bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antibody Avidity and Immunoglobulin G Isotype Distribution following Immunization with a Monovalent Meningococcal B Outer Membrane Vesicle Vaccine
Authors: Vermont C. L. , van Dijken H. H. , van Limpt C. J. P. , de Groot R. , van Alphen L. , van den Dobbelsteen G. P. J. M. 
Published: July 2002

ABSTRACTThe avidity maturation and immunoglobulin G (IgG) isotype distribution of antibodies after vaccination with a meningococcal B outer membrane vesicle (OMV) vaccine were evaluated as indicators of protective immunity. Pre- and postvaccination sera from 134 healthy toddlers (ages, 2 to 3 years) immunized with a monovalent meningococcal B OMV (serosubtype P1.7-2,4) vaccine adsorbed with AlPO4or Al(OH)3were analyzed by enzyme-linked immunosorbent assay (ELISA) methods. The children were vaccinated three times with intervals of 3 to 6 weeks between vaccinations or twice with an interval of 6 to 10 weeks between vaccinations. A booster was given after 20 to 40 weeks. The avidity index (AI) of antibodies increased significantly during the primary series of vaccinations and after the booster was given. No differences in AIs were found when the results obtained with the two vaccination schedules or with the two adjuvants were compared. After vaccination, IgG1 was the predominant IgG isotype, followed by IgG3. No IgG2 or IgG4 was detected. There was a strong correlation between serum bactericidal activity (SBA) and ELISA titers (r= 0.85 [P< 0.0001] for total IgG,r= 0.83 for IgG1 [P< 0.0001],r= 0.82 for IgG3 [P< 0.0001], andr= 0.84 [P< 0.0001] for the avidity titer). When two subgroups with similar anti-OMV IgG levels were compared before and after the booster vaccination, the higher AI after the booster vaccination was associated with significantly increased SBA. We concluded that avidity maturation occurs after vaccination with a monovalent meningococcal B OMV vaccine, especially after boosting, as indicated by a significant increase in the AI. Vaccination with the monovalent OMV vaccine induced mainly IgG1 and IgG3 isotypes, which are considered to be most important for protection against meningococcal disease. An increase in the AI of antibodies is associated with increased SBA, independent of the level of specific IgG and the IgG isotype distribution. Measuring the AI and IgG isotype distribution of antibodies after vaccination can be a supplementary method for predicting protective immunity for evaluation in future phase III trials with meningococcal serogroup B vaccines.
Dominant-Negative Rho, Rac, and Cdc42 Facilitate the Invasion Process of
Vibrio parahaemolyticus
into Caco-2 Cells
Authors: Akeda Yukihiro , Kodama Toshio , Kashimoto Takashige , Cantarelli Vlademir , Horiguchi Yasuhiko , Nagayama Kenichi , Iida Tetsuya , Honda Takeshi 
Published: July 2002

ABSTRACT

To clarify the invasive process of
Vibrio parahaemolyticus
, an invasion assay was performed using cells expressing dominant negative small GTPases of the Rho family. This assay showed that the dominant negative host phenotype facilitates bacterial invasion, suggesting that the mechanism of
V. parahaemolyticus
invasion differs from that reported for other invasive bacteria.
HLA-B*35-Restricted CD8+-T-Cell Epitope inMycobacterium tuberculosisRv2903c
Authors: Klein Michèl R. , Hammond Abdulrahman S. , Smith Steve M. , Jaye Assan , Lukey Pauline T. , McAdam Keith P. W. J. 
Published: July 2002

ABSTRACTFew human CD8+T-cell epitopes in mycobacterial antigens have been described to date. Here we have identified a novel HLA-B*35-restricted CD8+T-cell epitope inMycobacterium tuberculosisRv2903c based on a reverse immunogenetics approach. Peptide-specific CD8 T cells were able to killM. tuberculosis-infected macrophages and produce gamma interferon and tumor necrosis factor alpha.
Correlation between an In Vitro Invasion Assay and a Murine Model ofBurkholderia cepaciaLung Infection
Authors: Cieri Martin V. , Mayer-Hamblett Nicole , Griffith Adam , Burns Jane L. 
Published: July 2002

ABSTRACTOur understanding of the virulence ofBurkholderia cepaciacomplex lung infections in cystic fibrosis patients is incomplete. There is a great deal of variability in the clinical course, from simple colonization to severe and often fatal necrotizing pneumonia, termed cepacia syndrome. Multiple subspecies (called genomovars) have been identified, and these genomovars may hold the key to understanding the variable pathogenicity. Thirty-oneB. cepaciacomplex isolates belonging to five of the seven genomovars were examined by using a gentamicin protection assay of invasion with A549 cells. The level of epithelial cell invasion byB. cepaciain the A549 model was relatively low compared with the data obtained for other pathogens and was often variable from assay to assay. Thus, a statistical approach was used to determine invasiveness. When this model was used, one of four genomovar I strains (25%), three of eight genomovar II strains (37.5%), seven of nine genomovar III strains (77.8%), one of four genomovar IV strains (25%), and none of the four genomovar V strains examined were defined as invasive. All other strains were categorized as either noninvasive or indeterminate. Invasive, noninvasive, and indeterminate isolates belonging to genomovars II and III were subsequently tested for splenic invasion with the mouse agar bead model. Correlation between the models for six strains was demonstrated. Our results indicate that a statistical model used to determine invasiveness in an in vitro invasion assay can be used to predict in vivo invasiveness.
Genetic Variability and Stability of
Anaplasma phagocytophila msp2
(
p44
)
Authors: Caspersen Karen , Park Jin-Ho , Patil Surekha , Dumler J. Stephen 
Published: July 2002

ABSTRACT

Anaplasma
(
Ehrlichia
)
phagocytophila
's major immunodominant surface protein antigen, Msp2 (P44, 44-kDa antigen), is encoded by a family of paralogous genes characterized by conserved sequences flanking a hypervariable region. The antigenic profiles of most strains of
A. phagocytophila
are different, and the differences are principally related to Msp2 expression. To date, multiple unique
msp2
gene paralogs have been found in
A. phagocytophila
isolates, but the overall number in the genome of a single strain is not yet known. Changes in
msp2
expression may be related to antigenic variability; thus, we examined the minimal complement of
msp2
genes or pseudogenes in two strains of
A. phagocytophila
and the number of transcriptionally active
msp2
gene paralogs during low-passage, steady-state, in vitro propagation. Of 15 BDS strain clones, 1 had a hypervariable region identical to the region in a clone obtained from a BDS strain genomic library previously prepared from organisms after only two horse passages. When 124 Webster strain clones were examined, 18 unique hypervariable regions were identified. Of 64 Webster strain cDNA clones, 56 (87.5%) were derived from a single gene, and transcripts from six additional
msp2
genes were also identified. The sequences of several hypervariable regions that were ≥97% similar to regions present in other strains were identified by performing a BLAST analysis of sequences deposited in the GenBank database. These findings suggest that antigenic variability results from transcription of one or a few of the multiple paralogs and not from genetic instability that results in random accumulated mutations, although the possibility that gene recombination plays a role cannot be eliminated. The predominant Msp2 pattern in vitro is determined by transcription from a single gene.
Effect ofMycobacterium bovisBCG Vaccination on Interleukin-1β and RANTES mRNA Expression in Guinea Pig Cells Exposed to Attenuated and Virulent Mycobacteria
Authors: Jeevan Amminikutty , Yoshimura Teizo , Foster Gregory , McMurray David N. 
Published: July 2002

ABSTRACTThe effect ofMycobacterium bovisBCG vaccination on interleukin-1β (IL-1β) or regulated-upon-activation, normally T-cell-expressed and -secreted chemokine (RANTES) mRNA expression in guinea pig spleen cells stimulated with concanavalin A, lipopolysaccharide (LPS), phorbol myristate acetate (PMA) plus ionomycin, or purified protein derivative (PPD) was studied in vitro. Similarly, peritoneal exudate cell-derived macrophages from naïve and BCG-vaccinated guinea pigs were infected withM. bovisBCG,Mycobacterium avium, the attenuatedMycobacterium tuberculosisH37Ra strain, or virulent strains H37Rv and Erdman ofM. tuberculosis. Total RNA was subjected to Northern blot analysis using probes generated from guinea pig IL-1β or RANTES cDNA. Although IL-1β and RANTES mRNA could be detected in the spleen cells from naïve animals stimulated with LPS or PMA plus ionomycin, the levels were significantly enhanced after BCG vaccination. mRNA expression was also elevated in macrophages infected with live mycobacteria after BCG vaccination. However, macrophages infected with the virulent H37Rv strain ofM. tuberculosisshowed 75 to 90% reductions in IL-1β expression and 25 to 60% reductions in RANTES mRNA expression compared with macrophages infected with the attenuated H37Ra strain. The IL-1β mRNA levels peaked as soon as 1 h after PPD stimulation and 4 h afterM. tuberculosisH37Rv infection of macrophages. In contrast, RANTES mRNA expression was delayed until 48 h after infection. These results indicate that molecular mediators produced in response to various stimuli associated with protective immunity against mycobacteria are upregulated after BCG vaccination; however, a significantly weaker response was observed with virulentM. tuberculosis.These initial studies indicate that BCG vaccination has a positive effect on IL-1β and RANTES mRNA expression by host cells in a highly relevant animal tuberculosis model.
The Sortase SrtA of
Listeria monocytogenes
Is Involved in Processing of Internalin and in Virulence
Authors: Garandeau Caroline , Réglier-Poupet Hélène , Dubail Iharilalao , Beretti Jean-Luc , Berche Patrick , Charbit Alain 
Published: July 2002

ABSTRACT

Listeria monocytogenes
is an intracellular gram-positive human pathogen that invades eucaryotic cells. Among the surface-exposed proteins playing a role in this invasive process, internalin belongs to the family of LPXTG proteins, which are known to be covalently linked to the bacterial cell wall in gram-positive bacteria. Recently, it has been shown in
Staphylococcus aureus
that the covalent anchoring of protein A, a typical LPXTG protein, is due to a cysteine protease, named sortase, required for bacterial virulence. Here, we identified in silico from the genome of
L. monocytogenes
a gene, designated
srtA
, encoding a sortase homologue. The role of this previously unknown sortase was studied by constructing a sortase knockout mutant. Internalin was used as a reporter protein to study the effects of the
srtA
mutation on cell wall anchoring of this LPXTG protein in
L. monocytogenes
. We show that the
srtA
mutant (i) is affected in the display of internalin at the bacterial surface, (ii) is significantly less invasive in vitro, and (iii) is attenuated in its virulence in the mouse. These results demonstrate that
srtA
of
L. monocytogenes
acts as a sortase and plays a role in the pathogenicity.
Interaction of an Outer Membrane Protein of Enterotoxigenic
Escherichia coli
with Cell Surface Heparan Sulfate Proteoglycans
Authors: Fleckenstein James M. , Holland James T. , Hasty David L. 
Published: July 2002

ABSTRACT

We have previously shown that enterotoxigenic invasion protein A (Tia), a 25-kDa outer membrane protein encoded on an apparent pathogenicity island of enterotoxigenic
Escherichia coli
(ETEC) strain H10407, mediates attachment to and invasion into cultured human gastrointestinal epithelial cells. The epithelial cell receptor(s) for Tia has not been identified. Here we show that Tia interacts with cell surface heparan sulfate proteoglycans. Recombinant
E. coli
expressing Tia mediated invasion into wild-type epithelial cell lines but not invasion into proteoglycan-deficient cells. Furthermore, wild-type eukaryotic cells, but not proteoglycan-deficient eukaryotic cells, attached to immobilized polyhistidine-tagged recombinant Tia (rTia). Binding of epithelial cells to immobilized rTia was inhibited by exogenous heparan sulfate glycosaminoglycans but not by hyaluronic acid, dermatan sulfate, or chondroitin sulfate. Similarly, pretreatment of eukaryotic cells with heparinase I, but not pretreatment of eukaryotic cells with chrondroitinase ABC, inhibited attachment to rTia. In addition, we also observed heparin binding to both immobilized rTia and recombinant
E. coli
expressing Tia. Heparin binding was inhibited by a synthetic peptide representing a surface loop of Tia, as well as by antibodies directed against this peptide. Additional studies indicated that Tia, as a prokaryotic heparin binding protein, may also interact via sulfated proteoglycan molecular bridges with a number of mammalian heparan sulfate binding proteins. These findings suggest that the binding of Tia to host epithelial cells is mediated at least in part through heparan sulfate proteoglycans and that ETEC belongs on the growing list of pathogens that utilize these ubiquitous cell surface molecules as receptors.
Influence of Recombination and Niche Separation on the Population Genetic Structure of the Pathogen
Streptococcus pyogenes
Authors: Kalia Awdhesh , Spratt Brian G. , Enright Mark C. , Bessen Debra E. 
Published: July 2002

ABSTRACT

The throat and skin of the human host are the principal reservoirs for the bacterial pathogen
Streptococcus pyogenes
. The
emm
locus encodes structurally heterogeneous surface fibrils that play numerous roles in virulence, depending on the strain. Isolates harboring the
emm
pattern A-C marker exhibit a strong tendency to cause throat infection, whereas
emm
pattern D strains are usually recovered from impetigo lesions; as a group,
emm
pattern E organisms fail to display obvious tissue tropisms. The peak incidence for streptococcal pharyngitis and impetigo varies with season and locale, leading to wide spatial and temporal distances between throat and skin strains. To assess any impact of niche separation on genetic variation, the extent of recombinational exchange between
emm
pattern A-C, D, and E subpopulations was evaluated. Analysis of nucleotide sequence data for internal portions of seven housekeeping loci from 212 isolates provides evidence of extensive recombination between strains belonging to different
emm
pattern subpopulations. Furthermore, no fixed nucleotide differences were found between
emm
pattern A-C and D strains. Thus, despite some niche separation created by distinct epidemiological trends and innate tissue tropisms there is little evidence for neutral gene divergence between throat and skin strains. Maintenance of a relationship between
emm
pattern and tissue tropism in the face of underlying recombination suggests that tissue tropism is associated with
emm
or a closely linked gene.
Vaccination of Guinea Pigs with DNA Encoding the Mycobacterial Antigen MPB83 Influences Pulmonary Pathology but Not Hematogenous Spread following Aerogenic Infection withMycobacterium bovis
Authors: Chambers Mark A. , Williams Ann , Hatch Graham , Gavier-Widén Dolores , Hall Graham , Huygen Kris , Lowrie Douglas , Marsh Philip D. , Hewinson R. Glyn 
Published: July 2002

ABSTRACTProtection of cattle against bovine tuberculosis by vaccination could be an important control strategy in countries where there is persistentMycobacterium bovisinfection in wildlife and in developing countries where it is not economical to implement a tuberculin test and slaughter control program. The main aim of such a vaccination strategy would be to reduce transmission of infection by reducing the lung pathology caused by infection and preventing seeding of the organism to organs from whichM. boviscould be excreted. Recent reports of successful DNA vaccination againstMycobacterium tuberculosisin small-animal models have suggested that DNA vaccines act by reducing lung pathology without sensitizing animals to tuberculin testing. We therefore evaluated the ability of vaccines consisting of DNA encoding the mycobacterial antigens MPB83 and 85A to reduce lung pathology and prevent hematogenous spread in guinea pigs challenged with a low dose of aerosolizedM. bovis. Vaccination with MPB83 DNA reduced the severity of pulmonary lesions, as assessed by histopathology, and resembledM. bovisBCG vaccination in this respect. However, unlike BCG vaccination, MPB83 DNA vaccination did not protect challenged guinea pigs from hematogenous spread of organisms to the spleen. In contrast, vaccination with antigen 85A DNA, a promising DNA vaccine for human tuberculosis, had no measurable protective effect against infection withM. bovis.
Role ofNeisseria meningitidis luxSin Cell-to-Cell Signaling and Bacteremic Infection
Authors: Winzer Klaus , Sun Yao-hui , Green Andrew , Delory Marie , Blackley David , Hardie Kim R. , Baldwin Thomas J. , Tang Christoph M. 
Published: July 2002

ABSTRACTNumerous pathogenic bacteria containluxS, which is required for autoinducer-2 production. Here, we demonstrate thatNeisseria meningitidiscontains a functional copy ofluxSthat is necessary for full meningococcal virulence; strains with aluxSdeletion are defective for bacteremia, a prerequisite of meningococcal pathogenesis.
Pirfenidone Blocks the In Vitro and In Vivo Effects of Staphylococcal Enterotoxin B
Authors: Hale Martha L. , Margolin Solomon B. , Krakauer Teresa , Roy Chad J. , Stiles Bradley G. 
Published: July 2002

ABSTRACTPirfenidone [5-methyl-1-phenyl-2-(1H)-pyridone] down-regulates expression of cytokines and other mediators involved in the onset and development of pulmonary fibrosis. Pirfenidone also inhibits production of tumor necrosis factor alpha (TNF-α) from macrophages incubated with endotoxin and protects mice against endotoxin shock. Pirfenidone's ability to reduce cytokine expression in these disorders led us to investigate the drug's effect on another cytokine anomaly, superantigen-induced shock. BALB/c mice were exposed to staphylococcal enterotoxin B (SEB) either systemically or by aerosol and subsequently potentiated with a sublethal dose of lipopolysaccharide. In these experiments, pirfenidone given 2 to 4.25 h after SEB resulted in 80 to 100% survival versus only 0 to 10% survival among untreated control animals. Relative to serum cytokine levels from controls given toxin but no drug, there was a 35 to 80% decrease in TNF-α, interleukin 1, and other proinflammatory cytokines. In vitro experiments with human peripheral blood lymphocytes revealed that pirfenidone reduced SEB-induced cytokine levels 50 to 80% and inhibited 95% of SEB-induced T-cell proliferation. Overall, these studies demonstrated the potential utility of pirfenidone as a therapeutic against septic shock and the biological effects of SEB.
Quorum-Sensing
Escherichia coli
Regulator A: a Regulator of the LysR Family Involved in the Regulation of the Locus of Enterocyte Effacement Pathogenicity Island in Enterohemorrhagic
E. coli
Authors: Sperandio Vanessa , Li Caiyi C. , Kaper James B. 
Published: July 2002

ABSTRACT

The locus of enterocyte effacement (LEE) is a chromosomal pathogenicity island that encodes the proteins involved in the formation of the attaching and effacing lesions by enterohemorrhagic
Escherichia coli
(EHEC) and enteropathogenic
E. coli
(EPEC). The LEE comprises 41 open reading frames organized in five major operons,
LEE1
,
LEE2
,
LEE3
,
tir
(
LEE5
), and
LEE4
, which encode a type III secretion system, the intimin adhesin, the translocated intimin receptor (Tir), and other effector proteins. The first gene of
LEE1
encodes the Ler regulator, which activates all the other genes within the LEE. We previously reported that the LEE genes were activated by quorum sensing through Ler (V. Sperandio, J. L. Mellies, W. Nguyen, S. Shin, and J. B. Kaper, Proc. Natl. Acad. Sci. USA 96:15196-15201, 1999). In this study we report that a putative regulator in the
E. coli
genome is itself activated by quorum sensing. This regulator is encoded by open reading frame b3243; belongs to the LysR family of regulators; is present in EHEC, EPEC, and
E. coli
K-12; and shares homology with the AphB and PtxR regulators of
Vibrio cholerae
and
Pseudomonas aeruginosa
, respectively. We confirmed the activation of b3243 by quorum sensing by using transcriptional fusions and renamed this regulator quorum-sensing
E. coli
regulator A (QseA). We observed that QseA activated transcription of
ler
and therefore of the other LEE genes. An EHEC
qseA
mutant had a striking reduction of type III secretion activity, which was complemented when
qseA
was provided in
trans
. Similar results were also observed with a
qseA
mutant of EPEC. The QseA regulator is part of the regulatory cascade that regulates EHEC and EPEC virulence genes by quorum sensing.
Identification ofChlamydia pneumoniae-Derived Mouse CD8 Epitopes
Authors: Sarén Anne , Pascolo Steve , Stevanovic Stefan , Dumrese Tilman , Puolakkainen Mirja , Sarvas Matti , Rammensee Hans-Georg , Vuola Jenni M. 
Published: July 2002

ABSTRACTChlamydia pneumoniaeis a common intracellular human pathogen that has been associated with several severe pathological conditions, including coronary heart disease and atherosclerosis. There is no vaccine againstC. pneumoniaeinfection, but CD8+T cells have been shown to be crucial for protection during experimental infection. However, the effector functions and epitope specificity of the protective CD8+T cell remain unknown. The aim of this study was to identifyC. pneumoniae-derived mouse CD8 epitopes by using a recent epitope prediction method. Of fourC. pneumoniaeproteins (the major outer membrane protein, outer membrane protein 2, polymorphic outer membrane protein 5, and heat shock protein 60), 53 potential CD8+T-cell epitopes were predicted byH-2class I binding algorithms. Nineteen of the 53 peptides were identified as CD8 epitopes by testing for induction of a cytotoxic response after immunization. To test whether the predicted epitopes are naturally processed and presented byC. pneumoniae-infected cells, we generated a panel of seven peptide-specific cytotoxic T lymphocyte lines that were subsequently tested for recognition ofC. pneumoniae-infected target cells. By using this strategy, we were able to identify threeC. pneumoniaeCD8 epitopes that were, indeed, processed and presented on infected cells. Identification of these natural CD8 epitopes provides tools for characterization of CD8+T-cell function in vivo and generation of epitope-specific prevention strategies.