bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vitro Activity of Nystatin Compared with Those of Liposomal Nystatin, Amphotericin B, and Fluconazole against ClinicalCandidaIsolates
Authors: Arikan Sevtap , Ostrosky-Zeichner Luis , Lozano-Chiu Mario , Paetznick Victor , Gordon David , Wallace Tom , Rex John H. 
Published: July 2002

ABSTRACTWe investigated the in vitro activity of nystatin and liposomal nystatin against 103Candidaisolates to determine the effect of both time and medium on MICs. We also compared the nystatin MICs with those of amphotericin B and fluconazole. Testing was performed in accordance with the National Committee for Clinical Laboratory Standards M27-A microdilution methodology with RPMI 1640, RPMI 1640 supplemented with glucose to 2% (RPMI-2), and antibiotic medium 3 supplemented with glucose to 2% (AM3). While nystatin MICs were similar to or slightly lower than liposomal nystatin MICs in RPMI 1640 and RPMI-2, they were markedly higher than liposomal nystatin MICs in AM3. Use of AM3 and determination of the MIC after 24 h of incubation provided a slightly wider range of liposomal nystatin MICs (0.06 to >16 μg/ml). Under these conditions, the MICs at which 90% of isolates were inhibited of nystatin and liposomal nystatin were 2 and 1 μg/ml, respectively. Nystatin and liposomal nystatin in general showed good activity against allCandidaspp. tested. Although the MICs of nystatin and liposomal nystatin tended to rise in parallel with the amphotericin B MICs, nystatin and liposomal nystatin MICs of 1 to 2 and 0.5 to 1 μg/ml, respectively, were obtained for seven and six, respectively, of nine isolates for which amphotericin B MICs were ≥0.25 μg/ml. No correlation between fluconazole and nystatin or liposomal nystatin MICs was observed. As amphotericin B MICs of ≥0.25 μg/ml correlate with in vitro resistance, these results suggest that liposomal nystatin might have activity against some amphotericin B-resistant isolates. In vivo testing in animal models is required for clarification of this issue.
Multicenter Evaluation of a New Automated Fourth-Generation Human Immunodeficiency Virus Screening Assay with a Sensitive Antigen Detection Module and High Specificity
Authors: Weber Bernard , Gürtler Lutz , Thorstensson Rigmor , Michl Ulrike , Mühlbacher Annelies , Bürgisser Philippe , Villaescusa Roberto , Eiras Adolfo , Gabriel Christian , Stekel Herbert , Tanprasert Srivilai , Oota Sinenaart , Silvestre Maria-Jose , Marques Cristina , Ladeira Maria , Rabenau Holger , Berger Annemarie , Schmitt Urban , Melchior Walter 
Published: July 2002

ABSTRACT

Fourth-generation assays for the simultaneous detection of human immunodeficiency virus (HIV) antigen and antibody that were available on the international market until now have antigen detection modules with relatively poor sensitivity and produce a higher rate of false-positive results than third-generation enzyme immunoassays (EIAs). The new Cobas Core HIV Combi EIA with an improved sensitivity for HIV p24 antigen was compared to alternative fourth- and third-generation assays, the p24 antigen test, and HIV type 1 (HIV-1) RNA reverse transcriptase PCR (RT-PCR). A total of 94 seroconversion panels (
n
= 709 sera), samples from the acute phase of infection after seroconversion (
n
= 32), anti-HIV-1-positive specimens (
n
= 730) from patients in different stages of the disease, 462 subtyped samples from different geographical locations, anti-HIV-2-positive sera (
n
= 302), dilutions of cell culture supernatants (
n
= 62) from cells infected with different HIV-1 subtypes, selected performance panels from Boston Biomedica Inc., 7,579 unselected samples from blood donors, 303 unselected daily routine samples, 997 specimens from hospitalized patients, and potentially interfering samples (
n
= 1,222) were tested with Cobas Core HIV Combi EIA. The new assay showed a sensitivity comparable to that of the Abbott HIV-1 AG Monoclonal A for early detection of HIV infection in seroconversion panels. The mean time delay of Cobas Core HIV Combi EIA (last negative sample plus 1 day) in comparison to that for HIV-1 RT-PCR for 87 panels tested with both methods was 2.75 days. The diagnostic window was reduced with Cobas Core HIV Combi EIA by between 3.6 and 5.7 days from that for third-generation assays. The specificities of Cobas Core HIV Combi EIA in blood donors were 99.84 and 99.85% (after repeated testing). Overall, 30 repeatedly reactive false-positive results out of 10,031 HIV-negative samples were obtained with Cobas Core HIV Combi EIA. Our results show that a fourth-generation assay with improved specificity such as Cobas Core HIV Combi EIA is suitable for blood donor screening because of its low number of false positives and because it detects HIV p24 antigen with a sensitivity comparable to that of single-antigen assays.
Opposite Effects of Dextran Sulfate 500, the Polyene Antibiotic MS-8209, and Congo Red on Accumulation of the Protease-Resistant Isoform of PrP in the Spleens of Mice Inoculated Intraperitoneally with the Scrapie Agent
Authors: Beringue Vincent , Adjou Karim T. , Lamoury François , Maignien Thomas , Deslys Jean-Philippe , Race Richard , Dormont Dominique 
Published: July 2002

ABSTRACT
The mode and the site of action of the major antiscrapie drugs have been studied by investigating their effects on the abnormal protease-resistant isoform of PrP (PrPres) and on its accumulation in mouse spleen. Day-by-day PrPres accumulation in the spleen and in other peripheral organs was first monitored to describe the early steps of scrapie pathogenesis. Three phases were identified: the detection of scrapie inoculum on the day of scrapie infection, a clearance phase, and then the peripheral accumulation of PrPres. In a second step, the effects of the polyene antibiotic MS-8209, the polyanion dextran sulfate 500 (DS500), and Congo red were assessed on these phases, after the drugs were coincubated with scrapie inoculum. Highly different mechanisms and sites of action were apparent. MS-8209 had a weak effect on the accumulation of PrPres in spleen, suggesting another site of intervention for this drug. DS500 delayed the beginning of the clearance phase but then blocked PrPres synthesis for a long period of time, probably because of its immunological effects on the spleen. Surprisingly, Congo red suppressed the clearance phase of scrapie inoculum and then increased transiently accumulation of PrPres in spleen. We showed in vitro that this effect was related to a direct enhancement of the protease resistance of PrPres by the drug.
Feline Leukemia Virus Envelope Sequences That Affect T-Cell Tropism and Syncytium Formation Are Not Part of Known Receptor-Binding Domains
Authors: Gwynn Samuel R. , Hankenson F. Claire , Lauring Adam S. , Rohn Jennifer L. , Overbaugh Julie 
Published: July 2002

ABSTRACTThe envelope protein is a primary pathogenic determinant for T-cell-tropic feline leukemia virus (FeLV) variants, the best studied of which is the immunodeficiency-inducing virus, 61C. We have previously demonstrated that T-cell-tropic, cytopathic, and syncytium-inducing viruses evolve in cats infected with a relatively avirulent, transmissible form of FeLV, 61E. The envelope gene of an 81T variant, which encoded scattered single-amino-acid changes throughout the envelope as well as a 4-amino-acid insertion in the C-terminal half of the surface unit (SU) of envelope, was sufficient to confer the T-cell-tropic, cytopathic phenotype (J. L. Rohn, M. S. Moser, S. R. Gwynn, D. N. Baldwin, and J. Overbaugh, J. Virol. 72:2686–2696, 1998). In the present study, we examined the role of the 4-amino-acid insertion in determining viral replication and tropism of FeLV-81T. The 4-amino-acid insertion was found to be functionally equivalent to a 6-amino-acid insertion at an identical location in the 61C variant. However, viruses expressing a chimeric 61E/81T SU, containing the insertion together with the N terminus of 61E SU, were found to be replication defective and were impaired in the processing of the envelope precursor into the functional SU and transmembrane (TM) proteins. In approximately 10% of cultured feline T cells (3201) transfected with the 61E/81T envelope chimeras and maintained over time, replication-competent tissue culture-adapted variants were isolated. Compensatory mutations in the SU of the tissue culture-adapted viruses were identified at positions 7 and 375, and each was shown to restore envelope protein processing when combined with the C-terminal 81T insertion. Unexpectedly, these viruses displayed different phenotypes in feline T cells: the virus with a change from glutamine to proline at position 7 acquired a T-cell-tropic, cytopathic phenotype, whereas the virus with a change from valine to leucine at position 375 had slower replication kinetics and caused no cytopathic effects. Given the differences in the replication properties of these viruses, it is noteworthy that the insertion as well as the two single-amino-acid changes all occur outside of predicted FeLV receptor-binding domains.
DNA Sequence Motifs Which Direct Adeno-Associated Virus Site-Specific Integration in a Model System
Authors: Meneses Patricio , Berns Kenneth I. , Winocour Ernest 
Published: July 2002

ABSTRACT
The DNA sequence motifs which direct adeno-associated virus type 2 site-specific integration are being investigated using a shuttle vector, propagated as a stable episome in cultured cell lines, as the target for integration. Previously, we reported that the minimum episomal targeting elements comprise a 16-bp binding motif (Rep binding site [RBS]) for a viral regulatory protein (Rep) separated by a short DNA spacer from a sequence (terminal resolution site [TRS]) that can serve as a substrate for Rep-mediated nicking activity (R. M. Linden, P. Ward, C. Giraud, E. Winocour, and K. I. Berns, Proc. Natl. Acad. Sci. USA 93:11288–11294, 1996; R. M. Linden, E. Winocour, and K. I. Berns, Proc. Natl. Acad. Sci. USA 93:7966–7972, 1996). We now report that episomal integration depends upon both the sequence and the position of the spacer DNA separating the RBS and TRS motifs. The spacer thus constitutes a third element required for site-specific episomal integration.
Identification of a Gammaherpesvirus Selective Chemokine Binding Protein That Inhibits Chemokine Action
Authors: van Berkel Victor , Barrett John , Tiffany H. Lee , Fremont Daved H. , Murphy Philip M. , McFadden Grant , Speck Samuel H. , Virgin Herbert W. 
Published: July 2002

ABSTRACTChemokines are involved in recruitment and activation of hematopoietic cells at sites of infection and inflammation. The M3 gene of γHV68, a gamma-2 herpesvirus that infects and establishes a lifelong latent infection and chronic vasculitis in mice, encodes an abundant secreted protein during productive infection. The M3 gene is located in a region of the genome that is transcribed during latency. We report here that the M3 protein is a high-affinity broad-spectrum chemokine scavenger. The M3 protein bound the CC chemokines human regulated upon activation of normal T-cell expressed and secreted (RANTES), murine macrophage inflammatory protein 1α (MIP-1α), and murine monocyte chemoattractant protein 1 (MCP-1), as well as the human CXC chemokine interleukin-8, the murine C chemokine lymphotactin, and the murine CX3C chemokine fractalkine with high affinity (Kd= 1.6 to 18.7 nM). M3 protein chemokine binding was selective, since the protein did not bind seven other CXC chemokines (Kd> 1 μM). Furthermore, the M3 protein abolished calcium signaling in response to murine MIP-1α and murine MCP-1 and not to murine KC or human stromal cell-derived factor 1 (SDF-1), consistent with the binding data. The M3 protein was also capable of blocking the function of human CC and CXC chemokines, indicating the potential for therapeutic applications. Since the M3 protein lacks homology to known chemokines, chemokine receptors, or chemokine binding proteins, these studies suggest a novel herpesvirus mechanism of immune evasion.
Type 2 Cytokines Predominate in the Human CD4+T-Lymphocyte Response to Epstein-Barr Virus Nuclear Antigen 1
Authors: Steigerwald-Mullen Patricia , Kurilla Michael G. , Braciale Thomas J. 
Published: July 2002

ABSTRACTEpstein-Barr virus (EBV) is a ubiquitous human herpesvirus that persistently infects 85% of the adult population worldwide. In this report, we examine the proliferative response and cytokine secretion profile of CD4+T lymphocytes from a panel of unrelated EBV-positive donors against two EBV latent antigens, EBNA1 and EBNA3C. Substantial proliferative responses by CD4+lymphocytes were demonstrated to both antigens in multiple, randomly selected donors. Surprisingly, we observed a striking and consistent difference in cytokine response to EBNA1 and EBNA3C. EBNA1-specific CD4+T lymphocytes from multiple unrelated donors preferentially produced type 2-like cytokines in response to antigenic stimulation, while the response to EBNA3C was a characteristic type 1 response. The implications of these findings for EBV persistence and the development of EBV-associated malignancies are discussed.
Measles Virus-Induced Immunosuppression In Vitro Is Independent of Complex Glycosylation of Viral Glycoproteins and of Hemifusion
Authors: Weidmann Armin , Fischer Christian , Ohgimoto Shinji , Rüth Claudia , ter Meulen Volker , Schneider-Schaulies Sibylle 
Published: July 2002

ABSTRACTExpression of the measles virus (MV) F/H complex on the surface of viral particles, infected cells, or cells transfected to express these proteins (presenter cells [PC]) is necessary and sufficient to induce proliferative arrest in both human and rodent lymphoid cells (responder cells [RC]). This inhibition was found to occur independent of apoptosis and soluble mediators excluded by a pore size filter of 200 nm released from either PC or RC. We now show that reactive oxygen intermediates which might be released by RC or PC also do not contribute to MV-induced immunosuppression in vitro. Using an inhibitor of Golgi-resident mannosidases (deoxymannojirimycin), we found that complex glycosylation of the F and H proteins is not required for the induction of proliferative arrest of RC. As revealed by our previous studies, proteolytic cleavage of the MV F protein precursor into its F1 and F2 subunits, but not of F/H-mediated cellular fusion, was found to be required, since fusion-inhibitory peptides such as Z-d-Phe-l-Phe-Gly (Z-fFG) did not interfere with the induction of proliferative inhibition. We now show that Z-fFG inhibits cellular fusion at the stage of hemifusion by preventing lipid mixing of the outer membrane layer. These results provide strong evidence for a receptor-mediated signal elicited by the MV F/H complex which can be uncoupled from its fusogenic activity is required for the induction of proliferative arrest of human lymphocytes.
MM1, a Temperate Bacteriophage of the Type 23F Spanish/USA Multiresistant Epidemic Clone of
Streptococcus pneumoniae
: Structural Analysis of the Site-Specific Integration System
Authors: Gindreau Emmanuel , López Rubens , García Pedro 
Published: July 2002

ABSTRACT

We have characterized a temperate phage (MM1) from a clinical isolate of the multiply antibiotic-resistant Spanish/American 23F
Streptococcus pneumoniae
clone (Spain
23F
-1 strain). The 40-kb double-stranded genome of MM1 has been isolated as a DNA-protein complex. The use of MM1 DNA as a probe revealed that the phage genome is integrated in the host chromosome. The host and phage attachment sites,
attB
and
attP
, respectively, have been determined. Nucleotide sequencing of the attachment sites identified a 15-bp core site (5′-TTATAATTCATCCGC-3′) that has not been found in any bacterial genome described so far. Sequence information revealed the presence of an integrase gene (
int
), which represents the first identification of an integrase in the pneumococcal system. A 1.5-kb DNA fragment embracing
attP
and the
int
gene contained all of the genetic information needed for stable integration of a nonreplicative plasmid into the
attB
site of a pneumococcal strain. This vector will facilitate the introduction of foreign genes into the pneumococcal chromosome. Interestingly, DNAs highly similar to that of MM1 have been detected in several clinical pneumococcal isolates of different capsular types, suggesting a widespread distribution of these phages in relevant pathogenic strains.
Involvement of the Zinc-Binding Capacity of Sendai Virus V Protein in Viral Pathogenesis
Authors: Huang Cheng , Kiyotani Katsuhiro , Fujii Yutaka , Fukuhara Noriko , Kato Atsushi , Nagai Yoshiyuki , Yoshida Tetsuya , Sakaguchi Takemasa 
Published: July 2002

ABSTRACT

The V protein of Sendai virus (SeV) is nonessential to virus replication in cell culture but indispensable to viral pathogenicity in mice. The highly conserved cysteine-rich zinc finger-like domain in its carboxyl terminus is believed to be responsible for this viral pathogenicity. In the present study, we showed that the cysteine-rich domain of the SeV V protein could actually bind zinc by using glutathione-
S
-transferase fusion proteins. When the seven conserved cysteine residues at positions 337, 341, 353, 355, 358, 362, and 365 were replaced individually, the zinc-binding capacities of the mutant proteins were greatly impaired, ranging from 22 to 68% of that of the wild type. We then recovered two mutant SeVs from cDNA, which have V-C
341
S and V-C
365
R mutations and represent maximal and minimal zinc-binding capacities among the corresponding mutant fusion proteins, respectively. The mutant viruses showed viral protein synthesis and growth patterns similar to those of wild-type SeV in cultured cells. However, the mutant viruses were strongly attenuated in mice in a way similar to that of SeV V
ΔC
, which has a truncated V protein lacking the cysteine-rich domain, by exhibiting earlier viral clearance from the mouse lung and less virulence to mice. We therefore conclude that the zinc-binding capacity of the V protein is involved in viral pathogenesis.
Role of Viral Persistence in Retaining CD8+T Cells within the Central Nervous System
Authors: Marten Norman W. , Stohlman Stephen A. , Bergmann Cornelia C. 
Published: July 2002

ABSTRACTThe continued presence of virus-specific CD8+T cells within the central nervous system (CNS) following resolution of acute viral encephalomyelitis implicates organ-specific retention. The role of viral persistence in locally maintaining T cells was investigated by infecting mice with either a demyelinating, paralytic (V-1) or nonpathogenic (V-2) variant of a neurotropic mouse hepatitis virus, which differ in the ability to persist within the CNS. Class I tetramer technology revealed more infiltrating virus-specific CD8+T cells during acute V-1 compared to V-2 infection. However, both total and virus-specific CD8+T cells accumulated at similar peak levels in spinal cords by day 10 postinfection (p.i.). Decreasing viral RNA levels in both brains and spinal cords following initial virus clearance coincided with an overall progressive loss of both total and virus-specific CD8+T cells. By 9 weeks p.i., T cells had largely disappeared from brains of both infected groups, consistent with the decline of viral RNA. T cells also completely disappeared from V-2-infected spinal cords coincident with the absence of viral RNA. By contrast, a significant number of CD8+T cells which contained detectable viral RNA were recovered from spinal cords of V-1-infected mice. The data indicate that residual virus from a primary CNS infection is a vital component in mediating local retention of both CD8+and CD4+T cells and that once minimal thresholds of stimuli are lost, T cells within the CNS cannot survive in an autonomous fashion.
Characterization of a Replication-Defective Human Immunodeficiency Virus Type 1
att
Site Mutant That Is Blocked after the 3′ Processing Step of Retroviral Integration
Authors: Chen Hongmin , Engelman Alan 
Published: July 2002

ABSTRACT
Two activities of retroviral integrase, 3′ processing and DNA strand transfer, are required to integrate viral cDNA into a host cell chromosome. Integrase activity has been analyzed in vitro using purified protein and recombinant DNA substrates that model the U3 and U5 ends of viral cDNA or by using viral preintegration complexes (PICs) that form during virus infection. Numerous studies have investigated changes in integrase or viral DNA for effects on both 3′ processing and DNA strand transfer activities using purified protein, but similar analyses have not been carried out using PICs. Here, we analyzed PICs from human immunodeficiency virus type 1 (HIV-1) strain 604del, an integration-defective mutant lacking 26 bp of U5, and revE1, a revertant of 604del containing an additional 19-bp deletion, for levels of 3′ processing activity that occurred in infected cells and for levels of in vitro DNA strand transfer activity. Whereas revE1 supported one-third to one-half of the level of wild-type DNA strand transfer activity, the level of 604del DNA strand transfer activity was undetectable. Surprisingly, integrase similarly processed the 3′ ends of 604del and revE1 in vivo. We therefore conclude that 604del is blocked in its ability to replicate in cells after the 3′ processing step of retroviral integration. Whereas Western blotting showed that wild-type, revE1, and 604del PICs contained similar levels of integrase protein, Mu-mediated PCR footprinting revealed only minimal protein-DNA complex formation at the ends of 604del cDNA. We propose that 604del is replication defective because proteins important for DNA strand transfer activity do not stably associate with this cDNA after in vivo 3′ processing by integrase.
Prospective Characterization of Full-Length Hepatitis C Virus NS5A Quasispecies during Induction and Combination Antiviral Therapy
Authors: Nousbaum J.-B. , Polyak S. J. , Ray S. C. , Sullivan D. G. , Larson A. M. , Carithers R. L. , Gretch D. R. 
Published: July 2002

ABSTRACT

The hepatitis C virus (HCV) nonstructural 5A (NS5A) protein has been controversially implicated in the inherent resistance of HCV to interferon (IFN) antiviral therapy in clinical studies. In this study, the relationship between NS5A mutations and selection pressures before and during antiviral therapy and virologic response to therapy were investigated. Full-length NS5A clones were sequenced from 20 HCV genotype 1-infected patients in a prospective, randomized clinical trial of IFN induction (daily) therapy and IFN plus ribavirin combination therapy. Pretreatment NS5A nucleotide and amino acid phylogenies did not correlate with clinical IFN responses and domains involved in NS5A functions in vitro were all well conserved before and during treatment. A consensus IFN sensitivity-determining region (ISDR
237–276
) sequence associated with IFN resistance was not found, although the presence of Ala
245
within the ISDR was associated with nonresponse to treatment in genotype 1a-infected patients (
P
< 0.01). There were more mutations in the 26 amino acids downstream of the ISDR required for PKR binding in pretreatment isolates from responders versus nonresponders in both HCV-1a- and HCV-1b-infected patients (
P
< 0.05). In HCV-1a patients, more amino acid changes were observed in isolates from IFN-sensitive patients (
P
< 0.001), and the mutations appeared to be concentrated in two variable regions in the C terminus of NS5A, that corresponded to the previously described V3 region and a new variable region, 310 to 330. Selection of pretreatment minor V3 quasispecies was observed within the first 2 to 6 weeks of therapy in responders but not nonresponders, whereas the ISDR and PKR binding domains did not change in either patient response group. These data suggest that host-mediated selective pressures act primarily on the C terminus of NS5A and that NS5A can perturb or evade the IFN-induced antiviral response using sequences outside of the putative ISDR. Mechanistic studies are needed to address the role of the C terminus of NS5A in HCV replication and antiviral resistance.