bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rate of Inversion of the
Salmonella enterica
Shufflon Regulates Expression of Invertible DNA
Authors: Tam Connie K. P. , Hackett Jim , Morris Christina 
Published: August 2005

ABSTRACT

Salmonella enterica
serovar Typhi and some strains (Vi
+
) of serovar Dublin use type IVB pili to facilitate bacterial self-association, but only when the PilV proteins (potential minor pilus proteins) are not synthesized. Pilus-mediated self-association may be important in the pathogenesis of enteric fever. We have suggested that the rate of Rci-catalyzed inversion of DNA encoding the C-terminal portions of the PilV proteins controls PilV protein synthesis. This potentially represents a novel means of transcriptional control. Here, it is initially shown that DNA inversion per se is required for inhibition of gene expression from invertible DNA. Binding, without DNA scission, of Rci to its substrate sequences on DNA cannot explain the data obtained. Next, it is shown that inversion frequencies of
xylE
-encoding DNA, bracketed by Rci substrate sequences, may be modulated by changes in the 19-bp consensus sequences which are essential components of Rci substrate DNA. The affinity of Rci for these sequences affects inversion frequencies, so that a greater affinity is predictive of faster inversion, and therefore less synthesis of product encoded by invertible DNA. Inversion events may inhibit transcription of DNA from external promoters. In vivo, the frequency of Rci-mediated inversion is influenced by the extent of DNA supercoiling, with increasing levels of expression of invertible genes as novobiocin inhibits DNA supercoiling and thus Rci action. This inhibition of DNA supercoiling results in increased synthesis of PilV proteins as Rci activity decreases, and, in turn, bacterial self-association (particularly in serovar Dublin) decreases.
Helicobacter pylori-Specific CD4+T Cells Home to and Accumulate in the HumanHelicobacter pylori-Infected Gastric Mucosa
Authors: Lundgren Anna , Trollmo Christina , Edebo Anders , Svennerholm Ann-Mari , Lundin B. Samuel 
Published: August 2005

ABSTRACTHelicobacter pyloriinfects the stomach and duodenal mucosa. T cells are important components of theH. pylori-induced immune response, but little is currently known about how these cells are recruited to the infected mucosa. Here, we have characterized stomach and duodenal T cells isolated fromH. pylori-infected and noninfected subjects with regard to subtype, expression of homing and chemokine receptors, and in vitro reactivity toH. pyloriantigens. Higher numbers of CD4+but similar numbers of CD8+lamina propria T cells were isolated from stomach biopsies fromH. pylori-positive compared toH. pylori-negative individuals. CD4+T cells from infected stomach expressed increased levels of the homing receptor L-selectin and the chemokine receptor CCR4 compared to CD4+T cells from uninfected stomach. Infected stomach mucosa also contained increased levels of the CCR4 chemokine ligand MDC/CCL22. In contrast, comparable numbers of CD4+T cells with similar receptor expression were isolated from the duodenum ofH. pylori-positive andH. pylori-negative individuals. In vitro proliferation of mucosal T cells was strongly enhanced by the addition of interleukin-2 (IL-2) and IL-7 to the cell cultures. Using this approach,H. pylori-specific T-cell responses were detected in stomach CD4+T cells fromH. pylori-positive but notH. pylori-negative individuals. Duodenal T cells from only a few individuals responded toH. pyloristimulation, and the responsiveness was not restricted toH. pylori-positive individuals, suggesting limitedH. pylorispecificity in the duodenum and possible cross-reactivity with antigens from other bacteria in this compartment. In conclusion, these results suggest thatH. pylori-specific CD4+T cells preferentially home to and accumulate in the infected stomach and that L-selectin and CCR4/MDC are important for this recruitment.
Heteropentameric Cholera Toxin B Subunit Chimeric Molecules Genetically Fused to a Vaccine Antigen Induce Systemic and Mucosal Immune Responses: a Potential New Strategy To Target Recombinant Vaccine Antigens to Mucosal Immune Systems
Authors: Harakuni Tetsuya , Sugawa Hideki , Komesu Ai , Tadano Masayuki , Arakawa Takeshi 
Published: August 2005

ABSTRACTNoninvasive mucosal vaccines are attractive alternatives to parenteral vaccines. Although the conjugation of vaccine antigens with the B subunit of cholera toxin (CTB) is one of the most promising strategies for vaccine delivery to mucosal immune systems, the molecule cannot tolerate large-protein fusion, as it severely impairs pentamerization and loses affinity for GM1-ganglioside. Here we report a new strategy, in which steric hindrance between CTB-antigen fusion subunits is significantly reduced through the integration of unfused CTB “molecular buffers” into the pentamer unit, making them more efficiently self-assemble into biologically active pentamers. In addition, the chimeric protein took a compact configuration, becoming small enough to be secreted, and one-step affinity-purified proteins, when administered through a mucosal route, induced specific immune responses in mice. Since our results are not dependent on the use of a particular expression system or vaccine antigen, this strategy could be broadly applicable to bacterial enterotoxin-based vaccine design.
Characterization of Salivary Immunoglobulin A Responses in Children Heavily Exposed to the Oral Bacterium
Streptococcus mutans
: Influence of Specific Antigen Recognition in Infection
Authors: Nogueira Ruchele D. , Alves Alessandra C. , Napimoga Marcelo H. , Smith Daniel J. , Mattos-Graner Renata O. 
Published: August 2005

ABSTRACT

The initial infection of children by
Streptococcus mutans
, the main pathogen of dental caries, depends on the ability of
S. mutans
to adhere and accumulate on tooth surfaces. These processes involve the adhesin antigen I/II (AgI/II), glucosyltransferases (GTF) and glucan-binding protein B (GbpB), each a target for anticaries vaccines. The salivary immunoglobulin A (IgA) antibody responses to
S. mutans
antigens (Ags) were characterized in 21 pairs of 5- to 13-month-old children. Pairs were constructed with one early
S. mutans
-infected and one noninfected child matched by age, racial background, number of teeth, and salivary levels of IgA. Specific salivary IgA antibody response and
S. mutans
infection levels were then measured during a 1-year follow-up. Robust responses to
S. mutans
were detected from 6 months of age. Salivary IgA antibody to AgI/II and GTF was commonly detected in salivas of all 42 children. However, GbpB-specific IgA antibody was seldom detected in the subset of infected children (38.1% at baseline). In contrast, most of the subset of noninfected children (76.2%) showed GbpB-reactive IgA antibody during the same period. Frequencies of GbpB responses increased with age, but differences in intensities of GbpB-IgA antibody reactions were sustained between the subsets. At baseline, GbpB-reactive IgA antibody accounted for at least half of the total salivary IgA
S. mutans
-reactive antibody in 33.3 and 9.5% of noninfected and infected children, respectively. This study provides evidence that a robust natural response to
S. mutans
Ags can be achieved by 1 year of age and that IgA antibody specificities may be critical in modulating initial
S. mutans
infection.
Identification of a Protein Subset of the Anthrax Spore Immunome in Humans Immunized with the Anthrax Vaccine Adsorbed Preparation
Authors: Kudva Indira T. , Griffin Robert W. , Garren Jeonifer M. , Calderwood Stephen B. , John Manohar 
Published: August 2005

ABSTRACT

We
identified spore targets of Anthrax Vaccine Adsorbed (AVA)-induced
immunity in humans by screening recombinant clones of a previously
generated, limited genomic
Bacillus anthracis
Sterne
(pXO1
+
, pXO2
−
) expression library
of putative spore surface (spore-associated [SA]) proteins with pooled
sera from human adults immunized with AVA (immune sera), the anthrax
vaccine currently approved for use by humans in the United States. We
identified 69 clones that reacted specifically with pooled immune sera
but not with pooled sera obtained from the same individuals prior to
immunization. Positive clones expressed proteins previously identified
as localized on the anthrax spore surface, proteins highly expressed
during spore germination, orthologs of proteins of diverse pathogens
under investigation as drug targets, and orthologs of proteins
contributing to the virulence of both gram-positive and gram-negative
pathogens. Among the reactive clones identified by this immunological
screen was one expressing a 15.2-kDa hypothetical protein encoded by a
gene with no significant homology to sequences contained in databases.
Further studies are required to define the subset of SA proteins
identified in this study that contribute to the virulence of this
pathogen. We hypothesize that optimal delivery of a subset of SA
proteins identified by such studies to the immune system in combination
with protective antigen (PA), the principal immunogen in AVA, might
facilitate the development of defined, nonreactogenic, more-efficacious
PA-based anthrax vaccines. Future studies might also facilitate the
identification of SA proteins with potential to serve as targets for
drug design, spore inactivation, or spore detection
strategies.
Components of the
Legionella pneumophila
Flagellar Regulon Contribute to Multiple Virulence Traits, Including Lysosome Avoidance and Macrophage Death
Authors: Molofsky A. B. , Shetron-Rama L. M. , Swanson Michele S. 
Published: August 2005

ABSTRACT

Legionella pneumophila
is a motile intracellular pathogen of macrophages and amoebae. When nutrients become scarce, the bacterium induces expression of transmission traits, some of which are dependent on the flagellar sigma factor FliA (σ
28
). To test how particular components of the
L. pneumophila
flagellar regulon contribute to virulence, we compared a
fliA
mutant with strains whose flagellar construction is disrupted at various stages. We find that
L. pneumophila
requires FliA to avoid lysosomal degradation in murine bone marrow-derived macrophages (BMM), to regulate production of a melanin-like pigment, and to regulate binding to the dye crystal violet, whereas motility, flagellar secretion, and external flagella or flagellin are dispensable for these activities. Thus, in addition to flagellar genes, the FliA sigma factor regulates an effector(s) or regulator(s) that contributes to other transmissive traits, notably inhibition of phagosome maturation. Whether or not the microbes produced flagellin, all nonmotile
L. pneumophila
mutants bound BMM less efficiently than the wild type, resulting in poor infectivity and a loss of contact-dependent death of BMM. Therefore, bacterial motility increases contact with host cells during infection, but flagellin is not an adhesin. When BMM contact by each nonmotile strain was promoted by centrifugation, all the mutants bound BMM similarly, but only those microbes that synthesized flagellin induced BMM death. Thus, the flagellar regulon equips the aquatic pathogen
L. pneumophila
to coordinate motility with multiple traits vital to virulence.
Pulmonary Interleukin-23 Gene Delivery Increases Local T-Cell Immunity and Controls Growth ofMycobacterium tuberculosisin the Lungs
Authors: Happel Kyle I. , Lockhart Euan A. , Mason Carol M. , Porretta Elizabeth , Keoshkerian Elizabeth , Odden Anthony R. , Nelson Steve , Ramsay Alistair J. 
Published: August 2005

ABSTRACTInterleukin-23 (IL-23) is a heterodimeric cytokine that shares IL-12 p40 but contains a unique p19 subunit similar to IL-12 p35. Previous studies indicate a greater importance for intact IL-12/23 p40 expression than IL-12 p35 for immunity againstMycobacterium tuberculosis, suggesting a role for IL-23 in host defense. The effects of IL-23 on the outcome of pulmonary infection withM. tuberculosishave not been described. Here, we show that local delivery of replication-defective adenovirus vectors encoding IL-23 (AdIL-23) greatly stimulated expression of both gamma interferon (IFN-γ) and IL-17 in lung tissues of otherwise normal mice. When given 72 h prior to infection withM. tuberculosis, AdIL-23 significantly reduced the bacterial burden at 14, 21, and 28 days. Markedly lower levels of lung inflammation were observed at 28 days than in control mice pretreated with control adenovirus (AdNull) or vehicle controls. AdIL-23 pretreatment resulted in increased numbers of CD4+CD25+activated T cells in lungs and draining lymph nodes compared to control groups and more CD4+T cells bearing surface memory markers in lung lymph nodes. IL-23 gene delivery also significantly enhanced host anti-mycobacterial T-cell responses, as shown by elevated levels of IFN-γ and IL-17 secreted in vitro following restimulation withM. tuberculosispurified protein derivative. Overall, our data show that transient IL-23 gene delivery in the lung is well tolerated, and they provide the initial demonstration that this factor controls mycobacterial growth while augmenting early pulmonary T-cell immunity.
Immunogenicity of Recombinant Protective Antigen and Efficacy against Aerosol Challenge with Anthrax
Authors: Williamson E. D. , Hodgson I. , Walker N. J. , Topping A. W. , Duchars M. G. , Mott J. M. , Estep J. , LeButt C. , Flick-Smith H. C. , Jones H. E. , Li H. , Quinn C. P. 
Published: August 2005

ABSTRACTImmunization with a recombinant form of the protective antigen (rPA) fromBacillus anthracishas been carried out with rhesus macaques. Rhesus macaques immunized with 25 μg or more ofB. subtilis-expressed rPA bound to alhydrogel had a significantly increased immunoglobulin G (IgG) response to rPA compared with macaques receiving the existing licensed vaccine from the United Kingdom (anthrax vaccine precipitated [AVP]), although the isotype profile was unchanged, with bias towards the IgG1 and IgG2 subclasses. Immune macaque sera from all immunized groups contained toxin-neutralizing antibody and recognized all the domains of PA. While the recognition of the N terminus of PA (domains 1 to 3) was predominant in macaques immunized with the existing vaccines (AVP and the U.S. vaccine anthrax vaccine adsorbed), macaques immunized with rPA recognized the N- and C-terminal domains of PA. Antiserum derived from immunized macaques protected macrophages in vitro against the cytotoxic effects of lethal toxin. Passive transfer of IgG purified from immune macaque serum into naive A/J mice conferred protection against challenge withB. anthracisin a dose-related manner. The protection conferred by passive transfer of 500 μg macaque IgG correlated significantly (P= 0.003;r= 0.4) with the titers of neutralizing antibody in donor macaques. Subsequently, a separate group of rhesus macaques immunized with 50 μg ofEscherichia coli-derived rPA adsorbed to alhydrogel was fully protected against a target dose of 200 50% lethal doses of aerosolizedB. anthracis. These data provide some preliminary evidence for the existence of immune correlates of protection against anthrax infection in rhesus macaques immunized with rPA.
Bordetella pertussis risA
, but Not
risS
, Is Required for Maximal Expression of Bvg-Repressed Genes
Authors: Stenson Trevor H. , Allen Andrew G. , al-Meer Jehan A. , Maskell Duncan , Peppler Mark S. 
Published: August 2005

ABSTRACT

Expression of virulence determinants by
Bordetella pertussis
, the primary etiological agent of whooping cough, is regulated by the BvgAS two-component regulatory system. The role of a second two-component regulatory system, encoded by
risAS
, in this process is not defined. Here, we show that mutation of
B. pertussis risA
does not affect Bvg-activated genes or proteins. However, mutation of
risA
resulted in greatly diminished expression of Bvg-repressed antigens and decreased transcription of Bvg-repressed genes. In contrast, mutation of
risS
had no effect on the expression of Bvg-regulated molecules. Mutation of
risA
also resulted in decreased bacterial invasion in a HeLa cell model. However, decreased invasion could not be attributed to the decreased expression of Bvg-repressed products, suggesting that mutation of
risA
may affect the expression of a variety of genes. Unlike the
risAS
operons in
B. parapertussis
and
B. bronchiseptica
,
B. pertussis risS
is a pseudogene that encodes a truncated RisS sensor. Deletion of the intact part of the
B. pertussis risS
gene does not affect the expression of
risA
-dependent, Bvg-repressed genes. These observations suggest that RisA activation occurs through cross-regulation by a heterologous system.
Identification of Group A
Streptococcus
Antigenic Determinants Upregulated In Vivo
Authors: Salim Kowthar Y. , Cvitkovitch Dennis G. , Chang Peter , Bast Darrin J. , Handfield Martin , Hillman Jeffrey D. , de Azavedo Joyce C. S. 
Published: August 2005

ABSTRACT

Group A
Streptococcus
(GAS) causes a range of diseases in humans, from mild noninvasive infections to severe invasive infections. The molecular basis for the varying severity of disease remains unclear. We identified genes expressed during invasive disease using in vivo-induced antigen technology (IVIAT), applied for the first time in a gram-positive organism. Convalescent-phase sera from patients with invasive disease were pooled, adsorbed against antigens derived from in vitro-grown GAS, and used to screen a GAS genomic expression library. A murine model of invasive GAS disease was included as an additional source of sera for screening. Sequencing DNA inserts from clones reactive with both human and mouse sera indicated 16 open reading frames with homology to genes involved in metabolic activity to genes of unknown function. Of these, seven genes were assessed for their differential expression by quantitative real-time PCR both in vivo, utilizing a murine model of invasive GAS disease, and in vitro at different time points of growth. Three gene products—a putative penicillin-binding protein 1A, a putative lipoprotein, and a conserved hypothetical protein homologous to a putative translation initiation inhibitor in
Vibrio vulnificus
—were upregulated in vivo, suggesting that these genes play a role during invasive disease.
Isolation and Partial Purification of Macrophage- and Dendritic Cell-Activating Components fromMycoplasma arthritidis: Association with Organism Virulence and Involvement with Toll-Like Receptor 2
Authors: Cole Barry C. , Mu Hong-Hua , Pennock Nathan D. , Hasebe Akira , Chan Fok V. , Washburn Leigh R. , Peltier Morgan R. 
Published: August 2005

ABSTRACTMycoplasma arthritidisinduces toxicity, arthritis, and dermal necrosis in mice. Virulence factors include a superantigen and membrane adhesins and possibly also a bacteriophage component. Here we compare the biological properties of Triton X-114 extracts derived from avirulent and virulentM. arthritidisstrains. Macrophage cell lines and resident peritoneal macrophages were used to assess inflammatory potential as indicated by production of tumor necrosis factor alpha, interleukin-6, and/or nitric oxide. The activity resided exclusively within the hydrophobic detergent phase, was unaffected by heat treatment at 100°C for 30 min, and was resistant to proteinase K digestion, suggesting involvement of a lipopeptide. Contamination of extracts with endotoxin or superantigen was excluded. Extracts of the more virulent strain had higher activity than did those of the avirulent strain. Using CHO cells expressing Toll-like receptor 2 (TLR2) or TLR4, both with transfected CD14, we showed that extracts activated these cells via TLR2 but not by TLR4. Also, macrophages from C57BL/6 TLR2−/−mice failed to respond to the extracts, whereas those from TLR2+/+cells did respond. The preparations from the virulent strain ofM. arthritidiswere also more potent in activating dendritic cells, as evidenced by up-regulation of major histocompatibility complex class II, CD40, B7-1, and B7-2. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and subsequent elution of gel slices revealed the presence of three active moieties which corresponded to molecular masses of approximately 24, 28, and 40 kDa. Three active components were also found by reverse-phase chromatography. We suggest that macrophage activation byM. arthritidiscould play a significant role in the inflammatory response induced in the host by this organism.
CpG Oligodeoxynucleotides Increase the Susceptibility of Normal Mice to Infection byCandida albicans
Authors: Ito Shuichi , Pedras-Vasconcelos Joao , Klinman Dennis M. 
Published: August 2005

ABSTRACTSynthetic oligodeoxynucleotides containing CpG motifs trigger an innate immune response that typically increases host resistance to infection. Yet CpG treatment reduces the resistance of normal mice toCandida albicansinfection. This effect is mediated by CpG-induced interleukin-12, indicating that CpG-dependent cytokine production may have adverse consequences for the host.
Lightning-Initiation Locations as a Remote Sensing Tool of Large Thunderstorm Electric Field Vectors
Authors: Maggio Christopher , Coleman Lee , Marshall Thomas , Stolzenburg Maribeth , Stanley Mark , Hamlin Timothy , Krehbiel Paul , Rison William , Thomas Ron 
Published: August 2005

Abstract
The lightning data that are recorded with a three-dimensional lightning mapping array (LMA) are compared with data from an electric field change sensor (in this case a flat-plate antenna operated both as a “slow” and a “fast” antenna). The goal of these comparisons is to quantify any time difference that may exist between the initial responses of the two instruments to a lightning flash. The data consist of 136 flashes from two New Mexico thunderstorms. It is found that the initial radiation source detected by the LMA usually precedes the initial response of both the slow and fast antennas. In a small number of cases, the flat-plate antenna response precedes the initial LMA source, but by no more than 2 ms. The observations of such a close time coincidence suggest that the first LMA radiation source of each flash was located at or very near the flash-initiation point. Thus, the first LMA radiation source and the initial sequence of sources from a lightning flash can be used as remote sensing tools to give information about the magnitude of the electric field (relative to lightning-initiation thresholds) and the direction of the electric field at the initiation location.
Eddy-Induced Variability in a Transatlantic Section: Argo Observing System–Gyroscope 0302 Cruise Comparison
Authors: Vargas-Yáñez Manuel , Parrilla Gregorio , Lavín Alicia , Vélez-Belchí Pedro , González-Pola César , Hernández-Guerra Alonso 
Published: August 2005

Abstract
Ocean hydrological sections provide a very useful mean to study the ocean circulation as well as to determine water mass properties and to estimate fluxes. One basic method for their analysis is the spatial interpolation of data, obtained from a set of predefined stations, into a regular grid for contouring isolines and for further calculations. The shortest length scales that can be solved are limited by the distance between stations. Some of these scales, though resoluble by the sampling design, may be, with respect to time variability, shorter than the time that is needed to complete the section. This situation can produce a lack of synopticity in the obtained data, which is not usually addressed in oceanographic studies because the sequential repetition of oceanographic surveys is not an easy task. Here two samplings are compared—one by CTD- and another by Array for Real-Time Geostrophic Oceanography (Argo)-type profilers—of the same zonal section with a 5-day delay. The integral time scale for the mesoscale field is around 11 days, which implies that the mesoscale signal obtained from consecutive transmissions of the profilers are weakly correlated. The mesoscale field in a transatlantic section, which typically takes 20 days to be carried out, cannot be considered as synoptic.