bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of Methicillin-ResistantStaphylococcus aureusand Simultaneous Confirmation by Automated Nucleic Acid Extraction and Real-Time PCR
Authors: Grisold Andrea J. , Leitner Eva , Mühlbauer Gerhard , Marth Egon , Kessler Harald H. 
Published: July 2002

ABSTRACTA molecular assay for the simultaneous detection of aStaphylococcus aureus-specific gene and themecAgene, responsible for the resistance to methicillin in staphylococci, was evaluated. The assay included an automated DNA extraction protocol conducted with a MagNA Pure instrument and real-time PCR conducted with a LightCycler instrument. The performance and robustness of the assay were evaluated for a suspension of methicillin-resistantS. aureus(MRSA) strain with a turbidity equivalent to a McFarland standard of 0.5, which was found to be the ideal working concentration. The specificity of the new molecular assay was tested with a panel of 30 gram-negative and gram-positive bacterial strains other than MRSA. No cross-reactivity was observed. In a clinical study, 109 isolates of MRSA were investigated. All clinical MRSA isolates gave positive results for theS. aureus-specific genomic target, and all but one were positive for themecAgene. In conclusion, the new molecular assay was found to be quick, robust, and laborsaving, and it proved to be suitable for a routine molecular diagnostic laboratory.
Seroprevalence of Antibodies That React with
Anaplasma phagocytophila
, the Agent of Human Granulocytic Ehrlichiosis, in Different Populations in Westchester County, New York
Authors: Aguero-Rosenfeld Maria E. , Donnarumma Lorraine , Zentmaier Lois , Jacob Jobby , Frey Michael , Noto Richard , Carbonaro Carol A. , Wormser Gary P. 
Published: July 2002

ABSTRACT

We determined the frequencies of antibodies to
Anaplasma phagocytophila
, the agent of human granulocytic ehrlichiosis (HGE), in different groups of adults and children from Westchester County, New York. The groups included 159 adult blood donors and 215 children who were seronegative for
Borrelia burgdorferi
antibodies, 118 adult patients and 57 children who were seropositive for
B. burgdorferi
antibodies, and 42 adult patients with culture-confirmed erythema migrans. Eighteen (11.3%) of the blood donors and 11 (5.1%) of the
B. burgdorferi
-seronegative children were found to have
A. phagocytophila
antibodies by indirect immunofluorescent-antibody assay (IFA). Nine of 42 (21.4%) patients with culture-confirmed erythema migrans tested at the baseline visit, 42 of 118 (35.6%) adults, and 3 of 57 (5.3%) children whose sera were reactive for
B. burgdorferi
antibodies also tested positive for
A. phagocytophila
antibodies. The geometric mean titer ranged from 219 to 315 for all groups, and the differences in titers among the groups were not statistically significant. Only one-third of the healthy blood donors reactive by IFA were confirmed to be positive by immunoblotting. We conclude that a significant proportion of adults and children without clinical evidence of HGE will test positive for
A. phagocytophila
antibodies when the conventional cutoff titer of 80 is used in the IFA. This information must be considered in interpretation of test results.
NAD-Glycohydrolase Production and
speA
and
speC
Distribution in Group A Streptococcus (GAS) Isolates Do Not Correlate with Severe GAS Diseases in the Australian Population
Authors: DelVecchio Armando , Maley Michael , Currie Bart J. , Sriprakash K. S. 
Published: July 2002

ABSTRACT

Streptococcus pyogenes
isolates from a tropical region and a subtropical region of Australia with high and low incidences of severe streptococcal diseases, respectively, were analyzed for
speA
,
speB
, and
speC
gene distributions and NAD-glycohydrolase expression. No direct correlation of these characteristics with a propensity to cause invasive diseases was observed.
Impact of Cytokines on Replication in the Thymus of Primary Human Immunodeficiency Virus Type 1 Isolates from Infants
Authors: Pedroza-Martins Livia , Boscardin W. John , Anisman-Posner Deborah J. , Schols Dominique , Bryson Yvonne J. , Uittenbogaart Christel H. 
Published: July 2002

ABSTRACTEarly infection of the thymus with the human immunodeficiency virus (HIV) may explain the more rapid disease progression among children infected in utero than in children infected intrapartum. Therefore, we analyzed infection of thymocytes in vitro by HIV type 1 primary isolates, obtained at or near birth, from 10 children with different disease outcomes. HIV isolates able to replicate in the thymus and impact thymopoiesis were present in all infants, regardless of the timing of viral transmission and the rate of disease progression. Isolates from newborns utilized CCR5, CXCR4, or both chemokine receptors to enter thymocytes. Viral expression was observed in discrete thymocyte subsets postinfection with HIV isolates using CXCR4 (X4) and isolates using CCR5 (R5), despite the wider distribution of CXCR4 in the thymus. In contrast to previous findings, the X4 primary isolates were not more cytopathic for thymocytes than were the R5 isolates. The cytokines interleukin-2 (IL-2), IL-4, and IL-7 increased HIV replication in the thymus by inducing differentiation and expansion of mature CD27+thymocytes expressing CXCR4 or CCR5. IL-2 and IL-4 together increased expression of CXCR4 and CCR5 in this population, whereas IL-4 and IL-7 increased CXCR4 but not CCR5 expression. IL-2 plus IL-4 increased the viral production of all pediatric isolates, but IL-4 and IL-7 had a significantly higher impact on the replication of X4 isolates compared to R5 isolates. Our studies suggest that coreceptor use by HIV primary isolates is important but is not the sole determinant of HIV pathogenesis in the thymus.
The Lipopolysaccharide and β-1,3-Glucan Binding Protein Gene Is Upregulated in White Spot Virus-Infected Shrimp (Penaeus stylirostris)
Authors: Roux Michelle M. , Pain Arnab , Klimpel Kurt R. , Dhar Arun K. 
Published: July 2002

ABSTRACTPattern recognition proteins such as lipopolysaccharide and β-1,3-glucan binding protein (LGBP) play an important role in the innate immune response of crustaceans and insects. Random sequencing of cDNA clones from a hepatopancreas cDNA library of white spot virus (WSV)-infected shrimp provided a partial cDNA (PsEST-289) that showed similarity to the LGBP gene of crayfish and insects. Subsequently full-length cDNA was cloned by the 5′-RACE (rapid amplification of cDNA ends) technique and sequenced. The shrimp LGBP gene is 1,352 bases in length and is capable of encoding a polypeptide of 376 amino acids that showed significant similarity to homologous genes from crayfish, insects, earthworms, and sea urchins. Analysis of the shrimp LGBP deduced amino acid sequence identified conserved features of this gene family including a potential recognition motif for β-(1→3) linkage of polysaccharides and putative RGD cell adhesion sites. It is known that LGBP gene expression is upregulated in bacterial and fungal infection and that the binding of lipopolysaccharide and β-1,3-glucan to LGBP activates the prophenoloxidase (proPO) cascade. The temporal expression of LGBP and proPO genes in healthy and WSV-challengedPenaeus stylirostrisshrimp was measured by real-time quantitative reverse transcription-PCR, and we showed that LGBP gene expression in shrimp was upregulated as the WSV infection progressed. Interestingly, the proPO expression was upregulated initially after infection followed by a downregulation as the viral infection progressed. The downward trend in the expression of proPO coincided with the detection of WSV in the infected shrimp. Our data suggest that shrimp LGBP is an inducible acute-phase protein that may play a critical role in shrimp-WSV interaction and that the WSV infection regulates the activation and/or activity of the proPO cascade in a novel way.
Amino Acid Substitutions in the V Domain of Nectin-1 (HveC) That Impair Entry Activity for Herpes Simplex Virus Types 1 and 2 but Not for Pseudorabies Virus or Bovine Herpesvirus 1
Authors: Martinez Wanda M. , Spear Patricia G. 
Published: July 2002

ABSTRACTThe entry of herpes simplex virus (HSV) into cells requires the interaction of viral glycoprotein D (gD) with a cellular gD receptor to trigger the fusion of viral and cellular membranes. Nectin-1, a member of the immunoglobulin superfamily, can serve as a gD receptor for HSV types 1 and 2 (HSV-1 and HSV-2, respectively) as well as for the animal herpesviruses porcine pseudorabies virus (PRV) and bovine herpesvirus 1 (BHV-1). The HSV-1 gD binding domain of nectin-1 is hypothesized to overlap amino acids 64 to 104 of the N-terminal variable domain-like immunoglobulin domain. Moreover, the HSV-1 and PRV gDs compete for binding to nectin-1. Here we report that two amino acids within this region, at positions 77 and 85, are critical for HSV-1 and HSV-2 entry but not for the entry of PRV or BHV-1. Replacement of either amino acid 77 or amino acid 85 reduced HSV-1 and HSV-2 gD binding but had a lesser effect on HSV entry activity, suggesting that weak interactions between gD and nectin-1 are sufficient to trigger the mechanism of HSV entry. Substitution of both amino acid 77 and amino acid 85 in nectin-1 significantly impaired entry activity for HSV-1 and HSV-2 and eliminated binding to soluble forms of HSV-1 and HSV-2 gDs but did not impair the entry of PRV and BHV-1. Thus, amino acids 77 and 85 of nectin-1 form part of the interface with HSV gD or influence the conformation of that interface. Moreover, the binding sites for HSV and PRV or BHV-1 gDs on nectin-1 may overlap but are not identical.
pH Reduction as a Trigger for Dissociation of Herpes Simplex Virus Type 1 Scaffolds
Authors: McClelland David A. , Aitken James D. , Bhella David , McNab David , Mitchell Joyce , Kelly Sharon M. , Price Nicholas C. , Rixon Frazer J. 
Published: July 2002

ABSTRACT
Assembly of the infectious herpes simplex virus type 1 virion is a complex, multistage process that begins with the production of a procapsid, which is formed by the condensation of capsid shell proteins around an internal scaffold fashioned from multiple copies of the scaffolding protein, pre-VP22a. The ability of pre-VP22a to interact with itself is an essential feature of this process. However, this self-interaction must subsequently be reversed to allow the scaffolding proteins to exit from the capsid to make room for the viral genome to be packaged. The nature of the process by which dissociation of the scaffold is accomplished is unknown. Therefore, to investigate this process, the properties of isolated scaffold particles were investigated. Electron microscopy and gradient sedimentation studies showed that the particles could be dissociated by low concentrations of chaotropic agents and by moderate reductions in pH (from 7.2 to 5.5). Fluorescence spectroscopy and circular dichroism analyses revealed that there was relatively little change in tertiary and secondary structures under these conditions, indicating that major structural transformations are not required for the dissociation process. We suggest the possibility that dissociation of the scaffold may be triggered by a reduction in pH brought about by the entry of the viral DNA into the capsid.
Hepatitis C Virus Subgenomic Replicons Induce Endoplasmic Reticulum Stress Activating an Intracellular Signaling Pathway
Authors: Tardif Keith D. , Mori Kazutoshi , Siddiqui Aleem 
Published: July 2002

ABSTRACT
Hepatitis C virus (HCV) replicates from a ribonucleoprotein (RNP) complex that is associated with the endoplasmic reticulum (ER) membrane. The replication activities of the HCV subgenomic replicon are shown here to induce ER stress. In response to this stress, cells expressing HCV replicons induce the unfolded protein response (UPR), an ER-to-nucleus intracellular signaling pathway. The UPR is initiated by the proteolytic cleavage of a transmembrane protein, ATF6. The resulting cytoplasmic protein fragment of ATF6 functions as a transcription factor in the nucleus and activates selective genes required for an ER stress response. ATF6 activation leads to increased transcriptional levels of GRP78, an ER luminal chaperone protein. However, the overall level of GRP78 protein is decreased. While ER stress is also known to affect translational attenuation, cells expressing HCV replicons have lower levels of phosphorylation of the α subunit of eukaryotic initiation factor 2. Interestingly, cap-independent internal ribosome entry site-mediated translation directed by the 5′ noncoding region of HCV and GRP78 is activated in cells expressing HCV replicons. These studies provide insight into the effects of HCV replication on intracellular events and the mechanisms underlying liver pathogenesis.
Mutation of the Catalytic Domain of the Foamy Virus Reverse Transcriptase Leads to Loss of Processivity and Infectivity
Authors: Rinke Carolyn S. , Boyer Paul L. , Sullivan Mark D. , Hughes Stephen H. , Linial Maxine L. 
Published: July 2002

ABSTRACT
Foamy virus (FV) replication is resistant to most nucleoside analog reverse transcriptase (RT) inhibitors. In an attempt to create a 2′,3′-dideoxy-3′-thiacytidine (3TC)-sensitive virus, the second residue in the highly conserved YXDD motif of simian foamy virus-chimpanzee (human isolate) [SFVcpz(hu)] RT was changed from Val (V) to Met (M). Unexpectedly, the resultant virus, SFVcpz(hu) RT-V313M, replicated poorly, and Met rapidly reverted to Val. Despite the presence of approximately 50% of wild-type RT activity in RT-V313M virions, full-length DNA products were not detected in transfected cells. Using purified recombinant enzymes, we found that the wild-type FV RT is significantly more processive than human immunodeficiency virus type 1 RT. However, the V313M mutant has about 40% of the wild-type level of FV RT activity and has a lower processivity than the wild-type FV enzyme. The V313M mutant RT is also relatively resistant to 3TC. These results suggest that the decrease in RT activity and processivity of FV RT-V313M prevents completion of reverse transcription and greatly diminishes viral replication.
Analysis of Antigenicity and Topology of E2 Glycoprotein Present on Recombinant Hepatitis C Virus-Like Particles
Authors: Clayton Reginald F. , Owsianka Ania , Aitken Jim , Graham Susan , Bhella David , Patel Arvind H. 
Published: July 2002

ABSTRACT

Purification of hepatitis C virus (HCV) from sera of infected patients has proven elusive, hampering efforts to perform structure-function analysis of the viral components. Recombinant forms of the viral glycoproteins have been used instead for functional studies, but uncertainty exists as to whether they closely mimic the virion proteins. Here, we used HCV virus-like particles (VLPs) generated in insect cells infected with a recombinant baculovirus expressing viral structural proteins. Electron microscopic analysis revealed a population of pleomorphic VLPs that were at least partially enveloped with bilayer membranes and had viral glycoprotein spikes protruding from the surface. Immunogold labeling using specific monoclonal antibodies (MAbs) demonstrated these protrusions to be the E1 and E2 glycoproteins. A panel of anti-E2 MAbs was used to probe the surface topology of E2 on the VLPs and to compare the antigenicity of the VLPs with that of truncated E2 (E2
660
) or the full-length (FL) E1E2 complex expressed in mammalian cells. While most MAbs bound to all forms of antigen, a number of others showed striking differences in their abilities to recognize the various E2 forms. All MAbs directed against hypervariable region 1 (HVR-1) recognized both native and denatured E2
660
with comparable affinities, but most bound either weakly or not at all to the FL E1E2 complex or to VLPs. HVR-1 on VLPs was accessible to these MAbs only after denaturation. Importantly, a subset of MAbs specific for amino acids 464 to 475 and 524 to 535 recognized E2
660
but not VLPs or FL E1E2 complex. The antigenic differences between E2
660,
FL E1E2, and VLPs strongly point to the existence of structural differences, which may have functional relevance. Trypsin treatment of VLPs removed the N-terminal part of E2, resulting in a 42-kDa fragment. In the presence of detergent, this was further reduced to a trypsin-resistant 25-kDa fragment, which could be useful for structural studies.
Differential Transmission of Human Immunodeficiency Virus Type 1 by Distinct Subsets of Effector Dendritic Cells
Authors: Sanders Rogier W. , de Jong Esther C. , Baldwin Christopher E. , Schuitemaker Joost H. N. , Kapsenberg Martien L. , Berkhout Ben 
Published: July 2002

ABSTRACTDendritic cells (DC) support human immunodeficiency virus type 1 (HIV-1) transmission by capture of the virus particle in the mucosa and subsequent transport to the draining lymph node, where HIV-1 is presented to CD4+Th cells. Virus transmission involves a high-affinity interaction between the DC-specific surface molecule DC-SIGN and the viral envelope glycoprotein gp120 and subsequent internalization of the virus, which remains infectious. The mechanism of viral transmission from DC to T cells is currently unknown. Sentinel immature DC (iDC) develop into Th1-promoting effector DC1 or Th2-promoting DC2, depending on the activation signals. We studied the ability of these effector DC subsets to support HIV-1 transmission in vitro. Compared with iDC, virus transmission is greatly upregulated for the DC1 subset, whereas DC2 cells are inactive. Increased transmission by DC1 correlates with increased expression of ICAM-1, and blocking studies confirm that ICAM-1 expression on DC is important for HIV transmission. The ICAM-1-LFA-1 interaction is known to be important for immunological cross talk between DC and T cells, and our results indicate that this cell-cell contact is exploited by HIV-1 for efficient transmission.
Pharmacological Cyclin-Dependent Kinase Inhibitors Inhibit Replication of Wild-Type and Drug-Resistant Strains of Herpes Simplex Virus and Human Immunodeficiency Virus Type 1 by Targeting Cellular, Not Viral, Proteins
Authors: Schang Luis M. , Bantly Andrew , Knockaert Marie , Shaheen Farida , Meijer Laurent , Malim Michael H. , Gray Nathanael S. , Schaffer Priscilla A. 
Published: July 2002

ABSTRACTPharmacological cyclin-dependent kinase (cdk) inhibitors (PCIs) block replication of several viruses, including herpes simplex virus type 1 (HSV-1) and human immunodeficiency virus type 1 (HIV-1). Yet, these antiviral effects could result from inhibition of either cellular cdks or viral enzymes. For example, in addition to cellular cdks, PCIs could inhibit any of the herpesvirus-encoded kinases, DNA replication proteins, or proteins involved in nucleotide metabolism. To address this issue, we asked whether purine-derived PCIs (P-PCIs) inhibit HSV and HIV-1 replication by targeting cellular or viral proteins. P-PCIs inhibited replication of HSV-1 and -2 and HIV-1, which require cellular cdks to replicate, but not vaccinia virus or lymphocytic choriomeningitis virus, which are not known to require cdks to replicate. P-PCIs also inhibited strains of HSV-1 and HIV-1 that are resistant to conventional antiviral drugs, which target viral proteins. In addition, the anti-HSV effects of P-PCIs and a conventional antiherpesvirus drug, acyclovir, were additive, demonstrating that the two drugs act by distinct mechanisms. Lastly, the spectrum of proteins that bound to P-PCIs in extracts of mock- and HSV-infected cells was the same. Based on these observations, we conclude that P-PCIs inhibit virus replication by targeting cellular, not viral, proteins.
Bunyamwera Bunyavirus Nonstructural Protein NSs Counteracts the Induction of Alpha/Beta Interferon
Authors: Weber Friedemann , Bridgen Anne , Fazakerley John K. , Streitenfeld Hein , Kessler Nina , Randall Richard E. , Elliott Richard M. 
Published: July 2002

ABSTRACT

Production of alpha/beta interferons (IFN-α/β) in response to viral infection is one of the main defense mechanisms of the innate immune system. Many viruses therefore encode factors that subvert the IFN system to enhance their virulence.
Bunyamwera virus
(BUN) is the prototype of the
Bunyaviridae
family. By using reverse genetics, we previously produced a recombinant virus lacking the nonstructural protein NSs (BUNdelNSs) and showed that NSs is a nonessential gene product that contributes to viral pathogenesis. Here we demonstrate that BUNdelNSs is a strong inducer of IFN-α/β, whereas in cells infected with the wild-type counterpart expressing NSs (wild-type BUN), neither IFN nor IFN mRNA could be detected. IFN induction by BUNdelNSs correlated with activation of NF-κB and was dependent on virally produced double-stranded RNA and on the IFN transcription factor IRF-3. Furthermore, both in cultured cells and in mice lacking a functional IFN-α/β system, BUNdelNSs replicated to wild-type BUN levels, whereas in IFN-competent systems, wild-type BUN grew more efficiently. These results suggest that BUN NSs is an IFN induction antagonist that blocks the transcriptional activation of IFN-α/β in order to increase the virulence of Bunyamwera virus.
Role for Macrophage Inflammatory Protein 2 (MIP-2), MIP-1α, and Interleukin-1α in the Delayed-Type Hypersensitivity Response to Viral Antigen
Authors: Tumpey Terrence M. , Fenton Robin , Molesworth-Kenyon Sara , Oakes John E. , Lausch Robert N. 
Published: July 2002

ABSTRACTBALB/c mice sensitized to herpes simplex virus type 1 (HSV-1) develop a vigorous delayed-type hypersensitivity (DTH) response upon intradermal virus antigen challenge. Although CD4+T cells are a key mediator of this response, neutrophils are the most abundant cells at the antigen challenge site both initially and at the peak of the reaction. We investigated what role, if any, neutrophils play in the DTH to a viral antigen. We show here that antibody-mediated depletion of neutrophils 1 day before antigen challenge significantly suppressed ear swelling and markedly reduced cellular influx. Additionally, neutrophil depletion was associated with decreased expression of macrophage inflammatory protein 2 (MIP-2) and MIP-1α, as well as with a >60-fold increase in HSV-1 replication. Neutralizing antibodies to neutrophil chemoattractants MIP-2 or MIP-1α but not KC significantly suppressed DTH and sharply reduced neutrophil accumulation in the ear pinna. Purified bone marrow-derived neutrophils exposed to interleukin-1α (IL-1α) produced chemokines in an 8-h assay. Administration of neutralizing antibody to IL-1α significantly reduced ear swelling and suppressed the levels of MIP-2, MIP-1α, MIP-1β, and RANTES. We conclude that neutrophils are a critical component of the DTH response to viral antigen. They are recruited to the DTH test site by MIP-2 and MIP-1α, where they can be activated by IL-1α. The infiltrating cells also help suppress virus replication in immunized mice.