bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction betweenMycoplasma hyopneumoniaeand Swine Influenza Virus
Authors: Thacker Eileen L. , Thacker Brad J. , Janke Bruce H. 
Published: July 2002

ABSTRACTAn experimental respiratory model was used to investigate the interaction betweenMycoplasma hyopneumoniaeand swine influenza virus (SIV) in the induction of pneumonia in susceptible swine. Previous studies demonstrated thatM. hyopneumoniae, which produces a chronic bronchopneumonia in swine, potentiates a viral pneumonia induced by the porcine reproductive and respiratory syndrome virus (PRRSV). In this study, pigs were inoculated withM. hyopneumoniae21 days prior to inoculation with SIV. Clinical disease as characterized by the severity of cough and fever was evaluated daily. Percentages of lung tissue with visual lesions and microscopic lesions were assessed upon necropsy at 3, 7, 14, and 21 days following SIV inoculation. Clinical observations revealed that pigs infected with both SIV andM. hyopneumoniaecoughed significantly more than pigs inoculated with a single agent. Macroscopic pneumonia on necropsy at days 3 and 7 was greatest in both SIV-infected groups, with minimal levels of pneumonia in theM. hyopneumoniae-only-infected pigs. At 14 days post-SIV inoculation, pneumonia was significantly more severe in pigs infected with both pathogens. However, by 21 days postinoculation, the level of pneumonia in the dual-infected pigs was similar to that of theM. hyopneumoniae-only-infected group, and the pneumonia in the pigs inoculated with only SIV was nearly resolved. Microscopically, there was no apparent increase in the severity of pneumonia in pigs infected with both agents compared to that of single-agent-challenged pigs. The results of this study found that while pigs infected with both agents exhibited more severe clinical disease, the relationship between the two pathogens lacked the profound potentiation found with dual infection withM. hyopneumoniaeand PRRSV. These findings demonstrate that the relationship between mycoplasmas and viruses varies with the individual agent.
Heminested Multiplex Reverse Transcription-PCR for Detection and Differentiation of Norwalk-Like Virus Genogroups 1 and 2 in Fecal Samples
Authors: Yuen Lilly K. W. , Catton Michael G. , Cox Bradley J. , Wright Peter J. , Marshall John A. 
Published: July 2002

ABSTRACT
The present study describes a heminested multiplex reverse transcription (RT)-PCR assay which enables simultaneous detection and differentiation of Norwalk-like virus (NLV) genogroups from clinical fecal samples without the need to perform sequencing or hybridization. The assay developed was able to detect concentrations of fewer than 100 viral particles per 5 μl of clarified fecal extract and could differentiate the two genogroups with a specificity of 100%. Although the multiplex RT-PCR assay failed to detect NLV in about 3% of the fecal samples which were NLV positive by electron microscopy (EM), the assay was approximately six times more sensitive than EM for NLV detection.
Application of Real-Time Fluorescent PCR for Quantitative Assessment of
Neospora caninum
Infections in Organotypic Slice Cultures of Rat Central Nervous System Tissue
Authors: Müller Norbert , Vonlaufen Nathalie , Gianinazzi Christian , Leib Stephen L. , Hemphill Andrew 
Published: July 2002

ABSTRACT

The previously described Nc5-specific PCR test for the diagnosis of
Neospora caninum
infections was used to develop a quantitative PCR assay which allows the determination of infection intensities within different experimental and diagnostic sample groups. The quantitative PCR was performed by using a dual fluorescent hybridization probe system and the LightCycler Instrument for online detection of amplified DNA. This assay was successfully applied for demonstrating the parasite proliferation kinetics in organotypic slice cultures of rat brain which were infected in vitro with
N. caninum
tachyzoites. This PCR-based method of parasite quantitation with organotypic brain tissue samples can be regarded as a novel ex vivo approach for exploring different aspects of cerebral
N. caninum
infection.
Comparison of Real-Time, Quantitative PCR with Molecular Beacons to Nested PCR and Culture Methods for Detection ofMycobacterium aviumsubsp.paratuberculosisin Bovine Fecal Samples
Authors: Fang Ying , Wu Wai-Hong , Pepper Jessica L. , Larsen Jill L. , Marras Salvatore A. E. , Nelson Eric. A. , Epperson William B. , Christopher-Hennings Jane 
Published: July 2002

ABSTRACTAn automated PCR with fluorescent probes (molecular beacons) detectedMycobacterium aviumsubsp.paratuberculosisin bovine feces. When the PCR was compared with culture in testing 41 fecal samples, kappa scores of 0.94 to 0.96, a sensitivity of 93 to 96%, and a specificity of 92% were obtained. Results were quantitated by using a standard curve derived from a plasmid containing IS900. A minimum quantity of 1.7 × 10−4pg of DNA, correlating to 1 to 8 CFU, was detected.
Evaluation of Use of Epstein-Barr Viral Load in Patients after Allogeneic Stem Cell Transplantation To Diagnose and Monitor Posttransplant Lymphoproliferative Disease
Authors: Gärtner Barbara C. , Schäfer Hansjörg , Marggraff Katja , Eisele Günter , Schäfer Marco , Roemer Klaus , Laws Hans-Jürgen , Sester Martina , Sester Urban , Einsele Hermann , Mueller-Lantzsch Nikolaus 
Published: July 2002

ABSTRACT

Epstein-Barr virus (EBV)-induced posttransplant lymphoproliferative disease (PTLD) continues to be a serious complication following transplantation. The aim of the present study was to evaluate the EBV load as a parameter for the prediction and monitoring of PTLD. The EBV load was analyzed by a quantitative competitive PCR with 417 whole-blood samples of 59 patients after allogeneic stem cell transplantation (SCT). The EBV load was positive for all 9 patients with PTLD and for 17 patients without PTLD. The viral loads of patients with manifest PTLD differed from the loads of those without PTLD (median loads, 1.4 × 10
6
versus 4 × 10
4
copies/μg of DNA;
P
< 0.0001). A threshold value of 10
5
copies/μg of DNA showed the best diagnostic efficacy (sensitivity, 87%; specificity, 91%). However, in patients with less than three major risk factors for PTLD, the positive predictive value of this threshold was rather low. One week prior to the manifestation of PTLD, the EBV load was as low in patients who developed PTLD as in patients without disease (median, 2.2 × 10
4
copies/μg of DNA;
P
was not significant). EBV DNA tested positive first at 20 to 71 days prior to the clinical manifestation of PTLD and occurred with the same delay after transplantation regardless of disease (median delay, 52 versus 63 days;
P
was not significant). EBV DNA was detected earlier in patients with primary infections than in those with reactivations (33 versus 79 days;
P
= 0.01), but the peak levels were similar in the two groups. EBV primary infection or EBV reactivation is frequent in patients after allogeneic SCT but results in PTLD only in a subgroup of patients. Although evaluation of the EBV load has limitations, the EBV load represents a valuable parameter to guide therapy.
Quantification of Feline Herpesvirus 1 DNA in Ocular Fluid Samples of Clinically Diseased Cats by Real-Time TaqMan PCR
Authors: Vögtlin A. , Fraefel C. , Albini S. , Leutenegger C. M. , Schraner E. , Spiess B. , Lutz H. , Ackermann M. 
Published: July 2002

ABSTRACTA fluorogenic PCR was established for the quantification of feline herpesvirus 1 (FeHV-1) DNA in ocular fluid samples of clinically diseased cats. The new assay was specific for FeHV-1 and sensitive. The 100% detection rate ranged from 0.6 to 6 50% tissue culture infective doses per sample. When spiked samples with known quantities of virus were used, infectious virus titers and quantification of viral DNA by PCR correlated to each other in a linear fashion (R2= 0.9858) over a range of 4 orders of magnitude. Within this range, it was possible to calculate the FeHV-1 DNA content from a given infectious dose, and vice versa. The new diagnostic procedure was applied to ocular fluid samples from cats experimentally infected with FeHV-1 and specific FeHV-1-free cats. A good correlation between virus titer and quantitative PCR was observed, although only early in infection. In a second stage, the titer of infectious virus collapsed, while the PCR signal remained high. A constantly decreasing PCR signal accompanied by negative virus isolation was characteristic for a final stage of the infection. Finally, clinical samples from 20 cats that were suspected to suffer from FeHV-1 infection were analyzed. By comparing virus titers and quantitative PCR signals, it was possible to determine the current stage of the ongoing infection. Based on these findings, comparison of the results of consecutive samples allows the tracking of the course of the infection. Therefore, the new method combines the advantages of the two previously established conventional methods, qualitative PCR and virus isolation and titration.
Unusual Outbreak of Clinical Mastitis in Dairy Sheep Caused by
Streptococcus equi
subsp.
zooepidemicus
Authors: Las Heras Alfonso , Vela Ana I. , Fernández Elena , Legaz Emilio , Domínguez Lucas , Fernández-Garayzábal Jose F. 
Published: July 2002

ABSTRACT

This work describes an outbreak of clinical mastitis affecting 13 of 58 lactating ewes due to
Streptococcus equi
subsp.
zooepidemicus. S. equi
subsp.
zooepidemicus
was isolated in pure culture from all milk samples. All the clinical isolates had identical biochemical profiles and antimicrobial susceptibility patterns and also exhibited indistinguishable macrorestriction patterns by pulsed-field gel electrophoresis, indicating that all cases of mastitis were produced by a single strain.
Trends in Antifungal Susceptibility of
Candida
spp. Isolated from Pediatric and Adult Patients with Bloodstream Infections: SENTRY Antimicrobial Surveillance Program, 1997 to 2000
Authors: Pfaller M. A. , Diekema D. J. , Jones R. N. , Messer S. A. , Hollis R. J. 
Published: July 2002

ABSTRACT

From 1 January 1997 through 31 December 2000, 2,047 bloodstream infections (BSIs) due to
Candida
spp. were reported from hospitals in the United States, Canada, Latin America, and Europe participating in the SENTRY Antifungal Surveillance Program. Among individuals in four age groups (≤1, 2 to 15, 16 to 64, and ≥65 years)
Candida albicans
was the most common species, causing 60, 55, 55, and 50% of infections, respectively.
C. glabrata
caused 17 to 23% of BSIs in those ages 16 to 64 and ≥65 years, whereas it caused only 3% of BSIs in the individuals in the two younger age groups (
P
< 0.001).
C. parapsilosis
(which caused 21 to 24% of BSIs) and
C. tropicalis
(which caused 7 to 10% of BSIs) were more common than
C. glabrata
in individuals ages ≤1 year and 2 to 15 years. Isolates of
Candida
spp. showed a trend of decreasing susceptibility to fluconazole, itraconazole, and amphotericin B with increasing patient age (
P
≤ 0.01). None of the
C. glabrata
isolates from individuals ≤1 year old were resistant to fluconazole, whereas they made up 5 to 9% of isolates from individuals ages 16 to 64 and ≥65 years. Isolates of
C. tropicalis
from patients ≤1 year old were more susceptible to flucytosine (MIC at which 90% of isolates are inhibited [MIC
90
], 0.5 μg/ml; 0% resistant isolates) than those from patients ≥65 years old (MIC
90
, 32 μg/ml; 11% resistant isolates). The investigational triazoles posaconazole, ravuconazole, and voriconazole were all highly active against all species of
Candida
from individuals in all age groups. These data demonstrate differences in the species distributions of pathogens and differences in antifungal resistance among isolates from individuals in the pediatric and adult age groups. Ongoing surveillance will enhance efforts to limit the extent of antifungal resistance in individuals in various age groups.
Rapid Detection of Shiga Toxin-Producing Bacteria in Feces by Multiplex PCR with Molecular Beacons on the Smart Cycler
Authors: Bélanger Simon D. , Boissinot Maurice , Ménard Christian , Picard François J. , Bergeron Michel G. 
Published: July 2002

ABSTRACT

We have developed a rapid (1-h) real-time fluorescence-based PCR assay with the Smart Cycler thermal cycler (Cepheid, Sunnyvale, Calif.) for the detection of Shiga toxin-producing
Escherichia coli
(STEC), as well as other Shiga toxin-producing bacteria. Based on multiple-sequence alignments, we have designed two pairs of PCR primers that efficiently amplify all variants of the Shiga toxin genes
stx
1
and
stx
2
, respectively. These primer pairs were combined for use in a multiplex assay. Two molecular beacons bearing different fluorophores were used as internal probes specific for each amplicon. Assays performed with purified genomic DNA from a variety of STEC strains (
n
= 23) from diverse geographic locations showed analytical sensitivities of about 10 genome copies per PCR. Non-STEC strains (
n
= 20) were also tested, and no amplification was observed. The PCR results correlated perfectly with the phenotypic characterization of toxin production in both STEC and non-STEC strains, thereby confirming the specificity of the assay. The assay was validated by testing 38 fecal samples obtained from 27 patients. Of these samples, 26 were PCR positive for
stx
1
and/or
stx
2
. Compared with the culture results, both the sensitivity and the negative predictive value were 100%. The specificity was 92%, and the positive predictive value was 96%. Moreover, this assay detected STEC from a sample in which the STEC concentration was at the limit of detection of the conventional culture methods and from a sample in which STEC was not detected by the conventional culture methods. This real-time PCR assay is simple, rapid, sensitive, and specific and allows detection of all Shiga toxin-producing bacteria directly from fecal samples, irrespective of their serotypes.
Comparison of
gyrA
Mutations, Cyclohexane Resistance, and the Presence of Class I Integrons in
Salmonella enterica
from Farm Animals in England and Wales
Authors: Liebana Ernesto , Clouting Carol , Cassar Claire A. , Randall Luke P. , Walker Rachel A. , Threlfall E. John , Clifton-Hadley Felicity A. , Ridley Anne M. , Davies Robert H. 
Published: July 2002

ABSTRACT

This study is focused on real-time detection of
gyrA
mutations and of the presence of class I integrons in a panel of 100 veterinary isolates of
Salmonella enterica
from farm animals. The isolates were selected on the basis of resistance to nalidixic acid, representing a variety of the most prevalent serotypes in England and Wales. In addition, organic solvent (cyclohexane) resistance in these isolates was investigated in an attempt to elucidate the presence of efflux pump mechanisms. The most prevalent mutation among the isolates studied was Asp87-Asn (
n
= 42), followed by Ser83-Phe (
n
= 38), Ser83-Tyr (
n
= 12), Asp87-Tyr (
n
= 4), and Asp87-Gly (
n
= 3). Two distinct subpopulations were identified, separated at the 1-mg/liter breakpoint for ciprofloxacin: 86% of isolates with mutations in codon 83 showed MICs of ≥1 mg/liter, while 89.8% of isolates with mutations in codon 87 presented MICs of ≤0.5 mg/liter. Cyclohexane resistance was more prevalent among Ser83 mutants than among Asp87 mutants (34.7 and 4%, respectively), and in 79% of isolates that presented both
gyrA
mutations and cyclohexane resistance, the level of ciprofloxacin resistance was ≥2.0 mg/liter. Thirty-four isolates contained class I integrons, with 71% of the
S. enterica
serovar Typhimurium isolates and 6.9% of isolates belonging to other serotypes containing such elements. The methods used represent sensitive ways of investigating the presence of
gyrA
mutations and of detecting class-I integrons in
Salmonella
isolates. The results can be obtained in less than 1 h from single colonies without the need for purifying DNA.
Molecular Diagnosis of
Granulicatella elegans
on the Cardiac Valve of a Patient with Culture-Negative Endocarditis
Authors: Casalta J. P. , Habib G. , La Scola B. , Drancourt M. , Caus T. , Raoult D. 
Published: July 2002

ABSTRACT

We herein report one case of culture-negative infectious endocarditis (IE) where the organism,
Granulicatella elegans
, was identified by molecular analysis using broad-range PCR primers complementary to the 16S rRNA gene on the removed valve. The results and utility of this method are discussed.
Adenovirus Late Gene Expression Does Not Require a Rev-Like Nuclear RNA Export Pathway
Authors: Rabino Claudia , Aspegren Anders , Corbin-Lickfett Kara , Bridge Eileen 
Published: July 2002

ABSTRACT
Adenovirus late mRNA export is facilitated by viral early proteins of 55 and 34 kDa. The 34-kDa protein contains a leucine-rich nuclear export signal (NES) similar to that of the human immunodeficiency virus Rev protein. It was proposed that the 34-kDa protein might facilitate the export of adenovirus late mRNA through a Rev-like NES-mediated export pathway. We have tested the role of NES-mediated RNA export during adenovirus infection, and we find that it is not essential for the expression of adenovirus late genes.
The Interaction of Vpr with Uracil DNA Glycosylase Modulates the Human Immunodeficiency Virus Type 1 In Vivo Mutation Rate
Authors: Mansky Louis M. , Preveral Sandra , Selig Luc , Benarous Richard , Benichou Serge 
Published: July 2002

ABSTRACT

The Vpr protein of human immunodeficiency virus type 1 (HIV-1) influences the in vivo mutation rate of the virus. Since Vpr interacts with a cellular protein implicated in the DNA repair process, uracil DNA glycosylase (UNG), we have explored the contribution of this interaction to the mutation rate of HIV-1. Single-amino-acid variants of Vpr were characterized for their differential UNG-binding properties and used to
trans
complement
vpr
null mutant HIV-1. A striking correlation was established between the abilities of Vpr to interact with UNG and to influence the HIV-1 mutation rate. We demonstrate that Vpr incorporation into virus particles is required to influence the in vivo mutation rate and to mediate virion packaging of the nuclear form of UNG. The recruitment of UNG into virions indicates a mechanism for how Vpr can influence reverse transcription accuracy. Our data suggest that distinct mechanisms evolved in primate and nonprimate lentiviruses to reconcile uracil misincorporation into lentiviral DNA.
Activation of Interferon Regulatory Factor 3 Is Inhibited by the Influenza A Virus NS1 Protein
Authors: Talon Julie , Horvath Curt M. , Polley Rosalind , Basler Christopher F. , Muster Thomas , Palese Peter , García-Sastre Adolfo 
Published: July 2002

ABSTRACT

We present a novel mechanism by which viruses may inhibit the alpha/beta interferon (IFN-α/β) cascade. The double-stranded RNA (dsRNA) binding protein NS1 of influenza virus is shown to prevent the potent antiviral interferon response by inhibiting the activation of interferon regulatory factor 3 (IRF-3), a key regulator of IFN-α/β gene expression. IRF-3 activation and, as a consequence, IFN-β mRNA induction are inhibited in wild-type (PR8) influenza virus-infected cells but not in cells infected with an isogenic virus lacking the NS1 gene (delNS1 virus). Furthermore, NS1 is shown to be a general inhibitor of the interferon signaling pathway. Inhibition of IRF-3 activation can be achieved by the expression of wild-type NS1 in
trans
, not only in delNS1 virus-infected cells but also in cells infected with a heterologous RNA virus (Newcastle disease virus). We propose that inhibition of IRF-3 activation by a dsRNA binding protein significantly contributes to the virulence of influenza A viruses and possibly to that of other viruses.
Lack of Functional Receptors Is the Only Barrier That Prevents Caprine Arthritis-Encephalitis Virus from Infecting Human Cells
Authors: Mselli-Lakhal Laila , Favier Colette , Leung Kevin , Guiguen Francois , Grezel Delphine , Miossec Pierre , Mornex Jean-François , Narayan Opendra , Querat Gilles , Chebloune Yahia 
Published: July 2002

ABSTRACTBarriers to replication of viruses in potential host cells may occur at several levels. Lack of suitable and functional receptors on the host cell surface, thereby precluding entry of the virus, is a frequent reason for noninfectivity, as long as no alternative way of entry (e.g., pinocytosis, antibody-dependent adsorption) can be exploited by the virus. Other barriers can intervene at later stages of the virus life cycle, with restrictions on transcription of the viral genome, incorrect translation and posttranslational processing of viral proteins, inefficient viral assembly, and release or efficient early induction of apoptosis in the infected cell. The data we present here demonstrate that replication of caprine arthritis-encephalitis virus (CAEV) is restricted in a variety of human cell lines and primary tissue cultures. This barrier was efficiently overcome by transfection of a novel infectious complete-proviral CAEV construct into the same cells. The successful infection of human cells with a vesicular stomatitis virus (VSV) G-pseudotyped Env-defective CAEV confirmed that viral entry is the major obstacle to CAEV infection of human cells. The fully efficient productive infection obtained with the VSV-G-protein-pseudotyped infectious CAEV strengthened the evidence that lack of viral entry is the only practical barrier to CAEV replication in human cells. The virus thus produced retained its original host cell specificity and acquired no propensity to propagate further in human cultures.
Herpes Simplex Virus Types 1 and 2 Differ in Their Interaction with Heparan Sulfate
Authors: Trybala Edward , Liljeqvist Jan-Åke , Svennerholm Bo , Bergström Tomas 
Published: July 2002

ABSTRACTCell surface heparan sulfate (HS) serves as an initial receptor for many different viruses, including herpes simplex virus types 1 and 2 (HSV-1 and 2, respectively). Glycoproteins C and B (gC and gB) are the major components of the viral envelope that mediate binding to HS. In this study, purified gB and gC homologous proteins as well as purified HSV-1 and HSV-2 virions were compared for the ability to bind isolated HS receptor molecules. HSV-1 gC and HSV-2 gC bound comparable amounts of HS. Similarly, HSV-1 gB and its HSV-2 counterpart showed no difference in the HS-binding capabilities. Despite the similar HS-binding potentials of gB and gC homologs, HSV-1 virions bound more HS than HSV-2 particles. Purified gC and gB proteins differed with respect to sensitivity of their interaction with HS to increased concentrations of sodium chloride in the order gB-2 > gB-1 > gC-1 > gC-2. The corresponding pattern for binding of whole HSV virions to cells in the presence of increased ionic strength of the medium was HSV-2 gC-neg1 > HSV-1 gC−39 > HSV-1 KOS 321 > HSV-2 333. These results relate the HS-binding activities of individual glycoproteins with the cell-binding abilities of whole virus particles. In addition, these data suggest a greater contribution of electrostatic forces for binding of gB proteins and gC-negative mutants compared with binding of gC homologs and wild-type HSV strains. Binding of wild-type HSV-2 virions was the least sensitive to increased ionic strength of the medium, suggesting that the less extensive binding of HS molecules by HSV-2 than by HSV-1 can be compensated for by a relatively weak contribution of electrostatic forces to the binding. Furthermore, gB and gC homologs exhibited different patterns of sensitivity of binding to cells to inhibition with selectively N-, 2-O-, and 6-O-desulfated heparin compounds. The O-sulfate groups of heparin were found to be more important for interaction with gB-1 than gB-2. These results indicate that HSV-1 and HSV-2 differ in their interaction with HS.