bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response of
Leptospira interrogans
to Physiologic Osmolarity: Relevance in Signaling the Environment-to-Host Transition
Authors: Matsunaga James , Lo Miranda , Bulach Dieter M. , Zuerner Richard L. , Adler Ben , Haake David A. 
Published: March 2007

ABSTRACT

Transmission of pathogenic
Leptospira
between mammalian hosts usually involves dissemination via soil or water contaminated by the urine of carrier animals. The ability of
Leptospira
to adapt to the diverse conditions found inside and outside the host is reflected in its relatively large genome size and high percentage of signal transduction genes. An exception is
Leptospira borgpetersenii
serovar Hardjo, which is transmitted by direct contact and appears to have lost genes necessary for survival outside the mammalian host. Invasion of host tissues by
Leptospira interrogans
involves a transition from a low osmolar environment outside the host to a higher physiologic osmolar environment within the host. Expression of the lipoprotein LigA and LigB adhesins is strongly induced by an upshift in osmolarity to the level found in mammalian host tissues. These data suggest that
Leptospira
utilizes changes in osmolarity to regulate virulence characteristics. To better understand how
L. interrogans
serovar Copenhageni adapts to osmolar conditions that correspond with invasion of a mammalian host, we quantified alterations in transcript levels using whole-genome microarrays. Overnight exposure in leptospiral culture medium supplemented with sodium chloride to physiologic osmolarity significantly altered the transcript levels of 6% of
L. interrogans
genes. Repressed genes were significantly more likely to be absent or pseudogenes in
L. borgpetersenii
, suggesting that osmolarity is relevant in studying the adaptation of
L. interrogans
to host conditions. Genes induced by physiologic osmolarity encoded a higher than expected number of proteins involved in signal transduction. Further, genes predicted to encode lipoproteins and those coregulated by temperature were overrepresented among both salt-induced and salt-repressed genes. In contrast, leptospiral homologues of hyperosmotic or general stress genes were not induced at physiologic osmolarity. These findings suggest that physiologic osmolarity is an important signal for regulation of gene expression by pathogenic leptospires during transition from ambient conditions to the host tissue environment.
Anti-Lewis X Antibody PromotesHelicobacter pyloriAdhesion to Gastric Epithelial Cells
Authors: Sheu Shew-Meei , Sheu Bor-Shyang , Yang Hsiao-Bai , Lei Huan-Yao , Wu Jiunn-Jong 
Published: March 2007

ABSTRACTLewis X (Lex) antigen is expressed on the human gastric mucosa and the O-specific chain of lipopolysaccharides ofHelicobacter pylori. This antigen can induce autoantibodies, which may be involved in bacterial colonization and thus deserve further investigation. Flow cytometry was used to examine the effects of anti-Le monoclonal antibodies (MAbs) onH. pyloriadhesion. AbabA2mutant was also constructed to evaluate the effect of an anti-LexMAb on adhesion. The bacterial agglutination and in situ adhesion assays were used to confirm the anti-LexMAb effect onH. pyloriadhesion. This study revealed that an anti-LexMAb, but not an anti-LebMAb or an anti-LeyMAb, could enhance the adhesion ofH. pyloristrains that expressed high levels of Lexantigen to AGS cells. The enhancement was not found on anH. pyloristrain with a low level of Lexantigen. Anti-LexMAb could increase the adhesion of both the wild-type strain and its isogenicbabA2mutant to AGS cells. When AGS cells were pretreated with anti-LexMAb, the adhesion of thebabA2mutant also increased. Only anti-LexMAb could promote bacterial agglutination, and the in situ adhesion assay further confirmed that adding anti-LexMAb resulted in denser bacterial adhesion on the gastric epithelia collected from clinical patients. These results suggest anti-LexMAb could specifically enhance the adhesion abilities ofH. pyloristrains through a mechanism by which anti-LexMAb promotes bacterial aggregation and mediates bivalent interaction (antigen-antibody-antigen) between bacteria and host cells.
High-Throughput mRNA Profiling Characterizes the Expression of Inflammatory Molecules in Sepsis Caused by
Burkholderia pseudomallei
Authors: Wiersinga W. Joost , Dessing Mark C. , Kager Piet A. , Cheng Allen C. , Limmathurotsakul Direk , Day Nicholas P. , Dondorp Arjen M. , van der Poll Tom , Peacock Sharon J. 
Published: March 2007

ABSTRACT

Sepsis is characterized by an uncontrolled inflammatory response to invading microorganisms. We describe the inflammatory mRNA profiles in whole-blood leukocytes, monocytes, and granulocytes using a multigene system for 35 inflammatory markers that included pro- and anti-inflammatory cytokines, chemokines, and signal transduction molecules in a case-control study with 34 patients with sepsis caused by the gram-negative bacterium
Burkholderia pseudomallei
(the pathogen causing melioidosis) and 32 healthy volunteers. Relative to healthy controls, patients with sepsis showed increased transcription of a whole array of inflammatory genes in peripheral blood leukocytes, granulocytes, and monocytes. Specific monocyte and granulocyte mRNA profiles were identified. Strong correlations were found between inflammatory mRNA expression levels in monocytes and clinical outcome. These data underline the notion that circulating leukocytes are an important source for inflammatory mediators in patients with gram-negative sepsis. Gene profiling such as was done here provides an excellent tool to obtain insight into the extent of inflammation activation in patients with severe infection.
Protein F1 andStreptococcus pyogenesResistance to Phagocytosis
Authors: Hyland Kendra A. , Wang Beinan , Cleary P. Patrick 
Published: March 2007

ABSTRACTStreptococcus pyogenesis a major cause of pharyngitis in humans and encodes several fibronectin-binding proteins. M protein and protein F1 (PrtF1/SfbI) are differentially regulated by CO2and O2, respectively, and both mediate the invasion of epithelial cells. This study examined whether PrtF1/SfbI shares other properties with M protein. Expression of the PrtF1/SfbI protein by an M-negative mutant conferred resistance to phagocytosis and partial inhibition of C3 deposition on theS. pyogenessurface.
Environmental Strains of
Mycobacterium avium
Interfere with Immune Responses Associated with
Mycobacterium bovis
BCG Vaccination
Authors: Young Sarah L. , Slobbe Lynn , Wilson Rachel , Buddle Bryce M. , de Lisle Geofferey W. , Buchan Glenn S. 
Published: March 2007

ABSTRACT

Prior exposure of a vaccinee to certain species of environmental mycobacteria can prime the immune system against common mycobacterial antigens, which can in turn reduce the subsequent efficacy of live attenuated mycobacterial vaccines (such as
Mycobacterium bovis
BCG), in both human and livestock vaccination programs. In this study, two strains of
Mycobacterium avium
, both isolated from New Zealand livestock, were investigated to determine their growth characteristics and effects on the immune system in murine models. Markedly different effects on the immune system were observed; an IS
901
-negative strain (WAg 207) induced significant up-regulation of cell surface activation markers (major histocompatibility complex II, CD80, and CD86) on in vitro-derived dendritic cells and induced the release of proinflammatory monokines (interleukin-1β [IL-1β], IL-6, and tumor necrosis factor alpha) in dendritic cell-macrophage cocultures following direct in vitro contact of cells with bacteria. In contrast, an IS
901
-positive strain (WAg 206) had none of these effects. When mice were exposed to
M. avium
via oral infection prior to BCG parenteral immunization, both strains were shown to be capable of decreasing subsequent antigen-stimulated gamma interferon secretion by splenic lymphocytes, although this effect was more significant for strain WAg 206. Both strains also induced a mycobacterial antigen-specific serological response in
M. avium
-sensitized and BCG-immunized mice; this response was greater in WAg 206-sensitized mice, and there was a predominance of immunoglobulin G1 antibody. The down-regulation of IFN-γ responses and the up-regulation of antibody responses are characteristic of a switch to a type 2 immune response. The different results may be linked to the inherent growth characteristics of the two strains, since WAg 206 was shown to grow slowly in murine macrophages in vitro and to cause a persistent systemic infection following infection in vivo, while WAg 207 grew fast and did not persist in mice. The implications of these findings for BCG vaccination protocols are discussed.
Trivalent Vaccine against Botulinum Toxin Serotypes A, B, and E That Can Be Administered by the Mucosal Route
Authors: Ravichandran Easwaran , Al-Saleem Fetweh H. , Ancharski Denise M. , Elias Mohammad D. , Singh Ajay K. , Shamim Mohammad , Gong Yujing , Simpson Lance L. 
Published: March 2007

ABSTRACT
Most reports dealing with vaccines against botulinum toxin have focused on the injection route of administration. This is unfortunate, because a mucosal vaccine is likely to be more efficacious for patients and pose fewer risks to health care workers and to the environment. Therefore, efforts were made to generate a mucosal vaccine that provides protection against the botulinum serotypes that typically cause human illness (serotypes A, B, and E). This work demonstrated that carboxy-terminal peptides derived from each of the three serotypes were able to bind to and penetrate human epithelial barriers in vitro, and there was no cross inhibition of membrane binding and transcytosis. The three polypeptides were then tested in vivo as a trivalent vaccine that could be administered to mice by the intranasal route. The results indicated that the mucosal vaccine evoked high secretory titers of immunoglobulin A (IgA), as well as high circulating titers of IgG and IgA, and it also evoked a high level of resistance to challenge with toxin. The immunoglobulin responses and the levels of resistance to challenge were increased by coadministration of adjuvants, such as chitosan and vitamin E. At least three mechanisms were identified to account for the antibody-induced resistance: (i) blockade of toxin absorption across epithelial cells, (ii) enhanced clearance of toxin from the circulation, and (iii) blockade of toxin action at the neuromuscular junction. These results are a compelling demonstration that a mucosal vaccine against multiple serotypes of botulinum toxin has been identified.
Biological and Immunological Characteristics of Lipooligosaccharide-Based Conjugate Vaccines for Serotype C
Moraxella catarrhalis
Authors: Yu Shengqing , Gu Xin-Xing 
Published: March 2007

ABSTRACT

Moraxella catarrhalis
is an important bacterial cause of otitis media in children and respiratory tract infections in the elderly. Lipooligosaccharide (LOS), a major surface antigen of this bacterium, is a potential vaccine component against the organism. There are three major LOS serotypes (serotypes A, B, and C) in clinical isolates of
M. catarrhalis
. Our previous studies demonstrated that serotype A and B LOS-based conjugates were immunogenic in animals and elicited bactericidal antibodies. In this study, LOS from serotype C strain 26404 was isolated, detoxified, and conjugated to tetanus toxoid (TT) or the cross-reactive mutant (CRM) of diphtheria toxin to form detoxified LOS (dLOS)-TT, dLOS-CRM-1, and dLOS-CRM-2 vaccine candidates. The molar ratios (dLOS/protein) of the resulting conjugates were 47:1, 19:1, and 32:1, respectively, while the weight ratios were 0.94, 0.84 and 1.44, respectively. All conjugates were highly immunogenic in both mouse and rabbit models. Three subcutaneous injections of each conjugate formulated with the Ribi adjuvant elicited >700-fold increases in serum anti-LOS immunoglobulin G levels in mice (5 μg of dLOS) and >2,000-fold increases in rabbits (50 μg of dLOS). The resulting mouse and rabbit antisera showed complement-mediated bactericidal activity against the homologous strain. In addition, a representative rabbit antiserum showed bactericidal activity against 14 of 18 testable strains, and this bactericidal activity could be 100% inhibited by the serotype C or A LOS but only 30% inhibited by the serotype B LOS. These results indicate that the serotype C LOS-based conjugates can be used as vaccine components for further investigation in humans.
Inhibitory Effect of Enterohepatic
Helicobacter hepaticus
on Innate Immune Responses of Mouse Intestinal Epithelial Cells
Authors: Sterzenbach Torsten , Lee Sae Kyung , Brenneke Birgit , von Goetz Franz , Schauer David B. , Fox James G. , Suerbaum Sebastian , Josenhans Christine 
Published: March 2007

ABSTRACT

Enterohepatic
Helicobacter
species infect the intestinal tracts and biliary trees of various mammals, including mice and humans, and are associated with chronic inflammatory diseases of the intestine, gallstone formation, and malignant transformation. The recent analysis of the whole genome sequence of the mouse enterohepatic species
Helicobacter hepaticus
allowed us to perform a functional analysis of bacterial factors that may play a role in these diseases. We tested the hypothesis that
H. hepaticus
suppresses or evades innate immune responses of mouse intestinal epithelial cells, which allows this pathogen to induce or contribute to chronic inflammatory disease. We demonstrated in the present study that the innate immune responses of intestinal epithelial cells to lipopolysaccharide (LPS) via Toll-like receptor 4 (TLR4) and to flagellin-mediated activation via TLR5 are reduced by
H. hepaticus
infection through soluble bacterial factors. In particular,
H. hepaticus
lysate and the soluble component LPS antagonized TLR4- and TLR5-mediated immune responses of intestinal epithelial cells.
H. hepaticus
lysate and LPS inhibited development of endotoxin tolerance to
Escherichia coli
LPS. Suppression of innate immune responses by
H. hepaticus
LPS thus may affect intestinal responses to the resident microbial flora, epithelial homeostasis, and intestinal inflammatory conditions.
Legionella pneumophila
Infection Up-Regulates Dendritic Cell Toll-Like Receptor 2 (TLR2)/TLR4 Expression and Key Maturation Markers
Authors: Rogers James , Hakki Amal , Perkins Izabella , Newton Catherine , Widen Ray , Burdash Nicholas , Klein Thomas , Friedman Herman 
Published: March 2007

ABSTRACT

Dendritic cells (DCs) have a critical role in linking innate to adaptive immunity, and this transition is regulated by the up-regulation of costimulatory and major histocompatibility complex (MHC) molecules as well as Toll-like receptors. These changes in DCs have been observed to occur following microbial infection, and in the present study, we examined the effect of
Legionella pneumophila
infection on the expression of these DC markers. We showed that bone marrow-derived DC cultures from BALB/c mice infected with live
L. pneumophila
resulted in the up-regulation of Toll-like receptors 2 and 4 and the activation of CD40, CD86, and MHC class I/II molecules.
Glycine Residues in the Hydrophobic Core of the GspB Signal Sequence Route Export toward the Accessory Sec Pathway
Authors: Bensing Barbara A. , Siboo Ian R. , Sullam Paul M. 
Published: March 2007

ABSTRACT

The
Streptococcus gordonii
cell surface glycoprotein GspB mediates high-affinity binding to distinct sialylated carbohydrate structures on human platelets and salivary proteins. GspB is glycosylated in the cytoplasm of
S. gordonii
and is then transported to the cell surface via a dedicated transport system that includes the accessory Sec components SecA2 and SecY2. The means by which the GspB preprotein is selectively recognized by the accessory Sec system have not been characterized fully. GspB has a 90-residue amino-terminal signal sequence that displays a traditional tripartite structure, with an atypically long amino-terminal (N) region followed by hydrophobic (H) and cleavage regions. In this report, we investigate the relative importance of the N and H regions of the GspB signal peptide for trafficking of the preprotein. The results show that the extended N region does not prevent export by the canonical Sec system. Instead, three glycine residues in the H region not only are necessary for export via the accessory Sec pathway but also interfere with export via the canonical Sec route. Replacement of the H-region glycine residues with helix-promoting residues led to a decrease in the efficiency of SecA2-dependent transport of the preprotein and a simultaneous increase in SecA2-independent translocation. Thus, the hydrophobic core of the GspB signal sequence is responsible primarily for routing towards the accessory Sec system.
Initial Characterization of the Photosynthetic Apparatus of “
Candidatus
Chlorothrix halophila,” a Filamentous, Anoxygenic Photoautotroph
Authors: van de Meene Allison M. L. , Olson Tien Le , Collins Aaron M. , Blankenship Robert E. 
Published: March 2007

ABSTRACT

“
Candidatus
Chlorothrix halophila” is a recently described halophilic, filamentous, anoxygenic photoautotroph (J. A. Klappenbach and B. K. Pierson, Arch. Microbiol.
181:
17-25, 2004) that was enriched from the hypersaline microbial mats at Guerrero Negro, Mexico. Analysis of the photosynthetic apparatus by negative staining, spectroscopy, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the photosynthetic apparatus in this organism has similarities to the photosynthetic apparatus in both the
Chloroflexi
and
Chlorobi
phyla of green photosynthetic bacteria. The chlorosomes were found to be ellipsoidal and of various sizes, characteristics that are comparable to characteristics of chlorosomes in other species of green photosynthetic bacteria. The absorption spectrum of whole cells was dominated by the chlorosome bacteriochlorophyll
c
(BChl
c
) peak at 759 nm, with fluorescence emission at 760 nm. A second fluorescence emission band was observed at 870 nm and was tentatively attributed to a membrane-bound antenna complex. Fluorescence emission spectra obtained at 77 K revealed another complex that fluoresced at 820 nm, which probably resulted from the chlorosome baseplate complex. All of these results suggest that BChl
c
is present in the chlorosomes of “
Ca
. Chlorothrix halophila,” that BChl
a
is present in the baseplate, and that there is a membrane-bound antenna complex. Analysis of the proteins in the chlorosomes revealed an ∼6-kDa band, which was found to be related to the BChl
c
binding protein CsmA found in other green bacteria. Overall, the absorbance and fluorescence spectra of “
Ca
. Chlorothrix halophila” revealed an interesting mixture of photosynthetic characteristics that seemed to have properties similar to properties of both phyla of green bacteria when they were compared to the photosynthetic characteristics of
Chlorobium tepidum
and
Chloroflexus aurantiacus
.
Pigment Analysis of “
Candidatus
Chlorothrix halophila,” a Green Filamentous Anoxygenic Phototrophic Bacterium
Authors: Olson Tien Le , van de Meene Allison M. L. , Francis J. Nicholas , Pierson Beverly K. , Blankenship Robert E. 
Published: March 2007

ABSTRACT

The pigment composition of “
Candidatus
Chlorothrix halophila,” a filamentous anoxygenic phototrophic bacterium found in Baja California Sur, Mexico, was determined. Previous work showed that bacteriochlorophyll
c
(BChl
c
) was the major pigment in “
Ca
. Chlorothrix halophila,” but it was not clear if this bacterium also contains BChl
a
(J. A. Klappenbach and B. K. Pierson, Arch. Microbiol.
181:
17-25, 2004). Here we show that in addition to BChl
c
, a small amount of a pigment that is spectrally indistinguishable from BChl
a
is present in cell extracts of “
Ca
. Chlorothrix halophila.” Nevertheless, the BChl
a
-like pigment from “
Ca
. Chlorothrix halophila” has a different molecular weight and a different high-performance liquid chromatography elution time than BChl
a
from other photosynthetic bacteria. Based on mass spectrometry and other spectroscopic analysis, we determined that the BChl
a
-like pigment in “
Ca
. Chlorothrix halophila” contains a tetrahydrogeranylgeraniol tail rather than the phytol tail that is present in BChl
a
. The carotenoids and major BChl
c
homologs in “
Ca
. Chlorothrix halophila” were also identified. BChls
c
were found to be farnesol esterified and geranylgeraniol esterified.
Heterologous Expression and Identification of the Genes Involved in Anaerobic Degradation of 1,3-Dihydroxybenzene (Resorcinol) in
Azoarcus anaerobius
Authors: Darley Paula I. , Hellstern Jutta A. , Medina-Bellver Javier I. , Marqués Silvia , Schink Bernhard , Philipp Bodo 
Published: March 2007

ABSTRACT

Azoarcus anaerobius
, a strictly anaerobic, gram-negative bacterium, utilizes resorcinol as a sole carbon and energy source with nitrate as an electron acceptor. Previously, we showed that resorcinol degradation by this bacterium is initiated by two oxidative steps, both catalyzed by membrane-associated enzymes that lead to the formation of hydroxyhydroquinone (HHQ; 1,2,4-benzenetriol) and 2-hydroxy-1,4-benzoquinone (HBQ). This study presents evidence for the further degradation of HBQ in cell extracts to form acetic and malic acids. To identify the
A. anaerobius
genes required for anaerobic resorcinol catabolism, a cosmid library with genomic DNA was constructed and transformed into the phylogenetically related species
Thauera aromatica
, which cannot grow with resorcinol. By heterologous complementation, a transconjugant was identified that gained the ability to metabolize resorcinol. Its cosmid, designated R
+
, carries a 29.88-kb chromosomal DNA fragment containing 22 putative genes. In cell extracts of
T. aromatica
transconjugants, resorcinol was degraded to HHQ, HBQ, and acetate, suggesting that cosmid R
+
carried all of the genes necessary for resorcinol degradation. On the basis of the physiological characterization of
T. aromatica
transconjugants carrying transposon insertions in different genes of cosmid R
+
, eight open reading frames were found to be essential for resorcinol mineralization. Resorcinol hydroxylase-encoding genes were assigned on the basis of sequence analysis and enzyme assays with two mutants. Putative genes for hydroxyhydroquinone dehydrogenase and enzymes involved in ring fission have also been proposed. This work provides the first example of the identification of genes involved in the anaerobic degradation of aromatic compounds by heterologous expression of a cosmid library in a phylogenetically related organism.