bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Melanin Pigment Purified from an Epidemic Strain of
Burkholderia cepacia
Attenuates Monocyte Respiratory Burst Activity by Scavenging Superoxide Anion
Authors: Zughaier Susu M. , Ryley Henry C. , Jackson Simon K. 
Published: December 2019

ABSTRACT

The acquisition of
Burkholderia cepacia
in some cystic fibrosis patients is associated with symptoms of acute pulmonary inflammation that may be life threatening. The ability of lipopolysaccharide (LPS) from
B. cepacia
to prime a monocyte cell line for enhanced superoxide anion generation was investigated and compared with the priming activities of LPSs from
Pseudomonas aeruginosa
,
Stenotrophomonas maltophilia
, and
Escherichia coli
. The human monocyte cell line MonoMac-6 (MM6) was primed overnight with different LPSs (100 ng/ml), and the respiratory burst was triggered by exposure to opsonized zymosan (125 μg/ml). Superoxide generation was detected by enhanced chemiluminescence with Lucigenin.
B. cepacia
LPS was found to prime MM6 cells to produce more superoxide anion than
P. aeruginosa
or
S. maltophilia
LPS, and this priming response was CD14 dependent. In addition, the inhibition of respiratory burst responses in monocytes by a bacterial melanin-like pigment purified from an epidemic
B. cepacia
strain was investigated. The melanin-like pigment was isolated from tyrosine-enriched media on which
B. cepacia
had been grown and was purified by gel filtration, anion ion-exchange chromatography, and ethanol precipitation. The scavenging potential of the melanin-like pigment for superoxide anion radical (
•
O
2
−
) generated during the respiratory burst was confirmed with superoxide produced from a cell-free system with xanthine-xanthine oxidase and detected by electron paramagnetic resonance spectroscopy with the spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline-
n
-oxide. The addition of melanin during the LPS priming stage had no effect on the subsequent triggering of the respiratory burst, but melanin inhibited
•
O
2
−
detection when added at the triggering stage of the respiratory burst. We conclude that melanin-producing
B. cepacia
may derive protection from the free-radical-scavenging properties of this pigment.
Role of Lipopolysaccharide Sialylation in Serum Resistance of Serogroup B and C Meningococcal Disease Isolates
Authors: Vogel Ulrich , Claus Heike , Heinze Gabriele , Frosch Matthias 
Published: December 2019

ABSTRACT

α-2,3-Sialyltransferase mutants of three genetically and phenotypically diverse
Neisseria meningitidis
strains were compared with regard to resistance to human serum and systemic spread in the infant rat. Lipopolysaccharide sialylation was found to be of minor importance for the resistance of serogroup B and C meningococcal disease isolates to complement attack.
Production of Enterotoxin by
Yersinia bercovieri
, a Recently Identified
Yersinia enterocolitica
-Like Species
Authors: Sulakvelidze Alexander , Kreger Arnold , Joseph Aaron , Robins-Browne Roy M. , Fasano Alessio , Wauters Georges , Harnett Norma , DeTolla Louis , Morris J. Glenn 
Published: December 2019

ABSTRACT

Yersinia bercovieri
, a recently identified
Y. enterocolitica
-like species, produces a heat-stable enterotoxin (designated YbST) which has biologic activity in infant mice and increases short circuit current in Ussing chambers. Although YbST has some properties in common with the heat-stable enterotoxins of
Y. enterocolitica
(YST I and YST II), it appears to be a novel toxin because (i) it was not neutralized by anti-YST I antiserum, (ii) YbST-neutralizing antiserum did not neutralize YST I, and (iii)
Y. bercovieri
strains did not hybridize with genetic probes for
yst
I,
yst
II, and other known enterotoxins.
Vaccination with LiveEscherichia coliExpressingBrucella abortusCu/Zn Superoxide Dismutase Protects Mice against VirulentB. abortus
Authors: Oñate Angel A. , Vemulapalli Ramesh , Andrews Edilia , Schurig Gerhardt G. , Boyle Stephen , Folch Hugo 
Published: December 2019

ABSTRACTVaccination of mice withEscherichia coliexpressingBrucellaCu/Zn superoxide dismutase (SOD) [E. coli(pBSSOD)] induced a significant level of protection against virulentBrucella abortuschallenge, although this level was not as high as the one reached withB. abortusvaccine strain RB51. In addition, vaccination withE. coli(pBSSOD) induced antibodies to Cu/Zn SOD and a strong proliferative response of splenocytes when stimulated in vitro with a thioredoxin-Cu/Zn SOD fusion protein.
Polysaccharide Binding Potential of the Human A2 or A18 Kappa Light Chain Homologues
Authors: Reason Donald C. , Wagner T. Charis , Tang Vanessa R. , Moulton Karen D. , Lucas Alexander H. 
Published: December 2019

ABSTRACTAntibodies having light (L) chains encoded by the κII-A2 variable region gene segment predominate in the human response to theHaemophilus influenzaetype b polysaccharide (Hib PS). To determine whether the closely related homologue of the A2 gene, the κII-A18 gene, has the potential to contribute to the repertoire, we examined Hib PS binding to a series of recombinant Fab fragments having either A2 or A18 L chains isolated from a Hib PS-vaccinated adult. The ability to bind Hib PS resided exclusively with those Fab fragments having A2 and containing an insertional arginine at the variable-joining junction. Thus, despite the sequence similarity between A2 and A18, only A2 contributes to the canonical Hib PS paratope.
Role ofBordetella pertussisVirulence Factors in Adherence to Epithelial Cell Lines Derived from the Human Respiratory Tract
Authors: van den Berg Bernard M. , Beekhuizen Henry , Willems Rob J. L. , Mooi Frits R. , van Furth Ralph 
Published: December 2019

ABSTRACTDuring colonization of the respiratory tract byBordetella pertussis, virulence factors contribute to adherence of the bacterium to the respiratory tract epithelium. In the present study, we examined the roles of the virulence factors filamentous hemagglutinin (FHA), fimbriae, pertactin (Prn), and pertussis toxin (PT) in the adherence ofB. pertussisto cells of the human bronchial epithelial cell line NCI-H292and of the laryngeal epithelial cell line HEp-2. UsingB. pertussismutant strains and purified FHA, fimbriae, Prn, and PT, we demonstrated that both fimbriae and FHA are involved in the adhesion ofB. pertussisto laryngeal epithelial cells, whereas only FHA is involved in the adherence to bronchial epithelial cells. For PT and Prn, no role as adhesion factor was found. However, purified PT bound to both bronchial and laryngeal cells and as such reduced the adherence ofB. pertussisto these cells. These data may imply that fimbriae play a role in infection of only the laryngeal mucosa, while FHA is the major factor in colonization of the entire respiratory tract.
Non-Serum-Dependent Chemotactic Factors Produced byCandida albicansStimulate Chemotaxis by Binding to the Formyl Peptide Receptor on Neutrophils and to an Unknown Receptor on Macrophages
Authors: Edens Heather A. , Parkos Charles A. , Liang Tony W. , Jesaitis Algirdas J. , Cutler Jim E. , Miettinen Heini M. 
Published: December 2019

ABSTRACTSerum-free culture filtrates of sixCandidaspecies andSaccharomyces cerevisiaewere found to contain chemoattractants for human polymorphonuclear leukocytes (PMNs) and a mouse macrophage-like cell line, J774. The chemotactic factors differed for the PMN and J774 cells, however, in terms of heat stability, kinetics of liberation by the yeast cells, and divalent cation requirements for production. The chemoattractant inCandida albicansculture filtrates appeared to act through the formyl peptide receptor (FPR) of PMNs, since it was found to induce chemotaxis of Chinese hamster ovary (CHO) cells that were expressing the human FPR but did not induce chemotaxis of wild-type CHO cells. TheC. albicansculture filtrates also induced migration of PMNs across confluent monolayers of a human gastrointestinal epithelial cell line, T84; migration occurred in the basolateral-to-apical direction but not the reverse direction, unless the epithelial tight junctions were disrupted. J774 cells did not migrate toward the formylated peptide (fMet-Leu-Phe; fMLF), and chemotaxis toward theC. albicansculture filtrate was not inhibited by an FPR antagonist (t-butoxycarbonyl-Met-Leu-Phe), suggesting that a different receptor mediated J774 cell chemotaxis. In conclusion, we have identified a receptor by which a non-serum-dependent chemotactic factor (NSCF) produced byC. albicansinduced chemotaxis of PMNs. Additionally, we have shown that NSCF was active across epithelial monolayers. These findings suggest that NSCFs produced byC. albicansand other yeast species may influence host-pathogen interactions at the gastrointestinal tract mucosal surface by inducing phagocytic-cell infiltration.
Purification and Cloning of a Streptokinase from
Streptococcus uberis
Authors: Johnsen Laust B. , Poulsen Knud , Kilian Mogens , Petersen Torben E. 
Published: December 2019

ABSTRACT

A bovine plasminogen activator was purified from the culture supernatant of the bovine pathogen
Streptococcus uberis
NCTC 3858. After the final reverse-phase high-performance liquid chromatography step a single protein with a molecular mass of 32 kDa was detected in the active fraction. A partial peptide map was established, and degenerate primers were designed and used for amplification of fragments of the gene encoding the activator. Inverse PCR was subsequently used for obtaining the full-length gene. The
S. uberis
plasminogen activator gene (
skc
) encodes a protein consisting of 286 amino acids including a signal peptide of 25 amino acids. In an amino acid sequence comparison the cloned activator showed an identity of approximately 26% to the streptokinases isolated from
Streptococcus equisimilis
and
Streptococcus pyogenes
. Interestingly, the activator from
S. uberis
was found to lack the C-terminal domain possessed by the streptokinase from
S. equisimilis
. This is apparently a general feature of the streptokinases of this species; biochemical and genetic analysis of 10 additional strains of
S. uberis
revealed that 9 of these were highly similar to strain NCTC 3858. Sequencing of the
skc
gene from three of these strains indicated that the amino acid sequence of the protein is highly conserved within the species.
A Sustained Rat Model for Studying the Long-Lasting Catabolic State of Sepsis
Authors: Breuille Denis , Voisin Laure , Contrepois Michel , Arnal Maurice , Rose Francis , Obled Christiane 
Published: December 2019

ABSTRACT

Most animal models of sepsis induced high mortality or early recovery and do not mimic the long-lasting catabolic state observed in patients. The purpose of this study is to develop a model of sepsis which reproduces these disorders, especially the long-lasting muscle wasting. This report summarizes our observations in a series of seven experiments using this model with rats to study the route of live
Escherichia coli
administration, dose of bacteria, reproducibility of the model, bacterial count in tissues, comparison of injection of live or dead bacteria, metabolic perturbations linked to infection, and potential role of tumor necrosis factor alpha (TNF-α) in muscle wasting. After intravenous infection, animals were anorexic and the catabolic state was long-lasting: body weight loss for 2 to 3 days followed by a chronic wasting state for several days. Liver, spleen, lung protein content, and plasma concentration of α
2
-macroglobulin were increased 2 and 6 days after infection. At 6 days, muscle protein content was substantially (−40%) reduced. The plasma TNF-α level measured 1.5 h after infection correlated with body weight loss observed 9 days later. The inhibition of TNF-α secretion by administration of pentoxifylline 1 h before infection reduced muscle wasting and activation of proteolysis at day 2 and abolished them at day 6. This septic model mimics in rats the prolonged protein metabolism alterations and muscle atrophy characteristics of infected patients and thus is useful for studying the impact of nutritional support on outcome.
Pathogenicity Island 2 Mutants ofSalmonella typhimuriumAre Efficient Carriers for Heterologous Antigens and Enable Modulation of Immune Responses
Authors: Medina Eva , Paglia Paola , Nikolaus Thomas , Müller Astrid , Hensel Michael , Guzmán Carlos A. 
Published: December 2019

ABSTRACTThe potential use as vaccine delivery system ofSalmonella typhimuriumstrains harboring defined mutations in thesseC(HH104) andsseD(MvP101) genes, which encode putative effector proteins of the type III secretion system ofSalmonellapathogenicity island 2, was evaluated and compared with that of the well-characterizedaroAmutant strain SL7207 by using β-galactosidase (β-Gal) as a model antigen. When orally administered to immune-competent or gamma interferon-deficient (IFN-γ−/−) BALB/c mice, both mutants were found to be highly attenuated (50% lethal dose, >109bacteria). Both strains were also able to efficiently colonize and persist in Peyer’s patches. Immunization with HH104 and MvP101 triggered β-Gal-specific serum and mucosal antibody responses equivalent to or stronger than those observed in SL7207-immunized mice. Although immunoglobulin G2 (IgG2) serum antibodies were dominant in all groups, IgG1 was also significantly increased in mice vaccinated with MvP101 and SL7207. Comparable β-Gal-specific IgA and IgG antibodies were detected in intestinal lavages from mice immunized with the different strains. Antigen-specific CD4+T-helper cells were generated after vaccination with all vaccine prototypes; however, responses were significantly more efficient when HH104 and MvP101 were used (P< 0.05). Significantly higher levels of IFN-γ were produced by restimulated spleen cells from mice immunized with HH104 than from those vaccinated with the MvP101 or SL7207 derivatives (P≤ 0.05). Interestingly, the three strains induced major histocompatibility complex class I-restricted CD8+cytotoxic T cells against β-Gal; however, cytotoxic T-lymphocyte responses were significantly stronger after immunization with HH104 (P< 0.05). These novelS. typhimuriumattenuated strains constitute promising delivery systems for vaccine antigens. The qualitative differences observed in the obtained responses with different carriers may be useful for those applications in which a targeted immunomodulation is required.
Vibrio parahaemolyticus
Thermostable Direct Hemolysin Modulates Cytoskeletal Organization and Calcium Homeostasis in Intestinal Cultured Cells
Authors: Fabbri Alessia , Falzano Loredana , Frank Claudio , Donelli Gianfranco , Matarrese Paola , Raimondi Francesco , Fasano Alessio , Fiorentini Carla 
Published: December 2019

ABSTRACT

Vibrio parahaemolyticus
is a marine bacterium known to be the leading cause of seafood gastroenteritis worldwide. A 46-kDa homodimer protein secreted by this microorganism, the thermostable direct hemolysin (TDH), is considered a major virulence factor involved in bacterial pathogenesis since a high percentage of strains of clinical origin are positive for TDH production. TDH is a pore-forming toxin, and its most extensively studied effect is the ability to cause hemolysis of erythrocytes from different mammalian species. Moreover, TDH induces in a variety of cells cytotoxic effects consisting mainly of cell degeneration which often leads to loss of viability. In this work, we examined the cellular changes induced by TDH in monolayers of IEC-6 cells (derived from the rat crypt small intestine), which represent a useful cell model for studying toxins from enteric bacteria. In experimental conditions allowing cell survival, TDH induces a rapid transient increase in intracellular calcium as well as a significant though reversible decreased rate of progression through the cell cycle. The morphological changes seem to be dependent on the organization of the microtubular network, which appears to be the preferential cytoskeletal element involved in the cellular response to the toxin.
Virulence of a
spaP
Mutant of
Streptococcus mutans
in a Gnotobiotic Rat Model
Authors: Crowley Paula J. , Brady L. Jeannine , Michalek Suzanne M. , Bleiweis Arnold S. 
Published: December 2019

ABSTRACT

Streptococcus mutans
, the principal etiologic agent of dental caries in humans, possesses a variety of virulence traits that enable it to establish itself in the oral cavity and initiate disease. A 185-kDa cell surface-localized protein known variously as antigen I/II, antigen B, PAc, and P1 has been postulated to be a virulence factor in
S. mutans
. We showed previously that P1 expression is necessary for in vitro adherence of
S. mutans
to salivary agglutinin-coated hydroxyapatite as well as for fluid-phase aggregation. Since adherence of the organism is a necessary first step toward colonization of the tooth surface, we sought to determine what effect deletion of the gene for P1,
spaP
, has on the colonization and subsequent cariogenicity of this organism in vivo. Germ-free Fischer rats fed a diet containing 5% sucrose were infected with either
S. mutans
NG8 or an NG8-derived
spaP
mutant strain, PC3370, which had been constructed by allelic exchange mutagenesis. At 1-week intervals for 6 weeks after infection, total organisms recovered from mandibles were enumerated. At week 6, caries lesions also were scored. A significantly lower number of enamel and dentinal carious lesions was observed for the mutant-infected rats, although there was no difference between parent and mutant in the number of organisms recovered from teeth through 6 weeks postinfection. Coinfection of animals with both parent and mutant strains resulted in an increasing predominance of the mutant strain being recovered over time, suggesting that P1 is not a necessary prerequisite for colonization. These data do, however, suggest a role for P1 in the virulence of
S. mutans
, as reflected by a decrease in the cariogenicity of bacteria lacking this surface protein.
Linear Peptide Specificity of Bovine Antibody Responses to p67 of
Theileria parva
and Sequence Diversity of Sporozoite-Neutralizing Epitopes: Implications for a Vaccine
Authors: Nene Vishvanath , Gobright Elke , Bishop Richard , Morzaria Subhash , Musoke Antony 
Published: December 2019

ABSTRACT

A stage-specific surface antigen of
Theileria parva
, p67, is the basis for the development of an anti-sporozoite vaccine for the control of East Coast fever (ECF) in cattle. By Pepscan analysis with a series of overlapping synthetic p67 peptides, the antigen was shown to contain five distinct linear peptide sequences recognized by sporozoite-neutralizing murine monoclonal antibodies. Three epitopes were located between amino acid positions 105 to 229 and two were located between positions 617 to 639 on p67. Bovine antibodies to a synthetic peptide containing one of these epitopes neutralized sporozoites, validating this approach for defining immune responses that are likely to contribute to immunity. Comparison of the peptide specificity of antibodies from cattle inoculated with recombinant p67 that were immune or susceptible to ECF did not reveal statistically significant differences between the two groups. In general, antipeptide antibody levels in the susceptible animals were lower than in the immune group and neither group developed high responses to all sporozoite-neutralizing epitopes. The bovine antibody response to recombinant p67 was restricted to the N- and C-terminal regions of p67, and there was no activity against the central portion between positions 313 and 583. So far, p67 sequence polymorphisms have been identified only in buffalo-derived
T. parva
parasites, but the consequence of these for vaccine development remains to be defined. The data indicate that optimizations of the current vaccination protocol against ECF should include boosting of relevant antibody responses to neutralizing epitopes on p67.
Complete Nucleotide Sequence of the 27-Kilobase Virulence Related Locus (
vrl
) of
Dichelobacter nodosus
: Evidence for Extrachromosomal Origin
Authors: Billington Stephen J. , Huggins Andrea S. , Johanesen Priscilla A. , Crellin Paul K. , Cheung Jackie K. , Katz Margaret E. , Wright Catherine L. , Haring Volker , Rood Julian I. 
Published: December 2019

ABSTRACT

The
vrl
locus is preferentially associated with virulent isolates of the ovine footrot pathogen,
Dichelobacter nodosus
. The complete nucleotide sequence of this 27.1-kb region has now been determined. The data reveal that the locus has a G+C content much higher than the rest of the
D. nodosus
chromosome and contains 22 open reading frames (ORFs) encoding products including a putative adenine-specific methylase, two potential DEAH ATP-dependent helicases, and two products with sequence similarity to a bacteriophage resistance system. These ORFs are all in the same orientation, and most are either overlapping or separated by only a few nucleotides, suggesting that they comprise an operon and are translationally coupled. Expression vector studies have led to the identification of proteins that correspond to many of these ORFs. These data, in combination with evidence of insertion of
vrl
into the 3′ end of an
ssrA
gene, are consistent with the hypothesis that the
vrl
locus was derived from the insertion of a bacteriophage or plasmid into the
D. nodosus
genome.
Potent Immunoregulatory Effects ofSalmonella typhiFlagella on Antigenic Stimulation of Human Peripheral Blood Mononuclear Cells
Authors: Wyant Timothy L. , Tanner Michael K. , Sztein Marcelo B. 
Published: December 2019

ABSTRACTA key function of monocytes/macrophages (Mφ) is to present antigens to T cells. However, upon interaction with bacteria, Mφ lose their ability to effectively present soluble antigens. This functional loss was associated with alterations in the expression of adhesion molecules and CD14 and a reduction in the uptake of soluble antigen. Recently, we have demonstrated thatSalmonella typhiflagella (STF) markedly decrease CD14 expression and are potent inducers of proinflammatory cytokine production by human peripheral blood mononuclear cells (hPBMC). In order to determine whetherS. typhiand soluble STF also alter the ability of Mφ to activate T cells to proliferate to antigens and mitogens, hPBMC were cultured in the presence of tetanus toxoid (TT) or phytohemagglutinin (PHA) and either killed whole-cellS. typhior purified STF protein. Both whole-cellS. typhiand STF suppressed proliferation to PHA and TT. This decreased proliferation was not a result of increased Mφ production of nitric oxide, prostaglandin E2, or oxygen radicals or the release of interleukin-1β, tumor necrosis factor alpha, interleukin-6, or interleukin-10 following exposure to STF. However, the ability to take up soluble antigen, as determined by fluorescein isothiocyanate-labeled dextran uptake, was reduced in cells cultured with STF. Moreover, there was a dramatic reduction in the expression of CD54 on Mφ after exposure to STF. These results indicate that whole-cellS. typhiand STF have the ability to alter in vitro proliferation to soluble antigens and mitogens by affecting Mφ function.