bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Accumulation of Eosinophils in Lung Lesions in Guinea Pigs Infected with
Mycobacterium tuberculosis
Authors: Lasco Todd M. , Turner Oliver C. , Cassone Lynne , Sugawara Isamu , Yamada Hiroyuki , McMurray David N. , Orme Ian M.
Published: January 2004

Guinea pig eosinophils were positively identified in bronchoalveolar lavage populations and in the lung granulomas of
Mycobacterium tuberculosis
-infected guinea pigs. It is possible that the rapid influx of these cells, and their subsequent degranulation during acute pulmonary tuberculosis, may play a key role in the susceptibility of this animal model.
Type III Secretion: a Virulence Factor Delivery System Essential for the Pathogenicity of
Burkholderia mallei
Authors: Ulrich Ricky L. , DeShazer David
Published: January 2004

By creating mutations in the
Burkholderia mallei
ATCC 23344 animal pathogen-like type III secretion system (TTSS), this study analyzes the correlation between type III secretion and the pathogenicity of ATCC 23344 in vivo. Mutagenesis demonstrated that a functional TTSS was required for the full pathogenicity of ATCC 23344 in the BALB/c mouse and Syrian hamster models of infection. However, vaccination with each mutant failed to elicit a protective immunity against challenge with wild-type ATCC 23344.
Heat Shock Protein 60 Is the Major Antigen Which Stimulates Delayed-Type Hypersensitivity Reaction in the Macaque Model ofChlamydia trachomatisSalpingitis
Authors: Lichtenwalner Anne B. , Patton Dorothy L. , Van Voorhis Wesley C. , Sweeney Yvonne T. Cosgrove , Kuo Cho-Chou
Published: January 2004

Chlamydial delayed-type hypersensitivity antigens were analyzed by using the subcutaneous salpingeal autotransplant model ofMacaca nemestrinainfected withChlamydia trachomatisserovar E. Heat shock protein 60 was the only antigen shown to induce delayed-type hypersensitivity among other antigens tested, including UV-inactivated organisms, recombinant major outer membrane protein, purified outer membrane proteins, and heat shock protein 10.
Evidence for Acquisition of the Lipooligosaccharide Biosynthesis Locus inCampylobacter jejuniGB11, a Strain Isolated from a Patient with Guillain-Barré Syndrome, by Horizontal Exchange
Authors: Gilbert Michel , Godschalk Peggy C. R. , Karwaski Marie-France , Ang C. Wim , van Belkum Alex , Li Jianjun , Wakarchuk Warren W. , Endtz Hubert P.
Published: January 2004

Campylobacter jejuniGB11, a strain isolated from a patient with Guillain-Barré syndrome, has been shown to be genetically closely related to the completely sequenced strainC. jejuniNCTC 11168 by various molecular typing and serotyping methods. However, we observed that the lipooligosaccharide (LOS) biosynthesis genes strongly diverged between GB11 and NCTC 11168. We sequenced the LOS biosynthesis locus of GB11 and found that it was nearly identical to the class A LOS locus from theC. jejuniHS:19 Penner serotype strain (ATCC 43446). Analysis of the DNA sequencing data showed that a horizontal exchange event involving at least 14.26 kb had occurred in the LOS biosynthesis locus of GB11 betweengalE(Cj1131c in NCTC 11168) andgmhA(Cj1149 in NCTC 11168). Mass spectrometry of the GB11 LOS showed that GB11 expressed an LOS outer core that mimicked the carbohydrate portion of the gangliosides GM1a and GD1a, similar toC. jejuniATCC 43446. The serum from the GB11-infected patient was shown to react with the LOS from both GB11 and ATCC 43446 but not with that from NCTC 11168. These data indicate that the antiganglioside response in the GB11-infected patient was raised against the structures synthesized by the acquired class A LOS locus.
Periodontitis Vaccine Decreases Local Prostaglandin E
2
Levels in a Primate Model
Authors: Roberts Frank A. , Houston Laura S. , Lukehart Sheila A. , Mancl Lloyd A. , Persson G. Rutger , Page Roy C.
Published: January 2004

Interleukin-1β, tumor necrosis factor alpha, prostaglandin E
2
(PGE
2
), and
Porphyromonas gingivalis-
specific immunoglobulin G levels in gingival crevicular fluid were measured in primates immunized with a
P. gingivalis
vaccine followed by ligature-induced periodontitis. Only PGE
2
levels were dramatically suppressed (
P
< 0.0001) in immunized animals versus controls. A significant correlation (
P
< 0.027) was also found between PGE
2
levels and decreased bone loss scores. This study presents the first evidence of a potential mechanism involved in periodontitis vaccine-induced suppression of bone loss in a nonhuman primate model and offers insight into the role of PGE
2
in periodontal destruction.
Activated THP-1 Cells: an Attractive Model for the Assessment of Intracellular Growth Rates ofMycobacterium tuberculosisIsolates
Authors: Theus S. A. , Cave M. D. , Eisenach K. D.
Published: January 2004

Capacity of certainMycobacterium tuberculosisisolates to grow more rapidly in human macrophages may be indicative of increased virulence. Significant differences were observed in intracellular growth of two isolates from sites of tuberculosis transmission, with an outbreak-associated strain growing faster than a strain causing disease in only one person. Activated THP-1 cells are a suitable alternative to peripheral blood monocyte models.
An
msbB
Homologue Carried in Plasmid pO157 Encodes an Acyltransferase Involved in Lipid A Biosynthesis in
Escherichia coli
O157:H7
Authors: Kim Sang-Hyun , Jia Wenyi , Bishop Russell E. , Gyles Carlton
Published: January 2004

Escherichia coli
O157:H7 carries a chromosomal
msbB1
and a plasmid-encoded
msbB2
gene. We characterized
msbB2
function as a homologue of
msbB1
by examination of wild-type organisms and mutant strains that lacked functional
msbB1
,
msbB2
, and both
msbB1
and
msbB2.
The
msbB
double-mutant strain generated pentaacyl lipid A, while the single-mutant strains synthesized hexaacyl lipid A. Complementation with overexpressed
msbB2
converted pentaacyl into hexaacyl lipid A in the double-mutant strain. The transcription of both
msbB
genes occurred simultaneously. Lack of MsbB2 activity slightly increased the microheterogeneity of the lipid A species. These results suggest that the
msbB2
gene plays a role not only in the routine generation of fully hexaacylated lipid A but also in suppressing the microheterogeneity of lipid A species, the endotoxic determinant of the organism.
Needle-Free Skin Patch Vaccination Method for Anthrax
Authors: Matyas Gary R. , Friedlander Arthur M. , Glenn Gregory M. , Little Stephen , Yu Jianmei , Alving Carl R.
Published: January 2004

Three immunizations of mice with recombinant protective antigen (rPA) by transcutaneous immunization (TCI) induced long-term neutralizing antibody titers that were superior to those obtained with aluminum-adsorbed rPA. In addition, rPA alone exhibited adjuvant activity for TCI. Forty-six weeks after completion of TCI, 100% protection was observed against lethal anthrax challenge.
Intranasal Immunization of Mice with Group B Streptococcal Protein Rib and Cholera Toxin B Subunit Confers Protection against Lethal Infection
Authors: Larsson Charlotte , Holmgren Jan , Lindahl Gunnar , Bergquist Charlotta
Published: January 2004

Intranasal immunization of mice with Rib, a cell surface protein of group B streptococcus (GBS), conjugated to or simply coadministered with the recombinant cholera toxin B subunit, induces systemic immunoglobulin G (IgG) and local IgA antibody responses and confers protection against lethal GBS infection. These findings have implications for the development of a human GBS vaccine.
Downregulation of the DNA-Binding Activity of Nuclear Factor-κB p65 Subunit in
Porphyromonas gingivalis
Fimbria-Induced Tolerance
Authors: Hajishengallis George , Genco Robert J.
Published: January 2004

Porphyromonas gingivalis
fimbriae induce high levels of nuclear factor-κB (NF-κB)-dependent cytokine release upon primary but not secondary stimulation of monocytic cells (FimA tolerance). In this study, fimbriae induced Toll-like receptor-mediated activation of both p50 and p65 subunits of NF-κB upon primary cellular activation. However, activation of the transactivating p65 subunit (but not of the transcriptionally inactive p50 subunit) was significantly inhibited in fimbria-restimulated cells. Moreover, expression of a NF-κB-dependent reporter gene was inhibited upon secondary stimulation with fimbriae. NF-κB p65 downregulation may thus contribute to induction of FimA tolerance.
Hydrogen Peroxide-Mediated Killing of
Caenorhabditis elegans
: a Common Feature of Different Streptococcal Species
Authors: Bolm Maike , Jansen Wouter T. M. , Schnabel Ralf , Chhatwal Gursharan S.
Published: January 2004

Recently, we reported that
Streptococcus pyogenes
kills
Caenorhabditis elegans
by the use of hydrogen peroxide (H
2
O
2
). Here we show that diverse streptococcal species cause death of
C. elegans
larvae in proportion to the level of H
2
O
2
produced. H
2
O
2
may mask the effects of other pathogenicity factors of catalase-negative bacteria in the
C. elegans
infection model.
Identification of Five Outer Membrane-Associated Proteins among Cross-Protective Factor Proteins ofPasteurella multocida
Authors: Tabatabai Louisa B. , Zehr Emilie S.
Published: January 2004

Fowl cholera is caused byPasteurella multocidaserovars A:1, A:3, and A:4. The 39-kDa cross-protective factor protein and four other membrane proteins of the membrane proteome ofP. multocidawere identified. We determined that the 39-kDa cross-protective protein wasPasteurellalipoprotein B, or PlpB.
Comparison of
Campylobacter jejuni
Isolates Implicated in Guillain-Barré Syndrome and Strains That Cause Enteritis by a DNA Microarray
Authors: Leonard Edward E. , Tompkins Lucy S. , Falkow Stanley , Nachamkin Irving
Published: January 2004

We asked whether
Campylobacter jejuni
isolated from patients with Guillain-Barré syndrome (GBS) differ from isolates isolated from patients with uncomplicated gastrointestinal infection using DNA microarray analysis. We found that specific GBS genes or regions were not identified, and microarray analysis confirmed significant genomic heterogeneity among the isolates.
Haemophilus influenzaePorin Induces Toll-Like Receptor 2-Mediated Cytokine Production in Human Monocytes and Mouse Macrophages
Authors: Galdiero Marilena , Galdiero Massimiliano , Finamore Emiliana , Rossano Fabio , Gambuzza Maria , Catania Maria Rosaria , Teti Giuseppe , Midiri Angelina , Mancuso Giuseppe
Published: January 2004

The production of proinflammatory cytokines is likely to play a major pathophysiological role in meningitis and other infections caused byHaemophilus influenzaetype b (Hib). Previous studies have shown that Hib porin contributes to signaling of the inflammatory cascade. We examined here the role of Toll-like receptors (TLRs) and the TLR-associated adaptor protein MyD88 in Hib porin-induced production of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). Hib porin-induced TNF-α and IL-6 production was virtually eliminated in macrophages from TLR2- or MyD88-deficient mice. In contrast, macrophages from lipopolysaccharide (LPS)-hyporesponsive C3H/HeJ mice, which are defective in TLR4 function, responded normally to Hib porin. Moreover anti-TLR2 antibodies but not anti-TLR4 antibodies significantly reduced Hib porin-stimulated TNF-α and IL-6 release from the human monocytic cell line THP-1. These data indicate that the TLR2/MyD88 pathway plays an essential role in Hib porin-mediated cytokine production. These findings may be useful in the development of alternative therapies aimed at reducing excessive inflammatory responses during Hib infections.
The Bacterial Insertion Sequence Element IS
256
Occurs Preferentially in Nosocomial
Staphylococcus epidermidis
Isolates: Association with Biofilm Formation and Resistance to Aminoglycosides
Authors: Kozitskaya Svetlana , Cho Seung-Hak , Dietrich Katja , Marre Reinhard , Naber Kurt , Ziebuhr Wilma
Published: January 2004

Staphylococcus epidermidis
is a normal constituent of the healthy human microflora, but it is also the most common cause of nosocomial infections associated with the use of indwelling medical devices. Isolates from device-associated infections are known for their pronounced phenotypic and genetic variability, and in this study we searched for factors that might contribute to this flexibility. We show that mutator phenotypes, which exhibit elevated spontaneous mutation rates, are rare among both pathogenic and commensal
S. epidermidis
strains. However, the study revealed that, in contrast to those of commensal strains, the genomes of clinical
S. epidermidis
strains carry multiple copies of the insertion sequence IS
256
, while other typical staphylococcal insertion sequences, such as IS
257
and IS
1272
, are distributed equally among saprophytic and clinical isolates. Moreover, detection of IS
256
was found to be associated with biofilm formation and the presence of the
icaADBC
operon as well as with gentamicin and oxacillin resistance in the clinical strains. The data suggest that IS
256
is a characteristic element in the genome of multiresistant nosocomial
S. epidermidis
isolates that might be involved in the flexibility and adaptation of the genome in clinical isolates.
The Siderophore Receptor IroN, but Not the High-Pathogenicity Island or the Hemin Receptor ChuA, Contributes to the Bacteremic Step of
Escherichia coli
Neonatal Meningitis
Authors: Nègre Valérie Lefranc , Bonacorsi Stéphane , Schubert Soren , Bidet Philippe , Nassif Xavier , Bingen Edouard
Published: January 2004

Using a neonatal rat meningitis model, we examined the involvement of three iron uptake systems, namely, the high-pathogenicity island, the hemin receptor ChuA, and the siderophore receptor IroN, in the pathogenesis of
Escherichia coli
neonatal meningitis. Only IroN appeared to play a major role during the bacteremic step of the disease.
Contribution of CsrR-Regulated Virulence Factors to the Progress and Outcome of Murine Skin Infections byStreptococcus pyogenes
Authors: Engleberg N. Cary , Heath Andrew , Vardaman Kristal , DiRita Victor J.
Published: January 2004

Streptococcus pyogeneswith null mutations in thecsrRSregulatory locus are highly virulent in mice due to derepression of hyaluronic acid capsule synthesis and exotoxins, e.g., streptolysin S (SLS) and pyrogenic exotoxin B (SpeB). We generated derivatives of a ΔcsrRSstrain that also carry deletions inhasAB(leading to an acapsular phenotype) or insagA(phenotypically SLS−) or an interruption ofspeB(SpeB−) to test the relative contributions of these factors to the development of necrotic skin lesions. Inoculation of 2 × 106to 4 × 106CFU of either acapsular or SLS−strains into hairless mice resulted in lesions ∼70% smaller than those of the ΔcsrRSparent strain. Elimination of SLS also reduced lethality from 100% to 0% at this inoculum (P< 10−7; Fisher exact test). In contrast, SLS+SpeB−mutants yielded lesions that were only 41% smaller than the parent strain (t= 2.2;P= 0.04), but only 3 the 17 lesions had dermal sloughing (P= 10−5). The nonulcerative lesions associated with SpeB−strains appeared pale with surrounding erythema. We conclude that capsule and SLS contribute to the subcutaneous spread ofS. pyogenesand to a fatal outcome of infection. SpeB facilitates early dermal ulceration but has minor influence on lesion size and mortality. Large ulcerative lesions are observed only when both toxins are present.
Role of B7 Costimulatory Molecules in Immune Responses and T-Helper Cell Differentiation in Response to Recombinant HagB fromPorphyromonas gingivalis
Authors: Zhang Ping , Martin Michael , Yang Qiu-Bo , Michalek Suzanne M. , Katz Jannet
Published: January 2004

In addition to antigen-specific signals mediated through the T-cell receptor, T cells also require antigen nonspecific costimulation for activation. The B7 family of molecules on antigen-presenting cells, which include B7-1 (CD80) and B7-2 (CD86), play important roles in providing costimulatory signals required for development of antigen-specific immune responses. Hemagglutinin B (HagB) is a nonfimbrial adhesin of the periodontopathic microorganismPorphyromonas gingivalisand is thought to be involved in the attachment of the bacterium to host tissues. However, the immune mechanisms involved in responses to HagB and their roles in pathogenesis have yet to be elucidated. Therefore, the purpose of this study was to determine the role of B7 costimulatory molecules on T-helper-cell differentiation for the induction of immune responses to HagB. Mice deficient in either or both of the costimulatory molecules B7-1 and B7-2 were used to explore their role in immune responses to HagB after subcutaneous immunization. B7-1−/−mice had levels of immunoglobulin G (IgG) anti-HagB antibody activity in serum similar to those of wild-type mice, whereas lower serum IgG anti-HagB antibody responses were seen in B7-2−/−mice. Moreover, significantly lower numbers of IgG antibody-secreting cells and lower levels of CD4+-T-cell proliferation were observed in B7-2−/−mice compared to wild-type mice. No serum IgG response to HagB was detected in B7-1/B7-2−/−mice. Analysis of the subclass of the serum IgG responses and the cytokines induced in response to HagB revealed that B7-2−/−mice had significantly lower IgG1 and higher IgG2a anti-HagB antibody responses compared to wild-type mice. The B7-2−/−mice also had significantly reduced levels of interleukin-4 (IL-4) and IL-5 and enhanced level of gamma interferon. Furthermore, assessment of B7-1 and B7-2 expression on B cells and macrophages derived from wild-type BALB/c mice after in vitro stimulation with HagB revealed a predominant upregulation in the expression of the B7-2 costimulatory molecule on B cells and macrophages. Essentially no change was seen in the expression of B7-1. Taken together, these results suggest a critical role for B7, especially B7-2, for the preferential induction of a Th2-like response to HagB.
Surfactant Protein A Modulates the Inflammatory Response in Macrophages during Tuberculosis
Authors: Gold Jeffrey A. , Hoshino Yoshihiko , Tanaka Naohiko , Rom William N. , Raju Bindu , Condos Rany , Weiden Michael D.
Published: January 2004

Tuberculosis leads to immune activation and increased human immunodeficiency virus type 1 (HIV-1) replication in the lung. However, in vitro models of mycobacterial infection of human macrophages do not fully reproduce these in vivo observations, suggesting that there are additional host factors. Surfactant protein A (SP-A) is an important mediator of innate immunity in the lung. SP-A levels were assayed in the human lung by using bronchoalveolar lavage (BAL). There was a threefold reduction in SP-A levels during tuberculosis only in the radiographically involved lung segments, and the levels returned to normal after 1 month of treatment. The SP-A levels were inversely correlated with the percentage of neutrophils in BAL fluid, suggesting that low SP-A levels were associated with increased inflammation in the lung. Differentiated THP-1 macrophages were used to test the effect of decreasing SP-A levels on immune function. In the absence of infection withMycobacterium tuberculosis, SP-A at doses ranging from 5 to 0.01 μg/ml inhibited both interleukin-6 (IL-6) production and HIV-1 long terminal repeat (LTR) activity. In macrophages infected withM. tuberculosis, SP-A augmented both IL-6 production and HIV-1 LTR activity. To better understand the effect of SP-A, we measured expression of CAAT/enhancer binding protein beta (C/EBPβ), a transcription factor central to the regulation of IL-6 and the HIV-1 LTR. In macrophages infected withM. tuberculosis, SP-A reduced expression of a dominant negative isoform of C/EBPβ. These data suggest that SP-A has pleiotropic effects even at the low concentrations found in tuberculosis patients. This protein augments inflammation in the presence of infection and inhibits inflammation in uninfected macrophages, protecting uninvolved lung segments from the deleterious effects of inflammation.
Porphyromonas gingivalis
Genes Involved in
fimA
Regulation
Authors: Xie Hua , Kozlova Natalia , Lamont Richard J.
Published: January 2004

Porphyromonas gingivalis
is an important component of the complex plaque biofilm that is a direct precursor of periodontal disease. The major fimbriae are required for attachment to oral surfaces and are an important virulence factor. Fimbrillin (FimA) expression in
P. gingivalis
is inhibited by surface molecule of
Streptococcus cristatus
, an early colonizer of dental plaque. In this study, differential display PCR was used to identify
P. gingivalis
genes that are regulated in response to
S. cristatus
. Of several differentially expressed genes,
pg2131
and
pg2167
were upregulated by
S. cristatus
signaling molecules. A null mutant of
pg2167
did not transcriptionally regulate
fimA
following exposure to
S. cristatus
. In fact,
fimA
transcription was enhanced in the
pg2167
mutant, suggesting that
pg2167
may act to repress
fimA
expression. In contrast, a mutation in
pg2131
did not affect transcription of
fimA
in the presence of
S. cristatus
. However, production of fimbrillin was significantly diminished in the
pg2131
mutant, implicating involvement in posttranscriptional regulation in fimbriation. These data suggest that
P. gingivalis
fimbriation is controlled by more than one regulation mechanism, involving both transcriptional and posttranscriptional processes.
Release of a Potent Polymorphonuclear Leukocyte Chemoattractant Is Regulated by White-Opaque Switching inCandida albicans
Authors: Geiger Jeremy , Wessels Deborah , Lockhart Shawn R. , Soll David R.
Published: January 2004

Previous studies employing transmembrane assays suggested thatCandida albicansand related species, as well asSaccharomyces cerevisiae, release chemoattractants for human polymorphonuclear leukocytes (PMNs). Because transmembrane assays do not definitively distinguish between chemokinesis and chemotaxis, single-cell chemotaxis assays were used to confirm these findings and test whether mating-type or white-opaque switching affects the release of attractant. Our results demonstrate thatC. albicans,C. dubliniensis,C. tropicalis,C. parapsilosis, andC. glabratarelease bona fide chemoattractants for PMNs.S. cerevisiae, however, releases a chemokinetic factor but not a chemoattractant. Characterization of theC. albicanschemoattractant revealed that it is a peptide of approximately 1 kDa. Whereas the mating type ofC. albicansdid not affect the release of chemoattractant, switching did. White-phase cells released chemoattractant, but opaque-phase cells did not. Since the opaque phase ofC. albicansrepresents the mating-competent phenotype, it may be that opaque-phase cells selectively suppress the release of chemoattractant to facilitate mating.
Patterns of Variations in
Escherichia coli
Strains That Produce Cytolethal Distending Toxin
Authors: Pickett Carol L. , Lee Robert B. , Eyigor Aysegul , Elitzur Ben , Fox Emily M. , Strockbine Nancy A.
Published: January 2004

A collection of 20
Escherichia coli
strains that produce cytolethal distending toxin (CDT) were analyzed for their virulence-associated genes. All of these strains were serotyped, and multiplex PCR analysis was used to ascertain the presence of genes encoding other virulence factors, including Shiga toxin, intimin, enterohemolysin, cytotoxic necrotizing factor type 1 (CNF1) and CNF2, heat-stable toxin, and heat-labile toxin. These CDT-producing strains possessed various combinations of known virulence genes, some of which have not been noted before. Partial
cdtB
sequences were obtained from 10 of these strains, and their predicted CdtB sequences were compared to known
E. coli
CdtB sequences; some of the sequences were identical to known CdtB sequences, but two were not. PCR primers based on sequence differences between the known
cdt
sequences were tested for their ability to detect CDT producers and to determine CDT type. Correlations between the type of CDT produced, the presence of other virulence properties, and overall strain relatedness revealed that the CDT producers studied here can be divided into three general groups, with distinct differences in CDT type and in their complement of virulence-associated genes.
Host Cell Contact-Induced Transcription of the Type IV Fimbria Gene Cluster of
Actinobacillus pleuropneumoniae
Authors: Boekema Bouke K. H. L. , Van Putten Jos P. M. , Stockhofe-Zurwieden Norbert , Smith Hilde E.
Published: January 2004

Type IV pili (Tfp) of gram-negative species share many characteristics, including a common architecture and conserved biogenesis pathway. Much less is known about the regulation of Tfp expression in response to changing environmental conditions. We investigated the diversity of Tfp regulatory systems by searching for the molecular basis of the reported variable expression of the Tfp gene cluster of the pathogen
Actinobacillus pleuropneumoniae
. Despite the presence of an intact Tfp gene cluster consisting of four genes,
apfABCD
, no Tfp were formed under standard growth conditions. Sequence analysis of the predicted major subunit protein ApfA showed an atypical alanine residue at position −1 from the prepilin peptidase cleavage site in 42 strains. This alanine deviates from the consensus glycine at this position in Tfp from other species. Yet, cloning of the
apfABCD
genes under a constitutive promoter in
A. pleuropneumoniae
resulted in pilin and Tfp assembly. Tfp promoter-
luxAB
reporter gene fusions demonstrated that the Tfp promoter was intact but tightly regulated. Promoter activity varied with bacterial growth phase and was detected only when bacteria were grown in chemically defined medium. Infection experiments with cultured epithelial cells demonstrated that Tfp promoter activity was upregulated upon adherence of the pathogen to primary cultures of lung epithelial cells. Nonadherent bacteria in the culture supernatant exhibited virtually no promoter activity. A similar upregulation of Tfp promoter activity was observed in vivo during experimental infection of pigs. The host cell contact-induced and in vivo-upregulated Tfp promoter activity in
A. pleuropneumoniae
adds a new dimension to the diversity of Tfp regulation.
Two TonB Systems in
Actinobacillus pleuropneumoniae
: Their Roles in Iron Acquisition and Virulence
Authors: Beddek Amanda J. , Sheehan Brian J. , Bossé Janine T. , Rycroft Andrew N. , Kroll J. Simon , Langford Paul R.
Published: January 2004

Iron acquisition in vivo by
Actinobacillus pleuropneumoniae
depends upon a functional TonB system. Tonpitak et al. (W. Tonpitak, S. Thiede, W. Oswald, N. Baltes, and G.-F. Gerlach, Infect. Immun.
68:
1164-1170, 2000) have described one such system, associated with
tbpBA
encoding the transferrin receptor, and here we report a second, termed
tonB2
. This gene cluster (
exbB2
-
exbD2
-
tonB2
) is highly homologous to those in other
Pasteurellaceae
, unlike the earlier system described (now termed
tonB1
), suggesting that it is the indigenous system for this organism. Both
tonB2
and
tonB1
are upregulated upon iron restriction. TonB2, but not TonB1, was found to be essential for growth in vitro when the sole source of iron was hemin, porcine hemoglobin, or ferrichrome. In the case of iron provided as iron-loaded porcine transferrin, neither
tonB
mutant was viable. The
tonB1
phenotype could be explained by a polar effect of the mutation on transcription of downstream
tbp
genes. We propose that TonB2 is crucial for the acquisition of iron provided in this form, interacting with accessory proteins of the TonB1 system that have been demonstrated to be necessary by Tonpitak et al. TonB2 appears to play a much more important role in
A. pleuropneumoniae
virulence than TonB1. In an acute porcine infection model, the
tonB2
mutant was found to be highly attenuated, while the
tonB1
mutant was not. We hypothesize that acquisition of the
tonB1-tbp
gene cluster confers a biological advantage through its capacity to utilize transferrin-iron but that TonB1 itself plays little or no part in this process.
Binding and Agglutination of
Streptococcus pneumoniae
by Human Surfactant Protein D (SP-D) Vary between Strains, but SP-D Fails To Enhance Killing by Neutrophils
Authors: Jounblat Rania , Kadioglu Aras , Iannelli Francesco , Pozzi Gianni , Eggleton Paul , Andrew Peter W.
Published: January 2004

Recombinant human surfactant protein D (SP-D) expressed in
Escherichia coli
, consisting of the head and neck regions of the native molecule, bound to all strains of
Streptococcus pneumoniae
that were tested, but the extent of binding varied between strains of differing capsular serotypes. The recombinant protein expressed in the yeast
Pichia pastoris
did not bind. Full-length native SP-D aggregated pneumococci in a calcium-dependent manner that was inhibited by maltose acting as a competitive sugar. The ability of SP-D to modulate the uptake and killing of pneumococci by human neutrophils was also addressed. Neither recombinant truncated SP-D nor native full-length SP-D enhanced the killing of pneumococci by human neutrophils. Aggregation of pneumococci varied not only between strains of the same multilocus sequence type and different serotypes but also between strains of the same serotype. However, use of recombinant strains in which the serotype had been changed showed that the degree of aggregation was influenced by the capsular type. Indeed, a 19F serotype strain which was not aggregated by SP-D did exhibit aggregation when the original isogenic strain was capsule switched to capsular serotype 3. However, although our results show that SP-D is capable of aggregating most pneumococci, no correlation between the degree of aggregation and the capsule or multilocus sequence type of the pneumococcus was clearly apparent. Therefore, although the capsule serotype is not the only determinant of aggregation by SP-D, the data presented here indicate that it does have a role to play.
Disruption of Putative Regulatory Loci in
Listeria monocytogenes
Demonstrates a Significant Role for Fur and PerR in Virulence
Authors: Rea Rosemarie B. , Gahan Cormac G. M. , Hill Colin
Published: January 2004

The ability to adapt to adverse environmental conditions encountered in food and during host infection is a sine qua non for a successful
Listeria monocytogenes
infection. This ability is likely to depend on complex regulatory pathways controlled by a number of key regulators. We utilized the pORI19 plasmid integration system to analyze the role of six putative regulatory loci in growth under suboptimal environmental conditions and during murine infection. Disruption of loci encoding a topoisomerase III (
lmo2756
), a putative methyltransferase (
lmo0581
), and a regulator of the MarR family (
lmo1618
) revealed roles for the methyltransferase and the MarR regulator in growth under environmental stress conditions. However, plasmid integration into these loci had no impact on virulence potential in the murine model of infection. Disruption of the alternative sigma factor Sigma-H resulted in a mutant that demonstrated reduced growth potential in minimal medium. Murine studies indicated a minor role for this sigma factor in the infectious process. Strikingly, disruption of both
perR
and
fur
loci resulted in mutants that are significantly affected in virulence for mice, with the
fur
mutant demonstrating the greatest reduction in virulence potential. Both
perR
and
fur
mutants demonstrated increased resistance to hydrogen peroxide and the
fur
mutant was sensitive to low-iron conditions. The virulence defect of both
fur
and
perR
mutants could be rescued by iron-overload after esculetin treatment of mice, suggesting that the in vivo role of these gene products is to procure iron for bacterial growth.
Cytokine Production in Whole Blood Cultures from a Fishing Community in an Area of High Endemicity forSchistosoma mansoniin Uganda: the Differential Effect of Parasite Worm and Egg Antigens
Authors: Joseph Sarah , Jones Frances M. , Kimani Gachuhi , Mwatha Joseph K. , Kamau Timothy , Kazibwe Francis , Kemijumbi Jovanice , Kabatereine Narcis B. , Booth Mark , Kariuki Henry C. , Ouma John H. , Vennervald Birgitte J. , Dunne David W.
Published: January 2004

The human host is continuously exposed to the egg and the adult worm developmental stages ofSchistosoma mansoniduring chronic infections with the parasite. To assess the cytokine responses induced by these different costimulating stages and how they are influenced by host age and infection intensity, whole blood samples from a cross-sectional cohort of 226 members of a Ugandan fishing community who had been resident in an area with high transmission ofS. mansonifor the previous 10 years or from birth were stimulated withS. mansoniegg antigen (SEA) or worm antigen (SWA). SWA-specific gamma interferon (IFN-γ) production increased with age, and the levels of SWA- and SEA-specific interleukin 3 (IL-3) were weakly correlated with schistosome infection intensity. The production of most cytokines was little affected by age or infection intensity but was either SEA or SWA specific. One hundred thirty-two members of the cohort coproduced IL-5 and IL-13 specifically in response to SWA, whereas only 15 produced these cytokines, and at much lower levels, in response to SEA. IL-10, IL-4, and IFN-γ were also produced in response to SWA, whereas the response to SEA consisted almost exclusively of IL-10. Our results suggest that, in contrast to what has been described for the murine model ofS. mansoniand during acute human infections, chronic intense exposure to and infection withS. mansoniin this cohort resulted in very low levels of response to SEA in vitro in the presence of a vigorous and mixed Th1-Th2 response to SWA.
Measurement of Antibody Levels against Region II of the Erythrocyte-Binding Antigen 175 of
Plasmodium falciparum
in an Area of Malaria Holoendemicity in Western Kenya
Authors: Ohas Eunita A. , Adams John H. , Waitumbi John N. , Orago Alloys S. S. , Barbosa Arnoldo , Lanar David E. , Stoute José A.
Published: January 2004

Region II of the 175-kDa erythrocyte-binding antigen (EBA-175RII) of
Plasmodium falciparum
is functionally important in sialic acid-dependent erythrocyte invasion and is considered a prime target for an invasion-blocking vaccine. The objectives of this study were to (i) determine the prevalence of anti-EBA-175RII antibodies in a naturally exposed population, (ii) determine whether naturally acquired antibodies have a functional role by inhibiting binding of EBA-175RII to erythrocytes, and (iii) determine whether antibodies against EBA-175RII correlate with immunity to clinical malaria. We treated 301 lifelong residents of an area of malaria holoendemicity in western Kenya for malaria, monitored them during a high-transmission season, and identified 33 individuals who were asymptomatic despite parasitemia (clinically immune). We also identified 50 clinically susceptible individuals to serve as controls. These 83 individuals were treated and monitored again during the subsequent low-transmission season. Anti-EBA-175RII antibodies were present in 98.7% of the individuals studied. The antibody levels were relatively stable between the beginning and end of the high-transmission season and correlated with the plasma EBA-175RII erythrocyte-binding-inhibitory activity. There was no difference in anti-EBA-175RII levels or plasma EBA-175RII erythrocyte-binding-inhibitory activity between clinically immune and clinically susceptible groups. However, these parameters were higher in nonparasitemic than in parasitemic individuals at enrollment. These results suggest that although antibodies against EBA-175RII may be effective in suppressing some of the wild parasite strains, EBA-175RII is unlikely to be effective as a monovalent vaccine against malaria, perhaps due to allelic heterogeneity and/or presence of sialic acid-independent strains.
Host-Inducible Immunogenic Sphingomyelinase-Like Protein, Lk73.5, ofLeptospira interrogans
Authors: Artiushin S. , Timoney J. F. , Nally J. , Verma A.
Published: January 2004

Leptospira interroganscauses a variety of clinical syndromes in animals and humans. Although much information has accumulated on the importance of leptospiral lipopolysaccharide in protective antibody responses, relatively little is known about proteins that participate in immune responses. Identification of those proteins induced only in the host is particularly difficult. Using a novel double-antibody screen designed to identify clones in a gene library ofL. interrogansserovar Pomona expressing host-inducible proteins, we have characterized a gene (lk75.3) encoding a sphingomyelinase-like preprotein of 648 amino acids with cytotoxic activity for equine pulmonary endothelial cells and weak hemolytic activity for equine and rabbit erythrocytes.lk73.5was found as a single gene copy in all serovars ofL. interrogansbut not in otherLeptospiraspp. exceptL. inadai. The open reading frame (ORF) for Lk73.5 is followed by another partially homologous sequence containing an ORF (sph-like 2) for a 28.7-kDa peptide. Lk73.5 and Sph-like 2 share 95.1 and 97.7% amino acid identity with putative sphingomyelinases Sph2 and Sph1 (N terminus) fromL. interrogansserovar Lai (S.-X. Ren, G. Fu, X.-G. Jiangk, R. Zeng, Y.-G. Miao, H. Xu, Y.-X. Zhang, H. Xiong, G. Lu, L.-F. Lu, H.-Q. Jiang, J. Jia, Y.-F. Tu, J.-X. Jiang, W.-Y. Gu, Y.-Q. Zhang, Z. Cai, H.-H. Sheng, H.-F. Yin, Y. Zhang, G.-F. Zhu, M. Wank, H.-L. Huangk, Z. Qian, S.-Y. Wang, Wei Ma, Z.-J. Yao, Y. Shen, B.-Q. Qiang, Q.-C. Xia, X.-K. Guo, A. Danchinq, I. S. Girons, R. L. Somerville, Y.-M. Wen, M.-H. Shik, Z. Chen, J.-G. Xuk, and G.-P. Zhao, Nature422:88-893, 2003). Substantial homologies to sphingomyelinases from other leptospiras and other bacteria are also present. Lk73.5 was not detected in leptospiras cultured at 30 or 37°C. The recombinant protein reacted strongly with sera from recently infected mares but not with sera from horses vaccinated with commercial pentavalent bacterin. The host-inducible immunogenic Lk73.5 should have value in distinguishing vaccine from infection immune response.
Immunogenicity against Human Papillomavirus Type 16 Virus-Like Particles Is Strongly Enhanced by the PhoPcPhenotype inSalmonella entericaSerovar Typhimurium
Authors: Baud David , Benyacoub Jalil , Revaz Véronique , Kok Menno , Ponci Françoise , Bobst Martine , Curtiss Roy , De Grandi Pierre , Nardelli-Haefliger Denise
Published: January 2004

RecombinantSalmonellastrains have been widely used to deliver heterologous antigens and induce immune responses in vaccinated animals and humans. It remains to be established, however, how these bacteria mount an immune response; this has prevented the rational design of vaccines. Here we report for the first time that a particular genetic program, PhoPc, is necessary for recombinantSalmonellastrains to induce an antibody response to a heterologous antigen, the human papillomaviruses type 16 (HPV16) virus-like particle (VLP). The PhoPcphenotype results from a point mutation inphoQ, the gene encoding the sensor component of a two-component regulatory system (PhoP-PhoQ) that controls the expression of a number of virulence factors in Salmonellae. To demonstrate that immunogenicity of the viral antigen expressed by the bacterial vector was dependent on the PhoPcphenotype, we have expressed thephoQmutant gene (phoQ24) in two differently attenuatedSalmonella entericaserovar Typhimurium strains. Our data show extrachromosomalphoQ24to be dominant over the chromosomal copy of thephoQgene, conferring the PhoPcphenotype on the recipient strains. In addition, activation of PhoPQ-regulated genes by the plasmid-encoded PhoQ24 did not alter bacterial survival and conferred immunogenicity to the HPV16 VLP expressed in the twoS. entericaserovar Typhimurium backgrounds, inducing the production of HPV-specific antibodies in mice. This strongly suggests that at least one of the PhoP-regulated genes is necessary for mounting an efficient antibody response to HPV16 VLP. This finding sets the stage for further development of aSalmonella-based vaccine against HPV infection and cervical cancer.
Acid-Responsive Gene Induction of Ammonia-Producing Enzymes in
Helicobacter pylori
Is Mediated via a Metal-Responsive Repressor Cascade
Authors: van Vliet Arnoud H. M. , Kuipers Ernst J. , Stoof Jeroen , Poppelaars Sophie W. , Kusters Johannes G.
Published: January 2004

Although the adaptive mechanisms allowing the gastric pathogen
Helicobacter pylori
to survive acid shocks have been well documented, the mechanisms allowing growth at mildly acidic conditions (pH ∼5.5) are still poorly understood. Here we demonstrate that
H. pylori
strain 26695 increases the transcription and activity of its urease, amidase, and formamidase enzymes four- to ninefold in response to growth at pH 5.5. Supplementation of growth medium with NiCl
2
resulted in a similar induction of urease activity (at low NiCl
2
concentration) and amidase activity (at ≥500 μM NiCl
2
) but did not affect formamidase activity. Mutation of the
fur
gene, which encodes an iron-responsive repressor of both amidases, resulted in a constitutively high level of amidase and formamidase activity at either pH but did not affect urease activity at pH 7.0 or pH 5.5. In contrast, mutation of the
nikR
gene, encoding the nickel-responsive activator of urease expression, resulted in a significant reduction of acid-responsive induction of amidase and formamidase activity. Finally, acid-responsive repression of
fur
transcription was absent in the
H. pylori nikR
mutant, whereas transcription of the
nikR
gene itself was increased at pH 5.5 in wild-type
H. pylori
. We hypothesize that
H. pylori
uses a repressor cascade to respond to low pH, with NikR initiating the response directly via the urease operon and indirectly via the members of the Fur regulon.
Role ofToll-Like Receptor 4 in Gram-Positive and Gram-Negative Pneumonia inMice
Authors: Branger Judith , Knapp Sylvia , Weijer Sebastiaan , Leemans Jaklien C. , Pater Jennie M. , Speelman Peter , Florquin Sandrine , van der Poll Tom
Published: January 2004

To determine the role of Toll-like receptor 4 (TLR4) in the immune response to pneumonia, C3H/HeJ mice (which display a mutant nonfunctional TLR4) and C3H/HeN wild-type mice were intranasally infected with eitherStreptococcus pneumoniae(a common gram-positive respiratory pathogen) orKlebsiella pneumoniae(a common gram-negative respiratory pathogen). In cases of pneumococcal pneumonia, TLR4 mutant mice showed a reduced survival only after infection with low-level bacterial doses, which was associated with a higher bacterial burden in their lungs 48 h postinfection. InKlebsiellapneumonia, TLR4 mutant mice demonstrated a shortened survival after infection with either a low- or a high-level bacterial dose together with an enhanced bacterial outgrowth in their lungs. These data suggest that TLR4 contributes to a protective immune response in both pneumococcal andKlebsiellapneumonia and that its role is more important in respiratory tract infection caused by the latter (gram-negative) pathogen.
Immunoglobulin E and Eosinophil-Dependent Protective Immunity to LarvalOnchocerca volvulusin Mice Immunized with Irradiated Larvae
Authors: Abraham David , Leon Ofra , Schnyder-Candrian Silvia , Wang Chun Chi , Galioto Ann Marie , Kerepesi Laura A. , Lee James J. , Lustigman Sara
Published: January 2004

Mice immunized with irradiatedOnchocerca volvulusthird-stage larvae developed protective immunity. Eosinophil levels were elevated in the parasite microenvironment at the time of larval killing, and measurements of total serum antibody levels revealed an increase in the immunoglobulin E (IgE) level in immunized mice. The goal of the present study was to identify the role of granulocytes and antibodies in the protective immune response to the larval stages ofO. volvulusin mice immunized with irradiated larvae. Immunity did not develop in mice if granulocytes, including both neutrophils and eosinophils, were eliminated, nor did it develop if only eosinophils were eliminated. Moreover, larvae were killed in naïve interleukin-5 transgenic mice, and the killing coincided with an increase in the number of eosinophils and the eosinophil peroxidase (EPO) level in the animals. To determine if EPO was required for protective immunity, mice that were genetically deficient in EPO were immunized, and there were no differences in the rates of parasite recovery in EPO-deficient mice and wild-type mice. Two mouse strains were used to study B-cell function; μMT mice lacked all mature B cells, and Xid mice had deficiencies in the B-1 cell population. Immunity did not develop in the μMT mice but did develop in the Xid mice. Finally, protective immunity was abolished in mice treated to eliminate IgE from the blood. We therefore concluded that IgE and eosinophils are required for adaptive protective immunity to larvalO. volvulusin mice.
Host-Pathogen Interaction during Pneumococcal Infection in Patients with Chronic Obstructive Pulmonary Disease
Authors: Bogaert Debby , van der Valk Paul , Ramdin Reshmi , Sluijter Marcel , Monninkhof Evelyn , Hendrix Ron , de Groot Ronald , Hermans Peter W. M.
Published: January 2004

Acute exacerbation is a frequent complication of chronic obstructive pulmonary disease (COPD). Recent studies suggested a role for bacteria such as
Streptococcus pneumoniae
in the development of acute exacerbation. For this study, we investigated the following in COPD patients: (i) the epidemiology of pneumococcal colonization and infection, (ii) the effect of pneumococcal colonization on the development of exacerbation, and (iii) the immunological response against
S. pneumoniae
. We cultured sputa of 269 COPD patients during a stable state and during exacerbation of COPD and characterized 115 pneumococcal isolates by use of serotyping. Moreover, we studied serum immunoglobulin G (IgG) antibody titers, antibody avidities, and functional antibody titers against the seven conjugate vaccine serotypes in these patients. Colonization with only pneumococci (monocultures) increased the risk of exacerbation, with a hazard ratio of 2.93 (95% confidence interval, 1.41 to 6.07). The most prevalent pneumococcal serotypes found were serotypes 19F, 3, 14, 9L/N/V, 23A/B, and 11. We calculated the theoretical coverage for the 7- and 11-valent pneumococcal vaccines to be 60 and 73%, respectively. All patients had detectable IgG levels against the seven conjugate vaccine serotypes. These antibody titers were significantly lower than those in vaccinated healthy adults. Finally, on average, a 2.5-fold rise in serotype-specific and functional antibodies in
S. pneumoniae
-positive sputum cultures was observed during exacerbation. Our data indicate that pneumococcal colonization in COPD patients is frequently caused by vaccine serotype strains. Moreover, pneumococcal colonization is a risk factor for exacerbation of COPD. Finally, our findings demonstrate that COPD patients are able to mount a significant immune response to pneumococcal infection. COPD patients may therefore benefit from pneumococcal vaccination.