bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antibody Response to Fibronectin-Binding Adhesin FnbpA in Patients with
Staphylococcus aureus
Infections
Authors: Casolini Fabrizia , Visai Livia , Joh Danny , Conaldi Pier Giulio , Toniolo Antonio , Höök Magnus , Speziale Pietro 
Published: December 2019

ABSTRACT
We have analyzed antibody reactivity to a fibronectin-binding microbial surface component that recognizes adhesive matrix molecules (MSCRAMM) in blood plasma collected from patients with staphylococcal infections. All patients had elevated levels of anti-MSCRAMM antibodies compared to those of young children who, presumably, had not been exposed to staphylococcal infections. The anti-MSCRAMM antibodies preferentially reacted with the ligand-binding repeat domain of the adhesin. However, these antibodies did not inhibit fibronectin binding. Essentially, all patients had antibodies which specifically recognized the fibronectin-MSCRAMM complex but not the isolated components. Epitopes recognized by these anti-ligand-induced binding sites antibodies were found in each repeat unit of the MSCRAMM. These results demonstrate that staphylococci have bound fibronectin some time during infection and that each repeat unit in the MSCRAMM can engage in ligand binding. Furthermore, our previously proposed model, suggesting that an unordered structure in the MSCRAMM undergoes a conformational change upon ligand binding (K. House-Pompeo, Y. Xu, D. Joh, P. Speziale, and M. Höök, J. Biol. Chem. 271:1379–1384, 1996), is presumably operational in patients during infections.
Transmission and Serial Propagation of
Enterocytozoon bieneusi
from Humans and Rhesus Macaques in Gnotobiotic Piglets
Authors: Kondova Ivanela , Mansfield Keith , Buckholt Michael A. , Stein Barry , Widmer Giovanni , Carville Angela , Lackner Andrew , Tzipori Saul 
Published: December 2019

ABSTRACT

For over a decade
Enterocytozoon bieneusi
infections in people with AIDS have been linked with chronic diarrhea and wasting. The slow scientific progress in treating these infections is attributed to the inability of investigators to cultivate the parasite, which has also precluded evaluation of effective therapies. We report here successful serial transmissions of
E. bieneusi
from patients with AIDS and from macaques with AIDS to immunosuppressed gnotobiotic piglets. One infected piglet was still excreting spores at necropsy 50 days after an oral challenge. Spores in feces were detected microscopically by trichrome stain and by PCR and within enterocytes by in situ hybridization and immunohistochemistry.
E. bieneusi
infection induced no symptoms. The development of an animal model for
E. bieneusi
will open up new opportunities for investigating this parasite.
Protection against Exotoxin A (ETA) and
Pseudomonas aeruginosa
Infection in Mice with ETA-Specific Antipeptide Antibodies
Authors: El-Zaim Haissam S. , Chopra Ashok K. , Peterson Johnny W. , Vasil Michael L. , Heggers John P. 
Published: December 2019

ABSTRACT

Pseudomonas aeruginosa
is an opportunistic pathogen that causes serious and sometimes fatal infections in the compromised host, especially in patients with major trauma or thermal injuries. Exotoxin A (ETA) is the major and most lethal virulence factor produced by this ubiquitous microorganism. In a recent study (H. S. Elzaim, A. K. Chopra, J. W. Peterson, R. Goodheart, and J. P. Heggers, Infect. Immun. 66:2170–2179, 1998), we identified two major epitopes, one within the translocation domain (amino acid [aa] residues 289 to 333) of ETA and another within the enzymatic domain (aa 610 to 638), by using a panel of antipeptide antibodies. Synthetic peptides representing these two epitopes induced ETA-specific antibodies which were able to abrogate the cytotoxic activity of ETA, as measured by incorporation of [
3
H]leucine into 3T3 fibroblasts. In the present study, these antibodies were tested for the ability to provide protection against ETA and infection with a toxin-producing strain of
P. aeruginosa
in a mouse model. Antibodies to either of the synthetic peptides conferred protection against ETA. Also, when used for immunization, both peptides induced active immunity to ETA in mice. Antibodies to the peptide representing a region within the enzymatic domain of ETA, in combination with the antibiotic amikacin, enhanced the survival of mice infected with a toxin-producing strain of
P. aeruginosa
. Thus, antipeptide antibodies specific for ETA might be paired with antibiotic treatment for passive immunization of patients suffering from
P. aeruginosa
infection.
Effect of P39 Gene Deletion in Live
Brucella
Vaccine Strains on Residual Virulence and Protective Activity in Mice
Authors: Tibor Anne , Jacques Isabelle , Guilloteau Laurence , Verger Jean-Michel , Grayon Maggy , Wansard Valerie , Letesson Jean-Jacques 
Published: December 2019

ABSTRACT

The 39-kilodalton protein (P39) has previously been shown to be an immunodominant protein in
Brucella
infections. P39 gene deletion mutants of vaccine strains
Brucella abortus
S19 and
Brucella melitensis
Rev.1 were constructed by gene replacement. This deletion did not significantly modify the residual virulence of both vaccine strains in CD-1 mice. CD-1 mice vaccinated with the parent or mutant strains were protected against a virulent challenge. Mutant vaccine strains devoid of P39 could provide a means for differentiating vaccinated from infected animals.
A Globally Disseminated M1 Subclone of Group A Streptococci Differs from Other Subclones by 70 Kilobases of Prophage DNA and Capacity for High-Frequency Intracellular Invasion
Authors: Cleary P. P. , LaPenta D. , Vessela R. , Lam H. , Cue D. 
Published: December 2019

ABSTRACT
The M1inv+ subclone of M1 group A streptococci that spread globally in the late 1980s and early 1990s was previously identified by restriction fragment length polymorphism (RFLP), M protein, and SpeA exotoxin sequence analyses. Strains representing this subclone were characterized with regard to carriage of bacteriophage and capacity to invade cultured human epithelial cells. The M1inv+ subclone was found to harbor two entirely different prophages, phage T13 and phage T14, which together supplement its genome with nearly 70 kb of DNA. Phage T14 encodes the SpeA exotoxin and is closely related to the classic converting phage T12. Plaque-forming characteristics and RFLP analyses of phages T13 and T14 were compared to each other and to phage T12. Other subclones of M1, isolated in the 1970s to the early 1980s, lacked both prophages. The M1inv+ subclone was previously reported to be efficiently internalized by human epithelial cells. This potential was confirmed and expanded by comparing a variety of clinical isolates. The capacity for high-frequency invasion of epithelial cells was not transmitted to a laboratory strain of group A streptococci by the above-mentioned bacteriophages.
Identification of Immunodominant Regions within the C-Terminal Cell Binding Domain of Intimin α and Intimin β from Enteropathogenic
Escherichia coli
Authors: Adu-Bobie Jeannette , Trabulsi Luiz R. , Carneiro-Sampaio Magda M. S. , Dougan Gordon , Frankel Gad 
Published: December 2019

ABSTRACT

Enteropathogenic
Escherichia coli
(EPEC) strains are a common cause of infantile diarrhea in developing countries. EPEC strains induce a characteristic attaching and effacing (A/E) lesion on epithelial cells. A/E lesion formation requires intimin, an outer membrane adhesin protein. The cell-binding activity of intimin is localized at the C-terminal 280 amino acids of the polypeptide (Int280). So far, four distinct Int280 types (α, β, γ, and δ) have been identified. The aim of this study was to identify immunodominant regions within the Int280α and Int280β domains. Recombinant DNA was used to construct and express overlapping polypeptides spanning these domains. Rabbit anti-Int280 antisera and human colostral immunoglobulin A were reacted with these polypeptides in Western blots and enzyme-linked immunosorbent assays. The results obtained with the rabbit antisera showed the presence of two separate immunodominant regions which are common to both Int280α and Int280β. The first localized within the N-terminal region of Int280, and the second localized between amino acids 80 and 130. The results with the human colostra revealed one reactivity pattern against the Int280α fragments but two different reactivity patterns against the Int280β domain.
Environmental Growth Conditions Influence the Ability of
Escherichia coli
K1 To Invade Brain Microvascular Endothelial Cells and Confer Serum Resistance
Authors: Badger Julie L. , Kim Kwang Sik 
Published: December 2019

ABSTRACT

A major limitation to advances in prevention and therapy of neonatal meningitis is our incomplete understanding of the pathogenesis of this disease. In an effort to understand the pathogenesis of meningitis due to
Escherichia coli
K1, we examined whether environmental growth conditions similar to those that the bacteria might be exposed to in the blood could influence the ability of
E. coli
K1 to invade brain microvascular endothelial cells (BMEC) in vitro and to cross the blood-brain barrier in vivo. We found that the following bacterial growth conditions enhanced
E. coli
K1 invasion of BMEC 3- to 10-fold: microaerophilic growth, media buffered at pH 6.5, and media supplemented with 50% newborn bovine serum (NBS), magnesium, or iron. Growth conditions that significantly repressed invasion (i.e., 2- to 250-fold) included iron chelation, a pH of 8.5, and high osmolarity. More importantly,
E. coli
K1 traversal of the blood-brain barrier was significantly greater for the growth condition enhancing BMEC invasion (50% NBS) than for the condition repressing invasion (osmolarity) in newborn rats with experimental hematogenous meningitis. Of interest, bacterial growth conditions that enhanced or repressed invasion also elicited similar serum resistance phenotype patterns. This is the first demonstration that bacterial ability to enter the central nervous system can be affected by environmental growth conditions.
Helicobacter pylori
Alters Exogenous Antigen Absorption and Processing in a Digestive Tract Epithelial Cell Line Model
Authors: Matysiak-Budnik Tamara , Terpend Kathleen , Alain Sophie , Sanson le Pors Marie-José , Desjeux Jehan-Francois , Mégraud Francis , Heyman Martine 
Published: December 2019

ABSTRACT

To study the influence of
Helicobacter pylori
on epithelial barrier function, bacteria, bacterial sonicates, or broth culture supernatants were incubated for 24 h with HT29-19A intestinal cells grown as monolayers. Subsequently, the monolayers were mounted in Ussing chambers, and electrical resistance (R), fluxes of
22
Na (JNa) and
14
C-mannitol (JMan) (markers of the paracellular pathway), and fluxes of horseradish peroxidase (HRP) in total (J
3
H-HRP), intact (JHRPi), and degraded forms were measured.
H. pylori
did not induce any modification of the paracellular pathway (R = 148 ± 10 versus 174 ± 16 Ω · cm
2
; JNa = 4.16 ± 0.44 versus 3.51 ± 0.41 μEq/h · cm
2
; JMan = 0.081 ± 0.01 versus 0.058 ± 0.009 μmol/h · cm
2
), nor did it modify J
3
H-HRP (2,201 ± 255 versus 2,110 ± 210 ng/h · cm
2
for
H. pylori
-infected and control cells, respectively). However, in the presence of
H. pylori
, we observed a significant increase in JHRPi (520 ± 146 versus 171 ± 88 ng/h · cm
2
). This effect was not dependent of the
cag
status of the strain and was not reproduced by the sonicates or the culture supernatants. It was related to the presence of urease, since a urease-negative mutant of
H. pylori
did not induce this effect. Ammonia and bafilomycin A
1
, two agents known to increase the endolysosomal pH, reproduced the increase in JHRPi. In conclusion,
H. pylori
does not affect directly the integrity of intercellular junctions of epithelial cells in vitro, but it increases the passage of intact HRP, probably by inhibition of the intralysosomal degradation due to the release of ammonia. The increased transport of intact macromolecules may contribute to the induction and maintenance of gastric inflammation by
H. pylori
.
Modulation of Lipopolysaccharide-Induced Monocyte Activation by Heparin-Binding Protein and Fucoidan
Authors: Heinzelmann Michael , Polk Hiram C. , Miller Frederick N. 
Published: December 2019

ABSTRACTActivated polymorphonuclear leukocytes release heparin-binding protein (HBP; also known as CAP37 or azurocidin) from azurophilic granules. HBP is a strong chemoattractant for monocytes that also prolongs monocyte survival and potentiates endotoxin (lipopolysaccharide [LPS])-induced production of tumor necrosis factor alpha (TNF-α). We investigated the binding of fluorescein isothiocyanate-conjugated HBP to human monocytes in the presence of EDTA and the polysaccharide fucoidan. EDTA, which chelates divalent cations, has been widely used to study the role of divalent cations in receptor-ligand interactions or enzyme activity. Fucoidan has been used to inhibit the binding of various ligands to scavenger receptors or selectins. Scavenger receptors are multiligand receptors that mediate endocytosis of proteases, protease-inhibitor complexes, lipoproteins, and LPS-lipid A. Fucoidan also interferes with leukocyte rolling by binding to L-selectins (expressed on leukocytes) and P-selectins (expressed on platelets and endothelium). We demonstrate that the binding of the neutrophil-derived protein HBP to monocytes is inhibited in the presence of EDTA and fucoidan. In addition, fucoidan and EDTA abrogate the enhancing effect of HBP on LPS-induced TNF-α production. These data provide supporting evidence that HBP binds to a receptor expressed on monocytes. This receptor is dependent on divalent cations and is possibly related to the scavenger receptor. Furthermore, we demonstrate that fucoidan, by itself, stimulates TNF-α release from isolated monocytes in a CD14-independent fashion. This is an important finding for the interpretation of results from studies that use fucoidan to “block” either scavenger receptors or L- or P-selectins.
Phosphatidylcholine-Specific Phospholipase C fromListeria monocytogenesIs an Important Virulence Factor in Murine Cerebral Listeriosis
Authors: Schlüter Dirk , Domann Eugen , Buck Christine , Hain Torsten , Hof Herbert , Chakraborty Trinad , Deckert-Schlüter Martina 
Published: December 2019

ABSTRACTMeningoencephalitis is a serious and often fatal complication ofListeria monocytogenesinfection. The aim of the present study was to analyze the role of internalin A (InlA) and B, which are involved in the invasion ofL. monocytogenesinto cultivated host tissue cells, and that of phosphatidylcholine-specific phospholipase C (PlcB), which mainly promotes the direct cell-to-cell spread ofL. monocytogenes, in murine cerebral listeriosis by use of an InlA/B (ΔinlAB2)- and a PlcB (ΔplcB2)-deficient isogenic deletion mutant strain and the wild-type (WT)L. monocytogenesEGD.Listeriastrains were directly applied to the brain, a technique which has been employed previously to study the pathogenesis of cerebral listeriosis (D. Schlüter, S. B. Oprisiu, S. Chahoud, D. Weiner, O. D. Wiestler, H. Hof, and M. Deckert-Schlüter, Eur. J. Immunol. 25:2384–2391, 1995). We demonstrated that PlcB, but not InlA or InlB, is an important virulence factor in cerebral listeriosis. Nonimmunized mice infected intracerebrally with the ΔplcB2strain survived significantly longer and had a reduced intracerebral bacterial load compared to mice infected with the ΔinlAB2strain or WT bacteria. In addition, immunization with the WT prior to intracerebral infection significantly increased the survival rate of mice challenged intracerebrally with theΔplcB2strain compared to that of mice infected with the WT or ΔinlAB2strain. Histopathology revealed that the major difference between the various experimental groups was a significantly delayed intracerebral spread of the ΔplcB2mutant strain, indicating that cell-to-cell spread is an important pathogenic feature of cerebral listeriosis. Interestingly, irrespective of theListeriamutant used, the apoptosis of hippocampal and cerebellar neurons and an internal hydrocephalus developed in surviving mice, indicating that these complications are not dependent on the virulence factors InlA/B and PlcB. In conclusion, this study points to PlcB as a virulence factor important for the intracerebral pathogenesis of murineL. monocytogenesmeningoencephalitis.
Contrasting Roles of Mannan-Specific Monoclonal Immunoglobulin M Antibodies in the Activation of Classical and Alternative Pathways byCandida albicans
Authors: Zhang Mason X. , Cutler Jim E. , Han Yongmoon , Kozel Thomas R. 
Published: December 2019

ABSTRACTPolyclonal antimannan immunoglobulin G (IgG) activates the classical complement pathway and accelerates initiation of the alternative pathway byCanidida albicans. This dual role was assessed for two antimannan IgM monoclonal antibodies (MAbs). MAb B6.1 is specific for an epitope on the acid-labile portion ofC. albicansphosphomannan; MAb B6 is specific for an epitope on the acid-stable region. Both MAbs were potent activators of the classical pathway but poor facilitators of alternative pathway initiation.
Persistence of
Anaplasma ovis
Infection and Conservation of the
msp-2
and
msp-3
Multigene Families within the Genus
Anaplasma
Authors: Palmer Guy H. , Abbott Jeffrey R. , French Dorothy M. , McElwain Terry F. 
Published: December 2019

ABSTRACT

Goats which have recovered from acute
Anaplasma ovis
infection remain seropositive, although infected erythrocytes cannot be detected by microscopic examination. Persistence of
A. ovis
17 to 21 months following experimental infection was demonstrated by PCR detection of the
msp-5
gene. Quantitative analysis of persistent rickettsemia over time showed that all levels were below the limit of microscopic detection and ranged from a low of 10
2
organisms/ml to peaks of 10
6
organisms/ml. Two patterns of persistent rickettsemia were observed: the first was characterized by cyclic fluctuations at 6- to 9-week intervals, similar to the pattern described for
A. marginale
-infected cattle, while in the second pattern, repetitive cycles did not occur and the rickettsemia levels were relatively constant. The
msp-2
and
msp-3
multigene families, which provide the genetic capacity for outer membrane protein antigenic variation during persistent
A. marginale
rickettsemia, were identified in the
A. ovis
genome by Southern blot analysis, and expression of an MSP-2 homologue was confirmed by using immunoblots.
The Fimbria Gene Cluster of Nonencapsulated
Haemophilus influenzae
Authors: Geluk Forien , Eijk Paul P. , van Ham S. Marieke , Jansen Henk M. , van Alphen Loek 
Published: December 2019

ABSTRACT

The occurrence of fimbria gene clusters in nonencapsulated
Haemophilus influenzae
strains from chronic bronchitis patients (
n
= 58), patients with acute otitis media (
n
= 13), and healthy carriers (
n
= 12) was determined by DNA hybridization and PCR, based on sequences of fimbriate
H. influenzae
type b. Although an average of 18% of all nonencapsulated strains had a fimbria gene cluster consisting of
hifA
to
hifE
inserted in the chromosome between
purE
and
pepN
, differences in the frequency of fimbria cluster-positive strains were observed, depending on the source of isolates. The compositions of the fimbria gene clusters of seven strains from chronic bronchitis patients and one strain from an otitis media patient were analyzed in more detail. After enrichment for fimbria expression, the promoter of the gene cluster contained 10 TA repeats (
n
= 2), leading to optimal positioning between the −10 and −35 promoter regions. The promoter regions of five fimbria-negative strains were sequenced; four were found to have nine TA repeats, and one had only four TA repeats. The protein sequence of three ganglioside GM1-specific HifA adhesins consisted of conserved regions intermingled with regions of sequence diversity.
hifA
appeared to be flanked by intergenic regions that varied between strains and contained both direct and inverted DNA repeats. Since noncoding DNA between
hifA
and
purE
has not been found in
H. influenzae
type b, these DNA sequences are probably not essential for fimbria expression. An analysis of strains lacking the gene cluster revealed the presence of similar sequences in 13 of 15 strains from chronic bronchitis patients, 5 of 5 strains from otitis media patients, and 3 of 5 strains from healthy carriers. The lengths of these intergenic regions were the same for multiple isolates of strains obtained during persistent infections. The presence or absence and the composition of the fimbria gene cluster and other sequences between the flanking genes
purE
and
pepN
suggest that the fimbria gene cluster was originally contained on a mobile element.
Prevalence of the “High-Pathogenicity Island” of
Yersinia
Species among
Escherichia coli
Strains That Are Pathogenic to Humans
Authors: Schubert S. , Rakin A. , Karch H. , Carniel E. , Heesemann J. 
Published: December 2019

ABSTRACT

The
fyuA-irp
gene cluster contributes to the virulence of highly pathogenic
Yersinia
(
Yersinia pestis
,
Yersinia pseudotuberculosis
, and
Yersinia enterocolitica
1B). The cluster encodes an iron uptake system mediated by the siderophore yersiniabactin and reveals features of a pathogenicity island. Two evolutionary lineages of this “high pathogenicity island” (HPI) can be distinguished on the basis of DNA sequence comparison: a
Y. pestis
group and a
Y. enterocolitica
group. In this study we demonstrate that the HPI of the
Y. pestis
evolutionary group is disseminated among species of the family
Enterobacteriaceae
which are pathogenic to humans. It prevails in enteroaggregative
Escherichia coli
and in
E. coli
blood culture isolates (93 and 80%, respectively), but is rarely found in enteropathogenic
E. coli
, enteroinvasive
E. coli
, and enterotoxigenic
E. coli
isolates. In contrast, the HPI was absent from enterohemorrhagic
E. coli
,
Shigella
, and
Salmonella enterica
strains investigated. Polypeptides encoded by the
fyuA
,
irp1
, and
irp2
genes located on the HPI could be detected in
E. coli
strains pathogenic to humans. However, these
E. coli
strains showed a reduced sensitivity to the bacteriocin pesticin, whose uptake is mediated by the FyuA receptor.
Escherichia
strains do not possess the
hms
gene locus thought to be a part of the HPI of
Y. pestis
. Deletions of the
fyuA-irp
gene cluster affecting solely the
fyuA
part of the HPI were identified in 3% of the
E. coli
strains tested. These results suggest horizontal transfer of the HPI between
Y. pestis
and some pathogenic
E. coli
strains.
Identification and Characterization of a Novel Extracellular Ferric Reductase from
Mycobacterium paratuberculosis
Authors: Homuth Matthias , Valentin-Weigand Peter , Rohde M. , Gerlach Gerald-F. 
Published: December 2019

ABSTRACT

A novel extracellular mycobacterial enzyme was identified in the ruminant pathogen
Mycobacterium paratuberculosis
. The enzyme was capable of mobilizing iron from different sources such as ferric ammonium citrate, ferritin, and transferrin by reduction of the metal. The purified reductase had a calculated
M
r
of 17,000, was sensitive to proteinase K treatment, and had an isoelectric point of pH 9. Analysis of the amino acid composition revealed glycine, serine, asparagine (or aspartic acid), and glutamine (or glutamic acid) as the most frequently occurring residues. Enzymatic activity was highest at 37°C and between pH 5 and 10. The calculated

K
m

and
V
max
for ferric ammonium citrate were 0.213 mM and 0.345 mM min
−1
mg
−1
, respectively. Using a specific antireductase antibody in immunoelectron microscopy, we were able to detect the enzyme associated with intracellular mycobacteria in naturally
M. paratuberculosis
-infected bovine tissue. We propose that the reductase of
M. paratuberculosis
represents an alternative strategy of mycobacteria to mobilize ferric iron and discuss its potential role in bacterial evasion of intracellular defense mechanisms.