bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunity to Onchocerciasis: Cells from Putatively Immune Individuals Produce Enhanced Levels of Interleukin-5, Gamma Interferon, and Granulocyte-Macrophage Colony-Stimulating Factor in Response toOnchocerca volvulusLarval and Male Worm Antigens
Authors: Turaga Prasad S. D. , Tierney Tracy J. , Bennett Kristine E. , McCarthy Maggie C. , Simonek Scott C. , Enyong Peter A. , Moukatte Daniel W. , Lustigman Sara 
Published: July 2002

ABSTRACTAntigen-specific interleukin-5 (IL-5), gamma interferon (IFN-γ), and granulocyte-macrophage colony-stimulating factor (GM-CSF) responses in individuals living in an area of hyperendemicity for onchocerciasis in Cameroon were examined. The responses against antigens prepared fromOnchocerca volvulusthird-stage larvae (L3), molting L3 (mL3), and crude extract from adult males (M-OvAg) were compared to the responses against antigens from adult female worms and skin microfilariae. Cytokine responses for the putatively immune individuals (PI) and the infected individuals (INF) were compared. A differential cytokine profile of IL-5 (Th2 phenotype) and IFN-γ (Th1 phenotype) was found in these individuals in response to the antigens. In both the PI and the INF, Th2 responses against all the antigens tested were dominant. However, in the PI group as a whole, there was an enhanced Th2 response against the larval antigens and the adult male and adult female antigens, and a Th1 response in a subgroup of the PI (27 to 54.5%) against L3, mL3, and M-OvAg antigens was present. While the PI produced significantly higher levels of GM-CSF against L3, mL3, and M-OvAg antigens than the INF, there was no difference in the GM-CSF responses of the groups against the other antigens. The present study indicated that, in comparison to the INF, the PI have distinct larva-specific and adult male-specific cytokine responses, thus supporting the premise that immunological studies of the PI would lead to the identification of immune mechanisms and the target genes that play a role in protective immunity.
Brucella abortusand Its Closest Phylogenetic Relative,Ochrobactrumspp., Differ in Outer Membrane Permeability and Cationic Peptide Resistance
Authors: Velasco J. , Bengoechea J. A. , Brandenburg K. , Lindner B. , Seydel U. , González D. , Zähringer U. , Moreno E. , Moriyón I. 
Published: July 2002

ABSTRACTThe outer membrane (OM) of the intracellular parasiteBrucella abortusis permeable to hydrophobic probes and resistant to destabilization by polycationic peptides and EDTA. The significance of these unusual properties was investigated in a comparative study with the opportunistic pathogens of the genusOchrobactrum, the closest knownBrucellarelative.Ochrobactrumspp. OMs were impermeable to hydrophobic probes and sensitive to polymyxin B but resistant to EDTA. These properties were traced to lipopolysaccharide (LPS) because (i) insertion ofB. abortusLPS, but not ofEscherichia coliLPS, intoOchrobactrumOM increased its permeability; (ii) permeability and polymyxin B binding measured with LPS aggregates paralleled the results with live bacteria; and (iii) the predicted intermediate results were obtained withB. abortus-Ochrobactrum anthropiandE. coli-O. anthropiLPS hybrid aggregates. AlthoughOchrobactrumwas sensitive to polymyxin, self-promoted uptake and bacterial lysis occurred without OM morphological changes, suggesting an unusual OM structural rigidity.OchrobactrumandB. abortusLPSs showed no differences in phosphate, qualitative fatty acid composition, or acyl chain fluidity. However,OchrobactrumLPS, but notB. abortusLPS, contained galacturonic acid.B. abortusandOchrobactrumsmooth LPS aggregates had similar size and zeta potential (−12 to −15 mV). Upon saturation with polymyxin, zeta potential became positive (1 mV) forOchrobactrumsmooth LPS while remaining negative (−5 mV) forB. abortussmooth LPS, suggesting hindered access to inner targets. These results show that althoughOchrobactrumandBrucellashare a basic OM pattern, subtle modifications in LPS core cause markedly different OM properties, possibly reflecting the adaptive evolution ofB. abortusto pathogenicity.
In Vitro Cell Invasion of
Mycoplasma gallisepticum
Authors: Winner Florian , Rosengarten Renate , Citti Christine 
Published: July 2002

ABSTRACT

The ability of the widespread avian pathogen
Mycoplasma gallisepticum
to invade cultured human epithelial cells (HeLa-229) and chicken embryo fibroblasts (CEF) was investigated by using the gentamicin invasion assay and a double immunofluorescence microscopic technique for accurate localization of cell-associated mycoplasmas. The presence of intracellular mycoplasmas in both cell lines was clearly demonstrated, with organisms entering the eukaryotic cells within 20 min. Internalized mycoplasmas have the ability to leave the cell, but also to survive within the intracellular space over a 48-h period. Frequencies of invasion were shown to differ between the two cell lines, but were also considerably dependent on the mycoplasma input population. Of the prototype strain R, a low-passage population in artificial medium, R
low
, was capable of active cell invasion, while a high-passage population, R
high
, showed adherence to but nearly no uptake into HeLa-229 and CEF. By passaging R
low
and R
high
multiple times through HeLa-229 cells, the invasion frequency was significantly increased. Taken together, these findings demonstrate that
M. gallisepticum
has the capability of entering nonphagocytic host cells that may provide this pathogen with the opportunity for resisting host defenses and selective antibiotic therapy, establishing chronic infections, and passing through the respiratory mucosal barrier to cause systemic infections.
Salmonella enterica
Serovar Typhimurium
waaP
Mutants Show Increased Susceptibility to Polymyxin and Loss of Virulence In Vivo
Authors: Yethon Jeremy A. , Gunn John S. , Ernst Robert K. , Miller Samuel I. , Laroche Line , Malo Danielle , Whitfield Chris 
Published: July 2002

ABSTRACT

In
Escherichia coli
, the
waaP
(
rfaP
) gene product was recently shown to be responsible for phosphorylation of the first heptose residue of the lipopolysaccharide (LPS) inner core region. WaaP was also shown to be necessary for the formation of a stable outer membrane. These earlier studies were performed with an avirulent rough strain of
E. coli
(to facilitate the structural chemistry required to properly define
waaP
function); therefore, we undertook the creation of a
waaP
mutant of
Salmonella enterica
serovar Typhimurium to assess the contribution of WaaP and LPS core phosphorylation to the biology of an intracellular pathogen. The
S. enterica waaP
mutant described here is the first to be both genetically and structurally characterized, and its creation refutes an earlier claim that
waaP
mutations in
S. enterica
must be leaky to maintain viability. The mutant was shown to exhibit characteristics of the deep-rough phenotype, despite its ability to produce a full-length core capped with O antigen. Further, phosphoryl modifications in the LPS core region were shown to be required for resistance to polycationic antimicrobials. The
waaP
mutant was significantly more sensitive to polymyxin in both wild-type and polymyxin-resistant backgrounds, despite the decreased negative charge of the mutant LPSs. In addition, the
waaP
mutation was shown to cause a complete loss of virulence in mouse infection models. Taken together, these data indicate that WaaP is a potential target for the development of novel therapeutic agents.
Antigen Detection in Enteropathogenic
Escherichia coli
Using Secretory Immunoglobulin A Antibodies Isolated from Human Breast Milk
Authors: Manjarrez-Hernandez H. A. , Gavilanes-Parra S. , Chavez-Berrocal E. , Navarro-Ocaña A. , Cravioto A. 
Published: July 2002

ABSTRACT

Enteropathogenic
Escherichia coli
(EPEC) produces a characteristic attaching and effacing (A/E) lesion in the small intestines of infected children. The immune response to EPEC infection remains poorly characterized. The molecular targets that elicit protective immunity against EPEC disease are unknown. In this study protein antigens from EPEC were identified using secretory immunoglobulin A (sIgA) antibodies isolated from milk from Mexican women by Western blot analysis. Purified sIgA antibodies, which inhibit the adherence of EPEC to cells, reacted to many EPEC proteins, the most prominent of which were intimin (a 94-kDa outer membrane protein) and two unknown proteins with apparent molecular masses of 80 and 70 kDa. A culture supernatant protein of 110 kDa also reacted strongly with the sIgA antibodies. The molecular size of this protein and its reactivity with specific anti-EspC antiserum suggest that it is EPEC-secreted protein C (EspC). These EPEC surface protein antigens were consistently recognized by all the different sIgA samples obtained from 15 women. Screening of clinical isolates of various O serogroups from cases of severe infantile diarrhea revealed that all EPEC strains able to produce the A/E lesion showed expression of intimin and the 80- and 70-kDa proteins. Such proteins reacted strongly with the purified sIgA pool. Moreover, nonvirulent
E. coli
strains were unable to generate a sIgA response. The immunogenic capacities of the 80- and 70-kDa proteins as virulence antigens have not been previously reported. The strong sIgA response to intimin and the 80- and 70-kDa proteins obtained in this study indicates that such antigens stimulate intestinal immune responses and may elicit protective immunity against EPEC disease.
Babesia bovis-Stimulated Macrophages Express Interleukin-1β, Interleukin-12, Tumor Necrosis Factor Alpha, and Nitric Oxide and Inhibit Parasite Replication In Vitro
Authors: Shoda Lisl K. M. , Palmer Guy H. , Florin-Christensen Jorge , Florin-Christensen Monica , Godson Dale L. , Brown Wendy C. 
Published: July 2002

ABSTRACTThe tick-transmitted hemoparasiteBabesia boviscauses an acute infection that results in persistence and immunity against challenge infection in cattle that control the initial parasitemia. Resolution of acute infection with this protozoal pathogen is believed to be dependent on products of activated macrophages (Mφ), including inflammatory cytokines and nitric oxide (NO) and its derivatives.B. bovisstimulates inducible nitric oxide synthase (iNOS) and production of NO in bovine Mφ, and chemical donors of NO inhibit the growth ofB. bovisin vitro. However, the induction of inflammatory cytokines in Mφ by babesial parasites has not been described, and the antiparasitic activity of NO produced byB. bovis-stimulated Mφ has not been definitively demonstrated. We report that monocyte-derived Mφ activated byB. bovisexpressed enhanced levels of inflammatory cytokines interleukin-1β (IL-1β), IL-12, and tumor necrosis factor alpha that are important for stimulating innate and acquired immunity against protozoal pathogens. Furthermore, a lipid fraction ofB. bovis-infected erythrocytes stimulated iNOS expression and NO production by Mφ. Cocultures of Mφ andB. bovis-infected erythrocytes either in contact or physically separated resulted in reduced parasite viability. However, NO produced by bovine Mφ in response toB. bovis-infected erythrocytes was only partially responsible for parasite growth inhibition, suggesting that additional factors contribute to the inhibition ofB. bovisreplication. These findings demonstrate thatB. bovisinduces an innate immune response that is capable of controlling parasite replication and that could potentially result in host survival and parasite persistence.
Analysis of Genes Expressed at the Infective Larval Stage Validates Utility of
Litomosoides sigmodontis
as a Murine Model for Filarial Vaccine Development
Authors: Allen Judith E. , Daub Jennifer , Guiliano David , McDonnell Amanda , Lizotte-Waniewski Michelle , Taylor David W. , Blaxter Mark 
Published: July 2002

ABSTRACT

We used an expressed sequence tag approach to analyze genes expressed by the infective larvae of the rodent filarial parasite
Litomosoides sigmodontis
. One hundred fifty two new genes were identified, including several proposed as vaccine candidates in studies with human filarial parasites. Our findings have important implications for the use of
L. sigmodontis
as a model for filarial infection.
espC
Pathogenicity Island of Enteropathogenic
Escherichia coli
Encodes an Enterotoxin
Authors: Mellies Jay L. , Navarro-Garcia Fernando , Okeke Iruka , Frederickson Julie , Nataro James P. , Kaper James B. 
Published: July 2002

ABSTRACT

At least five proteins are secreted extracellularly by enteropathogenic
Escherichia coli
(EPEC), a leading cause of infant diarrhea in developing countries. However only one, EspC, is known to be secreted independently of the type III secretion apparatus encoded by genes located within the 35.6-kb locus of enterocyte effacement pathogenicity island. EspC is a member of the autotransporter family of proteins, and the secreted portion of the molecule is 110 kDa. Here we determine that the
espC
gene is located within a second EPEC pathogenicity island at 60 min on the chromosome of
E. coli
. We also show that EspC is an enterotoxin, indicated by rises in short-circuit current and potential difference in rat jejunal tissue mounted in Ussing chambers. In addition, preincubation with antiserum against the homologous Pet enterotoxin of enteroaggregative
E. coli
eliminated EspC enterotoxin activity. Like the EAF plasmid, the
espC
pathogenicity island was found only in a subset of EPEC, suggesting that EspC may play a role as an accessory virulence factor in some but not all EPEC strains.
Genetic Diversity of
Pseudomonas aeruginosa
Strains Isolated from Ventilated Patients with Nosocomial Pneumonia, Cancer Patients with Bacteremia, and Environmental Water
Authors: Ruimy Raymond , Genauzeau Emmanuel , Barnabe Christian , Beaulieu Arnaud , Tibayrenc Michel , Andremont Antoine 
Published: July 2002

ABSTRACT

Random amplified polymorphic DNA typing was used to study the genetic diversity of
Pseudomonas aeruginosa
strains from (i) ventilated patients with nosocomial pneumonia who were hospitalized in intensive care units, (ii) cases of bacteremia in cancer patients with severe neutropenia, and (iii) rivers and swimming pools. Genetic diversity was determined by three phylogenetic methods and by statistical analysis of population genetics. The population studied undergoes epidemic clonality with a high rate of genetic recombination.
P. aeruginosa
bacteremia and pneumonia are not caused by specific clones within this species.
CD4+T Lymphocytes from Calves Immunized withAnaplasma marginaleMajor Surface Protein 1 (MSP1), a Heteromeric Complex of MSP1a and MSP1b, Preferentially Recognize the MSP1a Carboxyl Terminus That Is Conserved among Strains
Authors: Brown Wendy C. , Palmer Guy H. , Lewin Harris A. , McGuire Travis C. 
Published: July 2002

ABSTRACTNative major surface protein 1 (MSP1) of the ehrlichial pathogenAnaplasma marginaleinduces protective immunity in calves challenged with homologous and heterologous strains. MSP1 is a heteromeric complex of a single MSP1a protein covalently associated with MSP1b polypeptides, of which at least two (designated MSP1F1 and MSP1F3) in the Florida strain are expressed. Immunization with recombinant MSP1a and MSP1b alone or in combination fails to provide protection. The protective immunity in calves immunized with native MSP1 is associated with the development of opsonizing and neutralizing antibodies, but CD4+T-lymphocyte responses have not been evaluated. CD4+T lymphocytes participate in protective immunity to ehrlichial pathogens through production of gamma interferon (IFN-γ), which promotes switching to high-affinity immunoglobulin G (IgG) and activation of phagocytic cells to produce nitric oxide. Thus, an effective vaccine forA. marginaleand related organisms should contain both T- and B-lymphocyte epitopes that induce a strong memory response that can be recalled upon challenge with homologous and heterologous strains. This study was designed to determine the relative contributions of MSP1a and MSP1b proteins, which contain both variant and conserved amino acid sequences, in stimulating memory CD4+T-lymphocyte responses in calves immunized with native MSP1. Peripheral blood mononuclear cells and CD4+T-cell lines from MSP1-immunized calves proliferated vigorously in response to the immunizing strain (Florida) and heterologous strains ofA. marginale. The conserved MSP1-specific response was preferentially directed to the carboxyl-terminal region of MSP1a, which stimulated high levels of IFN-γ production by CD4+T cells. In contrast, there was either weak or no recognition of MSP1b proteins. Paradoxically, all calves developed high titers of IgG antibodies to both MSP1a and MSP1b polypeptides. These findings suggest that in calves immunized with MSP1 heteromeric complex, MSP1a-specific T lymphocytes may provide help to MSP1b-specific B lymphocytes. The data provide a basis for determining whether selected MSP1a CD4+T-lymphocyte epitopes and selected MSP1a and MSP1b B-lymphocyte epitopes presented on the same molecule can stimulate a protective immune response.
Structural Analysis and Antibody Response to the Extracellular GlutathioneS-Transferases fromOnchocerca volvulus
Authors: Sommer Alexandra , Nimtz Manfred , Conradt Harald S. , Brattig Norbert , Boettcher Kay , Fischer Peter , Walter Rolf D. , Liebau Eva 
Published: July 2002

ABSTRACTOnchocerca volvulusis a human pathogenic filarial parasite which, like other parasitic nematodes, is capable of surviving in an immunologically competent host by employing a variety of immune evasion strategies and defense mechanisms including the detoxification and repair mechanisms of the glutathioneS-transferases (GSTs). In this study we analyzed the glycosylation pattern and the immunological properties of extracellularO. volvulusGST1a and -1b (OvGST1a and -1b). The enzymes differ in only 10 amino acids, and both are glycoproteins that have cleavable signal peptides and unusual N-terminal extensions. These characteristics have not been described for other GSTs so far. Mass spectrometry analyses indicate that both enzymes carry high-mannose type oligosaccharides on at least four glycosylation sites. Glycosylation sites 1 to 3 ofOvGST1a (OvGST1b sites 2 to 4) are occupied by truncated N-glycans (Man2GlcNAc2 to Man5GlcNAc2), and N glycosylation site 4 ofOvGST1a (OvGST1b site 5) carries Man5GlcNAc2 to Man9GlcNAc2. To analyze the capacity of these secretory GSTs to stimulate host immune responses, we studied the antibody responses of onchocerciasis patients against the native affinity-purifiedOvGST1a and -1b. By enzyme-linked immunosorbent assay we showed thatOvGST1a and -1b are immunodominant antigens, with less than 7% nonresponder patients. A direct comparison of the antibody responses to the glycosylated and deglycosylated forms demonstrates the high immunogenicity of the N-glycans. Analyses of the antibody responses to the unusual N-terminal extension show an enhanced recognition of this portion by patients as opposed to recognition of the recombinant protein without extension.
Prevention ofPorphyromonas gingivalis-Induced Oral Bone Loss following Immunization with Gingipain R1
Authors: Gibson Frank C. , Genco Caroline Attardo 
Published: July 2002

ABSTRACTThe arginine gingipains RgpA and RgpB ofPorphyromonas gingivalisare well-documented virulence factors of this organism. Structurally, RgpA and RgpB have nearly identical catalytic domains, while RgpA possesses an additional hemagglutinin domain. In this study, we examined the abilities of these proteins to elicit protection againstP. gingivalis-mediated oral bone loss in a murine oral challenge model. Mice immunized subcutaneously with heat-killedP. gingivalisor purified RgpA or RgpB possessed elevated levels ofP. gingivalis-specific immunoglobulin G; however, only the animals immunized withP. gingivaliswhole cells or RgpA were protected from maxillary bone loss. These data suggest that immunization with RgpA stimulates the production of hemagglutinin domain-specific antibodies, which contribute to the prevention ofP. gingivalis-mediated periodontal disease.
Toxin Synthesis and Mucin Breakdown Are Related to Swarming Phenomenon in
Clostridium septicum
Authors: Macfarlane Sandra , Hopkins Mark J. , Macfarlane George T. 
Published: July 2002

ABSTRACT

Clostridium septicum
is responsible for several diseases in humans and animals. The bacterium is capable of a simple kind of multicellular behavior known as swarming. In this investigation, environmental and physiologic factors affecting growth and swarm cell formation in
C. septicum
were studied over a range of dilution rates (
D
= 0.02 to 0.65 h
−1
) in glucose-limited, glucose-excess, and mucin-limited chemostats. Cellular differentiation was observed at low specific growth rates, irrespective of the carbon and energy source, showing that swarming occurred in response to nutrient depletion. Differential expression of virulence determinants was detected in swarm cells. Hemolysin was secreted by short motile rods but not swarm cells, whereas in cultures grown with glucose, only swarm cells formed DNase, hyaluronidase, and neuraminidase. However, neuraminidase and, to a lesser degree, hyaluronidase were induced in short motile rods in mucin-limited cultures. Both swarm cells and short rods were cytotoxic to Vero cells. Mucin was chemotaxic to
C. septicum
, and large amounts of mucin-degrading enzymes (β-galactosidase,
N
-acetyl β-glucosaminidase, glycosulfatase, and neuraminidase) were produced. Synthesis of these enzymes was catabolite regulated. In chemostat experiments, glycosulfatase secretion occurred only in swarm cells at low dilution rates in mucin-limited cultures. Determinations of oligosaccharide utilization demonstrated that
N
-acetylglucosamine, galactose, and
N
-acetylgalactosamine were the main carbon sources for
C. septicum
in mucin. Neuraminic acid was not assimilated, showing that neuraminidase does not have a direct nutritional function in this pathogen.
Study of
Staphylococcus aureus
Pathogenic Genes by Transfer and Expression in the Less Virulent Organism
Streptococcus gordonii
Authors: Stutzmann Meier P. , Entenza J. M. , Vaudaux P. , Francioli P. , Glauser M. P. , Moreillon P. 
Published: July 2002

ABSTRACT

Because
Staphylococcus aureus
strains contain multiple virulence factors, studying their pathogenic role by single-gene inactivation generated equivocal results. To circumvent this problem, we have expressed specific
S. aureus
genes in the less virulent organism
Streptococcus gordonii
and tested the recombinants for a gain of function both in vitro and in vivo. Clumping factor A (ClfA) and coagulase were investigated. Both gene products were expressed functionally and with similar kinetics during growth by streptococci and staphylococci. ClfA-positive
S. gordonii
was more adherent to platelet-fibrin clots mimicking cardiac vegetations in vitro and more infective in rats with experimental endocarditis (
P
< 0.05). Moreover, deleting
clfA
from
clfA
-positive streptococcal transformants restored both the low in vitro adherence and the low in vivo infectivity of the parent. Coagulase-positive transformants, on the other hand, were neither more adherent nor more infective than the parent. Furthermore, coagulase did not increase the pathogenicity of
clfA
-positive streptococci when both
clfA
and
coa
genes were simultaneously expressed in an artificial minioperon in streptococci. These results definitively attribute a role for ClfA, but not coagulase, in
S. aureus
endovascular infections. This gain-of-function strategy might help solve the role of individual factors in the complex the
S. aureus
-host relationship.