bluuebunny/crossref_metadata_2025_split huggingface dataset:
B Cells and Antibodies Are Required for Resistance to the Parasitic Gastrointestinal NematodeTrichuris muris
Authors: Blackwell Nathan M. , Else Kathryn J. 
Published: July 2002

ABSTRACTPrevious studies using cell transfers and antibody receptor knockout mice have shown that B cells and antibodies are not essential components of the expulsion mechanism inTrichuris murisinfections. Serum transfer experiments have given mixed results regarding the importance of antibodies in this infection model, and the role of B cells in initiating or maintaining T-cell responses has not been addressed. We used B-cell-deficient μMT mice to determine if B cells play a role in anti-T. murisimmune responses. In contrast to wild-type C57BL/6 mice, μMT mice were susceptible to infection. Antigen-restimulated mesenteric lymph node cells from infected μMT mice produced only naive levels of Th2-associated cytokines but had increased levels of gamma interferon. However, these mice appeared capable of mounting a Th2-dependent mucosal mastocytosis, though this was significantly delayed compared to that seen in wild-type mice. Resistance toT. muriswas restored following reconstitution with naive C57BL/6 splenic B cells, as was in vitro Th2 cytokine production in response to parasite antigen. Treatment of μMT mice with anti-interleukin-12 monoclonal antibody during the first 2 weeks of infection also restored immunity, suggesting that μMT mice can be manipulated to expel worms at the time of T-cell priming. Additionally, treatment of μMT mice with parasite-specific immunoglobulin G1 purified from the serum of resistant NIH mice prevented worm establishment, suggesting an important role for antibodies. Our results as a whole describe the first detailed report of a critical role for B cells in resistance to an intestinal nematode.
Brucella abortus
Cyclic β-1,2-Glucan Mutants Have Reduced Virulence in Mice and Are Defective in Intracellular Replication in HeLa Cells
Authors: Briones Gabriel , Iñón de Iannino Nora , Roset Mara , Vigliocco Ana , Paulo Patricia Silva , Ugalde Rodolfo A. 
Published: July 2002

ABSTRACT

Null cyclic β-1,2-glucan synthetase mutants (
cgs
mutants) were obtained from
Brucella abortus
virulent strain 2308 and from
B. abortus
attenuated vaccinal strain S19. Both mutants show greater sensitivity to surfactants like deoxycholic acid, sodium dodecyl sulfate, and Zwittergent than the parental strains, suggesting cell surface alterations. Although not to the same extent, both mutants display reduced virulence in mice and defective intracellular multiplication in HeLa cells. The
B. abortus
S19
cgs
mutant was completely cleared from the spleens of mice after 4 weeks, while the 2308 mutant showed a 1.5-log reduction of the number of brucellae isolated from the spleens after 12 weeks. These results suggest that cyclic β-1,2-glucan plays an important role in the residual virulence of the attenuated
B. abortus
S19 strain. Although the
cgs
mutant was cleared from the spleens earlier than the wild-type parental strain (
B. abortus
S19) and produced less inflammatory response, its ability to confer protection against the virulent strain
B. abortus
2308 was fully retained. Equivalent levels of induction of spleen gamma interferon mRNA and anti-lipopolysaccharide (LPS) of immunoglobulin G2a (IgG2a) subtype antibodies were observed in mice injected with
B. abortus
S19 or the
cgs
mutant. However, the titer of anti-LPS antibodies of the IgG1 subtype induced by the
cgs
mutant was lower than that observed with the parental S19 strain, thus suggesting that the
cgs
mutant induces a relatively exclusive Th1 response.
Immunoglobulin A-Mediated Protection againstBordetella pertussisInfection
Authors: Hellwig Sandra M. M. , van Spriel Annemiek B. , Schellekens Joop F. P. , Mooi Frits R. , van de Winkel Jan G. J. 
Published: July 2002

ABSTRACTInfection withBordetella pertussis, the causative agent of pertussis (whooping cough) in humans, is followed by the production of antibodies of several isotypes, including immunoglobulin A (IgA). Little is known, however, about the role of IgA in immunity against pertussis. Therefore, we studied targeting ofB. pertussisto the myeloid receptor for IgA, FcαRI (CD89), using either IgA purified from immune sera of pertussis patients or bispecific antibodies directed againstB. pertussisand FcαRI (CD89 BsAb). Both IgA and CD89 BsAb facilitated FcαRI-mediated binding, phagocytosis, and bacterial killing by human polymorphonuclear leukocytes (PMNL) and PMNL originating from human FcαRI-transgenic mice. Importantly, FcαRI targeting resulted in enhanced bacterial clearance in lungs of transgenic mice. These data support the capacity of IgA to induce anti-B. pertussiseffector functions via the myeloid IgA receptor, FcαRI. Increasing the amount of IgA antibodies induced by pertussis vaccines may result in higher vaccine efficacy.
Induction of T Helper Type 1 and 2 Responses to 19-Kilodalton Merozoite Surface Protein 1 in Vaccinated Healthy Volunteers and Adults Naturally Exposed to Malaria
Authors: Lee Edwin A. M. , Palmer Dupeh R. , Flanagan Katie L. , Reece William H. H. , Odhiambo Kennedy , Marsh Kevin , Pinder Margaret , Gravenor Michael B. , Keitel Wendy A. , Kester Kent E. , Diggs Carter , Kaslow David , Apostolopoulos V. , Ballou W. Ripley , Hill Adrian V. S. , Krzych Urszula , Plebanski Magdalena 
Published: July 2002

ABSTRACTPlasmodium falciparummalaria is a major cause of death in the tropics. The 19-kDa subunit ofP. falciparummerozoite surface protein 1 (MSP-119), a major blood stage vaccine candidate, is the target of cellular and humoral immune responses in animals and humans. In this phase I trial of MSP-119, immunization of nonexposed human volunteers with either of the two allelic forms of recombinant MSP-119induced high levels of antigen-specific Th1 (gamma interferon) and Th2 (interleukin 4 [IL-4] and IL-10) type lymphokines. The adjustment of the antigen dose and number of immunizations regulated the level of specificity of immune responses and Th1/Th2 bias of responses induced by vaccination. Novel conserved and allelic T-cell epitopes which induced cross-strain immune responses were identified. Importantly, responses to many of these novel epitopes were also present in adults exposed to malaria, both in east (Kenya) and west Africa (The Gambia). These data suggest that epitope-specific naturally acquired MSP-119immune responses in endemic populations can be boosted by vaccination.
Expression of Surfactant Protein D in the Human Gastric Mucosa and duringHelicobacter pyloriInfection
Authors: Murray Emma , Khamri Wafa , Walker Marjorie M. , Eggleton Paul , Moran Anthony P. , Ferris John A. , Knapp Susanne , Karim Q. Najma , Worku Mulegata , Strong Peter , Reid Kenneth B. M. , Thursz Mark R. 
Published: July 2002

ABSTRACTHelicobacterpyloriestablishes persistent infection of gastric mucosa with diverse clinical outcomes. The innate immune molecule surfactant protein D (SP-D) binds selectively to microorganisms, inducing aggregation and phagocytosis. In this study, we demonstrated the expression of SP-D in gastric mucosa by reverse transcription-PCR and immuohistochemical analysis. SP-D is present at the luminal surface and within the gastric pits, with maximal expression at the surface. Levels of expression are significantly increased inH. pylori-associated gastritis compared to those in the normal mucosa. Immunofluorescence microscopy was used to demonstrate binding and agglutination ofH. pyloriby SP-D in a lectin-specific manner. These activities resulted in a 50% reduction in the motility ofH. pylori, as judged on the basis of curvilinear velocity measured by using a Hobson BacTracker. Lipopolysaccharides extracted from threeH. pyloristrains were shown to bind SP-D in a concentration-dependent manner, and there was marked variation in the avidity of binding among the strains. SP-D may therefore play a significant role in the innate immune response toH. pyloriinfection.
Construction and Characterization of a Live, AttenuatedaroADeletion Mutant ofPseudomonas aeruginosaas a Candidate Intranasal Vaccine
Authors: Priebe Gregory P. , Brinig Mary M. , Hatano Kazue , Grout Martha , Coleman Fadie T. , Pier Gerald B. , Goldberg Joanna B. 
Published: July 2002

ABSTRACTAntibodies to the lipopolysaccharide O antigen ofPseudomonas aeruginosamediate high-level immunity, but protective epitopes have proven to be poorly immunogenic, while nonprotective or minimally protective O-antigen epitopes often elicit the best immune responses. With the goal of developing a broadly protectiveP. aeruginosavaccine, we used a gene replacement system based on the Flp recombinase to construct an unmarkedaroAdeletion mutant of theP. aeruginosaserogroup O2/O5 strain PAO1. The resultantaroAdeletion mutant of PAO1 is designated PAO1ΔaroA. ThearoAdeletion was confirmed by both PCR and failure of the mutant to grow on minimal media lacking aromatic amino acids. When evaluated for safety and immunogenicity in mice, PAO1ΔaroAcould be applied either intranasally or intraperitoneally at doses up to 5 × 109CFU per mouse without adverse effects. No dissemination of PAO1ΔaroAto blood, liver, or spleen was detected after intranasal application, and histological evidence of pneumonia was minimal. Intranasal immunization of mice and rabbits elicited high titers of immunoglobulin G to whole bacterial cells and to heat-stable bacterial antigens of all seven prototypicP. aeruginosaserogroup O2/O5 strains. The mouse antisera mediated potent phagocytic killing of most of the prototypic serogroup O2/O5 strains, while the rabbit antisera mediated phagocytic killing of several serogroup-heterologous strains in addition to killing all O2/O5 strains. This live, attenuatedP. aeruginosastrain PAO1ΔaroAappears to be safe for potential use as an intranasal vaccine and elicits high titers of opsonic antibodies against multiple strains of theP. aeruginosaO2/O5 serogroup.
Polarized Expression of Tamm-Horsfall Protein by Renal Tubular Epithelial Cells Activates Human Granulocytes
Authors: Kreft B. , Jabs W. J. , Laskay T. , Klinger M. , Solbach W. , Kumar S. , van Zandbergen G. 
Published: July 2002

ABSTRACTIn renal bacterial infections granulocytes are of major importance in the primary immune defense against invading pathogens. However, the mechanisms of granulocytic activation in renal interstitial invasion have not been clarified. Renal tubular epithelial cell mechanisms inducing granulocytic activation and bacterial killing may include tubular cell expression of Tamm-Horsfall protein (THP), a urinary protein that is known to enhance cytokine expression in monocytes. We studied the role of THP in granulocytic activation. A strong binding of THP to human granulocytes was demonstrated by fluorescence-activated cell sorter analysis. Urinary THP and supernatants of THP-expressing cultured tubular epithelial cells (MDCK) enhanced interleukin-8 (IL-8) expression by human granulocytes. Renal tubular cells growing polarized on polycarbonate membranes were used to study apical versus basal THP expression. By electron microscopy THP immunoreactivity was exclusively found on the apical surfaces of tubular cells and was absent on the basolateral cell membrane. In the apical cell culture compartment we found significantly more stimulatory activity for granulocytic IL-8 expression. CD62L, a selectin less expressed in activated granulocytes, was decreased in granulocytes incubated with urinary THP and in supernatants of THP-producing renal tubular cells but not in supernatants from THP-negative cells. Again, the effect on CD62L expression was found only in apical culture media and was absent in the basal compartment. In summary our data give evidence that renal tubular cell THP expression may be relevant in kidney diseases since THP is a potent activator of human granulocytes. The regulation of apical versus basal THP expression and release in vivo may be crucial in the induction of the inflammatory response, e.g., in bacterial renal diseases.
Increased Virulence of a Fibronectin-Binding Protein Mutant of
Staphylococcus aureus
in a Rat Model of Pneumonia
Authors: McElroy Mary C. , Cain David J. , Tyrrell Christine , Foster Timothy J. , Haslett Christopher 
Published: July 2002

ABSTRACT

Fibronectin-binding proteins mediate
Staphylococcus aureus
internalization into nonphagocytic cells in vitro. We have investigated whether fibronectin-binding proteins are virulence factors in the pathogenesis of pneumonia by using
S. aureus
strain 8325-4 and isogenic mutants in which fibronectin-binding proteins were either deleted (DU5883) or overexpressed [DU5883(pFnBPA4)]. We first demonstrated that fibronectin-binding proteins mediate
S. aureus
internalization into alveolar epithelial cells in vitro and that
S. aureus
internalization into alveolar epithelial cells requires actin rearrangement and protein kinase activity. Second, we established a rat model of
S. aureus
-induced pneumonia and measured lung injury and bacterial survival at 24 and 96 h postinoculation.
S. aureus
growth and the extent of lung injury were both increased in rats inoculated with the deletion mutant (DU5883) in comparison with rats inoculated with the wild-type (8325-4) and the fibronectin-binding protein-overexpressing strain DU5883(pFnBPA4) at 24 h postinfection. Morphological evaluation of infected lungs at the light and electron microscopic levels demonstrated that
S. aureus
was present within neutrophils from both 8325-4- and DU5883-inoculated lungs. Our data suggest that fibronectin-binding protein-mediated internalization into alveolar epithelial cells is not a virulence mechanism in a rat model of pneumonia. Instead, our data suggest that fibronectin-binding proteins decrease the virulence of
S. aureus
in pneumonia.
Purification and Characterization of a Membrane-Bound Hydrogenase from the Hyperthermophilic Archaeon
Pyrococcus furiosus
Authors: Sapra Rajat , Verhagen Marc F. J. M. , Adams Michael W. W. 
Published: July 2002

ABSTRACT

Highly washed membrane preparations from cells of the hyperthermophilic archaeon
Pyrococcus furiosus
contain high hydrogenase activity (9.4 μmol of H
2
evolved/mg at 80°C) using reduced methyl viologen as the electron donor. The enzyme was solubilized with
n
-dodecyl-β-
d
-maltoside and purified by multistep chromatography in the presence of Triton X-100. The purified preparation contained two major proteins (α and β) in an approximate 1:1 ratio with a minimum molecular mass near 65 kDa and contained ∼1 Ni and 4 Fe atoms/mol. The reduced enzyme gave rise to an electron paramagnetic resonance signal typical of the so-called Ni-C center of mesophilic NiFe-hydrogenases. Neither highly washed membranes nor the purified enzyme used NAD(P)(H) or
P. furiosus
ferredoxin as an electron carrier, nor did either catalyze the reduction of elemental sulfur with H
2
as the electron donor. Using N-terminal amino acid sequence information, the genes proposed to encode the α and β subunits were located in the genome database within a putative 14-gene operon (termed
mbh
). The deduced sequences of the two subunits (Mbh 11 and 12) were distinctly different from those of the four subunits that comprise each of the two cytoplasmic NiFe-hydrogenases of
P. furiosus
and show that the α subunit contains the NiFe-catalytic site. Six of the open reading frames (ORFs) in the operon, including those encoding the α and β subunits, show high sequence similarity (>30% identity) with proteins associated with the membrane-bound NiFe-hydrogenase complexes from
Methanosarcina barkeri
,
Escherichia coli
, and
Rhodospirillum rubrum
. The remaining eight ORFs encode small (<19-kDa) hypothetical proteins. These data suggest that
P. furiosus
, which was thought to be solely a fermentative organism, may contain a previously unrecognized respiratory system in which H
2
metabolism is coupled to energy conservation.
Identification of Iron-Responsive, Differential Gene Expression in the CyanobacteriumSynechocystissp. Strain PCC 6803 with a Customized Amplification Library
Authors: Singh Abhay K. , Sherman Louis A. 
Published: July 2002

ABSTRACTWe describe the use of a method called differential expression using customized amplification library (DECAL) to study the global changes in gene expression in iron-deficient versus iron-reconstituting cells ofSynechocystissp. strain PCC 6803. We identified a number of genes, such asisiA,idiA,psbA,cpcG, andslr0374, whose expression either increased or decreased in response to iron availability. Further analysis led to the identification of additional genes related to those identified by DECAL (e.g.,psbC,psbO,psaA,apcABC,cpcBAC1C2D, andnblA) that were differentially regulated by iron availability. Expression ofcpcG,psbC,psbO,psaA,apcABC, andcpcBAC1C2Dincreased, whereas that ofisiA,idiA,nblA,psbA, andslr0374 decreased, in iron-reconstituting cells. S1 nuclease protection studies showed that increased transcript levels ofpsbAin iron-deficient cells was due to the increased expression of bothpsbA2andpsbA3genes, although the steady-state level ofpsbA2remained higher than that ofpsbA3.
A Novel Bacterial ATP-Binding Cassette Transporter System That Allows Uptake of Macromolecules
Authors: Momma Keiko , Okamoto Masako , Mishima Yumiko , Mori Shigetarou , Hashimoto Wataru , Murata Kousaku 
Published: July 2002

ABSTRACT

A gram-negative bacterium,
Sphingomonas
sp. strain A1, isolated as a producer of alginate lyase, has a characteristic cell envelope structure and forms a mouth-like pit on its surface. The pit is produced only when the cells have to incorporate and assimilate alginate. An alginate uptake-deficient mutant was derived from cells of strain A1. One open reading frame,
algS
(1,089 bp), exhibiting homology to the bacterial ATP-binding domain of an ABC transporter, was cloned as a fragment complementing the mutation.
algS
was followed by two open reading frames,
algM1
(972 bp) and
algM2
(879 bp), which exhibit homology with the transmembrane permeases of ABC transporters. Disruption of
algS
of strain A1 resulted in the failure to incorporate alginate and to form a pit. Hexahistidine-tagged AlgS protein (AlgS
His6
) overexpressed in
Escherichia coli
and purified by Ni
2+
affinity column chromatography showed ATPase activity. Based on these results, we propose the occurrence of a novel pit-dependent ABC transporter system that allows the uptake of macromolecules.
Identification of the
Escherichia coli
Nicotinic Acid Mononucleotide Adenylyltransferase Gene
Authors: Mehl Ryan A. , Kinsland Cynthia , Begley Tadhg P. 
Published: July 2002

ABSTRACT

The gene (
ybeN
) coding for nicotinate mononucleotide adenylyltransferase, an NAD(P) biosynthetic enzyme, has been identified and overexpressed in
Escherichia coli
. This enzyme catalyzes the reversible adenylation of nicotinate mononucleotide and shows product inhibition. The rate of adenylation of nicotinate mononucleotide is at least 20 times faster than the rate of adenylation of nicotinamide mononucleotide.
Identification and Characterization of a Membrane Permease Involved in Iron-Hydroxamate Transport in
Staphylococcus aureus
Authors: Sebulsky M. Tom , Hohnstein Dan , Hunter Meredith D. , Heinrichs David E. 
Published: July 2002

ABSTRACT

Staphylococcus aureus
was shown to transport iron complexed to a variety of hydroxamate type siderophores, including ferrichrome, aerobactin, and desferrioxamine. An
S. aureus
mutant defective in the ability to transport ferric hydroxamate complexes was isolated from a Tn
917
-LTV1 transposon insertion library after selection on iron-limited media containing aerobactin and streptonigrin. Chromosomal DNA flanking the Tn
917
-LTV1 insertion was identified by sequencing of chromosomal DNA isolated from the mutant. This information localized the transposon insertion to a gene whose predicted product shares significant similarity with FhuG of
Bacillus subtilis
. DNA sequence information was then used to clone a larger fragment of DNA surrounding the
fhuG
gene, and this resulted in the identification of an operon of three genes,
fhuCBG
, all of which show significant similarities to ferric hydroxamate uptake (
fhu
) genes in
B. subtilis
. FhuB and FhuG are highly hydrophobic, suggesting that they are embedded within the cytoplasmic membrane, while FhuC shares significant homology with ATP-binding proteins. Given this, the
S. aureus
FhuCBG proteins were predicted to be part of a binding protein-dependent transport system for ferric hydroxamates. Exogenous iron levels were shown to regulate ferric hydroxamate uptake in
S. aureus
. This regulation is attributable to Fur in
S. aureus
because a strain containing an insertionally inactivated
fur
gene showed maximal levels of ferric hydroxamate uptake even when the cells were grown under iron-replete conditions. By using the Fur titration assay, it was shown that the Fur box sequences upstream of
fhuCBG
are recognized by the
Escherichia coli
Fur protein.
Identification of the
Pseudomonas aeruginosa glmM
Gene, Encoding Phosphoglucosamine Mutase
Authors: Tavares Isabel M. , Jolly Laure , Pompeo Frédérique , Leitão Jorge H. , Fialho Arsénio M. , Sá-Correia Isabel , Mengin-Lecreulx Dominique 
Published: July 2002

ABSTRACT

A search for a potential
algC
homologue within the
Pseudomonas aeruginosa
PAO1 genome database has revealed an open reading frame (ORF) of unknown function, ORF540 in contig 54 (July 1999
Pseudomonas
genome release), that theoretically coded for a 445-amino-acid-residue polypeptide (I. M. Tavares, J. H. Leitão, A. M. Fialho, and I. Sá-Correia, Res. Microbiol. 150:105–116, 1999). The product of this gene is here identified as the phosphoglucosamine mutase (GlmM) which catalyzes the conversion of glucosamine-6-phosphate to glucosamine-1-phosphate, an essential step in the formation of the cell wall precursor UDP-
N
-acetylglucosamine. The
P. aeruginosa
gene has been cloned into expression vectors and shown to restore normal peptidoglycan biosynthesis and cell growth of a
glmM Escherichia coli
mutant strain. The GlmM enzyme from
P. aeruginosa
has been overproduced to high levels and purified to homogeneity in a six-histidine-tagged form. Beside its phosphoglucosamine mutase activity, the
P. aeruginosa
enzyme is shown to exhibit phosphomannomutase and phosphoglucomutase activities, which represent about 20 and 2% of its GlmM activity, respectively.