bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epitope of the Vaccine-TypeBordetella pertussisStrain 186 Lipooligosaccharide and Antiendotoxin Activity of Antibodies Directed against the Terminal Pentasaccharide-Tetanus Toxoid Conjugate
Authors: Niedziela Tomasz , Letowska Iwona , Lukasiewicz Jolanta , Kaszowska Marta , Czarnecka Anna , Kenne Lennart , Lugowski Czeslaw 
Published: October 2005

ABSTRACTLipooligosaccharides (LOS) isolated fromBordetella pertussisstrains 186 and 606 were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high-resolution magic angle spinning nuclear magnetic resonsnace (NMR). These analyses distinguished between the LOS of strains 186 and 606, suggesting that the structure of LOS inB. pertussisis heterogeneous. The pentasaccharide was selectively cleaved from LOS ofB. pertussisstrain 186, purified, and covalently linked to a monomer fraction of tetanus toxoid. Injection of rabbits with the neoglycoconjugate emulsified in complete Freund's adjuvant yielded immunoglobulin G antibodies that were reactive with the LOS. These antibodies reacted strongly withB. pertussisLOS possessing the complete dodecasaccharide, as determined by an enzyme-linked immunosorbent assay, immunoblotting, and flow cytometry with intact, live bacterial cells. The binding epitope within the pentasaccharide was investigated by saturation transfer difference (STD) NMR spectroscopy. Protons H-1 and H-4 of the terminal α-d-GlcpNAc and proton H-6 and protons of anN-methyl group at H-4 of 3-substituted β-l-FucpNAc4NMe exhibited the largest saturation transfers. STD NMR experiments confirmed that the immunodominant epitope recognized by the antineoglycoconjugate antibodies is located predominantly in the distal trisaccharide ofB. pertussis186 LOS. The antipentasaccharide antibodies induced by the conjugate inhibited the secretion of tumor necrosis factor alpha, interleukin-6, and NO by LOS-stimulated J774A.1 cells.
Enhanced Factor H Binding to Sialylated Gonococci Is Restricted to the Sialylated Lacto-N-Neotetraose Lipooligosaccharide Species: Implications for Serum Resistance and Evidence for a Bifunctional Lipooligosaccharide Sialyltransferase in Gonococci
Authors: Gulati Sunita , Cox Andrew , Lewis Lisa A. , St. Michael Frank , Li Jianjun , Boden Ryan , Ram Sanjay , Rice Peter A. 
Published: October 2005

ABSTRACTWe isolated serologically identical (by serovar determination and porin variable region [VR] typing) strains ofNeisseria gonorrhoeaefrom an infected male and two of his monogamous female sex partners. One strain (termed 398078) expressed the L1 (Galα1 → 3Galβ1 → 4Glcβ1 → 4HepI) lipooligosaccharide (LOS) structure exclusively; the other (termed 398079) expressed the lacto-N-neotetraose (LNT; Galβ1 → 4GlcNAcβ1 → 3Galβ1 → 4Glcβ1 → 4HepI) LOS structure. The strain from the male index case expressed both glycoforms and exhibited both immunotypes. Nuclear magnetic resonance analysis revealed that sialic acid linked to the terminal Gal of L1 LOS via an α2 → 6 linkage and, as expected, to the terminal Gal of LNT LOS via an α2→ 3 linkage. Insertional inactivation of the sialyltransferase gene (known to sialylate LNT LOS) abrogated both L1 LOS sialylation and LNT LOS sialylation, suggesting a bifunctional nature of this enzyme in gonococci. Akin to our previous observations, sialylation of the LNT LOS of strain 398079 enhanced the binding of the complement regulatory molecule, factor H. Rather surprisingly, factor H did not bind to sialylated strain 398078. LOS sialylation conferred the LNT LOS-bearing strain complete (100%) resistance to killing by even 50% nonimmune normal human serum (NHS), whereas sialylation of L1 LOS conferred resistance only to 10% NHS. The ability of gonococcal sialylated LNT to bind factor H confers high-level serum resistance, which is not seen with sialylated L1 LOS. Thus, serum resistance mediated by sialylation of gonococcal L1 and LNT LOS occurs by different mechanisms, and specificity of factor H binding to sialylated gonococci is restricted to the LNT LOS species.
Analysis of a Heme-Dependent Signal Transduction System in
Corynebacterium diphtheriae
: Deletion of the
chrAS
Genes Results in Heme Sensitivity and Diminished Heme-Dependent Activation of the
hmuO
Promoter
Authors: Bibb Lori A. , King Natalie D. , Kunkle Carey A. , Schmitt Michael P. 
Published: October 2005

ABSTRACT

The
Corynebacterium diphtheriae hmuO
gene encodes a heme oxygenase that is involved in the utilization of heme as an iron source. Transcription of
hmuO
is activated by heme or hemoglobin and repressed by iron and DtxR. Previous studies with
Escherichia coli
showed that heme-dependent transcriptional activation of an
hmuO
promoter-
lacZ
fusion was dependent on the cloned
C. diphtheriae chrA
and
chrS
genes (
chrAS
), which encode the response regulator and sensor kinase, respectively, of a two-component signal transduction system. In this study, nonpolar deletions in the
chrAS
genes were constructed on the chromosome of
C. diphtheriae
. Mutations in
chrAS
resulted in marked reduction in heme-dependent transcription of
hmuO
, which indicates that the ChrA/S system is a key regulator at the
hmuO
promoter. However, low but significant levels of heme-specific transcriptional activity were observed at the
hmuO
promoter in the
chrAS
mutants, suggesting that an additional heme-dependent activator is involved in
hmuO
expression. The
chrAS
mutants were also sensitive to heme, which was observed only in stationary-phase cultures and correlated with reduced cell viability. The heme sensitivity of the mutants was not due to reduced expression of
hmuO
, and these results suggest that additional factors controlled by the ChrA/S system may be involved in protection against heme toxicity. Transcriptional analysis of the
chrAS
operon revealed that it was not autoregulated or affected by iron or heme levels.
Epsilon-Toxin Is Required for Most
Clostridium perfringens
Type D Vegetative Culture Supernatants To Cause Lethality in the Mouse Intravenous Injection Model
Authors: Sayeed Sameera , Fernandez-Miyakawa M. E. , Fisher Derek J. , Adams Vicki , Poon Rachael , Rood Julian I. , Uzal Francisco A. , McClane Bruce A. 
Published: October 2005

ABSTRACT

Clostridium perfringens
type D enterotoxemias have significant economic impact by causing rapid death of several domestic animal species. Consequently, domestic animals are commonly vaccinated, at varying efficacy, with inactivated type D vegetative supernatants. Improved type D vaccines might become possible if the lethal toxins produced by type D isolates were characterized and the contributions of those toxins to supernatant-induced lethality were established. Therefore, the current study evaluated the presence of lethal toxins in supernatants prepared from late-log-phase vegetative cultures of a large collection of genotype D isolates. Under this growth condition, most genotype D isolates produced variable levels of at least three different lethal toxins, including epsilon-toxin (ETX). To model the rapid lethality of type D enterotoxemias, studies were conducted involving intravenous (i.v.) injection of genotype D vegetative supernatants into mice, which were then observed for neurotoxic distress. Those experiments demonstrated a correlation between ETX (but not alpha-toxin or perfringolysin O) levels in late-log-phase genotype D supernatants and lethality. Consistent with the known proteolytic activation requirement for ETX toxicity, trypsin pretreatment was required for, or substantially increased, the lethality of nearly all of the tested genotype D vegetative supernatants. Finally, the lethality of these trypsin-pretreated genotype D supernatants could be completely neutralized by an ETX-specific monoclonal antibody but not by an alpha-toxin-specific monoclonal antibody. Collectively, these results indicate that, under the experimental conditions used in the present study, ETX is necessary for the lethal properties of most genotype D vegetative supernatants in the mouse i.v. injection model.
Toll-Like Receptor 2 Modulates the Proinflammatory Milieu inStaphylococcus aureus-Induced Brain Abscess
Authors: Kielian Tammy , Haney Anessa , Mayes Patrick M. , Garg Sarita , Esen Nilufer 
Published: October 2005

ABSTRACTToll-like receptor 2 (TLR2) is a pattern recognition receptor (PRR) that plays an important role in innate immune recognition of conserved structural motifs on a wide array of pathogens, includingStaphylococcus aureus. To ascertain the functional significance of TLR2 in the context of central nervous system (CNS) parenchymal infection, we evaluated the pathogenesis ofS. aureus-induced experimental brain abscess in TLR2 knockout (KO) and wild-type (WT) mice. The expression of several proinflammatory mediators, including inducible nitric oxide synthase, tumor necrosis factor alpha, and macrophage inflammatory protein-2, was significantly attenuated in brain abscesses of TLR2 KO mice compared to WT mice during the acute phase of infection. Conversely, interleukin-17 (IL-17), a cytokine produced by activated and memory T cells, was significantly elevated in lesions of TLR2 KO mice, suggesting an association between innate and adaptive immunity in brain abscess. Despite these differences, brain abscess severity in TLR2 KO and WT animals was similar, with comparable mortality rates, bacterial titers, and blood-brain barrier permeability, implying a role for alternative PRRs. Expression of the phagocytic PRRs macrophage scavenger receptor type AI/AII and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) was increased in brain abscesses of both TLR2 KO and WT mice compared to uninfected animals. However, LOX-1 induction in brain abscesses of TLR2 KO mice was significantly attenuated compared to WT animals, revealing that the TLR2-dependent signal(s) influence LOX-1 expression. Collectively, these findings reveal the complex nature of gram-positive bacterial recognition in the CNS which occurs, in part, through engagement of TLR2 and highlight the importance of receptor redundancy forS. aureusdetection in the CNS.
In Vitro Effector Activity ofPneumocystis murina-Specific T-Cytotoxic-1 CD8+T Cells: Role of Granulocyte-Macrophage Colony-Stimulating Factor
Authors: McAllister Florencia , Steele Chad , Zheng Mingquan , Shellito Judd E. , Kolls Jay K. 
Published: October 2005

ABSTRACTHuman immunodeficiency virus (HIV)-related opportunistic infections continue to occur in patients who are newly diagnosed with HIV infection, those in the early course of highly active antiretroviral therapy or nonadherent to HIV care, and other immunosuppressed individuals. One of the most common opportunistic infections in these patients isPneumocystispneumonia. CD8+T cells are recruited to the lung afterP. cariniiinfection and have been associated with both lung injury and host defense. This variability may be due to subpopulations of CD8+T cells recruited to the lung. We have previously shown using adoptive transfer studies that in vivo-generated T-cytotoxic-1 (Tc1) CD8+T cells, defined by the secretion of gamma interferon (IFN-γ), have effector activity against Pneumocystis spp. in vitro as well as in vivo. To better understand the mechanisms of these effects, we generated, expanded, and tested Tc1 and Tc2 CD8+T cells specific forP. murinaex vivo. Tc1-polarized CD8+T cells secreted higher levels of IFN-γ and granulocyte-macrophage colony-stimulating factor (GM-CSF) and lower levels of interleukin-4 (IL-4), IL-5, IL-10, and IL-13 than Tc2 CD8+T cells when stimulated withP. murinaantigen. Moreover, Tc1 CD8+T cells demonstrated enhanced effector activity in a macrophage-mediated killing assay which was independent of cell contact. The augmentation in macrophage-mediatedP. murinakilling was significantly abrogated when GM-CSF was neutralized in the Tc1 CD8+T cells. These data support the possibility that antigen-specific GM-CSF secretion is critical for effector activity ofP. murina-specific Tc1 CD8+T cells in vitro.
Immune Response to Pneumococcal Polysaccharides 4 and 14 in Elderly and Young Adults: Analysis of the Variable Heavy Chain Repertoire
Authors: Kolibab Kris , Smithson S. Louise , Rabquer Bradley , Khuder Sadik , Westerink M. A. Julie 
Published: October 2005

ABSTRACTStreptococcus pneumoniaeis a leading cause of morbidity and mortality in both developed and developing countries. The current pneumococcal polysaccharide (PPS) vaccine is highly effective in young adults; however, vaccine efficacy is dramatically decreased in the elderly population. We hypothesized that the decreased vaccine efficacy in the elderly results from altered variable gene family usage. We have characterized the immunoglobulin G gene usage of the antibody response to PPS4 and PPS14 in 20 young and 20 elderly adults. The variable heavy (VH) gene repertoire of human peripheral B cells was amplified by using PCR. A total of 364 heavy chain sequences with specificity for PPS4 and 305 heavy chain sequences for PPS14 were analyzed from young adults. In addition, a total of 325 sequences for PPS4 and 291 sequences for PPS14 were obtained from elderly adults. Complete sequence identity, somatic mutation frequencies, and VHgene usage was determined in response to PPS4 and PPS14. In all volunteers, the immune response to both polysaccharides consisted predominantly of heavy chains belonging to the VH3 gene family. There were significant differences in the variable gene repertoire between young and elderly adults. Somatic mutation occurred more frequently in sequences derived from young compared to elderly derived sequences. With aging, a loss of oligoclonality was noted in response to PPS4 and PPS14 compared to young adults. The observed differences in VHrepertoire, somatic mutation, and loss of oligoclonality may contribute to decreased vaccine efficacy in the elderly.
Immune Response to Pneumococcal Polysaccharides 4 and 14 in Elderly and Young Adults: Analysis of the Variable Light Chain Repertoire
Authors: Smithson S. Louise , Kolibab Kris , Shriner Anne K. , Srivastava Neeti , Khuder Sadik , Westerink M. A. Julie 
Published: October 2005

ABSTRACTStreptococcus pneumoniaeis a human bacterial pathogen responsible for serious infections including pneumonia. The currently licensed polysaccharide vaccine provides 60 to 80% protection in young adults, but in the elderly the vaccine efficacy is drastically reduced despite normal antibody levels. We hypothesized that the reduced vaccine efficacy in the elderly results from altered variable gene family usage. We have analyzed the light chain gene usage in 20 young (20 to 30 years of age) and 20 elderly (65 to 86 years of age) adults in response to pneumococcal polysaccharide 4 (PPS4) and PPS14. We generated a variable light chain library using B cells specific for PPS4 and PPS14 from each vaccinated individual. We determined complete sequences and somatic mutation frequencies in all isolated variable light chain fragments. Six gene families, κ1, κ2, κ3, κ4, λ1, and λ3, were identified in response to PPS4 and PPS14 in both age groups. Comparison of young and elderly adults demonstrated significant differences in κ4, λ1, and λ3 gene usage in response to PPS4 and PPS14. With aging, there was a significant increase in κ4 gene usage and a significant decrease in λ1 and λ3 gene usage in response to both PPS4 and PPS14. Although both Vκ1 and Vλ3 gene products demonstrated extensive mutations, there was no age-related difference in mutational frequency per gene family. These findings suggest an age-related change in light chain gene usage in response to PPS4 and PPS14.
Defining the Interaction of theTreponema pallidumAdhesin Tp0751 with Laminin
Authors: Cameron Caroline E. , Brouwer Nathan L. , Tisch Lisa M. , Kuroiwa Janelle M. Y. 
Published: October 2005

ABSTRACTVarious invasive pathogens attach to host tissues via the extracellular matrix component laminin, the major glycoprotein found within basement membranes. Previous investigations identified the laminin-binding adhesin Tp0751 within the spirochete bacteriumTreponema pallidum. In the current study, Tp0751 was shown to attach to a variety of laminin isoforms that are widely distributed throughout the host, including laminins 1, 2, 4, 8, and 10. Such universal attachment is conducive for an adhesin present within a highly invasive pathogen that encounters a variety of tissue sites during the course of infection. Additional studies systematically identified the amino acid residues within Tp0751 that contribute to laminin binding using synthetic peptides designed from the mature protein sequence. The minimum laminin-binding region of the adhesin was localized to 10 amino acids; peptides containing these residues inhibited attachment of Tp0751 andT. pallidumto laminin. Further, Tp0751-specific antibodies inhibited attachment ofT. pallidumto laminin. This study furthers our knowledge of the interaction ofT. pallidumwith laminin, an association that is proposed to facilitate bacterial traversal of basement membranes and subsequent entry into the circulation and tissue invasion. As such, these investigations will reveal new targets for possible prevention of bacterial dissemination and establishment of chronic infection.
The Glucocorticoid-Induced Tumor Necrosis Factor Receptor-Related Gene Modulates the Response toCandida albicansInfection
Authors: Agostini Massimiliano , Cenci Elio , Pericolini Eva , Nocentini Giuseppe , Bistoni Giovanni , Vecchiarelli Anna , Riccardi Carlo 
Published: October 2005

ABSTRACTThe glucocorticoid-induced tumor necrosis factor (TNF) receptor-related gene (GITR; TNFRSF18) modulates immune response activating coaccessory signals in T cells and is expressed at high levels in CD4+CD25+cells. Its ligand (GITRL) is expressed in antigen-presenting cells, where it is capable of promoting signaling. We investigated the role of GITR/GITRL interaction during disseminated candidiasis in GITR knockout (GITR−/−) mice. GITR−/−mice survived longer and had a significantly decreased yeast load in kidneys and brain compared to GITR+/+mice. Since protective immunity to the fungus is mediated by antigen-specific T helper (Th) 1 cells, we studied in vitro cytokine production following infection. CD4+T cells of GITR−/−mice demonstrated a more efficient Th1 polarization as suggested by a two- to threefold decreased production of interleukin- (IL-)4 and IL-10 and a four- to fivefold increased production of gamma interferon compared to GITR+/+mice. This effect was not due to differences in lymphocyte and dendritic cell (DC) subpopulations in infected mice as demonstrated by flow cytometric studies. To verify whether DC activity was differently modulated, DCs were cocultured with CD4+T cells in the presence of heat-inactivatedCandida albicans. DCs, cocultured with GITR+/+CD4+CD25+cells produced a lower amount of IL-12 than DCs cocultured with GITR−/−CD4+CD25+T cells. These results suggest that GITR regulates susceptibility to systemic candidiasis by negatively modulating IL-12 production and promoting polarization of CD4+T cells towards Th2 by analogy with OX40, another TNF receptor superfamily member.
A
prfA
Transposon Mutant of
Listeria monocytogenes
F2365, a Serotype 4b Strain, Is Able To Survive in the Gastrointestinal Tract but Does Not Cause Systemic Infection of the Spleens and Livers of Intragastrically Inoculated Mice
Authors: Faith N. , Uhlich G. , Luchansky J. B. , Neudeck B. , Czuprynski C. 
Published: October 2005

ABSTRACT

prfA
is a member of the Crp/Fnr family of global regulatory genes in
Listeria monocytogenes
that has been shown previously to regulate several key virulence determinants both in vitro and in parenterally inoculated laboratory rodents. However, the role of
prfA
in the ability of
L. monocytogenes
to cause infection via the gastrointestinal (GI) tract has not been clearly established. In this study, we used a
prfA
transposon mutant of
L. monocytogenes
F2365, a serotype 4b strain, to assess the role of
prfA
in the pathogenesis of gastrointestinal listeriosis in mice. We found that the
prfA
mutant was able to survive in the GI tract (i.e., cecum) of mice, albeit in numbers somewhat less than those of the wild-type parent strain of
L. monocytogenes
. However, mice inoculated with the
prfA
mutant did not exhibit systemic infection of the spleen and liver, as was noted for mice inoculated with the wild-type parent strain. Survival of the
prfA
mutant in synthetic gastric fluid at pH 2.5 or 5 was somewhat reduced compared to that of the wild-type strain, as was its ability to invade and multiply within differentiated human intestinal epithelial cells (Caco-2 cells). Prior infection with the
prfA
mutant gave mice some protection against a subsequent challenge with virulent
L. monocytogenes
, although much less than that gained by prior gastrointestinal infection with the wild-type parent strain. These findings indicate that the global regulatory gene
prfA
is dispensable for colonization of the GI tract in mice but not for systemic infection.
Invariant NKT Cells Are Essential for the Regulation of Hepatic CXCL10 Gene Expression duringLeishmania donovaniInfection
Authors: Svensson Mattias , Zubairi Soombul , Maroof Asher , Kazi Fatima , Taniguchi Masaru , Kaye Paul M. 
Published: October 2005

ABSTRACTGamma interferon (IFN-γ)-regulated chemokines of the CXC family have been implicated as key regulators of a variety of T-cell-dependent inflammatory processes. However, the cellular source(s) of IFN-γ that regulates their early expression has rarely been defined. Here, we have directly addressed this question in mice afterLeishmania donovaniinfection. Comparison of CXCL10 mRNA accumulation in normal and IFN-γ-deficient mice confirmed an absolute requirement for IFN-γ for sustained (24 h) expression of CXCL10 mRNA accumulation in this model. In normal mice, IFN-γ was produced by both CD3intNK1.1+NKT cells and CD3−NK1.1+NK cells, as detected by intracellular flow cytometry. Strikingly, B6.Jα281−/−mice lacking NKT cells that express the invariant Vα14Jα18 T-cell-receptor α chain, although retaining a significant population of IFN-γ-producing NK cells and NKT cells, were unable to sustain CXCL10 mRNA accumulation. These data indicate that invariant NKT cells are indispensable for the regulation of hepatic CXCL10 gene expression duringL. donovaniinfection.
Metalloproteinase Inhibitors, Nonantimicrobial Chemically Modified Tetracyclines, and Ilomastat BlockBacillus anthracisLethal Factor Activity in Viable Cells
Authors: Kocer Salih S. , Walker Stephen G. , Zerler Brad , Golub Lorne M. , Simon Sanford R. 
Published: October 2005

ABSTRACTLethal toxin, produced by the bacteriumBacillus anthracis, is a major contributor to morbidity and mortality in animals and humans who have contracted anthrax. One component of this toxin, lethal factor (LF), proteolytically inactivates members of the mitogen-activated protein kinase kinase (MAPKK or MEK) family. In this study we show that CMT-300, CMT-308, and Ilomastat, agents initially characterized as matrix metalloproteinase inhibitors which are in early stages of development as pharmaceuticals, effectively inhibit the zinc metalloproteinase activity of LF. All three inhibitors, CMT-300, CMT-308, and Ilomastat, inhibit LF-mediated cleavage of a synthetic peptide substrate based on the N-terminal domain of MEKs. Inhibition of LF-mediated MEK proteolysis by all three agents was also achieved using lysates of the human monocytoid line MonoMac 6 as sources of MAPKKs and visualization of the extent of cleavage after separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by detection by Western blotting. Finally, we have demonstrated inhibition of intracellular MEKs in viable human monocytes and MonoMac 6 cells by these agents after incubation of the cells with a reconstituted preparation of recombinant lethal toxin. All three agents are effective inhibitors when incubated with LF prior to exposure to cells, while the CMTs, but not Ilomastat, are also effective when added after LF has already entered the viable cell targets. These results offer promise for strategies to combat effects of the lethal toxin ofB. anthracis.