bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catheter-Related Candidemia Caused byCandida lipolyticain a Patient Receiving Allogeneic Bone Marrow Transplantation
Authors: D'Antonio Domenico , Romano Ferdinando , Pontieri Eugenio , Fioritoni Giuseppe , Caracciolo Claudia , Bianchini Stefano , Olioso Paola , Staniscia Tommaso , Sferra Roberta , Boccia Stefania , Vetuschi Antonella , Federico Giovanni , Gaudio Eugenio , Carruba Giuseppe 
Published: July 2002

ABSTRACTCandida lipolyticawas recovered from the blood and the central venous catheter in a patient receiving allogeneic bone marrow transplantation. TwoC.lipolyticastrains from different geographical areas and the ATCC 9773 strain ofC.lipolyticawere used as controls.C.lipolyticawas identified by standard methods. MICs indicated antifungal susceptibilities to amphotericin B, fluconazole, and itraconazole for all strains. In vitro testing and scanning electron microscopy showed thatC.lipolyticawas capable of producing large amounts of viscid slime material in glucose-containing solution, likely responsible for the ability of the yeast to adhere to catheter surfaces. Restriction fragment length polymorphisms revealed an identical profile for all clinical isolates, unrelated to those observed for the control strains. This finding suggested the absence of microevolutionary changes in the population of the infecting strain, despite the length of the sepsis and the potential selective pressure of amphotericin B, which had been administered to the patient for about 20 days. The genomic differences that emerged between the isolates and the control strains were indicative of a certain degree of genetic diversity betweenC.lipolyticaisolates from different geographical areas.
Evaluation of a Triplex PCR Assay To DiscriminateStaphylococcus aureusfrom Coagulase-Negative Staphylococci and Determine Methicillin Resistance from Blood Cultures
Authors: Maes N. , Magdalena J. , Rottiers S. , De Gheldre Y. , Struelens M. J. 
Published: July 2002

ABSTRACTA triplex PCR targeting the 16S rRNA,mecA, andnucgenes was developed for identification of staphylococci and detection of methicillin resistance. After validation of the assay with a collection of strains of staphylococci and enterococci (n= 169), the assay was evaluated with cultures of blood with gram-positive cocci from 40 patients. Accurate results were obtained for 59 (98%) of 61 cultures within 6 h of growth detection.
Detection of Replication-Competent Human Immunodeficiency Virus Type 1 (HIV-1) in Cultures from Patients with Levels of HIV-1 RNA in Plasma Suppressed to Less Than 500 or 50 Copies Per Milliliter
Authors: Demeter Lisa M. , Bosch Ronald J. , Coombs Robert W. , Fiscus Susan , Bremer James , Johnson Victoria A. , Erice Alejo , Jackson J. Brooks , Spector Stephen A. , Squires Kathleen M. , Fischl Margaret A. , Hughes Michael D. , Hammer Scott M. 
Published: July 2002

ABSTRACT

We determined the frequency with which human immunodeficiency virus (HIV) peripheral blood mononuclear cell cultures convert from positive to negative in subjects enrolled in a substudy of AIDS Clinical Trials Group (ACTG) 320, which compared the efficacy of treatment with a combination of indinavir, zidovudine, and lamivudine (indinavir arm) to that of a combination of zidovudine and lamivudine (dual-nucleoside arm). All subjects included for study had positive baseline HIV cultures. Cultures were performed in real time with 10
7
fresh patient peripheral blood mononuclear cells, using the ACTG consensus method. We found lower rates of positive HIV cultures in the indinavir treatment arm than in the dual-nucleoside treatment arm (64 versus 96% at week 24,
P
< 0.001). Within the indinavir arm of the study, we found that positive cultures were less likely to occur in samples with a plasma HIV type 1 (HIV-1) RNA level of <500 copies/ml than in those with a level of ≥500 copies/ml (44 versus 90%,
P
< 0.001). In addition, HIV cultures from samples with HIV-1 RNA levels of ≥500 copies/ml turned positive 8.5 days earlier, on average, than those from samples with levels of <500 copies/ml (
P
< 0.001). However, 38% of samples with plasma RNA levels of <50 copies/ml still were positive for HIV by culture. Thus, the rates of HIV isolation by standard culture procedures decrease as the plasma viral load decreases below 1,000 copies/ml; however, HIV isolates were still obtained from a substantial proportion of subjects with RNA levels of <50 copies/ml. The delay in the time required for HIV cultures to turn positive should be considered when attempting to obtain an HIV isolate from patients with suppression of plasma viral load.
Development and Evaluation of a PCR Method for Detection of the
Clostridium difficile
Toxin B Gene in Stool Specimens
Authors: Guilbault C. , Labbé A.-C. , Poirier L. , Busque L. , Béliveau C. , Laverdière M. 
Published: July 2002

ABSTRACT

A PCR assay detecting
Clostridium difficile
toxin B gene in stool specimens was compared to the cytotoxicity assay as the reference standard for the diagnosis of
C. difficile
antibiotic-associated diarrhea (CDAD). Overall, 118 stool samples were tested. All of the specimens that were negative by the cytotoxicity assay (59 out of 118) were also negative by the PCR method (specificity of 100%). Of the 59 cytotoxin-positive samples, 54 were PCR positive (sensitivity of 91.5%). This PCR method is promising for rapid diagnosis of CDAD.
Failure of Commercial Ligase Chain Reaction To Detect
Mycobacterium tuberculosis
DNA in Sputum Samples from a Patient with Smear-Positive Pulmonary Tuberculosis Due to a Deletion of the Target Region
Authors: Gilpin Christopher M. , Dawson David J. , O'Kane Gabrielle , Armstrong John G. , Coulter Christopher 
Published: July 2002

ABSTRACT

We report on a strain of
Mycobacterium tuberculosis
with a deletion in the protein antigen B gene overlapping the probe binding sites for the Abbott Diagnostics LCx
M. tuberculosis
(LCx-MTB) probe assay. A false-negative result with the LCx-MTB assay delayed a laboratory diagnosis of tuberculosis.
V2 Loop Glycosylation of the Human Immunodeficiency Virus Type 1 SF162 Envelope Facilitates Interaction of This Protein with CD4 and CCR5 Receptors and Protects the Virus from Neutralization by Anti-V3 Loop and Anti-CD4 Binding Site Antibodies
Authors: Ly Amy , Stamatatos Leonidas 
Published: July 2002

ABSTRACTWe examined the role of asparagine-linked glycosylation of the V2 loop of the human immunodeficiency virus (HIV) SF162 envelope on viral replication potential and neutralization susceptibility. We report that the asparagines located at the amino- and carboxy-terminal sites (at positions 154 and 195, respectively), as well as within the V2 loop of the SF162 envelope (at position 186), are glycosylated during in vitro replication of this virus in human peripheral blood mononuclear cells. Our studies indicate that glycosylation of the V2 loop, in particular at its base, facilitates the interaction of the HIV envelope with the CD4 and CCR5 receptor molecules present on the surface of target cells and affects viral replication kinetics in a cell type-dependent manner. In cells expressing high numbers of receptor molecules on their surfaces, the SF162-derived V2 loop-deglycosylated mutant viruses replicate as efficiently as the parental SF162 virus, while in cells expressing small numbers of receptor molecules, the mutant viruses replicate with markedly reduced efficiency. In addition to expanding the viral tropism, V2 loop glycosylation at the three sites examined prevents neutralization by anti-CD4 binding site antibodies. In contrast, glycosylation at the amino- and carboxy-terminal sites of the V2 loop but not within the loop itself offers protection against anti-V3 loop antibodies. Thus, the epitopes masked by the sugar molecules present on the three glycosylation sites examined are not identical but overlap.
Recombinant Yellow Fever Viruses Are Effective Therapeutic Vaccines for Treatment of Murine Experimental Solid Tumors and Pulmonary Metastases
Authors: McAllister Andrés , Arbetman Alejandra E. , Mandl Stefanie , Peña-Rossi Claudia , Andino Raul 
Published: July 2002

ABSTRACTWe have genetically engineered an attenuated yellow fever (YF) virus to carry and express foreign antigenic sequences and evaluated the potential of this type of recombinant virus to serve as a safe and effective tumor vaccine. Live-attenuated YF vaccine is one of the most effective viral vaccines available today. Important advantages include its ability to induce long-lasting immunity, its safety, its affordability, and its documented efficacy. In this study, recombinant live-attenuated (strain 17D) YF viruses were constructed to express a cytotoxic T-lymphocyte epitope derived from chicken ovalbumin (SIINFEKL). These recombinant viruses replicated comparably to the 17D vaccine strain in cell culture and stably expressed the ovalbumin antigen, and infected cells presented the antigen in the context of major histocompatibility complex class I. Inoculation of mice with recombinant YF virus elicited SIINFEKL-specific CD8+lymphocytes and induced protective immunity against challenge with lethal doses of malignant melanoma cells expressing ovalbumin. Furthermore, active immunotherapy with recombinant YF viruses induced regression of established solid tumors and pulmonary metastases. Thus, recombinant YF viruses are attractive viral vaccine vector candidates for the development of therapeutic anticancer vaccines.
The Enhancer I Core Region Contributes to the Replication Level of Hepatitis B Virus In Vivo and In Vitro
Authors: Bock C.-Thomas , Malek Nisar P. , Tillmann Hans L. , Manns Michael P. , Trautwein Christian 
Published: July 2002

ABSTRACTChronic hepatitis B virus (HBV) infection can lead to liver cirrhosis and hepatocellular carcinoma. Long-term interaction of the immune system with the virus results in the selection of escape mutants and viral persistence. In this work we characterize mutations in the enhancer I region isolated prior to liver transplantation from the HBV genomes of 10 patients with chronic HBV infection. The HBV-genomes were sequenced, and the enhancer I region was cloned into luciferase reporter constructs to determine the transcriptional activity. Functional studies were performed by transfecting HBV replication-competent plasmids into hepatoma cells. Analyses of the replication fitness of the mutant strains were conducted by biochemical analysis. In all HBV genomes the enhancer I region was mutated. Most of these mutations resulted in decreased transcriptional activity. The strongest effects were detectable in strains with mutations in the hepatocyte nuclear factor 3 and 4 (HNF3 and HNF4) binding sites of the enhancer I core domain. Replication-competent HBV constructs containing these mutations demonstrated up to 10-fold-reduced levels of virus replication. Before liver transplantation, when the mutant strains were detected in the patients' sera, low HBV DNA levels were found. After transplantation and reinfection with a wild-type virus, the levels of replication were up to 240-fold higher. Our results show that mutations in the enhancer I region of HBV have a major impact on HBV replication. These mutations may also determine the switch from high to low levels of viral replication which is frequently observed during chronic HBV infection.
Intrahepatic Induction of Alpha/Beta Interferon Eliminates Viral RNA-Containing Capsids in Hepatitis B Virus Transgenic Mice
Authors: Wieland Stefan F. , Guidotti Luca G. , Chisari Francis V. 
Published: July 2002

ABSTRACT
We have previously shown that hepatitis B virus (HBV) replication is abolished in the liver of HBV transgenic mice by stimuli that induce alpha/beta interferon (IFN-α/β) in the liver. The present study was done to identify the step(s) in HBV replication that is affected by this cytokine in transgenic mice treated with the IFN-α/β inducer polyinosinic-polycytidylic acid [poly(I-C)]. Here we show that the pool of cytoplasmic HBV pregenomic RNA (pgRNA)-containing capsids is reduced 10-fold within 9 h after poly(I-C) administration, while there is no change in the abundance of HBV mRNA or in the translational status of cytoplasmic HBV transcripts. In addition, we show that the pool of HBV DNA-containing capsids is not reduced to the same degree until at least 15 h posttreatment, and we show that virus export is not accelerated and the half-life of virions in the serum is unchanged. These results indicate that IFN-α/β triggers intracellular events that either inhibit the assembly of pgRNA-containing capsids or accelerate their degradation, and that maturation and secretion of virus is responsible for clearance of HBV capsids and their cargo of replicative intermediates from the cytoplasm of the hepatocyte.
Induction and Inhibition of Apoptosis by Pseudorabies Virus in the Trigeminal Ganglion during Acute Infection of Swine
Authors: Alemañ Nuria , Quiroga Marı́a Isabel , López-Peña Mónica , Vázquez Sonia , Guerrero Florentina H. , Nieto José M. 
Published: July 2002

ABSTRACTWe examined the ability of pseudorabies virus (PRV) to induce and suppress apoptosis in the trigeminal ganglion during acute infection of its natural host. Eight pigs were intranasally inoculated with a virulent field strain of PRV, and at various early times after inoculation, the trigeminal ganglia were assessed histologically. PRV-infected cells were detected by use of immunohistochemistry and in situ hybridization, and apoptosis was identified by in situ terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling. Light and electron microscopy was also used for morphological studies. Apoptosis was readily detected among infiltrating immune cells that were located surrounding PRV-infected neurons. The majority of PRV-infected neurons did not show morphological or histochemical evidence of apoptosis, even including those neurons that were surrounded by numerous inflammatory cells and exhibited profound pathological changes. However, neuronal virus-induced apoptosis also occurred but at a sporadic low level. These findings suggest that PRV is able to block apoptosis of infected trigeminal ganglionic neurons during acute infection of swine. Furthermore, our results also suggest that apoptosis of infiltrating inflammatory cells may represent an important viral mechanism of immune evasion.
Roles of Disulfide Linkage and Calcium Ion-Mediated Interactions in Assembly and Disassembly of Virus-Like Particles Composed of Simian Virus 40 VP1 Capsid Protein
Authors: Ishizu Ken-Ichiro , Watanabe Hajime , Han Song-Iee , Kanesashi Shin-Nosuke , Hoque Mainul , Yajima Hiroaki , Kataoka Kohsuke , Handa Hiroshi 
Published: July 2002

ABSTRACT
The simian virus 40 capsid is composed of 72 pentamers of VP1 protein. Although the capsid is known to dissociate to pentamers in vitro following simultaneous treatment with reducing and chelating agents, the functional roles of disulfide linkage and calcium ion-mediated interactions are not clear. To elucidate the roles of these interactions, we introduced amino acid substitutions in VP1 at cysteine residues and at residues involved in calcium binding. We expressed the mutant proteins in a baculovirus system and analyzed both their assembly into virus-like particles (VLPs) in insect cells and the disassembly of those VLPs in vitro. We found that disulfide linkages at both Cys-9 and Cys-104 conferred resistance to proteinase K digestion on VLPs, although neither linkage was essential for the formation of VLPs in insect cells. In particular, reduction of the disulfide linkage at Cys-9 was found to be critical for VLP dissociation to VP1 pentamers in the absence of calcium ions, indicating that disulfide linkage at Cys-9 prevents VLP dissociation, probably by increasing the stability of calcium ion binding. We found that amino acid substitutions at carboxy-terminal calcium ion binding sites (Glu-329, Glu-330, and Asp-345) resulted in the frequent formation of unusual tubular particles as well as VLPs in insect cells, indicating that these residues affect the accuracy of capsid assembly. In addition, unexpectedly, amino acid substitutions at any of the calcium ion binding sites tested, especially at Glu-157, resulted in increased stability of VLPs in the absence of calcium ions in vitro. These results suggest that appropriate affinities of calcium ion binding are responsible for both assembly and disassembly of the capsid.
Sustained Dysfunction of Antiviral CD8+T Lymphocytes after Infection with Hepatitis C Virus
Authors: Gruener Norbert H. , Lechner Franziska , Jung Maria-Christina , Diepolder Helmut , Gerlach Tilman , Lauer Georg , Walker Bruce , Sullivan John , Phillips Rodney , Pape Gerd R. , Klenerman Paul 
Published: July 2002

ABSTRACTHepatitis C virus (HCV) sets up persistent infection in the majority of those exposed. It is likely that, as with other persistent viral infections, the efficacy of T-lymphocyte responses influences long-term outcome. However, little is known about the functional capacity of HCV-specific T-lymphocyte responses induced after acute infection. We investigated this by using major histocompatibility complex class I-peptide tetrameric complexes (tetramers), which allow direct detection of specific CD8+T lymphocytes ex vivo, independently of function. Here we show that, early after infection, virus-specific CD8+T lymphocytes detected with a panel of four such tetramers are abnormal in terms of their synthesis of antiviral cytokines and lytic activity. Furthermore, this phenotype is commonly maintained long term, since large sustained populations of HCV-specific CD8+T lymphocytes were identified, which consistently had very poor antiviral cytokine responses as measured in vitro. Overall, HCV-specific CD8+T lymphocytes show reduced synthesis of tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) after stimulation with either mitogens or peptides, compared to responses to Epstein-Barr virus and/or cytomegalovirus. This behavior of antiviral CD8+T lymphocytes induced after HCV infection may contribute to viral persistence through failure to effectively suppress viral replication.
High Numbers of Viral RNA Copies in the Central Nervous System of Mice during Persistent Infection with Theiler's Virus
Authors: Trottier Mark , Kallio Pat , Wang Wei , Lipton Howard L. 
Published: July 2002

ABSTRACTThe low-neurovirulence Theiler's murine encephalomyelitis viruses (TMEV), such as BeAn virus, cause a persistent infection of the central nervous system (CNS) in susceptible mouse strains that results in inflammatory demyelination. The ability of TMEV to persist in the mouse CNS has traditionally been demonstrated by recovering infectious virus from the spinal cord. Results of infectivity assays led to the notion that TMEV persists at low levels. In the present study, we analyzed the copy number of TMEV genomes, plus- to minus-strand ratios, and full-length species in the spinal cords of infected mice and infected tissue culture cells by using Northern hybridization. Considering the low levels of infectious virus in the spinal cord, a surprisingly large number of viral genomes (mean of 3.0 × 109) was detected in persistently infected mice. In the transition from the acute (approximately postinfection [p.i.] day 7) to the persistent (beginning on p.i. day 28) phase of infection, viral RNA copy numbers steadily increased, indicating that TMEV persistence involves active viral RNA replication. Further, BeAn viral genomes were full-length in size; i.e., no subgenomic species were detected and the ratio of BeAn virus plus- to minus-strand RNA indicated that viral RNA replication is unperturbed in the mouse spinal cord. Analysis of cultured macrophages and oligodendrocytes suggests that either of these cell types can potentially synthesize high numbers of viral RNA copies if infected in the spinal cord and therefore account for the heavy viral load. A scheme is presented for the direct isolation of both cell types directly from infected spinal cords for further viral analyses.
Requirements for the Induction of Interleukin-6 by Herpes Simplex Virus-Infected Leukocytes
Authors: Paludan Søren R. 
Published: July 2002

ABSTRACTCytokines play important roles in the clearance of herpes simplex virus (HSV) infections and in virus-induced immunopathology. One cytokine known to contribute to resistance against HSV is interleukin-6 (IL-6). Here we have investigated virus-cell interactions responsible for IL-6 induction by HSV in leukocytes. Both HSV type 1 and type 2 are potent inducers of IL-6, and this phenomenon is augmented in the presence of gamma interferon. The ability to induce IL-6 is dependent on de novo protein synthesis and is sensitive to UV irradiation of the virus. Virus mutants lacking the virion-transactivating protein VP16 or any of the immediate-early proteins ICP0, ICP4, or ICP27 displayed unaltered capacities to induce IL-6. However, wild-type virus was unable to induce IL-6 in a macrophage cell line overexpressing a mutant of double-stranded RNA-activated protein kinase (PKR). This suggests a role for PKR in HSV-induced IL-6 expression. HSV infection led to enhanced binding to the κB, CRE, and AP-1 sites of the IL-6 promoter, and inhibitors against NF-κB and the p38 kinase strongly reduced accumulation of IL-6 mRNA in infected cells. Moreover, macrophage cell lines expressing dominant negative mutants of IκBα and p38 responded to HSV-1 infection with reduced IL-6 expression compared to the control-vector-transfected cell line. The results show that induction of IL-6 by HSV in leukocytes is dependent on PKR and cellular signaling through NF-κB and a p38-dependent pathway.
Morbillivirus Infection of the Mouse Central Nervous System Induces Region-Specific Upregulation of MMPs and TIMPs Correlated to Inflammatory Cytokine Expression
Authors: Khuth Seng-Thuon , Akaoka Hideo , Pagenstecher Axel , Verlaeten Olivier , Belin Marie-Françoise , Giraudon Pascale , Bernard Arlette 
Published: July 2002

ABSTRACTViral infection of the central nervous system (CNS) can result in perturbation of cell-to-cell communication involving the extracellular matrix (ECM). ECM integrity is maintained by a dynamic balance between the synthesis and proteolysis of its components, mainly as a result of the action of matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs). An MMP/TIMP imbalance may be critical in triggering neurological disorders, in particular in virally induced neural disorders. In the present study, a mouse model of brain infection using a neurotropic strain of canine distemper virus (CDV) was used to study the effect of CNS infection on the MMP/TIMP balance and cytokine expression. CDV replicates almost exclusively in neurons and has a unique pattern of expression (cortex, hypothalamus, monoaminergic nuclei, hippocampus, and spinal cord). Here we show that although several mouse brain structures were infected, they exhibited a differential pattern in terms of MMP, TIMP, and cytokine expression, exemplified by (i) a large increase in pro-MMP9 levels, in particular in the hippocampus, which occurred mainly in neurons and was associated with in situ gelatinolytic activity, (ii) specific and significant upregulation of MT1-MMP mRNA expression in the cortex and hypothalamus, (iii) an MMP/TIMP imbalance, suggested by the upregulation of TIMP-1 mRNA in the cortex, hippocampus, and hypothalamus and of TIMP-3 mRNA in the cortex, and (iv) a concomitant region-specific large increase in expression of Th1-like cytokines, such as gamma interferon, tumor necrosis factor alpha, and interleukin 6 (IL-6), contrasting with weaker induction of Th2-like cytokines, such as IL-4 and IL-10. These data indicate that an MMP/TIMP imbalance in specific brain structures, which is tightly associated with a local inflammatory process as shown by the presence of immune infiltrating cells, differentially impairs CNS integrity and may contribute to the multiplicity of late neurological disorders observed in this viral mouse model.