gD-A3C/Y38C) failed to trigger fusion in the absence of receptor, suggesting that formation of the loop is not the sole fusion trigger. Unexpectedly, although gD-A3C/Y38C bound HVEM, it failed to bind nectin-1. This was due to the key role played by Y38 in interacting with nectin-1. Since tyrosines are often “hot spot” residues at the center of protein-protein interfaces, we mutated residues that surround Y38 on the same face of gD and tested their binding and functional properties. Our results suggest that this region of gD is important for nectin-1 interaction and is distinct from but partially overlaps the site of HVEM binding. Unique gD mutants with altered receptor usage generated in this study may help dissect the roles played by various HSV receptors during infection.
Terminal Differentiation into Plasma Cells Initiates the Replicative Cycle of Epstein-Barr Virus In Vivo
Authors: Laichalk Lauri L. , Thorley-Lawson David A. 
Published: December 2004

ABSTRACT

In this paper we demonstrate that the cells which initiate replication of Epstein-Barr virus (EBV) in the tonsils of healthy carriers are plasma cells (CD38
hi
, CD10
−
, CD19
+
, CD20
lo
, surface immunoglobulin negative, and cytoplasmic immunoglobulin positive). We further conclude that differentiation into plasma cells, and not the signals that induce differentiation, initiates viral replication. This was confirmed by in vitro studies showing that the promoter for BZLF1, the gene that begins viral replication, becomes active only after memory cells differentiate into plasma cells and is also active in plasma cell lines. This differs from the reactivation of BZLF1 in vitro, which occurs acutely and is associated with apoptosis and not with differentiation. We suggest that differentiation and acute stress represent two distinct pathways of EBV reactivation in vivo. The fraction of cells replicating the virus decreases as the cells progress through the lytic cycle such that only a tiny fraction actually release infectious virus. This may reflect abortive replication or elimination of cells by the cellular immune response. Consistent with the later conclusion, the cells did not down regulate major histocompatibility complex class I molecules, suggesting that this is not an immune evasion tactic used by EBV and that the cells remain vulnerable to cytotoxic-T-lymphocyte attack.
Simian Immunodeficiency Virus Infection in Wild-Caught Chimpanzees from Cameroon
Authors: Nerrienet Eric , Santiago Mario L. , Foupouapouognigni Yacouba , Bailes Elizabeth , Mundy Nicolas I. , Njinku Bernadette , Kfutwah Anfumbom , Muller-Trutwin Michaela C. , Barre-Sinoussi Françoise , Shaw George M. , Sharp Paul M. , Hahn Beatrice H. , Ayouba Ahidjo 
Published: December 2004

ABSTRACTSimian immunodeficiency viruses (SIVcpz) infecting chimpanzees (Pan troglodytes) in west central Africa are the closest relatives to all major variants of human immunodeficiency virus type 1 ([HIV-1]; groups M, N and O), and have thus been implicated as the source of the human infections; however, information concerning the prevalence, geographic distribution, and subspecies association of SIVcpz still remains limited. In this study, we tested 71 wild-caught chimpanzees from Cameroon for evidence of SIVcpz infection. Thirty-nine of these were of the central subspecies (Pan troglodytes troglodytes), and 32 were of the Nigerian subspecies (Pan troglodytes vellerosus), as determined by mitochondrial DNA analysis. Serological analysis determined that oneP. t. troglodytesape (CAM13) harbored serum antibodies that cross-reacted strongly with HIV-1 antigens; all other apes were seronegative. To characterize the newly identified virus, 14 partially overlapping viral fragments were amplified from fecal virion RNA and concatenated to yield a complete SIVcpz genome (9,284 bp). Phylogenetic analyses revealed that SIVcpzCAM13 fell well within the radiation of the SIVcpzPttgroup of viruses, as part of a clade including all other SIVcpzPttstrains as well as HIV-1 groups M and N. However, SIVcpzCAM13 clustered most closely with SIVcpzGAB1 from Gabon rather than with SIVcpzCAM3 and SIVcpzCAM5 from Cameroon, indicating the existence of divergent SIVcpzPttlineages within the same geographic region. These data, together with evidence of recombination among ancestral SIVcpzPttlineages, indicate long-standing endemic infection of central chimpanzees and reaffirm a west central African origin of HIV-1. WhetherP. t. vellerosusapes are naturally infected with SIVcpz requires further study.