bluuebunny/crossref_metadata_2025_split huggingface dataset:
Divergent Interactions ofEhrlichiachaffeensis-andAnaplasma phagocytophilum-InfectedLeukocytes with Endothelial CellBarriers
Authors: Park Jinho , Choi Kyoung-Seong , Grab Dennis J. , Dumler J. Stephen 
Published: November 2003

ABSTRACTHuman anaplasmosis (formerly human granulocytic ehrlichiosis) and human monocytic ehrlichiosis (HME) are emerging tick-borne infections caused by obligate intracellular bacteria in the familyAnaplasmataceae. Clinical findings include fever, headache, myalgia, leukopenia, thrombocytopenia, and hepatic inflammatory injury. WhereasEhrlichia chaffeensis(HME) often causes meningoencephalitis, this is rare withAnaplasma phagocytophiluminfection. The abilities of infected primary host monocytes and neutrophils and of infected HL-60 cells to cross human umbilical vein endothelial cell-derived EA.hy926 cell barriers and human brain microvascular cells (BMEC), a human blood-brain barrier model, were studied. Uninfected monocyte/macrophages crossed endothelial cell barriers six times more efficiently than neutrophils. MoreE. chaffeensis-infected monocytes transmigrated than uninfected monocytes, whereasA. phagocytophilumsuppressed neutrophil transmigration. Differences were not due to barrier dysfunction, as transendothelial cell resistivities were the same for uninfected cell controls. Similar results were obtained for HL-60 cells used as hosts forE. chaffeensisandA. phagocytophilum. Differential transmigration ofE. chaffeensis-andA. phagocytophilum-infected leukocytes and HL-60 cells confirmed a role for the pathogen in modifying cell migratory capacity. These results support the hypothesis thatAnaplasmataceaeintracellular infections lead to unique pathogen-specific host cell functional alterations that are likely important for pathogen survival, pathogenesis, and disease induction.
Biochemical and Immunological Characterization of Bacterially Expressed and RefoldedPlasmodium falciparum42-Kilodalton C-Terminal Merozoite Surface Protein 1
Authors: Singh Sanjay , Kennedy Michael C. , Long Carole A. , Saul Allan J. , Miller Louis H. , Stowers Anthony W. 
Published: November 2003

ABSTRACTProtection againstPlasmodium falciparumcan be induced by vaccination in animal models with merozoite surface protein 1 (MSP1), which makes this protein an attractive vaccine candidate for malaria. In an attempt to produce a product that is easily scaleable and inexpensive, we expressed the C-terminal 42 kDa of MSP1 (MSP142) inEscherichia coli, refolded the protein to its native form from insoluble inclusion bodies, and tested its ability to elicit antibodies with in vitro and in vivo activities. Biochemical, biophysical, and immunological characterization confirmed that refoldedE. coliMSP142was homogeneous and highly immunogenic. In a formulation suitable for human use, rabbit antibodies were raised against refoldedE. coliMSP142and tested in vitro in aP. falciparumgrowth invasion assay. The antibodies inhibited the growth of parasites expressing either homologous or heterologous forms ofP. falciparumMSP142. However, the inhibitory activity was primarily a consequence of antibodies directed against the C- terminal 19 kDa of MSP1 (MSP119). Vaccination of nonhuman primates withE. coliMSP142in Freund's adjuvant protected six of sevenAotusmonkeys from virulent infection withP. falciparum. The protection correlated with antibody-dependent mechanisms. Thus, this new construct,E. coliMSP142, is a viable candidate for human vaccine trials.
Identification of Dimethyl Sulfoxide Reductase inActinobacillus pleuropneumoniaeand Its Role in Infection
Authors: Baltes Nina , Hennig-Pauka Isabel , Jacobsen Ilse , Gruber Achim D. , Gerlach Gerald F. 
Published: November 2003

ABSTRACTActinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is capable of persisting in oxygen-deprived surroundings, namely, tonsils and sequestered necrotic lung tissue. Utilization of alternative terminal electron acceptors in the absence of oxygen is a common strategy in bacteria under anaerobic growth conditions. In an experiment aimed at identification of genes expressed in vivo, the putative catalytic subunit DmsA of anaerobic dimethyl sulfoxide reductase was identified in anA. pleuropneumoniaeserotype 7 strain. The 90-kDa protein exhibits 85% identity to the putative DmsA protein ofHaemophilus influenzae, and its expression was found to be upregulated under anaerobic conditions. Analysis of the unfinishedA. pleuropneumoniaegenome sequence revealed putative open reading frames (ORFs) encoding DmsB and DmsC proteins situated downstream of thedmsAORF. In order to investigate the role of theA. pleuropneumoniaeDmsA protein in virulence, an isogenic deletion mutant,A. pleuropneumoniaeΔdmsA, was constructed and examined in an aerosol infection model.A. pleuropneumoniaeΔdmsAwas attenuated in acute disease, which suggests that genes involved in oxidative metabolism under anaerobic conditions might contribute significantly toA. pleuropneumoniaevirulence.
An Enzymatically Active A Domain Is Required for Cholera-Like Enterotoxins To Induce a Long-Lived Blockade on the Induction of Oral Tolerance: New Method for Screening Mucosal Adjuvants
Authors: Bagley Kenneth C. , Abdelwahab Sayed F. , Tuskan Robert G. , Lewis George K. 
Published: November 2003

ABSTRACTThe cholera-like enterotoxins (CLETS), cholera toxin (CT) andEscherichia coliheat-labile toxin (LT), are powerful mucosal adjuvants. Here we show that these toxins also induce a long-lived blockade (of at least 6 months) on the induction of oral tolerance when they are coadministered with the antigen ovalbumin. Strikingly, only enzymatically active CLETS induced this blockade on the induction of oral tolerance. In this regard, the enzymatically inactive mutants of CT and LT, CTK63 and LTK63, and their recombinant B pentamers, rCTB and rLTB, failed to block the induction of oral tolerance, demonstrating a stringent requirement for an enzymatically active A domain in this phenomenon. Together with the results of other recent studies, these results indicate that the enzymatic activity of CLETS, most likely cyclic AMP elevation, is responsible for their adjuvant effects. The results of this study also indicate that measuring the ability of putative mucosal adjuvants to block the induction of oral tolerance may be a superior method for measuring mucosal adjuvanticity.
Subtractive Hybridization Identifies a Novel Predicted Protein Mediating Epithelial Cell Invasion by Virulent Serotype III Group B
Streptococcus agalactiae
Authors: Adderson Elisabeth E. , Takahashi Shinji , Wang Yan , Armstrong Jianling , Miller Dylan V. , Bohnsack John F. 
Published: November 2003

ABSTRACT

Group B
Streptococcus agalactiae
bacteria (group B streptococci [GBS]) are the most common cause of serious bacterial infection in newborn infants. The majority of serotype III-related cases of neonatal disease are caused by a genetically related subgroup of bacteria, restriction fragment digest pattern (RDP) type III-3, suggesting that these strains possess unique genes contributing to virulence. We used genomic subtractive hybridization to identify regions of genomic DNA unique to virulent RDP type III-3 GBS strains. Within one of these III-3-specific regions is a 1,506-bp open reading frame,
spb1
(surface protein of group B streptococcus 1). A mutant type III GBS strain lacking Spb1 was constructed in virulent RDP type III-3 strain 874391, and the interactions of the wild-type and
spb1
isogenic mutant with a variety of epithelial cells important to GBS colonization and infection were compared. While adherence of the
spb1
isogenic mutant to A549 respiratory, C2Bbe1 colonic, and HeLa cervical epithelial cells was slightly lower than that of the 874391 strain, invasion of the Spb1
−
mutant was significantly reduced with these cell lines compared to what was seen with 874391. The defect in epithelial invasion was corrected by supplying
spb1
in
trans
. These observations suggest that Spb1 contributes to the pathogenesis of neonatal GBS infection by mediating internalization of virulent serotype III GBS and confirm that understanding of the population structure of bacteria may lead to insights into the pathogenesis of human infections.
Characterization of a Protective Monoclonal AntibodyRecognizing
Staphylococcus aureus
MSCRAMM ProteinClumping FactorA
Authors: Hall Andrea E. , Domanski Paul J. , Patel Pratiksha R. , Vernachio John H. , Syribeys Peter J. , Gorovits Elena L. , Johnson Michael A. , Ross Julia M. , Hutchins Jeff T. , Patti Joseph M. 
Published: November 2003

ABSTRACT

The
Staphylococcus aureus
MSCRAMM (microbial surface
components recognizing adhesive matrix molecules) protein clumping
factor A (ClfA) has been shown to be a critical virulence
factor in several experimental models of infection. This report
describes the generation, characterization, and in vivo evaluation of a
murine monoclonal antibody (MAb) against ClfA. Flow cytometric analysis
revealed that MAb 12-9 recognized ClfA protein expressed by all of the
clinical
S. aureus
strains obtained from a variety of
sources. In assays measuring whole-cell
S. aureus
binding to human fibrinogen, MAb 12-9 inhibited
S
.
aureus
binding by over 90% and displaced up to
35% of the previously adherent
S. aureus
bacteria. Furthermore, a single infusion of MAb 12-9 was protective
against an intravenous challenge with a methicillin-resistant strain of
S. aureus
in a murine sepsis model (
P
< 0.0001). These data suggest that anti-ClfA MAb 12-9 should be
further investigated as a novel immunotherapy for the treatment and
prevention of life-threatening
S. aureus
infections.
HumanAntibodies Specific for the High-Molecular-Weight Adhesion Proteins ofNontypeable
Haemophilus influenzae
Mediate OpsonophagocyticActivity
Authors: Winter Linda E. , Barenkamp Stephen J. 
Published: November 2003

ABSTRACT

The
HMW1- and HMW2-like adhesion proteins of nontypeable
Haemophilus
influenzae
are expressed by 75% of these strains, and
antibodies directed against these proteins are protective in animal
models of infection. The purpose of the present study was to define the
functional activity of human antibodies specific for these proteins in
an in vitro complement-dependent opsonophagocytic assay. Human
promyelocytic cell line HL-60 served as the source of phagocytic cells,
and a commercial preparation of intravenous immunoglobulin (IVIG)
served as the source of human antibodies. High-molecular-weight (HMW)
proteins were purified from four prototype nontypeable
H.
influenzae
strains and used to prepare solid-phase affinity
columns. IVIG was adsorbed on each column to remove strain-specific
anti-HMW antibodies and to allow recovery of affinity-purified anti-HMW
antibody fractions. Unadsorbed IVIG killed each of the prototype
strains at titers of 1:80 to 1:320. HMW-adsorbed sera demonstrated
fourfold decreases in opsonophagocytic titer against the homologous
strains compared to unadsorbed IVIG. Affinity-purified anti-HMW
antibody preparations demonstrated opsonophagocytic titers of 1:20 to
1:80 against the respective homologous strains and opsonophagocytic
titers as high as 1:80 against heterologous strains. None of the
affinity-purified anti-HMW antibody preparations was opsonophagocytic
for a representative nontypeable
H. influenzae
strain that did
not express HMW1- or HMW2-like proteins. These data demonstrate that
human antibodies specific for the HMW1/HMW2-like adhesion proteins of
nontypeable
H. influenzae
are opsonophagocytic and that such
antibodies recognize epitopes shared by the HMW proteins of unrelated
nontypeable
H. influenzae
strains. These results argue for
continued investigation of the HMW1/HMW2-like proteins as potential
vaccine candidates for prevention of disease due to
nontypeable
H.
influenzae
.
In Situ Studyof Abundant Expression of Proinflammatory Chemokines and Cytokines inPulmonary Granulomas That Develop in Cynomolgus MacaquesExperimentally Infected withMycobacteriumtuberculosis
Authors: Fuller Craig L. , Flynn JoAnne L. , Reinhart Todd A. 
Published: November 2003

ABSTRACTTuberculosis remains a major public health problem worldwide. Chemokines and cytokines organize and direct infiltrating cells to sites of infection, and these molecules likely play crucial roles in granuloma formation and maintenance. To address this issue, we used in situ hybridization (ISH) to measure chemokine and cytokine mRNA expression levels and patterns directly in lung tissues from cynomolgus macaques (Macaca fascicularis) experimentally infected with a low dose of virulentMycobacterium tuberculosis. We examined more than 300 granulomas and observed abundant expression of gamma interferon (IFN-γ)-inducible chemokine mRNAs (CXCL9/monokine induced by IFN-γ, CXCL10/IFN-γ-inducible protein, and CXCL11/IFN-γ-inducible T-cell α-chemoattractant) within solid and caseous granulomas, and there was only minimal expression in nongranulomatous regions of tissue. The mRNA expression patterns of IFN-γ and tumor necrosis factor alpha were examined in parallel, and the results revealed that cytokine mRNA+cells were abundant and generally localized to the granulomas. Mycobacterial 16S rRNA expression was also measured by ISH, and the results revealed that there was localization predominantly to the granulomas and that the highest signal intensity was in caseous granulomas. We observed several granulomatous lesions with exceptionally high levels of RNA for mycobacterial 16S rRNA, IFN-γ, and IFN-γ-inducible chemokines, suggesting that the local presence of mycobacteria is partially responsible for the upregulation of IFN-γ-inducible chemokines and recruitment of CXCR3+cells, which were also abundant in granulomatous lesions. These results suggest that expression of CXCR3 ligands and the subsequent recruitment of CXCR3+cells are involved in granuloma formation and maintenance.
Attenuated Signature-Tagged Mutagenesis Mutants of
Brucella melitensis
Identified during the Acute Phase ofInfection inMice
Authors: Lestrate P. , Dricot A. , Delrue R.-M. , Lambert C. , Martinelli V. , De Bolle X. , Letesson J.-J. , Tibor A. 
Published: November 2003

ABSTRACT

For
this study, we screened 1,152 signature-tagged mutagenesis mutants of
Brucella melitensis
16M in a mouse model of infection and
found 36 of them to be attenuated in vivo. Molecular characterization
of transposon insertion sites showed that for four mutants, the
affected genes were only present in
Rhizobiaceae
. Another
mutant contained a disruption in a gene homologous to
mosA
,
which is involved in rhizopine biosynthesis in some strains of
Rhizobium
, suggesting that this sugar may be involved in
Brucella
pathogenicity. A mutant was disrupted in a gene
homologous to
fliF
, a gene potentially coding for the MS ring,
a basal component of the flagellar system. Surprisingly, a mutant was
affected in the
rpoA
gene, coding for the essentialα
-subunit of the RNA polymerase. This disruption leaves a
partially functional protein, impaired for the activation of
virB
transcription, as demonstrated by the absence of
induction of the
virB
promoter in the
Tn
5
::
rpoA
background. The results
presented here highlight the fact that the ability of
Brucella
to induce pathogenesis shares similarities with the molecular
mechanisms used by both
Rhizobium
and
Agrobacterium
to colonize their
hosts.
Prophage Induction and Expression of Prophage-EncodedVirulence Factors in Group A
Streptococcus
Serotype M3 StrainMGAS315
Authors: Banks David J. , Lei Benfang , Musser James M. 
Published: November 2003

ABSTRACT

The
genome of the highly virulent group A
Streptococcus
(GAS)
serotype M3 strain MGAS315 has six prophages that encode six proven or
putative virulence factors. We examined prophage induction and
expression of prophage-encoded virulence factors by this strain under
in vitro conditions inferred to approximate in vivo conditions.
Coculture of strain MGAS315 with Detroit 562 (D562) human epithelial
pharyngeal cells induced the prophage encoding streptococcal pyrogenic
exotoxin K (SpeK) and extracellular phospholipase
A
2
(Sla) and the prophage encoding streptodornase
(Sdn). Increased gene copy numbers after induction correlated with
increased
speK
,
sla
, and
sdn
transcript
levels. Although
speK
and
sla
are located
contiguously in prophage Φ315.4, these genes were transcribed
independently. Whereas production of immunoreactive SpeK was either
absent or minimal during coculture of GAS with D562 cells, production
of immunoreactive Sla increased substantially. In contrast, despite a
lack of induction of the prophage encoding speA during
coculture of GAS with D562 cells, the
speA
transcript level
and production of immunoreactive streptococcal pyrogenic exotoxin A
(SpeA) increased. Exposure of strain MGAS315 to hydrogen peroxide, an
oxidative stressor, induced the prophage encoding mitogenic factor 4
(MF4), and there was a concomitant increase in the
mf4
transcript. All prophages of strain MGAS315 that encode virulence
factors were induced during culture with mitomycin C, a DNA-damaging
agent. However, the virulence factor gene transcript levels and
production of the encoded proteins decreased after mitomycin C
treatment. Taken together, the results indicate that a complex
relationship exists among environmental culture conditions, prophage
induction, and production of prophage-encoded virulence
factors.
Infection and Inflammation in Skeletal Muscle fromNonhuman Primates Infected with Different Genospecies of theLyme Disease SpirocheteBorreliaburgdorferi
Authors: Cadavid Diego , Bai Yunhong , Dail Donna , Hurd Marie , Narayan Kavi , Hodzic Emir , Barthold Stephen W. , Pachner Andrew R. 
Published: November 2003

ABSTRACTLyme borreliosis is a multisystemic disease caused by various genospecies of the spirocheteBorrelia burgdorferi. To investigate muscle involvement in the nonhuman primate (NHP) model of Lyme disease, 16 adultMacaca mulattaanimals inoculated with strain N40 ofB. burgdorferisensu strictu by syringe or by tick bite or with strain Pbi ofB. burgdorferigenospeciesgariniiby syringe were studied. Animals were necropsied while immunosuppressed on day 50 (two animals each inoculated withB.burgdorferiN40 by syringe and withB.gariniiPbi by syringe) or on day 90, 40 days after immunosuppression had been discontinued (four animals each inoculated with strain N40 by syringe, with strain N40 by tick bite, and with strain Pbi by syringe). Skeletal muscles removed at necropsy were studied by (i) microscopic examination of hematoxylin-eosin-stained sections for inflammation and tissue injury; (ii) immunohistochemical and digital image analyses for antibody and complement deposition and cellular inflammation; (iii) Western blot densitometry for the presence of antibodies; and (iv) reverse transcription-PCR for measurement of the spirochetal load or C1q (the first component of the complement cascade) synthesis. The results showed that N40 was more infectious for NHPs than Pbi. NHPs inoculated with N40 but not with Pbi developed myositis. The inflammation in skeletal muscle was more severe in NHPs inoculated with N40 by syringe than in those inoculated by tick bite. The predominant cells in the inflammatory infiltrate were T cells and plasma cells. The deposition of antibody and complement in inflamed muscles from N40-inoculated NHPs was significantly higher than that in Pbi-inoculated NHPs. The spirochetal load was very high in the two N40-inoculated NHPs examined while they were immunosuppressed but decreased to minimal levels in the NHPs when immunocompetence was restored. We conclude that myositis can be a prominent feature of Lyme borreliosis depending on the infecting organism and host immune status.
Role for Complement in Development ofHelicobacter-Induced Gastritis in Interleukin-10-Deficient Mice
Authors: Ismail Hanan F. , Zhang Juan , Lynch Richard G. , Wang Yi , Berg Daniel J. 
Published: November 2003

ABSTRACTThe mechanisms by which the immune response can eradicate gastricHelicobacterinfection are unknown. We hypothesized thatHelicobacter-induced activation of the complement system could promote both inflammation and eradication ofHelicobacterfrom the stomach. In vitro studies demonstrated thatHelicobacter felisactivates complement in normal mouse serum but not in serum from Rag2−/−mice, indicating thatH. felisactivates complement through the classical pathway. Next, we infected complement-depleted wild-type control and interleukin-10-deficient (IL-10−/−) mice withH. felis. Helicobacterinfection of wild-type mice elicited a mild, focal gastritis and did not alter serum complement levels. Infection of IL-10−/−mice withH. feliselicited severe gastritis. After the initial colonization, the IL-10−/−mice completely clearedHelicobacterfrom the stomach by day 8. In contrast to wild-type mice,H. felis-infected IL-10−/−mice had a marked increase in serum complement levels. Complement depletion of wild-type mice did not affect the intensity of gastric inflammation or the extent ofHelicobactercolonization compared to that for the wild-type control mice. In contrast, complement depletion ofHelicobacter-infected IL-10−/−mice decreased the severity of gastritis, decreased theHelicobacter-induced infiltration of neutrophils into the stomach, and delayed the clearance of bacteria. In vitro studies of stimulated splenocytes and neutrophils from IL-10−/−mice produced a twofold increase in complement production compared to that for wild-type mice. Pretreatment with IL-10 inhibited this increase. These studies identify a role for complement in the local immune response to gastricHelicobacterin IL-10−/−mice and suggest a role for IL-10 in the regulation of complement production.
Haemophilusducreyi
Requires an Intact
flp
Gene Cluster for VirulenceinHumans
Authors: Spinola Stanley M. , Fortney Kate R. , Katz Barry P. , Latimer Jo L. , Mock Jason R. , Vakevainen Merja , Hansen Eric J. 
Published: November 2003

ABSTRACT

An
intact
Haemophilus ducreyi flp
operon is essential for
microcolony formation in vitro.
tadA
is the 9th of 15 genes in
the operon and has homology to NTPases of type IV secretion systems.
Fifteen human volunteers were experimentally infected with both
H.
ducreyi
35000HP and the
tadA
mutant, 35000HP.400. Papules
developed at similar rates at sites inoculated with the mutant and
parent, while pustules formed at 36.4% of parent sites and at
0% of mutant sites (
P
= 0.001). Compared to
35000HP, 35000HP.400 had only a modest but significant reduction in
lesion scores in the temperature-dependent rabbit model of chancroid.
These data suggest that proteins secreted by the
flp
locus are
required for full expression of virulence by
H. ducreyi
in
humans but have less of a role in virulence in an animal model of
infection.
Identification of B- and T-Cell Epitopes within the Fibronectin-Binding Domain of the SfbI Protein ofStreptococcus pyogenes
Authors: Schulze Kai , Medina Eva , Chhatwal Gursharan S. , Guzmán Carlos A. 
Published: November 2003

ABSTRACTThe fibronectin-binding repeats of the SfbI protein ofStreptococcus pyogenesconstitute the minimal domain able to confer protection against lethal infection. We investigated the presence of B- and T-cell epitopes within this region in congenic mice. One linear B-cell epitope was recognized by BALB/b and BALB/k mice, whereas two epitopes were found in BALB/c animals. A unique T-cell epitope was recognized by all three mouse strains. All identified epitopes clustered in a 30-amino-acid fragment. These results suggest that this polypeptide may be suitable for incorporation into a polyepitope-based vaccine formulation againstS. pyogenes.