bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transduction-Mediated Transfer of Unmarked Deletion and Point Mutations through Use of Counterselectable Suicide Vectors
Authors: Kang Ho Young , Dozois Charles M. , Tinge Steven A. , Lee Tae Ho , Curtiss Roy 
Published: July 2002

ABSTRACT

A challenge in strain construction is that unmarked deletion and nucleotide substitution alleles generally do not confer selectable phenotypes. We describe here a rapid and efficient strategy for transferring such alleles via generalized transduction. The desired allele is first constructed and introduced into the chromosome by conventional allelic-exchange methods. The suicide vector containing the same allele is then integrated into the mutant chromosome, generating a tandem duplication homozygous for that allele. The resulting strain is used as a donor for transductional crosses, and selection is made for a marker carried by the integrated suicide vector. Segregation of the tandem duplication results in haploid individuals, each of which carries the desired allele. To demonstrate this mutagenesis strategy, we used bacteriophage P22H
int
for generalized transduction-mediated introduction of unmarked mutations to
Salmonella enterica
serovar Typhimurium. This method is applicable to any species for which generalized transduction is established.
Mutational Analysis of the TonB1 Energy Coupler ofPseudomonas aeruginosa
Authors: Zhao Qixun , Poole Keith 
Published: July 2002

ABSTRACTSiderophore-mediated iron transport inPseudomonas aeruginosais dependent upon the cytoplasmic membrane-associated TonB1 energy coupling protein for activity. To assess the functional significance of the various regions of this molecule and to identify functionally important residues, thetonB1gene was subjected to site-directed mutagenesis, and the influence on iron acquisition was determined. The novel N-terminal extension of TonB1, which is absent in all other examples of TonB, was required for TonB1 activity in bothP. aeruginosaandEscherichia coli. Appending it to the N terminus of the nonfunctional (inP. aeruginosa)Escherichia coliTonB protein (TonBEc) rendered TonBEcweakly active inP. aeruginosaand did not compromise the activity of this protein inE. coli. Elimination of the membrane-spanning, presumed membrane anchor sequence of TonB1 abrogated TonB1 activity inP. aeruginosaandE. coli. Interestingly, however, a conserved His residue within the membrane anchor sequence, shown to be required for TonBEcfunction inE. coli, was shown here to be essential for TonB1 activity inE. colibut not inP. aeruginosa. Several mutations within the C-terminal end of TonB1, within a region exhibiting the greatest similarity to other TonB proteins, compromised a TonB1 contribution to iron acquisition in bothP. aeruginosaandE. coli, including substitutions at Tyr264, Glu274, Lys278, and Asp304. Mutations at Pro265, Gln293, and Val294 also impacted negatively on TonB1 function inE. colibut not inP. aeruginosa. The Asp304 mutation was suppressed by a second mutation at Glu274 of TonB1 but only inP. aeruginosa. Several TonB1-TonBEcchimeras were constructed, and assessment of their activities revealed that substitutions at the N or C terminus of TonB1 compromised its activity inP. aeruginosa, although chimeras possessing anE. coliC terminus were active inE. coli.
Multiyear Prospective Study of Intestinal Parasitism in a Cohort of Peace Corps Volunteers in Guatemala
Authors: Herwaldt Barbara L. , de Arroyave Kathleen R. , Wahlquist Susanne P. , de Merida Anna Maria , Lopez Adriana S. , Juranek Dennis D. 
Published: July 2002

ABSTRACT

We conducted a prospective, longitudinal study in a cohort of 36 Peace Corps volunteers (PCVs) in Guatemala to study the incidence and natural history of intestinal parasitic infections during the PCVs' >2-year overseas stay. PCVs collected stool specimens at least monthly and when ill with gastrointestinal symptoms. Of the 1,168 specimens tested, 453 (38.8%) were positive for at least one parasite and 48 (4.1%) were positive for a pathogenic parasite. A median interval of 187 days (range, 14 to 752 days) elapsed before the first documented parasitic infection, and the median intervals from arrival until subsequent infections (e.g., second or third) were >300 days. The PCVs had 116 episodes of infection with 11 parasites, including up to 4 episodes per PCV with specific nonpathogens and
Blastocystis hominis
. The incidence, in episodes per 100 person-years, was highest for
B. hominis
(65), followed by
Entamoeba coli
(31),
Cryptosporidium parvum
(17), and
Entamoeba hartmanni
(17). The PCVs'
B. hominis
episodes lasted 6,809 person-days (28.7% of the 23,689 person-days in the study), the
E. coli
episodes lasted 2,055 person-days (8.7%), and each of the other types of episodes lasted <2% of the person-days in the study. Gastrointestinal symptoms were somewhat more common and more persistent, but not significantly so, in association with pathogen episodes than with
B. hominis
and nonpathogen episodes. Although infections with pathogenic parasites could account for only a minority of the PCVs' diarrheal episodes, the continued acquisition of parasitic infections throughout the PCVs' >2-year stay in Guatemala suggests that PCVs repeatedly had fecal exposures and thus were at risk for infections with both parasitic and nonparasitic pathogens throughout their overseas service.
Molecular Epidemiology of
Scedosporium apiospermum
Infection Determined by PCR Amplification of Ribosomal Intergenic Spacer Sequences in Patients with Chronic Lung Disease
Authors: Williamson Emma C. M. , Speers David , Arthur Ian H. , Harnett Gerald , Ryan Gerard , Inglis Tim J. J. 
Published: July 2002

ABSTRACT

Respiratory tract colonization with
Scedosporium apiospermum
in patients with chronic suppurative lung disease is a significant concern for lung transplantation candidates, since
Scedosporium
infections occurring posttransplantation are usually untreatable. Up to 10% of patients with cystic fibrosis attending our respiratory medicine unit have had
Scedosporium
organisms isolated from sputum samples. We therefore developed a molecular typing method to examine these isolates. Typing by PCR amplification of ribosomal intergenic spacer sequences demonstrated 20 different types from 52 isolates collected from the respiratory medicine unit and elsewhere in Australia. A single common type was isolated from 11 respiratory medicine unit inpatients. Two other types were isolated from more than one source: one from two respiratory medicine unit inpatients and one from two epidemiologically linked nonhuman sources. Multiple isolates were obtained from nine patients. This method demonstrated persistent carriage of isolates of the same type in one patient for 7 months. Two patients showed carriage of isolates with multiple typing patterns within a 3-month period. The high rate of isolation and the predominance of isolates with a single typing pattern from respiratory medicine unit patients may suggest transmission to patients from a source in the unit. There was no epidemiological evidence of direct patient-to-patient spread, and
Scedosporium
organisms were not isolated from dust, soil, or air samples from the unit. The source and route of transmission have yet to be determined.
Epidemiologic Usefulness of Spoligotyping for Secondary Typing of
Mycobacterium tuberculosis
Isolates with Low Copy Numbers of IS
6110
Authors: Cronin Wendy A. , Golub Jonathan E. , Magder Laurence S. , Baruch Nancy G. , Lathan Monica J. , Mukasa Leonard N. , Hooper Nancy , Razeq Jafar H. , Mulcahy Donna , Benjamin William H. , Bishai William R. 
Published: July 2002

ABSTRACT

Restriction fragment length polymorphism (RFLP) analysis of IS
6110
is commonly used to DNA fingerprint
Mycobacterium tuberculosis
. However, low-copy (≤5) IS
6110 M. tuberculosis
strains are poorly differentiated, requiring secondary typing. When spoligotyping was used as the secondary method, only 13% of Maryland culture-positive tuberculosis (TB) patients with low-copy IS
6110
-spoligotyped clustered strains had epidemiologic linkages to another patient, compared to 48% of those with high-copy strains clustered by IS
6110
alone (
P
< 0.01). Spoligotyping did not improve a population-based molecular epidemiologic study of recent TB transmission.
Flagella as a Potential Marker forCampylobacter jejuniStrains Associated with Guillain-Barré Syndrome
Authors: Tsang Raymond S. W. , Figueroa Guillermo , Bryden Louis , Ng Lai-King 
Published: July 2002

ABSTRACTCampylobacter jejunirecovered from patients with Guillain-Barré syndrome (GBS) in different geographical locations and bearing different heat-labile and heat-stable antigens were found to have identical amino acid sequences in their flagellarflaAshort variable region, suggesting that it may be a potentially useful marker for GBS association.
Comparison of Two Methods for Serotyping
Campylobacter
spp
Authors: McKay Dorothy , Fletcher June , Cooper Peggy , Thomson-Carter Fiona M. 
Published: July 2002

ABSTRACT

Two serotyping schemes (Penner and Laboratory of Enteric Pathogens [LEP]) based on soluble heat-stable antigens were used to analyze 3,788
Campylobacter
sp. isolates. A significant percentage (36.6%) was untypeable using LEP serotyping; greater cross-reaction was also observed. The relative discrimination capabilities of the techniques were similar. Penner serotyping fulfils more of the requisite criteria for typing methods.
Evaluation of Methods for SubtypingCampylobacter jejuniduring an Outbreak Involving a Food Handler
Authors: Fitzgerald Collette , Helsel Leta O. , Nicholson Mabel A. , Olsen Sonja J. , Swerdlow David L. , Flahart Robert , Sexton June , Fields Patricia I. 
Published: July 2002

ABSTRACTIn October 1998, the Centers for Disease Control and Prevention (CDC) assisted in an investigation of an outbreak of campylobacteriosis at a school in Salina, Kansas. Twenty-two isolates were submitted from the Kansas state public health laboratory to CDC, 9 associated with the outbreak and 13 epidemiologically unrelated sporadic isolates. Pulsed-field gel electrophoresis (PFGE) usingSmaI andSalI was initially used to validate the epidemiologic data. We then tested the ability of other subtyping techniques to distinguish the outbreak-associated isolates from unrelated sporadic isolates. The methods employed were somatic O serotyping, PCR-restriction fragment length polymorphism (RFLP) analysis offlaA, DNA sequence analysis of 582 bp offlaAthat included the short variable region (SVR), and sequencing of the entireflaAgene. PFGE was the most discriminatory technique, yielding 11SmaI and 10SalI restriction profiles. All outbreak isolates were indistinguishable by PFGE, somatic O serotyping, and sequencing of the 582-bp region of theflaAgene.flatyping by PCR-RFLP grouped one sporadic isolate with the outbreak strain. Analysis of the DNA sequence of a 582-bp segment offlaAproduced strain groupings similar to that generated by PCR-RFLP but further differentiated twoflaAPCR-RFLP types (with a 1-bp difference in the 582-bp region). Two sporadic strains were distinct byflaAPCR-RFLP but differed only by a single base substitution in the 582-bp region. The entireflaAgene was sequenced from strains differing by a single base pair in the 582-bp region, and the data revealed that additional discrimination may in some cases be obtained by sequencing outside the SVR. PFGE was superior to all other typing methods tested for strain discrimination; it was crucial for understanding the Kansas outbreak and, whenSmaI was used, provided adequate discrimination between unrelated isolates.
Evaluation of the OptiMAL Rapid Antigen Test and Species-Specific PCR To Detect Placental
Plasmodium falciparum
Infection at Delivery
Authors: Mankhambo Limangeni , Kanjala Maxwell , Rudman Sarah , Lema Valentino M. , Rogerson Stephen J. 
Published: July 2002

ABSTRACT

During pregnancy,
Plasmodium falciparum
infection of the placenta frequently occurs in the absence of parasites in peripheral blood. We investigated the abilities of the OptiMAL rapid immunochromatographic strip test for
P. falciparum
lactate dehydrogenase and species-specific PCR performed on peripheral blood to detect placental infection or malaria-associated low birth weight. Of 509 Malawian women screened by microscopy, 76 had malaria infection. Among these 509 women, the frequency of peripheral blood parasitemia was low. The OptiMAL test gave positive results in 37 of 171 women tested (one of whom had placental but not peripheral blood parasitemia) and had sensitivities of 71% for peripheral parasitemia and 38% for placental parasitemia compared to the microscopy values. The specificity for peripheral parasitemia was 94%. In 135 women, PCR had sensitivities of 94% for peripheral blood malaria detected by microscopy and 72% for placental infection. In samples examined by PCR, the prevalence of malaria in peripheral blood increased from 26.7% by microscopy to 51.9%. Women with placental malaria and women with malaria in peripheral blood samples by microscopy or OptiMAL testing, but not women with malaria detected only by PCR, had lower-birth-weight babies than did women without malaria by these criteria. Positive results by PCR in the absence of microscopic parasitemia were not associated with low birth weight. Neither OptiMAL nor PCR testing of peripheral blood is adequately sensitive to detect all placental malaria infection, but a positive result by OptiMAL testing identifies women with a high proportion of low-birth-weight babies.
Detection of Measles Virus-Specific Immunoglobulin M in Dried Venous Blood Samples by Using a Commercial Enzyme Immunoassay
Authors: Riddell Michaela A. , Leydon Jennie A. , Catton Mike G. , Kelly Heath A. 
Published: July 2002

ABSTRACT
The optical densities (ODs) of 216 dried venous blood (DVB) samples submitted to the Victorian Infectious Diseases Reference Laboratory as part of enhanced measles surveillance were compared to the ODs of the corresponding serum samples collected at the same time. DVB samples, stored for up to 24 months at 4°C, were tested by the Dade Behring Enzygnost Anti-Measles-Virus/IgM immunoassay. Elution and testing conditions were optimized with the use of spiked DVB samples. The assay showed an overall sensitivity of 90.2% and a specificity of 98.8% for DVB samples compared to the results for serum. When the results were analyzed according to the length of time that the DVB sample had been stored, the assay was 100% sensitive and 97% specific according to the ODs for those samples stored for less than 6 months compared to the results for the corresponding serum samples, with 97.7% agreement between the results for the two sample types. These results demonstrate the potential for the use of DVB samples for the diagnosis of measles in routine diagnostic laboratories.
Successful Outcome of Treatment of a Disseminated Infection Due toFusarium dimerumin a Leukemia Patient
Authors: Letscher-Bru Valérie , Campos France , Waller Jocelyn , Randriamahazaka Raoul , Candolfi Ermanno , Herbrecht Raoul 
Published: July 2002

ABSTRACTWe report the first case of proven disseminated infection due toFusarium dimerumassociated with a favorable outcome in a patient with acute leukemia and prolonged neutropenia. The patient presented persistent fever, multiple necrotic skin lesions, and bilateral pneumopathy.F. dimerumwas first isolated from three blood cultures and then from a skin biopsy and a mouth wash. Microscopy of positive blood cultures showed hyphae with phialides and few curved unicellular and some rare bicellular phialoconidia, permitting immediate presumptive identification of the genusFusarium. The patient failed to respond to conventional amphotericin B but recovered after treatment was switched to amphotericin B-lipid complex and neutrophil recovery.
Detection and Characterization of Rotaviruses in Hospitalized Neonates in Blantyre, Malawi
Authors: Cunliffe N. A. , Rogerson S. , Dove W. , Thindwa B. D. M. , Greensill J. , Kirkwood C. D. , Broadhead R. L. , Hart C. A. 
Published: July 2002

ABSTRACT
In five separate fecal collections spanning three years, group A rotaviruses were detected by enzyme-linked immunosorbent assay in 35 (25%) of 142 specimens obtained from nondiarrheic, hospitalized neonates in Blantyre, Malawi. Molecular characterization of each strain identified, for the first time in neonates, a short electropherotype, genotype P[6], G8 strain type, similar to the dominant, cocirculating community strain detected in symptomatic infants in Blantyre. Partial sequence analysis of the VP4 and NSP4 genes of neonatal and community strains failed to identify changes which could explain the differences in clinical outcome. Neonatal serotype G8 rotaviruses should be considered as potential rotavirus vaccine candidates for use in Malawi.
A Hypothesis for DNA Viruses as the Origin of Eukaryotic Replication Proteins
Authors: Villarreal Luis P. , DeFilippis Victor R. 
Published: July 2002

ABSTRACT
The eukaryotic replicative DNA polymerases are similar to those of large DNA viruses of eukaryotic and bacterial T4 phages but not to those of eubacteria. We develop and examine the hypothesis that DNA virus replication proteins gave rise to those of eukaryotes during evolution. We chose the DNA polymerase from phycodnavirus (which infects microalgae) as the basis of this analysis, as it represents a virus of a primitive eukaryote. We show that it has significant similarity with replicative DNA polymerases of eukaryotes and certain of their large DNA viruses. Sequence alignment confirms this similarity and establishes the presence of highly conserved domains in the polymerase amino terminus. Subsequent reconstruction of a phylogenetic tree indicates that these algal viral DNA polymerases are near the root of the clade containing all eukaryotic DNA polymerase delta members but that this clade does not contain the polymerases of other DNA viruses. We consider arguments for the polarity of this relationship and present the hypothesis that the replication genes of DNA viruses gave rise to those of eukaryotes and not the reverse direction.
Incoming Human Cytomegalovirus pp65 (UL83) Contained in Apoptotic Infected Fibroblasts Is Cross-Presented to CD8+T Cells by Dendritic Cells
Authors: Arrode Géraldine , Boccaccio Claire , Lulé Jacqueline , Allart Sophie , Moinard Nathalie , Abastado Jean-Pierre , Alam Antoine , Davrinche Christian 
Published: July 2002

ABSTRACTHuman cytomegalovirus (HCMV) infection is well controlled mainly by cytotoxic CD8+T lymphocytes (CTL) directed against the matrix protein pp65 despite the numerous immune escape mechanisms developed by the virus. Dendritic cells (DCs) are key antigen-presenting cells for the generation of an immune response which have the capacity to acquire antigens via endocytosis of apoptotic cells and thus present peptides to major histocompatibility complex class I-restricted T cells. We examined whether this mechanism could contribute to the activation of anti-pp65 CTL. In this study, we show that infection by HCMV AD169 induced sensitization of MRC5 fibroblasts to tumor necrosis factor alpha-mediated apoptosis very early after virus inoculation and that pp65 contained in apoptotic cells came from the delivery of the matrix protein into the cell. We observed that immature DCs derived from peripheral monocytes were not permissive to HCMV AD169 infection but were able to internalize pp65-positive apoptotic infected MRC5 cells. We then demonstrated that following exposure to these apoptotic bodies, DCs could activate HLA-A2- or HLA-B35-restricted anti-pp65 CTL, suggesting that they acquired and processed properly fibroblast-derived pp65. Together, our data suggest that cross-presentation of incoming pp65 contained in apoptotic cells may provide a quick and efficient way to prime anti-HCMV CD8+T cells.
Adenovirus Types 11p and 35p Show High Binding Efficiencies for Committed Hematopoietic Cell Lines and Are Infective to These Cell Lines
Authors: Segerman Anna , Mei Ya-Fang , Wadell Göran 
Published: July 2002

ABSTRACT

Hematopoietic cells are attractive targets for gene therapy. However, no satisfactory vectors are currently available. A major problem with the most commonly used adenovirus vectors, based on adenovirus type 2 (Ad2) or Ad5, is their low binding efficiency for hematopoietic cells. In this study we identify two adenovirus serotypes with high affinity for hematopoietic cells. The binding efficiency of prototype serotypes Ad4p, Ad11p, and Ad35p for different committed hematopoietic cell lines representing T cells (Jurkat), B cells (DG75), monocytes (U937-2), myeloblasts (K562), and granulocytes (HL-60) was evaluated and compared to that of Ad5v, the commonly used adenovirus vector, using flow cytometry. In contrast to Ad5v, which bound to less than 10% of the cells in all experiments, Ad11p and Ad35p showed high binding efficiency for all of the different hematopoietic cell lines. Ad4p bound to the lymphocytic cell lines to some extent but less well to the myelomonocytic cell lines. The abilities of the different serotypes to infect, replicate, and form complete infectious particles in the hematopoietic cell lines were also investigated by immunostaining,
35
S labeling of viral proteins, and titrations of cell lysates. Ad11p and Ad35p infected the highest proportion of cells, and Ad11p infected all of the cell lines investigated. The Ad11p hexon was expressed equally well in K562 and A549 cells. Jurkat cells also showed high levels of expression of Ad11p hexons, but the production of infectious particles was low. The binding properties of virions were correlated to their ability to infect and be expressed.
Viral Load Increases in SJL/J Mice Persistently Infected by Theiler's Virus after Inactivation of the β2mGene
Authors: Aubagnac Stéphanie , Brahic Michel , Bureau Jean-François 
Published: July 2002

ABSTRACTWe show that inactivating the β2mgene increases the viral load of SJL/J mice persistently infected by Theiler's virus. Together with previous results, this shows that the characteristics ofTmevp1, a locus which controls the amount of viral RNA that persists in the central nervous system, are those of anH-2class I gene.