bluuebunny/crossref_metadata_2025_split huggingface dataset:
The CXC Chemokines Gamma Interferon (IFN-γ)-Inducible Protein 10 and Monokine Induced by IFN-γ Are Released during Severe Melioidosis
Authors: Lauw Fanny N. , Simpson Andrew J. H. , Prins Jan M. , van Deventer Sander J. H. , Chaowagul Wipada , White Nicholas J. , van der Poll Tom 
Published: July 2002

ABSTRACTGamma interferon (IFN-γ)-inducible protein 10 (IP-10) and monokine induced by IFN-γ (Mig) are related CXC chemokines which bind to the CXCR3 receptor and specifically target activated T lymphocytes and natural killer (NK) cells. The production of IP-10 and Mig by various cell types in vitro is strongly dependent on IFN-γ. To determine whether IP-10 and Mig are released during bacterial infection in humans, we measured plasma levels of IP-10 and Mig in patients with melioidosis, a severe gram-negative infection caused byBurkholderia pseudomallei. IP-10 and Mig were markedly elevated in patients with melioidosis on admission, particularly in blood culture-positive patients, and remained elevated during the 72-h study period. Levels of IP-10 and Mig showed a positive correlation with IFN-γ concentrations and also correlated with clinical outcome. In whole blood stimulated with heat-killedB. pseudomallei, neutralization of IFN-γ and tumor necrosis factor alpha (TNF-α) partly attenuated IP-10 and Mig release, while anti-interleukin-12 (IL-12) and anti-IL-18 had a synergistic effect. Stimulation with other bacteria or endotoxin also induced strong secretion of IP-10 and Mig. These data suggest that IP-10 and Mig are part of the innate immune response to bacterial infection. IP-10 and Mig may contribute to host defense in Th1-mediated host defense during infections by attracting CXCR3+Th1 cells to the site of inflammation.
Identification of Glycosaminoglycan Binding Domains in
Plasmodium falciparum
Erythrocyte Membrane Protein 1 of a Chondroitin Sulfate A-Adherent Parasite
Authors: Reeder John C. , Hodder Anthony N. , Beeson James G. , Brown Graham V. 
Published: July 2002

ABSTRACT

Accumulation of
Plasmodium falciparum
-infected erythrocytes in the placenta is a key feature of maternal malaria. This process is mediated in part by the parasite ligand
P. falciparum
erythrocyte membrane protein 1 (PfEMP1) at the surface of the infected erythrocyte interacting with the host receptor chondroitin sulfate A (CSA) on the placental lining. We have localized CSA binding activity to two adjacent domains in PfEMP1 of an adherent parasite line and shown the presence of at least three active glycosaminoglycan binding sites. A putative CSA binding sequence was identified in one domain, but nonlinear binding motifs are also likely to be present, since binding activity in the region was shown to be dependent on conformation. Characterization of this binding region provides an opportunity to investigate further its potential as a target for antiadhesion therapy.
The C Terminus of Component C2II of
Clostridium botulinum
C2 Toxin Is Essential for Receptor Binding
Authors: Blöcker Dagmar , Barth Holger , Maier Elke , Benz Roland , Barbieri Joseph T. , Aktories Klaus 
Published: July 2002

ABSTRACT

The binary
Clostridium botulinum
C2 toxin consists of two separate proteins, the binding component C2II (80.5 kDa) and the actin-ADP-ribosylating enzyme component C2I (49.4 kDa). For its cytotoxic action, C2II binds to a cell membrane receptor and induces cell entry of C2I via receptor-mediated endocytosis. Here we studied the structure-function relationship of C2II by constructing truncated C2II proteins and producing polyclonal antisera against selective regions of C2II. An antibody raised against the C terminus (amino acids 592 to 721) of C2II inhibited binding of C2II to cells. The antibody prevented pore formation by C2II oligomers in artificial membranes but did not influence the properties of existing channels. To further define the region responsible for receptor binding, we constructed proteins with deletions in C2II; specifically, they lacked amino acid residues 592 to 721 and the 7 C-terminal amino acid residues. The truncated proteins still formed sodium dodecyl sulfate-stable oligomers but were unable to bind to cells. Our data indicate that the C terminus of C2II mediates binding of the protein to cells and that the 7 C-terminal amino acids are structurally important for receptor binding.
Switching of Flagellar Motility in
Helicobacter pylori
by Reversible Length Variation of a Short Homopolymeric Sequence Repeat in
fliP
, a Gene Encoding a Basal Body Protein
Authors: Josenhans Christine , Eaton Kathryn A. , Thevenot Tracy , Suerbaum Sebastian 
Published: July 2002

ABSTRACT

The genome of
Helicobacter pylori
contains numerous simple nucleotide repeats that have been proposed to have regulatory functions and to compensate for the conspicuous dearth of master regulatory pathways in this highly host-adapted bacterium.
H. pylori
strain 26695, whose genomic sequence was determined by The Institute for Genomic Research (TIGR), contains a repeat of nine cytidines in the
fliP
flagellar basal body gene that splits the open reading frame in two parts. In this work, we demonstrate that the 26695
C9
strain with a split
fliP
gene as sequenced by TIGR was nonflagellated and nonmotile. In contrast, earlier isolates of strain 26695 selected by positive motility testing as well as pig-passaged derivatives of 26695 were all flagellated and highly motile. All of these motile strains had a C
8
repeat and consequently a contiguous
fliP
reading frame. By screening approximately 50,000 colonies of 26695
C9
for motility in soft agar, a motile revertant with a C
8
repeat could be isolated, proving that the described switch is reversible. The
fliP
genes of 20 motile clinical
H. pylori
isolates from different geographic regions possessed intact
fliP
genes with repeats of eight cytidines or the sequence CCCCACCC in its place. Isogenic
fliP
mutants of a motile, C
8
repeat isolate of strain 26695 were constructed by allelic exchange mutagenesis and found to be defective in flagellum biogenesis. Mutants produced only small amounts of flagellins, while the transcription of flagellin genes appeared unchanged. These results strongly suggest a unique mechanism regulating motility in
H. pylori
which relies on slipped-strand mispairing-mediated mutagenesis of
fliP
.
Apically Exposed, Tight Junction-Associated β1-Integrins Allow Binding and YopE-Mediated Perturbation of Epithelial Barriers by Wild-Type
Yersinia
Bacteria
Authors: Tafazoli Farideh , Holmström Anna , Forsberg Åke , Magnusson Karl-Eric 
Published: July 2002

ABSTRACT

Using polarized epithelial cells, primarily MDCK-1, we assessed the mode of binding and effects on epithelial cell structure and permeability of
Yersinia pseudotuberculosis yadA
-deficient mutants. Initially, all bacteria except the invasin-deficient (
inv
) mutant adhered apically to the tight junction areas. These contact points of adjacent cells displayed β1-integrins together with tight junction-associated ZO-1 and occludin proteins. Indeed, β1-integrin expression was maximal in the tight junction area and then gradually decreased along the basolateral membranes. Wild-type bacteria also opened gradually the tight junction to paracellular permeation of different-sized markers, viz., 20-, 40-, and 70-kDa dextrans and 45-kDa ovalbumin, as well as to their own translocation between adjacent cells in intimate contact with β1-integrins. The effects on the epithelial cells and their barrier properties could primarily be attributed to expression of the
Yersinia
outer membrane protein YopE, as the
yopE
mutant bound but caused no cytotoxicity. Moreover, the apical structure of filamentous actin (F-actin) was disturbed and tight junction-associated proteins (ZO-1 and occludin) were dispersed along the basolateral membranes. It is concluded that the
Yersinia
bacteria attach to β1-integrins at tight junctions. Via this localized injection of YopE, they perturb the F-actin structure and distribution of proteins forming and regulating tight junctions. Thereby they promote paracellular translocation of bacteria and soluble compounds.
Detection of Bacterial Virulence Genes by Subtractive Hybridization: Identification of Capsular Polysaccharide of
Burkholderia pseudomallei
as a Major Virulence Determinant
Authors: Reckseidler Shauna L. , DeShazer David , Sokol Pamela A. , Woods Donald E. 
Published: July 2002

ABSTRACT

Burkholderia pseudomallei
, the etiologic agent of melioidosis, is responsible for a broad spectrum of illnesses in humans and animals particularly in Southeast Asia and northern Australia, where it is endemic.
Burkholderia thailandensis
is a nonpathogenic environmental organism closely related to
B. pseudomallei
. Subtractive hybridization was carried out between these two species to identify genes encoding virulence determinants in
B. pseudomallei
. Screening of the subtraction library revealed A-T-rich DNA sequences unique to
B. pseudomallei
, suggesting they may have been acquired by horizontal transfer. One of the subtraction clones, pDD1015, encoded a protein with homology to a glycosyltransferase from
Pseudomonas aeruginosa
. This gene was insertionally inactivated in wild-type
B. pseudomallei
to create SR1015. It was determined by enzyme-linked immunosorbent assay and immunoelectron microscopy that the inactivated gene was involved in the production of a major surface polysaccharide. The 50% lethal dose (LD
50
) for wild-type
B. pseudomallei
is <10 CFU; the LD
50
for SR1015 was determined to be 3.5 × 10
5
CFU, similar to that of
B. thailandensis
(6.8 × 10
5
CFU). DNA sequencing of the region flanking the glycosyltransferase gene revealed open reading frames similar to capsular polysaccharide genes in
Haemophilus influenzae
,
Escherichia coli
, and
Neisseria meningitidis
. In addition, DNA from
Burkholderia mallei
and
Burkholderia stabilis
hybridized to a glycosyltransferase fragment probe, and a capsular structure was identified on the surface of
B. stabilis
via immunoelectron microscopy. Thus, the combination of PCR-based subtractive hybridization, insertional inactivation, and animal virulence studies has facilitated the identification of an important virulence determinant in
B. pseudomallei
.
Characterization of
Vibrio cholerae
O1 El Tor
galU
and
galE
Mutants: Influence on Lipopolysaccharide Structure, Colonization, and Biofilm Formation
Authors: Nesper Jutta , Lauriano Crystal M. , Klose Karl E. , Kapfhammer Dagmar , Kraiß Anita , Reidl Joachim 
Published: July 2002

ABSTRACT

Recently we described the isolation of spontaneous bacteriophage K139-resistant
Vibrio cholerae
O1 El Tor mutants. In this study, we identified phage-resistant isolates with intact O antigen but altered core oligosaccharide which were also affected in galactose catabolism; this strains have mutations in the
galU
gene. We inactivated another
gal
gene,
galE
, and the mutant was also found to be defective in the catabolism of exogenous galactose but synthesized an apparently normal lipopolysaccharide (LPS). Both
gal
mutants as well as a rough LPS (R-LPS) mutant were investigated for the ability to colonize the mouse small intestine. The
galU
and R-LPS mutants, but not the
galE
mutant, were defective in colonization, a phenotype also associated with O-antigen-negative mutants. By investigating several parameters in vitro, we could show that
galU
and R-LPS mutants were more sensitive to short-chain organic acids, cationic antimicrobial peptides, the complement system, and bile salts as well as other hydrophobic agents, indicating that their outer membrane no longer provides an effective barrier function. O-antigen-negative strains were found to be sensitive to complement and cationic peptides, but they displayed significant resistance to bile salts and short-chain organic acids. Furthermore, we found that
galU
and
galE
are essential for the formation of a biofilm in a spontaneous phage-resistant rugose variant, suggesting that the synthesis of UDP-galactose via UDP-glucose is necessary for biosynthesis of the exopolysaccharide. In addition, we provide evidence that the production of exopolysaccharide limits the access of phage K139 to its receptor, the O antigen. In conclusion, our results indicate involvement of
galU
in
V. cholerae
virulence, correlated with the observed change in LPS structure, and a role for
galU
and
galE
in environmental survival of
V. cholerae
.
Both Th1 and Th2 Cytokines Affect the Ability of Monoclonal Antibodies To Protect Mice againstCryptococcus neoformans
Authors: Beenhouwer David O. , Shapiro Scott , Feldmesser Marta , Casadevall Arturo , Scharff Matthew D. 
Published: July 2002

ABSTRACTVariable-region-identical mouse immunoglobulin G1 (IgG1), IgG2b, and IgG2a monoclonal antibodies to the capsular polysaccharide ofCryptococcus neoformansprolong the lives of mice infected with this fungus, while IgG3 is either not protective or enhances infection. CD4+T cells are required for IgG1-mediated protection, and CD8+T cells are required for IgG3-mediated enhancement. Gamma interferon is required for both effects. These findings revealed that T cells and cytokines play a role in the modulation of cryptococcal infection by antibodies and suggested that it was important to more fully define the cytokine requirements of each of the antibody isotypes. We therefore investigated the efficacy of passively administered variable-region-identical IgG1, IgG2a, IgG2b, and IgG3 monoclonal antibodies against intravenous infection withC. neoformansin mice genetically deficient in interleukin-12 (IL-12), IL-6, IL-4, or IL-10, as well as in the parental C57BL/6J strain. The relative inherent susceptibilities of these mouse strains toC. neoformanswere as follows: IL-12−/−> IL-6−/−> C57BL/6J ≈ IL-4−/−≫ IL-10−/−. This is consistent with the notion that a Th1 response is necessary for natural immunity against cryptococcal infection. However, none of the IgG isotypes prolonged survival in IL-12−/−, IL-6−/−, or IL-4−/−mice, and all isotypes significantly enhanced infection in IL-10−/−mice. These results indicate that passive antibody-mediated protection againstC. neoformansrequires both Th1- and Th2-associated cytokines and reveal the complexity of the mechanisms through which antibodies modulate infection with this organism.
Determination of the Infectious Dose of
Helicobacter pylori
during Primary and Secondary Infection in Rhesus Monkeys (
Macaca mulatta
)
Authors: Solnick Jay V. , Hansen Lori M. , Canfield Don R. , Parsonnet Julie 
Published: July 2002

ABSTRACT

We sought to determine the infectious dose of
Helicobacter pylori
during primary and secondary infection in the rhesus monkey and to determine whether preinoculation acid suppression is necessary to produce colonization. Mixed inoculation with three human-derived strains showed that
H. pylori
J166 is particularly adapted to colonization of rhesus monkeys, since it outcompeted two other strains. The minimum infectious dose of
H. pylori
J166 was 10
4
bacteria in specific-pathogen (
H. pylori
)-free monkeys. Rechallenge of these monkeys after antibiotic therapy was characterized by a 10- to 100-fold decrease in bacterial load compared to primary infection, but with little change in the infectious dose. Acid suppression prior to inoculation was not necessary for colonization to occur. These results provide a basis for future animal experiments using more ecologically relevant conditions of inoculation and suggest that reduction in bacterial load rather than complete protection may be a more realistic goal for
H. pylori
vaccination.
Temporal Sequence and Kinetics of Proinflammatory and Anti-Inflammatory Cytokine Secretion Induced by Toxic Shock Syndrome Toxin 1 in Human Peripheral Blood Mononuclear Cells
Authors: Kum Winnie W. S. , Cameron Scott B. , Hung Ryan W. Y. , Kalyan Shirin , Chow Anthony W. 
Published: July 2002

ABSTRACTThe staphylococcal superantigen toxic shock syndrome toxin 1 (TSST-1) induces massive cytokine production, which is believed to be the key factor in the pathogenesis of TSS. The temporal sequence and kinetics of both proinflammatory and anti-inflammatory cytokines induced by TSST-1 in human peripheral blood mononuclear cells were investigated. A panel of loss-of-function single-amino-acid-substitution mutants of TSST-1, previously demonstrated to be defective in either major histocompatibility complex (MHC) class II binding (G31R) or T-cell receptor (TCR) interaction (H135A, S14N), was studied in parallel to further elucidate the mechanisms of cytokine secretion. Wild-type recombinant (WT r) TSST-1 induced a biphasic pattern of cytokine secretion: an early phase with rapid release of proinflammatory cytokines (especially gamma interferon, interleukin-2 [IL-2], and tumor necrosis factor alpha [TNF-α]) within 3 to 4 h poststimulation, and a later phase with more gradual production of both proinflammatory (IL-1β, IL-12, and TNF-β) and anti-inflammatory (IL-6, IL-10) cytokines within 16 to 72 h poststimulation. G31R, which is defective in MHC class II binding, induced a cytokine profile similar to that of WT rTSST-1, except that secretion of the early-phase proinflammatory cytokines was delayed and production of IL-1β and IL-12 was markedly reduced. In contrast, mutant toxins defective in TCR interaction either demonstrated complete absence of any cytokine secretion during the entire observation period (H135A) or resulted in complete abolishment of IL-2 and other early-phase proinflammatory cytokines, while secretion of IL-10 appeared unaffected (S14N). Neither WT rTSST-1 nor the mutant toxins induced IL-4 or transforming growth factor β. Our data indicate that effective TCR interaction is critical for the induction of the early-phase proinflammatory cytokine response, thus underscoring the importance of T-cell signaling in TSS.
Characterization of Murine Lung Dendritic Cells Infected withMycobacterium tuberculosis
Authors: Gonzalez-Juarrero Mercedes , Orme Ian M. 
Published: July 2002

ABSTRACTLung dendritic cells were identified by immunohistochemistry in lung tissue sections from C57BL/6 mice. Following isolation from the lungs using CD11c magnetic beads, the flow cytometric analysis of I-Ab+and CD11c+cells indicated a mixed population of dendritic cells at different stages of maturation, with most expressing an immature phenotype. When cultured for 7 days with recombinant murine granulocyte-macrophage colony-stimulating factor, 99% of cells were CD11c+and had a morphology typical of immature dendritic cells. These cells were negative for CD34, CD14, and CD8α antigens but expressed low levels of the myeloid marker F4/80 and moderate levels of MAC3. All expressed high levels of CD11a (LFA-1), CD11b (Mac1), and CD54 antigens, with low levels of class II major histocompatibility complex. Most cells expressed CD80 but only a small percentage of cells were positive for CD40 and CD86. Both overnight and 7-day cultures of lung dendritic cells were able to phagocytoseMycobacterium tuberculosis, and this was associated with the production of interleukin-12 and stimulation of both naı̈ve and immune T cells to produce gamma interferon.
Influence of Costimulatory Molecules on Immune Response toLeishmania majorby Human Cells In Vitro
Authors: Brodskyn Claudia I. , DeKrey Gregory K. , Titus Richard G. 
Published: July 2002

ABSTRACTThe importance of CD40, CD80, and CD86 costimulatory molecules in anti-Leishmaniaimmune responses has been established in murine models. A role for these costimulatory molecules in human anti-Leishmaniaimmune responses was investigated in this study. Autologous macrophages and peripheral blood leukocytes (PBL) were prepared from peripheral blood mononuclear cells ofLeishmania-naive donors and cultured with or withoutLeishmania majorin various combinations. After 7 days of culture, high levels of CD40 and CD86 were expressed on macrophages in the presence or absence ofL. major. When macrophages were cultured for an additional 7 days with PBL, expression of all three costimulatory molecules was detected. WhenL. majorwas present in these cultures, the expression of CD80, and to a lesser extent CD40, on macrophages was enhanced. Blockade of CD80, CD86, or both molecules (in the order of greatest effect) in cultures containing macrophages, PBL, andL. majorsignificantly inhibited the production of gamma interferon, interleukin-5 (IL-5), and IL-12. Blockade of CD40-CD154 interactions also significantly inhibited production of these cytokines in response toL. major. Production of IL-10 was unaltered by the blockade of these costimulatory molecules. Thus, these data suggest that CD40, CD80, and CD86 expression and regulation may significantly impact anti-Leishmaniaimmune responses in humans.
afa-8
Gene Cluster Is Carried by a Pathogenicity Island Inserted into the tRNA
Phe
of Human and Bovine Pathogenic
Escherichia coli
Isolates
Authors: Lalioui Lila , Le Bouguénec Chantal 
Published: July 2002

ABSTRACT

We recently described a new afimbrial adhesin, AfaE-VIII, produced by animal strains associated with diarrhea and septicemia and by human isolates associated with extraintestinal infections. Here, we report that the
afa-8
operon, encoding AfaE-VIII adhesin, from the human blood isolate
Escherichia coli
AL862 is carried by a 61-kb genomic region with characteristics typical of a pathogenicity island (PAI), including a size larger than 10 kb, the presence of an integrase-encoding gene, the insertion into a tRNA locus (
pheR
), and the presence of a small direct repeat at each extremity. Moreover, the G+C content of the
afa-8
operon (46.4%) is lower than that of the
E. coli
K-12/MG1655 chromosome (50.8%). Within this PAI, designated PAI I
AL862
, we identified open reading frames able to code for products similar to proteins involved in sugar utilization. Four probes spanning these sequences hybridized with 74.3% of pathogenic
afa-8
-positive
E. coli
strains isolated from humans and animals, 25% of human pathogenic
afa-8
-negative
E. coli
strains, and only 8% of fecal strains (
P
= 0.05), indicating that these sequences are strongly associated with the
afa-8
operon and that this genetic association may define a PAI widely distributed among human and animal
afa-8
-positive strains. One of the distinctive features of this study is that
E. coli
AL862 also carries another
afa-8
-containing PAI (PAI II
AL862
), which appeared to be similar in size and genetic organization to PAI I
AL862
and was inserted into the
pheV
gene. We investigated the insertion sites of
afa-8
-containing PAI in human and bovine pathogenic
E. coli
strains and found that this PAI preferentially inserted into the
pheV
gene.