bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intestinal P Glycoprotein Acts as a Natural Defense Mechanism againstListeria monocytogenes
Authors: Neudeck Brien L. , Loeb Jennifer M. , Faith Nancy G. , Czuprynski Charles J. 
Published: June 2004

ABSTRACTMechanisms by which the intestinal epithelium resists invasion by food-borne pathogens such asListeria monocytogenesare an evolving area of research. Intestinal P glycoprotein is well known to limit the absorption of xenobiotics and is believed to act as a cytotoxic defense mechanism. The aim of this study was to determine if intestinal P glycoprotein is involved in host defense againstL. monocytogenes. Caco-2 cells and a P-glycoprotein-overexpressing subclone (Caco-2/MDR) were employed in addition tomdr1a−/−mice and wild-type controls. In vitro invasion assays and in vivo experiments were employed to measure bacterial invasion and dissemination. In addition,L. monocytogenesproteins were labeled with [35S]methionine, and the transepithelial transport across Caco-2 monolayers was characterized in both directions. Overexpression of P glycoprotein in Caco-2/MDR cells led to increased resistance toL. monocytogenesinvasion, whereas P-glycoprotein inhibition led to increased invasion. Flux of [35S]methionine-labeledL. monocytogenesproteins was significantly greater in the basolateral-to-apical direction than in the apical-to-basolateral direction, indicating dependence on an apically located efflux transporter. Moreover, inhibiting P glycoprotein reduced the basolateral-to-apical flux of the proteins. Early dissemination ofL. monocytogenesfrom the gastrointestinal tract was significantly greater in themdr1a−/−mice than in wild-type controls. Expression and function of intestinal P glycoprotein is an important determinant in resistance to early invasion ofL. monocytogenes.
Anaplasma phagocytophilum
Has a Functional
msp2
Gene That Is Distinct from
p44
Authors: Lin Quan , Rikihisa Yasuko , Felek Suleyman , Wang Xueqi , Massung Robert F. , Woldehiwet Zerai 
Published: June 2004

ABSTRACT

The
msp2
and
p44
genes encode polymorphic major outer membrane proteins that are considered unique to the intraerythrocytic agent of
Anaplasma marginale
and the intragranulocytic agent of
Anaplasma phagocytophilum
, respectively. In the present study, however, we found an
msp2
gene in
A. phagocytophilum
that was remarkably conserved among
A. phagocytophilum
strains from human granulocytic anaplasmosis (HGA) patients, ticks, and a horse from various regions in the United States, but the gene was different in a sheep isolate from the United Kingdom. The
msp2
gene in the
A. phagocytophilum
strain HZ genome was a single-copy gene and was located downstream of two
Ehrlichia chaffeensis omp-1
homologs and a decarboxylase gene (
ubiD
). The
msp2
gene was expressed by
A. phagocytophilum
in the blood from HGA patients NY36 and NY37 and by
A. phagocytophilum
isolates from these patients cultured in HL-60 cells at 37°C. The
msp2
gene was also expressed in a DBA/2 mouse infected by attaching ticks infected with strain NTN-1 and in a horse experimentally infected by attaching strain HZ-infected ticks. However, the transcript of the
msp2
gene was undetectable in
A. phagocytophilum
strain HZ in SCID mice and
Ixodes scapularis
ticks infected with strain NTN-1. These results indicate that
msp2
is functional in various strains of
A. phagocytophilum
, and relative expression ratios of
msp2
to
p44
vary in different infected hosts. These findings may be important in understanding roles that Msp2 proteins play in granulocytic ehrlichia infection and evolution of the polymorphic major outer membrane protein gene families in
Anaplasma
species.
Identification of an I-Ed-Restricted T-Cell Epitope ofEscherichia coliOuter Membrane Protein F
Authors: Williams Kristina M. , Bigley Elmer C. 
Published: June 2004

ABSTRACTA predominant T-cell epitope ofEscherichia coliouter membrane protein F (OmpF) that encompasses amino acids 295 to 314 was identified in H-2dmice. BALB/c-derived T-cell hybridomas generated against this region were CD3+, CD4+, CD8−, and T-cell receptor αβ+and secreted TH-1-associated cytokines (interleukin-2 [IL-2] and gamma interferon), but not a TH-2-associated cytokine (IL-4), when restimulated with peptide 295-314. Class II+mouse lymphoma (A20) cells, but not class II(−) mouse mastocytoma (P815) cells, supported IL-2 secretion of hybridomas when substituted for syngeneic splenocytes as antigen-presenting cells (APCs). Antibodies specific for I-Edblocked IL-2 secretion by hybridomas, but I-Ad-specific antiserum did not. When transfected L cells expressing I-Ad(AαAβd), I-Ed(EαEβd), or the hybrid molecule I-EαAβdwere used as APCs, hybridomas recognized peptide only when presented by the I-Ed-transfected cells. When peptide 295-314 truncated at either the C or the N terminus of the sequence was used, the minimal epitope was determined. Critical residues were determined by using alanine-substituted peptide analogues. T-cell hybridomas were only stimulated by peptides that encompassed amino acids 295 to 303 (9-mer), and the core sequence required a minimum of three additional amino acids at either the amino or the carboxy terminus to induce IL-2 secretion. Critical residues were determined to be phenylalanine at position 295, threonine at position 300, and tyrosines at positions 301 and 302. This study is the first to identify a minimal T-cell epitope and major histocompatibility complex restriction element of the OmpF protein and confirms previous observations that there is considerable degeneracy in the length of peptides that can bind I-Edand variability in the amino acid composition of the C and N termini of these peptides.
Ultrastructure ofProteus mirabilisSwarmer Cell Rafts and Role of Swarming in Catheter-Associated Urinary Tract Infection
Authors: Jones Brian V. , Young Robert , Mahenthiralingam Eshwar , Stickler David J. 
Published: June 2004

ABSTRACTProteus mirabilisis a common cause of catheter-associated urinary tract infection (C-UTI). It blocks indwelling urethral catheters through the formation of extensive crystalline biofilms. The obstruction of urine flow can induce episodes of pyelonephritis, septicemia, and shock.P. mirabilisexhibits a type of motility referred to as swarming, in which multicellular rafts of elongated, hyperflagellated swarmer cells form and move rapidly in concert over solid surfaces. It has been suggested that swarming is important in the pathogenesis of C-UTI. In this study we generated a set of stable transposon mutants deficient in swarming and used them to assess the role of swarming in the migration ofP. mirabilisover urinary catheters. Swarming was found to be essential for migration over all-silicone catheters. Swarming-deficient mutants were attenuated in migration over hydrogel-coated latex catheters, but those capable of swimming motility were able to move over and infect these surfaces. A novel vapor fixation technique for the preparation of specimens and scanning electron microscopy were used to resolve the ultrastructure ofP. mirabilismulticellular rafts. The flagellar filaments ofP. mirabiliswere found to be highly organized during raft migration and were interwoven in phase to form helical connections between adjacent swarmer cells. Mutants lacking these novel organized structures failed to swarm successfully. We suggest that these structures are important for migration and formation of multicellular rafts. In addition, the highly organized structure of multicellular rafts enablesP. mirabilisto initiate C-UTI by migration over catheter surfaces from the urethral meatus into the bladder.
Murine Oviduct Epithelial Cell Cytokine Responses toChlamydia muridarumInfection Include Interleukin-12-p70 Secretion
Authors: Johnson Raymond M. 
Published: June 2004

ABSTRACTEpithelial cells play an important role in host defense as sentinels for invading microbial pathogens.Chlamydia trachomatisis an intracellular bacterial pathogen that replicates in reproductive tract epithelium. Epithelial cells lining the reproductive tract likely play a key role in triggering inflammation and adaptive immunity duringChlamydiainfections. For this report a murine oviduct epithelial cell line was derived in order to determine how epithelial cells influence innate and adaptive immune responses duringChlamydiainfections. As expected, oviduct epithelial cells infected byChlamydia muridarumproduced a broad spectrum of chemokines, including CXCL16, and regulators of the acute-phase response, including interleukin-1α (IL-1α), IL-6, and tumor necrosis factor alpha. In addition, infected epithelial cells expressed cytokines that augment gamma interferon (IFN) production, including IFN-α/β and IL-12-p70. To my knowledge this is the first report of a non-myeloid/lymphoid cell type making IL-12-p70 in response to an infection. Equally interesting, infected epithelial cells significantly upregulated transforming growth factor alpha precursor expression, suggesting a mechanism by which they might play a direct role in the pathological scarring seen as a consequence ofChlamydiainfections. Data from these in vitro studies predict that infected oviduct epithelium contributes significantly to host innate and adaptive defenses but may also participate in the immunopathology seen withChlamydiainfections.
Identification of
Burkholderia cenocepacia
Genes Required for Bacterial Survival In Vivo
Authors: Hunt Tracey A. , Kooi Cora , Sokol Pamela A. , Valvano Miguel A. 
Published: June 2004

ABSTRACT

Burkholderia cenocepacia
(formerly
Burkholderia cepacia
complex genomovar III) causes chronic lung infections in patients with cystic fibrosis. In this work, we used a modified signature-tagged mutagenesis (STM) strategy for the isolation of
B. cenocepacia
mutants that cannot survive in vivo. Thirty-seven specialized plasposons, each carrying a unique oligonucleotide tag signature, were constructed and used to examine the survival of 2,627
B. cenocepacia
transposon mutants, arranged in pools of 37 unique mutants, after a 10-day lung infection in rats by using the agar bead model. The recovered mutants were screened by real-time PCR, resulting in the identification of 260 mutants which presumably did not survive within the lungs. These mutants were repooled into smaller pools, and the infections were repeated. After a second screen, we isolated 102 mutants unable to survive in the rat model. The location of the transposon in each of these mutants was mapped within the
B. cenocepacia
chromosomes. We identified mutations in genes involved in cellular metabolism, global regulation, DNA replication and repair, and those encoding bacterial surface structures, including transmembrane proteins and cell surface polysaccharides. Also, we found 18 genes of unknown function, which are conserved in other bacteria. A subset of 12 representative mutants that were individually examined using the rat model in competition with the wild-type strain displayed reduced survival, confirming the predictive value of our STM screen. This study provides a blueprint to investigate at the molecular level the basis for survival and persistence of
B. cenocepacia
within the airways.
Mucosal Vaccination against Serogroup B Meningococci: Induction of Bactericidal Antibodies and Cellular Immunity following Intranasal Immunization with NadA of
Neisseria meningitidis
and Mutants of
Escherichia coli
Heat-Labile Enterotoxin
Authors: Bowe Frances , Lavelle Ed C. , McNeela Edel A. , Hale Christine , Clare Simon , Arico Beatrice , Giuliani Marzia M. , Rae Aaron , Huett Alan , Rappuoli Rino , Dougan Gordon , Mills Kingston H. G. 
Published: June 2004

ABSTRACT

Conjugated polysaccharide vaccines protect against serogroup C meningococci. However, this approach cannot be applied to serogroup B, which is still a major cause of meningitis. We evaluated the immunogenicity of three surface-exposed proteins from serogroup B
Neisseria meningitidis
(App, NhhA, and NadA) identified during whole-genome sequencing. Mice were immunized intranasally with individual proteins in the presence of wild-type
Escherichia coli
heat-labile enterotoxin (LTwt), LTR72, a partially inactivated mutant, or LTK63, a completely nontoxic mutant, as the adjuvant. Each of the meningococcal proteins induced significant cellular responses; NhhA and NadA induced strong antibody responses, but only NadA induced bactericidal antibody when administered intranasally with mucosal adjuvants. In addition, immunoglobulin A and bactericidal antibodies were detected in the respiratory tract following intranasal delivery of NadA. Analysis of antigen-specific cytokine production by T cells from immunized mice revealed that intranasal immunization with NadA alone failed to generate detectable cellular immune responses. In contrast, LTK63, LTR72, and LTwt significantly augmented NadA-specific gamma interferon, interleukin-4 (IL-4), IL-5, and IL-10 production by spleen and lymph node cells, suggesting that both Th1 and Th2 cells were induced in vivo. The strongest cellular responses and highest bactericidal antibody titers were generated with LTR72 as the adjuvant. These findings demonstrate that the quality and magnitude of the immune responses generated by mucosal vaccines are influenced by the antigen as well as the adjuvant and suggest that nasal delivery of NadA with mucosal adjuvants has considerable potential in the development of a mucosal vaccine against serogroup B meningococci.
egc
-Encoded Superantigens from
Staphylococcus aureus
Are Neutralized by Human Sera Much Less Efficiently than Are Classical Staphylococcal Enterotoxins or Toxic Shock Syndrome Toxin
Authors: Holtfreter Silva , Bauer Kristin , Thomas Damien , Feig Christine , Lorenz Vera , Roschack Katharina , Friebe Erika , Selleng Kathleen , Lövenich Sandra , Greve Timm , Greinacher Andreas , Panzig Brigitte , Engelmann Susanne , Lina Gérard , Bröker Barbara M. 
Published: June 2004

ABSTRACT

PCR was employed to determine the presence of all known superantigen genes (
sea
,
seq
, and
tst
) and of the exotoxin-like gene cluster (
set
) in 40
Staphylococcus aureus
isolates from blood cultures and throat swabs; 28 isolates harbored superantigen genes, five on average, and this strictly correlated with their ability to stimulate T-cell proliferation. In contrast, the
set
gene cluster was detected in every
S. aureus
strain, suggesting a nonredundant function for these genes which is different from T-cell activation. No more than 10% of normal human serum samples inhibited the T-cell stimulation elicited by
egc
-encoded enterotoxins (staphylococcal enterotoxins G, I, M, N, and O), whereas between 32 and 86% neutralized the classical superantigens. Similarly, intravenous human immunoglobulin G preparations inhibited
egc
-encoded superantigens with 10- to 100-fold-reduced potency compared with the classical enterotoxins. Thus, there are surprisingly large gaps in the capacity of human serum samples to neutralize
S. aureus
superantigens.
Nasal Delivery of Antigen with the B Subunit ofEscherichia coliHeat-Labile Enterotoxin Augments Antigen-Specific T-Cell Clonal Expansion and Differentiation
Authors: Apostolaki Maria , Williams Neil A. 
Published: June 2004

ABSTRACTEscherichia coliheat-labile enterotoxin has unique immunogenic and adjuvant properties when administered mucosally to mice. These properties have revealed the potential for its use in the development of mucosal vaccines, an area of increasing interest. However, the inherent toxicity mediated by the A subunit precludes its widespread use. This problem has led to attempts to dissociate toxicity from adjuvant function by use of the B subunit. The ability of the B subunit ofE. coliheat-labile enterotoxin (EtxB) to enhance responses against antigens coadministered intranasally is demonstrated here with the use of the DO11.10 adoptive-transfer model, in which ovalbumin (OVA)-specific adoptively transferred T cells can be monitored directly by flow cytometry. Intranasal delivery of OVA with EtxB resulted in increased T-cell proliferative and systemic antibody responses against antigens. The increased Th2 cytokine production detected following in vitro restimulation of splenocyte and cervical lymph node (CLN) cells from the immunized mice correlated with increased OVA-specific immunoglobulin G1 antibody production. Flow cytometric analysis of T cells from mice early after immunization directly revealed the ability of EtxB to support antigen-specific clonal expansion and differentiation. Furthermore, while responses were first detected in the CLNs, they rapidly progressed to the spleen, where they were further sustained. Examination of CD69 expression on dividing cells supported the notion that activation induced by the presence of antigens is not sufficient to drive T-cell differentiation. Furthermore, a lack of CD25 expression on dividing cells suggested that EtxB-mediated T-cell clonal expansion may occur without a sustained requirement for interleukin 2.
Description of the Transcriptomes of Immune Response-Activated Hemocytes from the Mosquito Vectors
Aedes aegypti
and
Armigeres subalbatus
Authors: Bartholomay Lyric C. , Cho Wen-Long , Rocheleau Thomas A. , Boyle Jon P. , Beck Eric T. , Fuchs Jeremy F. , Liss Paul , Rusch Michael , Butler Katherine M. , Wu Roy Chen-Chih , Lin Shih-Pei , Kuo Hang-Yen , Tsao I-Yu , Huang Chiung-Yin , Liu Tze-Tze , Hsiao Kwang-Jen , Tsai Shih-Feng , Yang Ueng-Cheng , Nappi Anthony J. , Perna Nicole T. , Chen Chen-Cheng , Christensen Bruce M. 
Published: June 2004

ABSTRACT

Mosquito-borne diseases, including dengue, malaria, and lymphatic filariasis, exact a devastating toll on global health and economics, killing or debilitating millions every year (54). Mosquito innate immune responses are at the forefront of concerted research efforts aimed at defining potential target genes that could be manipulated to engineer pathogen resistance in vector populations. We aimed to describe the pivotal role that circulating blood cells (called hemocytes) play in immunity by generating a total of 11,952
Aedes aegypti
and 12,790
Armigeres subalbatus
expressed sequence tag (EST) sequences from immune response-activated hemocyte libraries. These ESTs collapsed into 2,686 and 2,107 EST clusters, respectively. The clusters were used to adapt the web-based interface for annotating bacterial genomes called A Systematic Annotation Package for Community Analysis of Genomes (ASAP) for analysis of ESTs. Each cluster was categorically characterized and annotated in ASAP based on sequence similarity to five sequence databases. The sequence data and annotations can be viewed in ASAP at
https://asap.ahabs.wisc.edu/annotation/php/ASAP1.htm
. The data presented here represent the results of the first high-throughput in vivo analysis of the transcriptome of immunocytes from an invertebrate. Among the sequences are those for numerous immunity-related genes, many of which parallel those employed in vertebrate innate immunity, that have never been described for these mosquitoes.
Flagella and Chemotaxis Are Required for Efficient Induction ofSalmonella entericaSerovar Typhimurium Colitis in Streptomycin-Pretreated Mice
Authors: Stecher Bärbel , Hapfelmeier Siegfried , Müller Catherine , Kremer Marcus , Stallmach Thomas , Hardt Wolf-Dietrich 
Published: June 2004

ABSTRACTSalmonella entericasubspecies 1 serovar Typhimurium is a common cause of gastrointestinal infections. The host's innate immune system and a complex set ofSalmonellavirulence factors are thought to contribute to enteric disease. The serovar Typhimurium virulence factors have been studied extensively by using tissue culture assays, and bovine infection models have been used to verify the role of these factors in enterocolitis. Streptomycin-pretreated mice provide an alternative animal model to study enteric salmonellosis. In this model, theSalmonellapathogenicity island 1 type III secretion system has a key virulence function. Nothing is known about the role of other virulence factors. We investigated the role of flagella in murine serovar Typhimurium colitis. A nonflagellated serovar Typhimurium mutant (fliGHI) efficiently colonized the intestine but caused little colitis during the early phase of infection (10 and 24 h postinfection). In competition assays with differentially labeled strains, thefliGHImutant had a reduced capacity to get near the intestinal epithelium, as determined by fluorescence microscopy. A flagellated but nonchemotacticcheYmutant had the same virulence defects as thefliGHImutant for causing colitis. In competitive infections, both mutants colonized the intestine of streptomycin-pretreated mice by day 1 postinfection but were outcompeted by the wild-type strain by day 3 postinfection. Together, these data demonstrate that flagella are required for efficient colonization and induction of colitis in streptomycin-pretreated mice. This effect is mostly attributable to chemotaxis. Recognition of flagellar subunits (i.e., flagellin) by innate immune receptors (i.e., Toll-like receptor 5) may be less important.
Tritrichomonas foetusInduces Apoptotic Cell Death in Bovine Vaginal Epithelial Cells
Authors: Singh B. N. , Lucas J. J. , Hayes G. R. , Kumar Ish , Beach D. H. , Frajblat Marcel , Gilbert R. O. , Sommer U. , Costello C. E. 
Published: June 2004

ABSTRACTTritrichomonas foetusis a serious veterinary pathogen, causing bovine trichomoniasis, a sexually transmitted disease leading to infertility and abortion.T. foetusinfects the mucosal surfaces of the reproductive tract. Infection withT. foetusleads to apoptotic cell death of bovine vaginal epithelial cells (BVECs) in culture. An affinity-purified cysteine protease (CP) fraction yielding on sodium dodecyl sulfate-polyacrylamide gel electrophoresis a single band with an apparent molecular mass of 30 kDa (CP30) also induces BVEC apoptosis. Treatment of CP30 with the protease inhibitors TLCK (Nα-p-tosyl-l-lysine chloromethyl ketone) and E-64 [l-trans-epoxysuccinyl-leucylamide-(4-guanido)-butane] greatly reduces induction of BVEC apoptosis. Matrix-assisted laser desorption ionization-time-of-flight MALDI-TOF mass spectrometry analysis of CP30 reveals a single peak with a molecular mass of 23.7 kDa. Mass spectral peptide sequence analysis of proteolytically digested CP30 reveals homologies to a previously reported cDNA clone, CP8 (D. J. Mallinson, J. Livingstone, K. M. Appleton, S. J. Lees, G. H. Coombs, and M. J. North, Microbiology141:3077-3085, 1995). Induction of apoptosis is highly species specific, since the related human parasiteTrichomonas vaginalisand associated purified CPs did not induce BVEC death. Fluorescence microscopy along with the Cell Death Detection ELISAPLUSassay and flow cytometry analyses were used to detect apoptotic nuclear condensation, DNA fragmentation, and changes in plasma membrane asymmetry in host cells undergoing apoptosis in response toT. foetusinfection or incubation with CP30. Additionally, the activation of caspase-3 and inhibition of cell death by caspase inhibitors indicates that caspases are involved in BVEC apoptosis. These results imply that apoptosis is involved in the pathogenesis ofT. foetusinfection in vivo, which may have important implications for therapeutic interference with host cell death that could alter the course of the pathology in vivo.