bluuebunny/crossref_metadata_2025_split huggingface dataset:
Constitutive Expression of the Vi Polysaccharide Capsular Antigen in AttenuatedSalmonella entericaSerovar Typhi Oral Vaccine Strain CVD 909
Authors: Wang Jin Yuan , Noriega Fernando R. , Galen James E. , Barry Eileen , Levine Myron M. 
Published: July 2002

ABSTRACTLive oral Ty21a and parenteral Vi polysaccharide vaccines provide significant protection against typhoid fever, albeit by distinct immune mechanisms. Vi stimulates serum immunoglobulin G Vi antibodies, whereas Ty21a, which does not express Vi, elicits humoral and cell-mediated immune responses other than Vi antibodies. Protection may be enhanced if serum Vi antibody as well as cell-mediated and humoral responses can be stimulated. Disappointingly, several new attenuatedSalmonella entericaserovar Typhi oral vaccines (e.g., CVD 908-htrAand Ty800) that elicit serum O and H antibody and cell-mediated responses following a single dose do not stimulate serum Vi antibody. Vi expression is regulated in response to environmental signals such as osmolarity by controlling the transcription oftviAin theviaBlocus. To investigate if Vi antibodies can be stimulated if Vi expression is rendered constitutive, we replaced PtviAin serovar Typhi vaccine CVD 908-htrAwith the constitutive promoter Ptac, resulting in CVD 909. CVD 909 expresses Vi even under high-osmolarity conditions and is less invasive for Henle 407 cells. In mice immunized with a single intranasal dose, CVD 909 was more immunogenic than CVD 908-htrAin eliciting serum Vi antibodies (geometric mean titer of 160 versus 49,P= 0.0007), whereas O antibody responses were virtually identical (geometric mean titer of 87 versus 80). In mice challenged intraperitoneally with wild-type serovar Typhi 4 weeks after a single intranasal immunization, the mortality of those immunized with CVD 909 (3 of 8) was significantly lower than that of control mice (10 of 10,P= 0.043) or mice given CVD 908-htrA(9 of 10,P= 0.0065).
Characterization of Adherence of Nontypeable
Haemophilus influenzae
to Human Epithelial Cells
Authors: van Schilfgaarde Muriel , van Ulsen Peter , Eijk Paul , Brand Michiel , Stam Martin , Kouame Jamal , van Alphen Loek , Dankert Jacob 
Published: July 2002

ABSTRACT

The adherence of 58 nontypeable
Haemophilus influenzae
isolates obtained from patients with otitis media or chronic obstructive pulmonary disease (COPD) and obtained from the throats of healthy individuals to Chang and NCI-H292 epithelial cells was compared. Otitis media isolates, but not COPD isolates, adhered significantly more to both cell lines than did throat isolates. Since high-molecular-weight (HMW) proteins are major adhesins of nontypeable
H. influenzae
, the isolates were screened for HMW protein expression by Western blotting with two polyclonal sera and PCR with
hmw
-specific primers. Twenty-three of the 32 adhering isolates (72%) and only 1 of the 26 nonadherent strains were HMW protein or
hmw
gene positive. Among the 32 isolates adhering to either cell line, 5 different adherence patterns were distinguished based on the inhibiting effect of dextran sulfate. Using
H. influenzae
strain 12 expressing two well-defined HMW proteins (HMW1 and HMW2) and its isogenic mutants as a reference, we observed HMW1-like adherence to both cell lines for 16 of the 32 adherent isolates. Four others showed HMW2-like adherence to NCI-H292. Of the three other patterns of adherence, one probably also involved HMW protein. Screening of the isolates with six HMW-specific monoclonal antibodies in a whole-cell enzyme-linked immunosorbent assay showed that the HMW proteins of COPD isolates and carrier isolates were more distinct from the HMW proteins from
H. influenzae
strain 12 than those from otitis media isolates. Characterization of the HMW protein of a COPD isolate by adherence and DNA sequence analysis showed that despite large sequence diversity in the
hmwA
gene, probably resulting in the antigenic differences, the HMW protein mediated the HMW2-like adherence of this strain.
Down-Regulation of GATA-2 Transcription during
Pneumocystis carinii
Infection
Authors: Tang Xing , Lasbury Mark E. , Davidson Darrell D. , Bartlett Marilyn S. , Smith James W. , Lee Chao-Hung 
Published: July 2002

ABSTRACT

Differences in gene expression between
Pneumocystis carinii
-infected and noninfected rats were examined. Total RNA was isolated from homogenized rat lungs and then subjected to differential display with combinations of oligo(dT) and various arbitrary PCR primers. Approximately 50 differentially expressed bands were observed. Several of these DNA bands were isolated, reamplified, and cloned. The cloned DNA fragments were used as probes to perform Northern hybridization on RNA from
P. carinii
-infected and noninfected rat lungs. One clone was found to react with a 3-kb mRNA from noninfected but not from
P. carinii
-infected rat lung, suggesting that the gene represented by this clone was down-regulated during
P. carinii
infection. The nucleotide sequence of this clone was determined and found to be 97% homologous to the mouse GATA-2 transcription factor. In situ hybridization using RNA probes derived from this clone revealed that alveolar macrophages, resident lung monocytes, and bronchial epithelial cells express the GATA-2 gene in the lung.
Antigenic and Sequence Diversity in Gonococcal Transferrin-Binding Protein A
Authors: Cornelissen Cynthia Nau , Anderson James E. , Boulton Ian C. , Sparling P. Frederick 
Published: July 2002

ABSTRACTNeisseria gonorrhoeaeis a gram-negative pathogen that is capable of satisfying its iron requirement with human iron-binding proteins such as transferrin and lactoferrin. Transferrin-iron utilization involves specific binding of human transferrin at the cell surface to what is believed to be a complex of two iron-regulated, transferrin-binding proteins, TbpA and TbpB. The genes encoding these proteins have been cloned and sequenced from a number of pathogenic, gram-negative bacteria. In the current study, we sequenced four additionaltbpAgenes from otherN. gonorrhoeaestrains to begin to assess the sequence diversity among gonococci. We compared these sequences to those from other pathogenic bacteria to identify conserved regions that might be important for the structure and function of these receptors. We generated polyclonal mouse sera against synthetic peptides deduced from the TbpA sequence from gonococcal strain FA19. Most of these synthetic peptides were predicted to correspond to surface-exposed regions of TbpA. We found that, while most reacted with denatured TbpA in Western blots, only one antipeptide serum reacted with native TbpA in the context of intact gonococci, consistent with surface exposure of the peptide to which this serum was raised. In addition, we evaluated a panel of gonococcal strains for antigenic diversity using these antipeptide sera.
Streptococcus pneumoniaeInduces Secretion of Vascular Endothelial Growth Factor by Human Neutrophils
Authors: van der Flier Michiel , Coenjaerts Frank , Kimpen Jan L. L. , Hoepelman Andy M. , Geelen Sibyl P. M. 
Published: July 2002

ABSTRACTInfection by pneumococci causes an acute inflammatory response associated with neutrophil influx, increased vascular permeability, and edema. Vascular endothelial growth factor (VEGF) is one of the most potent regulators of endothelial permeability. In vitro stimulation of neutrophils showed that pneumococci and purified pneumococcal cell wall induce VEGF secretion, independent of the presence of pneumolysin or polysaccharide capsule. The results of this study indicate VEGF is secreted in pneumococcal disease, suggesting a role as a mediator of increased vascular permeability.
Invasion of Human Vascular Endothelial Cells by
Actinobacillus actinomycetemcomitans
via the Receptor for Platelet-Activating Factor
Authors: Schenkein Harvey A. , Barbour Suzanne E. , Berry C. R. , Kipps Barbara , Tew John G. 
Published: July 2002

ABSTRACT

Strains of the periodontal pathogen
Actinobacillus actinomycetemcomitans
are variable with respect to display of phosphorylcholine (PC)-bearing antigens. We have examined strains of
A. actinomycetemcomitans
with and without PC to assess their ability to invade endothelial cells via the receptor for platelet-activating factor (PAF). Results of antibiotic protection assays indicate that PC-bearing
A. actinomycetemcomitans
invade human vascular endothelial cells by a mechanism inhibitable by CV3988, a PAF receptor antagonist, and by PAF itself. The invasive phenotype was verified by transmission electron microscopy. A PC-deficient strain of this organism was not invasive. This property, in addition to the established ability of
A. actinomycetemcomitans
to invade epithelial cells, may provide this organism with access to the systemic circulation. The ability of PC-bearing oral bacteria to access the circulation may also explain the elevated levels of anti-PC antibody in serum found in patients with periodontitis.
Biochemical and Biological Properties of Staphylococcal Enterotoxin K
Authors: Orwin Paul M. , Leung Donald Y. M. , Donahue Heather L. , Novick Richard P. , Schlievert Patrick M. 
Published: July 2002

ABSTRACT

Staphylococcus aureus
is an important human pathogen which is implicated in a wide variety of diseases. Major determinants of the virulence of this organism include extracellular virulence factors. Staphylococcal enterotoxins (SEs) are important causative agents in staphylococcal toxic shock syndrome and food poisoning. Our study identified a novel enterotoxin, SEK, and examined its biochemical and biological properties. SEK had a molecular weight of 26,000 and an experimentally determined pI of between 7.0 and 7.5. SEK was secreted by clinical isolates of
S. aureus
. We demonstrated that SEK had many of the biological activities associated with the SEs, including superantigenicity, pyrogenicity, the ability to enhance the lethal effect of endotoxin, and lethality in a rabbit model when administered by subcutaneous miniosmotic pump. Recombinant SEK was shown to stimulate human CD4
+
and CD8
+
T cells in a Vβ-specific manner; T-cells bearing Vβ 5.1, 5.2, and 6.7 were significantly stimulated to proliferate.
Identification and Disruption of Two Discrete Loci Encoding Hyaluronic Acid Capsule Biosynthesis Genes
hasA
,
hasB
, and
hasC
in
Streptococcus uberis
Authors: Ward Philip N. , Field Terence R. , Ditcham William G. F. , Maguin Emmanuelle , Leigh James A. 
Published: July 2002

ABSTRACT

The hyaluronic acid capsule of
Streptococcus uberis
has been implicated in conferring resistance to phagocytosis by bovine neutrophils. Construction of a bank of random insertion mutants of
S. uberis
(strain 0140J) was achieved using the pGh9::IS
S1
mutagenesis system (22). Phenotypic screening of approximately 5,000 clones enabled the isolation of 11 acapsular mutants. Southern hybridization indicated that two mutants carried a lesion within a group of genes similar to those involved in the assembly of the hyaluronic acid capsule found in the group A
Streptococcus
(GAS)
has
operon. The DNA sequence flanking the points of insertion confirmed the presence of homologues of GAS
hasA
and
hasB
in
S. uberis
. The DNA sequence flanking the IS
S1
insertion in another mutant identified a homologue of
hasC
in
S. uberis
. The GAS
hasABC
operon structure was not conserved in
S. uberis
, and two discrete loci comprising homologues of either
hasAB
or
hasC
were identified. Disruption of
S. uberis hasA
or
hasC
resulted in the complete cessation of hyaluronic acid capsule production. Correspondingly, these mutants were found to have lost their resistance to phagocytosis by bovine neutrophils. The bactericidal action of bovine neutrophils on
S. uberis
0140J was shown unequivocally to depend upon the capsule status of the bacterium.
Staphylococcus aureus agrGenotypes with Enterotoxin Production Capabilities Can Resist Neutrophil Bactericidal Activity
Authors: Mullarky I. K. , Su C. , Frieze N. , Park Y. H. , Sordillo L. M. 
Published: July 2002

ABSTRACTStaphylococcus aureuspathogenicity is mainly due to the production of a number of secreted and cell surface-associated proteins under the regulation of theagrgene. A region of theagrgene was used to subgroupS. aureusstrains according to restriction fragment length polymorphisms. Additionally, strains were subtyped according to the coagulase gene in order to strengthen discriminatory power. Virulence capabilities ofagrgenotype subgroups were evaluated using an in vitro neutrophil bactericidal assay, which showed that prevalent genotypes were significantly better at evading this primary host defense. Multiplex PCR was then used to detect enterotoxin genes among the genotype subgroups in order to determine possible virulence candidates that enable strains to combat neutrophil killing. The prevalent genotype strains were found to possess higher production capabilities for enterotoxin A than did low-prevalence strains. The significance of enterotoxin A production capabilities in affecting pathogenicity ofS. aureusstrains was evaluated and found to have a profound effect on neutrophil killing abilities. The use of a large epidemiological database as a tool for subgrouping strains with varying degrees of pathogenicity has allowed the identification of relevant and previously undefined virulence factors that affect a pathogen's capability to overcome host immune defenses.
Brucella suis
-Impaired Specific Recognition of Phagosomes by Lysosomes due to Phagosomal Membrane Modifications
Authors: Naroeni Aroem , Jouy Nicolas , Ouahrani-Bettache Safia , Liautard Jean-Pierre , Porte Françoise 
Published: July 2002

ABSTRACT

Brucella
species are gram-negative, facultatively intracellular bacteria that infect humans and animals. These organisms can survive and replicate within a membrane-bound compartment in phagocytic and nonprofessional phagocytic cells. Inhibition of phagosome-lysosome fusion has been proposed as a mechanism for intracellular survival in both types of cells. However, the biochemical mechanisms and microbial factors implicated in
Brucella
maturation are still completely unknown. We developed two different approaches in an attempt to gain further insight into these mechanisms: (i) a fluorescence microscopy analysis of general intracellular trafficking on whole cells in the presence of
Brucella
and (ii) a flow cytometry analysis of in vitro reconstitution assays showing the interaction between
Brucella suis
-containing phagosomes and lysosomes. The fluorescence microscopy results revealed that fusion properties of latex bead-containing phagosomes with lysosomes were not modified in the presence of live
Brucella suis
in the cells. We concluded that fusion inhibition was restricted to the pathogen phagosome and that the host cell fusion machinery was not altered by the presence of live
Brucella
in the cell. By in vitro reconstitution experiments, we observed a specific association between killed
B. suis
-containing phagosomes and lysosomes, which was dependent on exogenously supplied cytosol, energy, and temperature. This association was observed with killed bacteria but not with live bacteria. Hence, this specific recognition inhibition seemed to be restricted to the pathogen phagosomal membrane, as noted in the in vivo experiments.
Role of ADP-Ribosyltransferase Activity of Pertussis Toxin in Toxin-Adhesin Redundancy with Filamentous Hemagglutinin duringBordetella pertussisInfection
Authors: Alonso Sylvie , Pethe Kévin , Mielcarek Nathalie , Raze Dominique , Locht Camille 
Published: July 2002

ABSTRACTPertussis toxin (PT) and filamentous hemagglutinin (FHA) are two major virulence factors ofBordetella pertussis. FHA is the main adhesin, whereas PT is a toxin with an A-B structure, in which the A protomer expresses ADP-ribosyltransferase activity and the B moiety is responsible for binding to the target cells. Here, we show redundancy of FHA and PT during infection. Whereas PT-deficient and FHA-deficient mutants colonized the mouse respiratory tract nearly as efficiently as did the isogenic parent strain, a mutant deficient for both factors colonized substantially less well. This was not due to redundant functions of PT and FHA as adhesins, since in vitro studies of epithelial cells and macrophages indicated that FHA, but not PT, acts as an adhesin. An FHA-deficientB.pertussisstrain producing enzymatically inactive PT colonized as poorly as did the FHA-deficient, PT-deficient strain, indicating that the ADP-ribosyltransferase activity of PT is required for redundancy with FHA. Only strains producing active PT induced a local transient release of tumor necrosis factor alpha (TNF-α), suggesting that the pharmacological effects of PT are the basis of the redundancy with FHA, through the release of TNF-α. This may lead to damage of the pulmonary epithelium, allowing the bacteria to colonize even in the absence of FHA.
Identification of the Hemolysis-Associated Protein 1 as a Cross-Protective Immunogen ofLeptospira interrogansby Adenovirus-Mediated Vaccination
Authors: Branger C. , Sonrier C. , Chatrenet B. , Klonjkowski B. , Ruvoen-Clouet N. , Aubert A. , André-Fontaine G. , Eloit M. 
Published: July 2002

ABSTRACTNew vaccine strategies are needed for the prevention of leptospirosis, a widespread human and animal disease caused by pathogenic leptospires. Our previous work determined that a protein leptospiral extract conferred cross-protection in a gerbil model of leptospirosis. The 31- to 34-kDa protein fraction ofLeptospira interrogansserovar autumnalis was shown sufficient for this purpose. In the present study, N-terminal sequencing of a 32-kDa fraction and Southern blotting of genomic DNA with corresponding degenerated oligonucleotide probes identified two of its constituents: hemolysis-associated protein 1 (Hap1) and the outer membraneLeptospiraprotein 1 (OmpL1). Adenovirus-mediated Hap1 vaccination induces significant protection against a virulent heterologousLeptospirachallenge in gerbils, whereas a similar OmpL1 construct failed to protect the animals. These data indicate that Hap1 could be a good candidate for developing a new generation of vaccines able to induce broad protection against leptospirosis disease.
Sera from Adult Patients with Cystic Fibrosis Contain Antibodies to
Pseudomonas aeruginosa
Type III Apparatus
Authors: Moss Joel , Ehrmantraut Mary E. , Banwart Bruce D. , Frank Dara W. , Barbieri Joseph T. 
Published: July 2002

ABSTRACT

Expression of type III proteins of
Pseudomonas aeruginosa
in patients with cystic fibrosis (CF) was investigated by measuring the immune response against components of the type III pathway. Twenty-three of the 33 sera contained antibodies against PcrV, a protein involved in translocation of type III cytotoxins into eukaryotic cells, and 11 of 33 had antibodies against ExoS, while most CF sera contained antibodies against PopB and PopD, components of the type III apparatus. These data indicate that
P. aeruginosa
commonly expresses components of the type III translocation apparatus in adult CF patients.
Cytotoxic T Lymphocyte Antigen Costimulation Influences T-Cell Activation in Response toCryptococcus neoformans
Authors: Pietrella Donatella , Perito Stefano , Bistoni Francesco , Vecchiarelli Anna 
Published: July 2002

ABSTRACTThe kinetics of cytotoxic T lymphocyte antigen 4 (CTLA-4) expression on T cells responding toCryptococcus neoformansand its role in regulating the T-cell response were examined. Using peripheral blood mononuclear cells stimulated with encapsulated or acapsularC. neoformanswe showed that (i) the encapsulated strain augmented CTLA-4 expression on the T-cell surface while the acapsular strain was a weaker modulator, (ii) CTLA-4 molecules were rapidly up-regulated after the addition of encapsulatedC. neoformans, (iii) CTLA-4 was up-regulated predominantly in CD4+T cells responding toC. neoformans, and (iv) blockage of CTLA-4 with (Fab′)2of monoclonal antibody to CTLA-4 induced T-cell proliferation that paralleled the enhancement of interleukin-2 and gamma interferon production. These results suggest that capsular material, the major virulence factor ofC. neoformans, promotes synthesis and expression of CTLA-4 molecules predominantly in CD4+T cells. CTLA-4-mediated deactivation is due not to lack of costimulation but to specific recognition of CTLA-4 for B7 molecules. This appears to be a new mechanism by whichC. neoformansmay elude the host immune response.
Micrococcus luteusTeichuronic Acids Activate Human and Murine Monocytic Cells in a CD14- and Toll-Like Receptor 4-Dependent Manner
Authors: Yang Shuhua , Sugawara Shunji , Monodane Toshihiko , Nishijima Masahiro , Adachi Yoshiyuki , Akashi Sachiko , Miyake Kensuke , Hase Sumihiro , Takada Haruhiko 
Published: July 2002

ABSTRACTTeichuronic acid (TUA), a component of the cell walls of the gram-positive organismMicrococcus luteus(formerlyMicrococcus lysodeikticus), induced inflammatory cytokines in C3H/HeN mice but not in lipopolysaccharide (LPS)-resistant C3H/HeJ mice that have a defect in the Toll-like receptor 4 (TLR4) gene, both in vivo and in vitro, similarly to LPS (T. Monodane, Y. Kawabata, S. Yang, S. Hase, and H. Takada, J. Med. Microbiol. 50:4–12, 2001). In this study, we found that purified TUA (p-TUA) induced tumor necrosis factor alpha (TNF-α) in murine monocytic J774.1 cells but not in mutant LR-9 cells expressing membrane CD14 at a lower level than the parent J774.1 cells. The TNF-α-inducing activity of p-TUA in J774.1 cells was completely inhibited by anti-mouse CD14 monoclonal antibody (MAb). p-TUA also induced interleukin-8 (IL-8) in human monocytic THP-1 cells differentiated to macrophage-like cells expressing CD14. Anti-human CD14 MAb, anti-human TLR4 MAb, and synthetic lipid A precursor IVA, an LPS antagonist, almost completely inhibited the IL-8-inducing ability of p-TUA, as well as LPS, in the differentiated THP-1 cells. Reduced p-TUA did not exhibit any activities in J774.1 or THP-1 cells. These findings strongly suggested thatM. luteusTUA activates murine and human monocytic cells in a CD14- and TLR4-dependent manner, similar to LPS.
Micrococci and Peptidoglycan Activate TLR2→MyD88→IRAK→TRAF→NIK→IKK→NF-κB Signal Transduction Pathway That Induces Transcription of Interleukin-8
Authors: Wang Qiuling , Dziarski Roman , Kirschning Carsten J. , Muzio Marta , Gupta Dipika 
Published: July 2002

ABSTRACTThis study was done to elucidate the signal transduction pathway of interleukin-8 (IL-8) induction by gram-positive bacteria. Bacteria (micrococci) and peptidoglycan (PGN) induced transcription of IL-8 in HEK293 cells expressing Toll-like receptor 2 (TLR2) and CD14 but not in those expressing TLR1 or TLR4. A mutation within the NF-κB site in the IL-8 promoter abrogated transcriptional induction of IL-8 by the two stimulants. Dominant negative myeloid differentiation protein (MyD88), IL-1 receptor-associated kinase (IRAK), NFκB-inducing kinase (NIK), and IκB kinase (IKK) mutant forms completely inhibited micrococcus- and PGN-induced activation of NF-κB and expression of the gene for IL-8. Induction of NF-κB was partially inhibited by dominant negative tumor necrosis factor receptor-associated kinase 6 (TRAF6) but not TRAF2, whereas induction of IL-8 gene was partially inhibited by both TRAF6 and TRAF2. These data indicate that micrococci and PGN induce TLR2-dependent activation of the gene for IL-8 and that this activation requires MyD88, IRAK, NIK, IKK, and NF-κB and may also utilize TRAF6 and, to a lesser extent, TRAF2.