bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protective Immune Responses to a Recombinant Adenovirus Type 35 Tuberculosis Vaccine in Two Mouse Strains: CD4 and CD8 T-Cell Epitope Mapping and Role of Gamma Interferon
Authors: Radošević Katarina , Wieland Catharina W. , Rodriguez Ariane , Weverling Gerrit Jan , Mintardjo Ratna , Gillissen Gert , Vogels Ronald , Skeiky Yasir A. W. , Hone David M. , Sadoff Jerald C. , van der Poll Tom , Havenga Menzo , Goudsmit Jaap 
Published: May 2007

ABSTRACT

There is an urgent need for an efficacious vaccine against tuberculosis (TB). Cellular immune responses are key to an effective protective response against TB. Recombinant adenovirus (rAd) vectors are especially suited to the induction of strong T-cell immunity and thus represent promising vaccine vehicles for the prevention of TB. We have previously reported on rAd vector serotype 35, the serotype of choice due to low preexisting immunity worldwide, which expresses a unique fusion protein of
Mycobacterium tuberculosis
antigens Ag85A, Ag85B, and TB10.4 (Ad35-TBS). Here, we demonstrate that Ad35-TBS confers protection against
M. tuberculosis
when administered to mice through either an intranasal or an intramuscular route. Histological evaluation of lung tissue corroborated the protection and, in addition, demonstrated differences between two mouse strains, with diffuse inflammation in BALB/c mice and distinct granuloma formation in C57BL/6 mice. Epitope mapping analysis in these mouse strains showed that the major T-cell epitopes are conserved in the artificial fusion protein, while three novel CD8 peptides were discovered. Using a defined set of T-cell epitopes, we reveal differences between the two mouse strains in the type of protective immune response, demonstrating that different antigen-specific gamma interferon (IFN-γ)-producing T cells can provide protection against
M. tuberculosis
challenge. While in BALB/c (H-2
d
) mice, a dominant CD8 T-cell response was detected, in C57BL/6 (H-2
b
) mice, more balanced CD4/CD8 T-cell responses were observed, with a more pronounced CD4 response in the lungs. These results unify conflicting reports on the relative importance of CD4 versus CD8 T-cell responses in protection and emphasize the key role of IFN-γ.
Transcriptome Analysis of Murine Macrophages in Response to Infection withStreptococcus pyogenesReveals an Unusual Activation Program
Authors: Goldmann Oliver , von Köckritz-Blickwede Maren , Höltje Claudia , Chhatwal Gursharan S. , Geffers Robert , Medina Eva 
Published: May 2007

ABSTRACTThe complex response of murine macrophages to infection withStreptococcus pyogeneswas investigated at the level of gene expression with a high-density oligomer microarray. More than 400 genes were identified as being differentially regulated. Many of the up-regulated genes encode molecules involved in the immune response and in inflammation, transcription, signaling, apoptosis, the cell cycle, electron transport, and cell adhesion. Of particular interest was the up-regulation of proinflammatory cytokines, typical of the classically activated macrophages (M1 phenotype), such as tumor necrosis factor alpha, interleukin 1 (IL-1), and IL-6, and as well as the up-regulation of anti-inflammatory mediators, such as IL-1 decoy receptor and IL-10, associated with alternative macrophage activation (M2 phenotype). Furthermore, the gene encoding inducible nitric oxide synthase (iNOS), an enzyme typically implicated in classical activation, was not induced in infected macrophages. Instead, the gene encoding arginase, a competitor for the iNOS substrate arginine involved in the alternative activation pathway, was up-regulated inS. pyogenes-infected cells. Thus, the microarray-based gene expression analysis demonstrated thatS. pyogenesinduces an atypical activation program in macrophages, with some but not all features of the classical or alternative activation phenotypes. The microarray data also suggested that the bactericidal activity of macrophages againstS. pyogenesis mediated by phagocyte oxidase, asp47phoxwas up-regulated in infected cells. Indeed, the in vivo and in vitro killing ofS. pyogeneswas markedly diminished in the absence of functional phagocyte (p47phox−/−) but not in the absence of iNOS (iNOS−/−). An understanding of how macrophages respond toS. pyogenesat the molecular level may facilitate the development of new therapeutic paradigms.
Nitrate Sensing and Metabolism Modulate Motility, Biofilm Formation, and Virulence in
Pseudomonas aeruginosa
Authors: Van Alst Nadine E. , Picardo Kristin F. , Iglewski Barbara H. , Haidaris Constantine G. 
Published: May 2007

ABSTRACT

Infection by the bacterial opportunist
Pseudomonas aeruginosa
frequently assumes the form of a biofilm, requiring motility for biofilm formation and dispersal and an ability to grow in nutrient- and oxygen-limited environments. Anaerobic growth by
P. aeruginosa
is accomplished through the denitrification enzyme pathway that catalyzes the sequential reduction of nitrate to nitrogen gas. Mutants mutated in the two-component nitrate sensor-response regulator and in membrane nitrate reductase displayed altered motility and biofilm formation compared to wild-type
P. aeruginosa
PAO1. Analysis of additional nitrate dissimilation mutants demonstrated a second level of regulation in
P. aeruginosa
motility that is independent of nitrate sensor-response regulator function and is associated with nitric oxide production. Because motility and biofilm formation are important for
P. aeruginosa
pathogenicity, we examined the virulence of selected regulatory and structural gene mutants in the surrogate model host
Caenorhabditis elegans
. Interestingly, the membrane nitrate reductase mutant was avirulent in
C. elegans
, while nitrate sensor-response regulator mutants were fully virulent. The data demonstrate that nitrate sensing, response regulation, and metabolism are linked directly to factors important in
P. aeruginosa
pathogenesis.
Sequential Chemotactic and Phagocytic Activation of Human Polymorphonuclear Neutrophils
Authors: Herrmann Jens Martin , Bernardo John , Long Heidi J. , Seetoo Kurt , McMenamin Mary E. , Batista Eraldo L. , Van Dyke Thomas E. , Simons Elizabeth R. 
Published: May 2007

ABSTRACTHuman polymorphonuclear neutrophils (PMN) chemotax to a foreign entity. When the chemoattractants’ origins are reached, specific receptors bind to the invader's surface, initiating phagocytosis, phagosome formation, and fusion with granule membranes, generating the bactericidal oxidative burst, and releasing lytic enzymes, specific peptides, and proteins. We explored the initial signaling involved in these functions by observing naïve, unprimed PMN in suspension using fluorescent indicators of cytoplasmic signals (Δ[Ca2+]iand ΔpHi) and of bactericidal entities (oxidative species and elastase) exposed toN-formyl-methionyl-leucyl-phenylalanine (fMLP) and/or multivalent immune complexes (IC). fMLP and IC each initiate a rapid transient rise in [Ca2+]i, mostly from intracellular stores, simultaneously with a drop in pHi; these are followed by a drop in [Ca2+]iand a rise in pHi, with the latter being due to a Na+/H+antiport. The impact of a second stimulation depends on the order in which stimuli are applied, on their dose, and on their nature. Provided that [Ca2+]iis restored, 10−7M fMLP, previously shown to elicit maximal Δ[Ca2+]ibut no bactericidal functions, did not prevent the cells’ responses with Δ[Ca2+]ito a subsequent high dose of fMLP or IC; conversely, cells first exposed to 120 μg/ml IC, previously shown to elicit maximal Δ[Ca2+]iand bactericidal functions, exhibited no subsequent Δ[Ca2+]ior ΔpHito either stimulus. While exposure to 10−7M fMLP, which saturates the PMN high-affinity receptor, did not elicit bactericidal release from these naïve unprimed PMN in suspension, 10−5M fMLP did, presumably via the low-affinity receptor, using a different Ca2+source.
Induction of Nitric Oxide Synthase and Activation of Signaling Proteins inAnophelesMosquitoes by the Malaria Pigment, Hemozoin
Authors: Akman-Anderson Leyla , Olivier Martin , Luckhart Shirley 
Published: May 2007

ABSTRACTAnopheles stephensi, a major vector for malaria parasite transmission, responds toPlasmodiuminfection by synthesis of inflammatory levels of nitric oxide (NO), which can limit parasite development in the midgut. We have previously shown thatPlasmodium falciparumglycosylphosphatidylinositols (PfGPIs) can induceA. stephensiNO synthase (AsNOS) expression in the midgut epithelium in vivo in a manner similar to the manner in which cytokines and NO are induced by PfGPIs in mammalian cells. In mosquito cells, signaling by PfGPIs andP. falciparummerozoites is mediated through Akt/protein kinase B (Akt/PKB), the mitogen-activated protein kinase kinase DSOR1, and extracellular signal-regulated kinase (ERK). In mammalian cells, a second parasite factor, malaria pigment or hemozoin (Hz), signals NOS induction through ERK- and nuclear factor kappa B-dependent pathways and has been demonstrated to be a novel proinflammatory ligand for Toll-like receptor 9. In this study, we demonstrate that Hz can also induce AsNOS gene expression in immortalizedA. stephensiandAnopheles gambiaecell lines in vitro and inA. stephensimidgut tissue in vivo. In mosquito cells, Hz signaling is mediated through transforming growth factor β-associated kinase 1, Akt/PKB, ERK, and atypical protein kinase C zeta/lambda. Our results show that Hz is a prominent parasite-derived signal forAnophelesand that signaling pathways activated by PfGPIs and Hz have both unique and shared components. Together with our previous findings, our data indicate that parasite signaling of innate immunity is conserved in mosquito and mammalian cells.
Soluble CD14 and CD83 from Human Neonatal Antigen-Presenting Cells Are Inducible by Commensal Bacteria and Suppress Allergen-Induced Human Neonatal Th2 Differentiation
Authors: Lundell Anna-Carin , Andersson Kerstin , Josefsson Elisabet , Steinkasserer Alexander , Rudin Anna 
Published: May 2007

ABSTRACTCD14 is expressed on the cell surface of various antigen-presenting cells, and CD83 is a maturation marker for dendritic cells (DC). CD14 and CD83 are also present as soluble proteins, and both have immunoregulatory functions. We examined whether neonatal cord blood monocytes or DC released soluble CD14 (sCD14) or sCD83 when exposed to the commensal intestinal bacteriaClostridium perfringens,Staphylococcus aureus,Lactobacillus rhamnosus,Escherichia coli, andBacteroides fragilis. We found that the gram-positive bacteriaC. perfringensandS. aureus, but not gram-negative bacteria, induced the release of sCD14 from monocytes. DC, on the other hand, released sCD14 in response to both gram-positive and gram-negative bacteria. Moreover, the expression of the virulence factor staphylococcal protein A seemed to be important forS. aureus-induced sCD14 production from both monocytes and DC. Soluble CD83 was released from DC, but not from monocytes, when exposed to both gram-positive and gram-negative bacteria. Finally, to investigate whether sCD14 or sCD83 could modulate neonatal allergen-induced T-cell differentiation, DC were exposed to birch allergen alone or in the presence of sCD14 or sCD83 and then cocultured with autologous T cells. We demonstrate that sCD14 and sCD83 inhibited the birch allergen-induced Th2 differentiation by suppressing interleukin 13 production. Together, these results suggest that the commensal intestinal flora may be an important stimulus for the developing immune system by inducing the immunoregulatory proteins sCD14 and sCD83, which may be involved in preventing T-cell sensitization to allergens in infants.
Interactions between the Lipoprotein PilP and the Secretin PilQ inNeisseria meningitidis
Authors: Balasingham Seetha V. , Collins Richard F. , Assalkhou Reza , Homberset Håvard , Frye Stephan A. , Derrick Jeremy P. , Tønjum Tone 
Published: May 2007

ABSTRACTNeisseria meningitidiscan be the causative agent of meningitis or septicemia. This bacterium expresses type IV pili, which mediate a variety of functions, including autoagglutination, twitching motility, biofilm formation, adherence, and DNA uptake during transformation. The secretin PilQ supports type IV pilus extrusion and retraction, but it also requires auxiliary proteins for its assembly and localization in the outer membrane. Here we have studied the physical properties of the lipoprotein PilP and examined its interaction with PilQ. We found that PilP was an inner membrane protein required for pilus expression and transformation, sincepilPmutants were nonpiliated and noncompetent. These mutant phenotypes were restored by the expression of PilP intrans. ThepilPgene is located upstream ofpilQ, and analysis of their transcripts indicated thatpilPandpilQwere cotranscribed. Furthermore, analysis of the level of PilQ expression inpilPmutants revealed greatly reduced amounts of PilQ only in the deletion mutant, exhibiting a polar effect onpilQtranscription. In vitro experiments using recombinant fragments of PilP and PilQ showed that the N-terminal region of PilP interacted with the middle part of the PilQ polypeptide. A three-dimensional reconstruction of the PilQ-PilP interacting complex was obtained at low resolution by transmission electron microscopy, and PilP was shown to localize around the cap region of the PilQ oligomer. These findings suggest a role for PilP in pilus biogenesis. Although PilQ does not need PilP for its stabilization or membrane localization, the specific interaction between these two proteins suggests that they might have another coordinated activity in pilus extrusion/retraction or related functions.
Gene Expression Analysis of
Corynebacterium glutamicum
Subjected to Long-Term Lactic Acid Adaptation
Authors: Jakob Kinga , Satorhelyi Peter , Lange Christian , Wendisch Volker F. , Silakowski Barbara , Scherer Siegfried , Neuhaus Klaus 
Published: May 2007

ABSTRACT

Corynebacteria form an important part of the red smear cheese microbial surface consortium. To gain a better understanding of molecular adaptation due to low pH induced by lactose fermentation, the global gene expression profile of
Corynebacterium glutamicum
adapted to pH 5.7 with lactic acid under continuous growth in a chemostat was characterized by DNA microarray analysis. Expression of a total of 116 genes was increased and that of 90 genes was decreased compared to pH 7.5 without lactic acid, representing 7% of the genes in the genome. The up-regulated genes encode mainly transcriptional regulators, proteins responsible for export, import, and metabolism, and several proteins of unknown function. As much as 45% of the up-regulated open reading frames code for hypothetical proteins. These results were validated using real-time reverse transcription-PCR. To characterize the functions of 38 up-regulated genes, 36 single-crossover disruption mutants were generated and analyzed for their lactic acid sensitivities. However, only a
sigB
knockout mutant showed a highly significant negative effect on growth at low pH, suggesting a function in organic-acid adaptation. A
sigE
mutant already displayed growth retardation at neutral pH but grew better at acidic pH than the
sigB
mutant. The lack of acid-sensitive phenotypes in 34 out of 36 disrupted genes suggests either a considerable redundancy in acid adaptation response or coincidental effects. Other up-regulated genes included genes for ion transporters and metabolic pathways, including carbohydrate and respiratory metabolism. The enhanced expression of the
nrd
(ribonucleotide reductase) operon and a DNA ATPase repair protein implies a cellular response to combat acid-induced DNA damage. Surprisingly, multiple iron uptake systems (totaling 15% of the genes induced ≥2-fold) were induced at low pH. This induction was shown to be coincidental and could be attributed to iron-sequestering effects in complex media at low pH.
The Two-Component Regulatory System
senX3-regX3
Regulates Phosphate-Dependent Gene Expression in
Mycobacterium smegmatis
Authors: Glover Robert T. , Kriakov Jordan , Garforth Scott J. , Baughn Anthony D. , Jacobs William R. 
Published: May 2007

ABSTRACT

Phosphate import is required for the growth of mycobacteria and is regulated by environmental inorganic phosphate (P
i
) concentrations, although the mechanism of this regulation has not been characterized. The expression of genes involved in P
i
acquisition is frequently regulated by two-component regulatory systems (2CRs) consisting of a sensor histidine kinase and a DNA-binding response regulator. In this work, we have identified the
senX3-regX3
2CR as a P
i
-dependent regulator of genes involved in phosphate acquisition in
Mycobacterium smegmatis
. Characterization of
senX3
mutants with different PhoA phenotypes suggests a dual role for SenX3 as a phosphatase or a phosphodonor for the response regulator RegX3, depending upon P
i
availability. Expression of PhoA activity required phosphorylation of RegX3, consistent with a role for phosphorylated RegX3 (RegX3∼P) as a transcriptional activator of
phoA
. Furthermore, purified RegX3∼P bound to promoter sequences from
phoA
,
senX3
, and the high-affinity phosphate transporter component
pstS
, demonstrating direct transcriptional control of all three genes. DNase I footprinting and primer extension analyses have further defined the DNA-binding region and transcriptional start site within the
phoA
promoter. A DNA motif consisting of an inverted repeat was identified in each of the promoters bound by RegX3∼P. Based upon our findings, we propose a model for P
i
-regulated gene expression mediated by SenX3-RegX3 in mycobacteria.
Functional Incorporation of Chimeric
b
Subunits into F
1
F
o
ATP Synthase
Authors: Claggett Shane B. , Grabar Tammy Bohannon , Dunn Stanley D. , Cain Brian D. 
Published: May 2007

ABSTRACT

F
1
F
o
ATP synthases function by a rotary mechanism. The enzyme's peripheral stalk serves as the stator that holds the F
1
sector and its catalytic sites against the movement of the rotor. In
Escherichia coli
, the peripheral stalk is a homodimer of identical
b
subunits, but photosynthetic bacteria have open reading frames for two different
b
-like subunits thought to form heterodimeric
b
/
b
′ peripheral stalks. Chimeric
b
subunit genes have been constructed by substituting sequence from the
Thermosynechococcus elongatus b
and
b
′ genes in the
E. coli uncF
gene, encoding the
b
subunit. The recombinant genes were expressed alone and in combination in the
E. coli
deletion strain KM2 (Δ
b
). Although not all of the chimeric subunits were incorporated into F
1
F
o
ATP synthase complexes, plasmids expressing either chimeric
b
E39-I86
or
b
′
E39-I86
were capable of functionally complementing strain KM2 (Δ
b
). Strains expressing these subunits grew better than cells with smaller chimeric segments, such as those expressing the
b
′
E39-D53
or
b
L54-I86
subunit, indicating intragenic suppression. In general, the chimeric subunits modeled on the
T. elongatus b
subunit proved to be more stable than the
b
′ subunit in vitro. Coexpression of the
b
E39-I86
and
b
′
E39-I86
subunits in strain KM2 (Δ
b
) yielded F
1
F
o
complexes containing heterodimeric peripheral stalks composed of both subunits.
The Pneumococcal Two-Component Signal Transduction System RR/HK06 Regulates CbpA and PspA by Two Distinct Mechanisms
Authors: Standish Alistair J. , Stroeher Uwe H. , Paton James C. 
Published: May 2007

ABSTRACTWe have previously shown that CbpA, a major pneumococcal virulence factor, is regulated by the two-component signal transduction system RR/HK06 (A. J. Standish, U. H. Stroeher, and J. C. Paton, Proc. Natl. Acad. Sci. USA 102:7701-7706, 2005). However, additional unidentified regulated factors appeared to be responsible for differences in adherence and the ability ofStreptococcus pneumoniaeto cause disease in a mouse model. Here, we identified a number of other regulated genes by overexpressing the system.cbpA, along with a cotranscribed upstream gene, showed substantial increases in expression when RR06 was overexpressed inS. pneumoniaestrains D39 and TIGR4. However, there were no other similarities between these strains. In D39,rr06overexpression decreased expression of numerous factors, including the major virulence factor genepspA. Further investigation ofcbpAregulation by RR/HK06, using mutants with mutations in both HK06 and RR06, suggested that rather than the norm,cbpAtranscription was activated when RR06 was in the nonphosphorylated form. Although other factors, such aspspAandgls24, are regulated by this system, these genes appear to be repressed when RR06 is in its phosphorylated form.
Characterization of the Fucosylation Pathway in the Biosynthesis of Glycopeptidolipids fromMycobacterium aviumComplex
Authors: Miyamoto Yuji , Mukai Tetsu , Maeda Yumi , Nakata Noboru , Kai Masanori , Naka Takashi , Yano Ikuya , Makino Masahiko 
Published: May 2007

ABSTRACTThe cell envelopes of several species of nontuberculous mycobacteria, including theMycobacterium aviumcomplex, contain glycopeptidolipids (GPLs) as major glycolipid components. GPLs are highly antigenic surface molecules, and their variant oligosaccharides define each serotype of theM. aviumcomplex. In the oligosaccharide portion of GPLs, the fucose residue is one of the major sugar moieties, but its biosynthesis remains unclear. To elucidate it, we focused on the 5.0-kb chromosomal region of theM. aviumcomplex that includes five genes, two of which showed high levels of similarity to the genes involved in fucose synthesis. For the characterization of this region by deletion and expression analyses, we constructed a recombinantMycobacterium smegmatisstrain that possesses thertfAgene of theM. aviumcomplex to produce serovar 1 GPL. The results revealed that the 5.0-kb chromosomal region is responsible for the addition of the fucose residue to serovar 1 GPL and that the three genesmdhtA,merA, andgtfDare indispensable for the fucosylation. Functional characterization revealed that thegtfDgene encodes a glycosyltransferase that transfers a fucose residue via 1→3 linkage to a rhamnose residue of serovar 1 GPL. The other two genes,mdhtAandmerA, contributed to the formation of the fucose residue and were predicted to encode the enzymes responsible for the synthesis of fucose from mannose based on their deduced amino acid sequences. These results indicate that the fucosylation pathway in GPL biosynthesis is controlled by a combination of themdhtA,merA, andgtfDgenes. Our findings may contribute to the clarification of the complex glycosylation pathways involved in forming the oligosaccharide portion of GPLs from theM. aviumcomplex, which are structurally distinct.