bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of Mycobacterial Surface Proteins Released into Subcellular Compartments of Infected Macrophages
Authors: Beatty Wandy L. , Russell David G. 
Published: July 2002

ABSTRACTConsiderable effort has focused on the identification of proteins secreted fromMycobacteriumspp. that contribute to the development of protective immunity. Little is known, however, about the release of mycobacterial proteins from the bacterial phagosome and the potential role of these molecules in chronically infected macrophages. In the present study, the release of mycobacterial surface proteins from the bacterial phagosome into subcellular compartments of infected macrophages was analyzed.Mycobacterium bovisBCG was surface labeled with fluorescein-tagged succinimidyl ester, an amine-reactive probe. The fluorescein tag was then used as a marker for the release of bacterial proteins in infected macrophages. Fractionation studies revealed bacterial proteins within subcellular compartments distinct from mycobacteria and mycobacterial phagosomes. To identify these proteins, subcellular fractions free of bacteria were probed with mycobacterium-specific antibodies. The fibronectin attachment protein and proteins of the antigen 85-kDa complex were identified among the mycobacterial proteins released from the bacterial phagosome.
A NovelLeishmania infantumRecombinant Antigen Which Elicits Interleukin 10 Production by Peripheral Blood Mononuclear Cells of Patients with Visceral Leishmaniasis
Authors: Suffia Isabelle , Ferrua Bernard , Stien Xavier , Mograbi Baharia , Marty Pierre , Rousseau Deborah , Fragaki Konstantina , Kubar Joanna 
Published: July 2002

ABSTRACTWe report here the characterization of a novelLeishmania infantumprotein termed papLe22 (22-kDa potentially aggravating protein ofLeishmania). A positive clone from a cDNA library was identified by serum of a visceral leishmaniasis (VL) patient. Full-length cDNA obtained using rapid amplification of cDNA ends-PCR codes for a 22-kDa protein. InL. infantumpromastigotes an endogenous nuclear protein of 14-kDa electrophoretic mobility was found by using an antiserum prepared against the fusion protein glutathioneS-transferase–papLe22. Its expression was also shown inL. infantumamastigotes and inLeishmania majorandLeishmania guyanensispromastigotes. VL patients' sera showed anti-papLe22 immunoglobulin M (IgM) and IgG reactivities, indicating that a primary response against the leishmanial protein papLe22 accompanied acute VL manifestations. Specific IgG levels were correlated with patients' clinical status. The presence of IgG1, IgG2, and IgG3 subclasses suggested a mixed Th1- and Th2-type response; there was no correlation between subclass reactivity and the disease course. The recombinant papLe22 specifically activated interleukin-10 production by VL patients' peripheral blood mononuclear cells collected at diagnosis and after treatment-induced cure, indicating its contribution to VL pathogenesis and concomitant immunosuppression and its potential role in the reactivation of latent parasites. As a dominant immunogen, papLe22 might be used as a vaccine component, provided that the vaccination protocol directs the response toward the Th1 pattern.
MTSA-10, the Product of the Rv3874 Gene of
Mycobacterium tuberculosis
, Elicits Tuberculosis-Specific, Delayed-Type Hypersensitivity in Guinea Pigs
Authors: Colangeli Roberto , Spencer John S. , Bifani Pablo , Williams Alan , Lyashchenko Konstantin , Keen Marc A. , Hill Preston J. , Belisle John , Gennaro Maria Laura 
Published: July 2002

ABSTRACT

In a search for new skin test reagents specific for tuberculosis, we found that the antigen encoded by gene Rv3874 of
Mycobacterium tuberculosis
elicited delayed-type hypersensitivity in
M. tuberculosis
-infected guinea pigs but not in control animals immunized with
Mycobacterium bovis
bacillus Calmette-Guérin (BCG) or
Mycobacterium avium
. The antigen, which was named MTSA-10 (for
M. tuberculosis
-specific antigen 10), is a prime candidate for a component of a new tuberculin that will allow discrimination by a skin test of latent
M. tuberculosis
infection from vaccination with BCG or from sensitization with environmental, nontuberculous mycobacteria.
Pseudomonas aeruginosa
Cystic Fibrosis Isolates Induce Rapid, Type III Secretion-Dependent, but ExoU-Independent, Oncosis of Macrophages and Polymorphonuclear Neutrophils
Authors: Dacheux Denis , Toussaint Bertrand , Richard Marceline , Brochier Guy , Croize Jacques , Attree Ina 
Published: July 2002

ABSTRACT

Pseudomonas aeruginosa
, an opportunistic pathogen responsible most notably for severe infections in cystic fibrosis (CF) patients, utilizes the type III secretion system for eukaryotic cell intoxication. The CF clinical isolate CHA shows toxicity towards human polymorphonuclear neutrophils (PMNs) which is dependent on the type III secretion system but independent of the cytotoxin ExoU. In the present study, the cytotoxicity of this strain toward human and murine macrophages was demonstrated. In low-multiplicity infections (multiplicity of infection, 10), approximately 40% of the cells die within 60 min. Analysis of CHA-infected cells by transmission electron microscopy, DNA fragmentation assay, and Hoechst staining revealed the hallmarks of oncosis: cellular and nuclear swelling, disintegration of the plasma membrane, and absence of DNA fragmentation. A panel of 29
P. aeruginosa
CF isolates was screened for type III system genotype, protein secretion profile, and cytotoxicity toward PMNs and macrophages. This study showed that six CF isolates were able to induce rapid ExoU-independent oncosis on phagocyte cells.
Evolution of Lesion Formation, Parasitic Load, Immune Response, and Reservoir Potential in C57BL/6 Mice following High- and Low-Dose Challenge withLeishmania major
Authors: Lira Rosalia , Doherty Mark , Modi Govind , Sacks David 
Published: July 2002

ABSTRACTA model of cutaneous leishmaniasis using 102Leishmania majormetacyclic promastigotes inoculated into the footpads of genetically resistant C57BL/6 mice was studied in order to more accurately reproduce the evolution of lesion formation and the kinetics of parasite growth and immune response as they might occur in naturally exposed reservoirs and in human hosts. In contrast to the more conventional experimental model employing 106metacyclic promastigotes, in which the rapid development of footpad lesions was associated with an increasing number of amastigotes in the site, the low-dose model revealed a remarkably “silent” phase of parasite growth, lasting approximately 6 weeks, during which peak parasitic loads were established in the absence of any overt pathology. Footpad swelling was observed after 6 weeks, coincident with the onset of parasite clearance and with production of high levels of interleukin-12 (IL-12) and gamma interferon (IFN-γ) in draining lymph nodes. Low-dose challenge of IL-12- and IFN-γ-depleted or -deficient mice provided strong evidence that the induction or expression of cellular immunity is essentially absent during the first 6 to 8 weeks of intracellular growth, since the concentration of amastigotes in the site was not enhanced compared to that for wild-type animals during this time. By monitoring the ability of infected mice to transmit parasites to vector sand flies, it was observed that following low-dose challenge, footpads without apparent lesions provided an efficient source of parasites for exposed flies and that the low-dose challenge actually extended the duration of parasite transmissibility during the course of infection.
Cytokine Responses toPlasmodium falciparumLiver-Stage Antigen 1 Vary in Rainy and Dry Seasons in Highland Kenya
Authors: John C. C. , Sumba P. O. , Ouma J. H. , Nahlen B. L. , King C. L. , Kazura J. W. 
Published: July 2002

ABSTRACTSeasonal epidemics of malaria occur in highland areas of western Kenya where transmission intensity varies according to rainfall. This study describes the seasonal changes in cytokine responses toPlasmodium falciparumliver-stage antigen 1 (LSA-1) by children (≤17 years old) and adults (≥18 years old) living in such a highland area. Fourteen- to 24-mer peptides corresponding to the N- and C-terminal nonrepeat regions of LSA-1 stimulated production of interleukin-5 (IL-5), interleukin-10 (IL-10), gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α) by peripheral blood mononuclear cells (PBMC) from 17 to 73% of individuals in both age groups in both seasons. IL-10 and TNF-α responses were more frequent during the high-transmission, rainy season than during the low-transmission, dry season (73 and 67% versus 17 and 25% response rates, respectively). In contrast, there was no seasonal change in the proportion of LSA-1-driven IFN-γ and IL-5 responses. Children produced less IFN-γ than adults, but IL-5, IL-10, and TNF-α levels were similar for both age groups. Depletion of CD8+cells from PBMC decreased IFN-γ but increased IL-10 production. Individuals with LSA-1-stimulated IL-10 responses in the dry season were less likely to become reinfected in the subsequent rainy season than those without IL-10 responses (25% versus 49%;P= 0.083). These data support the notion that maintenance of LSA-1-driven IL-10 and TNF-α responses requires repeated and sustained exposure to liver-stageP. falciparum. In contrast, IFN-γ responses increase slowly with age but persist once acquired. CD8+T cells are the major source of IFN-γ but may suppress production or secretion of IL-10.
Modulation of Human Immune Response byEchinococcus granulosusAntigen B and Its Possible Role in Evading Host Defenses
Authors: Riganò R. , Profumo E. , Bruschi F. , Carulli G. , Azzarà A. , Ioppolo S. , Buttari B. , Ortona E. , Margutti P. , Teggi A. , Siracusano A. 
Published: July 2002

ABSTRACTBy directly suppressing the function of certain immune cell subsets and by stimulating other cell populations related to immunopathology, parasite-derived substances play an important role in the chronic establishment of parasitic disease. Our objective was twofold: (i) to investigate further the role ofEchinococcus granulosusantigen B (AgB) in the human early inflammatory response by determining its effect on polymorphonuclear cell (PMN) random migration, chemotaxis, and oxidative metabolism and (ii) to determine its action in acquired immunity by evaluating AgB and sheep hydatid fluid (SHF)-driven Th1 (gamma interferon [IFN-γ] and interleukin 12 [IL-12]) and Th2 (IL-4 and IL-13) cytokine production by peripheral blood mononuclear cells (PBMC) from 40 patients who had cured or stable or progressive cystic echinococcosis. AgB significantly inhibited PMN recruitment but left their random migration and oxidative metabolism unchanged. Patients' PBMC stimulated with AgB produced IL-4 and IL-13 but did not produce IL-12. They also produced significantly lower IFN-γ concentrations than did PBMC stimulated with SHF (P= 10−5). AgB skewed the Th1/Th2 cytokine ratios towards a preferentially immunopathology-associated Th2 polarization, predominantly in patients with progressive disease. AgB-stimulated patients' PBMC also proliferated less than SHF-stimulated PBMC (P= 9 × 10−3). In vitro Th2 cytokine production was reflected in vivo by elevated specific immunoglobulin E (IgE) and IgG4 antibodies binding to AgB. These findings confirm that AgB plays a role in the escape from early immunity by inhibiting PMN chemotaxis. They also add new information on the host-parasite relationship, suggesting that AgB exploits the activation of T helper cells by eliciting a nonprotective Th2 cell response.
Three-Dimensional Tissue Assemblies: Novel Models for the Study ofSalmonella entericaSerovar Typhimurium Pathogenesis
Authors: Nickerson Cheryl A. , Goodwin Thomas J. , Terlonge Jacqueline , Ott C. Mark , Buchanan Kent L. , Uicker William C. , Emami Kamal , LeBlanc Carly L. , Ramamurthy Rajee , Clarke Mark S. , Vanderburg Charles R. , Hammond Timothy , Pierson Duane L. 
Published: July 2002

ABSTRACTThe lack of readily available experimental systems has limited knowledge pertaining to the development ofSalmonella-induced gastroenteritis and diarrheal disease in humans. We used a novel low-shear stress cell culture system developed at the National Aeronautics and Space Administration in conjunction with cultivation of three-dimensional (3-D) aggregates of human intestinal tissue to study the infectivity ofSalmonella entericaserovar Typhimurium for human intestinal epithelium. Immunohistochemical characterization and microscopic analysis of 3-D aggregates of the human intestinal epithelial cell line Int-407 revealed that the 3-D cells more accurately modeled human in vivo differentiated tissues than did conventional monolayer cultures of the same cells. Results from infectivity studies showed thatSalmonellaestablished infection of the 3-D cells in a much different manner than that observed for monolayers. Following the same time course of infection withSalmonella, 3-D Int-407 cells displayed minimal loss of structural integrity compared to that of Int-407 monolayers. Furthermore,Salmonellaexhibited significantly lower abilities to adhere to, invade, and induce apoptosis of 3-D Int-407 cells than it did for infected Int-407 monolayers. Analysis of cytokine expression profiles of 3-D Int-407 cells and monolayers following infection withSalmonellarevealed significant differences in expression of interleukin 1α (IL-1α), IL-1β, IL-6, IL-1Ra, and tumor necrosis factor alpha mRNAs between the two cultures. In addition, uninfected 3-D Int-407 cells constitutively expressed higher levels of transforming growth factor β1 mRNA and prostaglandin E2than did uninfected Int-407 monolayers. By more accurately modeling many aspects of human in vivo tissues, the 3-D intestinal cell model generated in this study offers a novel approach for studying microbial infectivity from the perspective of the host-pathogen interaction.
Distribution and Genetic Diversity of Suilysin in
Streptococcus suis
Isolated from Different Diseases of Pigs and Characterization of the Genetic Basis of Suilysin Absence
Authors: King Samantha J. , Heath Peter J. , Luque Inmaculada , Tarradas Carmen , Dowson Christopher G. , Whatmore Adrian M. 
Published: July 2002

ABSTRACT

Streptococcus suis
is an economically important pathogen of pigs responsible for a variety of diseases including meningitis, septicemia, arthritis, and pneumonia, although little is known about the mechanisms of pathogenesis or virulence factors associated with this organism. Here, we report on the distribution and genetic diversity of the putative virulence factor suilysin, a member of the thiol-activated toxin family of gram-positive bacteria. On the basis of PCR analysis of over 300 isolates of
S. suis
, the suilysin-encoding gene,
sly
, was detected in 69.4% of isolates. However,
sly
was present in a considerably higher proportion of isolates obtained from cases of meningitis, septicemia, and arthritis (>80%) and isolates obtained from asymptomatic tonsillar carriage (>90%) than lung isolates associated with pneumonia (44%). With the exception of serotypes 1, 14, and 1/14, there was no strong correlation between the presence of suilysin and serotype. Analysis of the genetic diversity of suilysin by restriction fragment length polymorphism and sequence analysis found that the suilysin gene, where present, is highly conserved with a maximum of 1.79% diversity at the nucleotide level seen between
sly
alleles. Assays of hemolytic activity and hybridization analysis provided no evidence for a second member of the thiol-activated toxin family in
S. suis
. Inverse PCR was used to characterize regions flanking
sly
, which in turn allowed the first characterization of the equivalent region in a strain lacking
sly
. Sequence comparison of these regions from
sly
-positive (P1/7) and
sly
-negative (DH5) strains indicated that two alternative arrangements are both flanked by genes with highest similarity to haloacid dehalogenase-like hydrolases (5′ end) and putative
N
-acetylmannosamine-6-phosphate epimerases (3′ end). However,
sly
appears to be completely absent from the alternative arrangement, and a gene of unknown function is located in the equivalent position. Finally, PCR analysis of multiple
sly
-positive and -negative strains indicated that these two alternative genetic arrangements are conserved among many
S. suis
isolates.
Mycobacterium tuberculosis19-Kilodalton Lipoprotein InhibitsMycobacterium smegmatis-Induced Cytokine Production by Human Macrophages In Vitro
Authors: Post Frank A. , Manca Claudia , Neyrolles Olivier , Ryffel Bernhard , Young Douglas B. , Kaplan Gilla 
Published: July 2002

ABSTRACTVaccination of mice withMycobacterium vaccaeorM. smegmatisinduces some protection againstM. tuberculosischallenge. The 19-kDa lipoprotein ofM. tuberculosis, expressed inM. vaccaeorM. smegmatis(M. smeg19kDa), abrogates this protective immunity. To investigate the mechanism of this suppression of immunity, human monocyte-derived macrophages (MDM) were infected withM. smeg19kDa. Infection resulted in reduced production of tumor necrosis factor alpha (TNF-α) (P< 0.01), interleukin-12 (IL-12) (P< 0.05), IL-6 (P< 0.05), and IL-10 (P< 0.05), compared to infection withM. smegmatisvector (M. smegV). Infection withM. smeg19kDa and withM. smegV had no differential effect on expression of costimulatory molecules on MDM, nor did it affect the proliferation of presensitized T cells cocultured with infected MDM. When MDM were infected withM. smegmatisexpressing mutated forms of the 19-kDa lipoprotein, including non-O-glycosylated (M. smeg19NOG), nonsecreted (M. smeg19NS), and nonacylated (M. smeg19NA) variants, the reduced production of TNF-α or IL-12 was not observed. When the purified 19-kDa lipoprotein was added directly to cultures of infected monocytes, there was little effect on either induction of cytokine production or its inhibition. Thus, the immunosuppressive effect is dependent on glycosylated and acylated 19-kDa lipoprotein present in the phagosome containing the mycobacterium. These results suggest that the diminished protection against challenge withM. tuberculosisseen in mice vaccinated withM. smegmatisexpressing the 19-kDa lipoprotein is the result of reduced TNF-α and IL-12 production, possibly leading to reduced induction of T-cell activation.
Staphylococcus aureusandSalmonella entericaSerovar Dublin Induce Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Expression by Normal Mouse and Human Osteoblasts
Authors: Alexander Emily H. , Bento Jennifer L. , Hughes Francis M. , Marriott Ian , Hudson Michael C. , Bost Kenneth L. 
Published: July 2002

ABSTRACTStaphylococcus aureusandSalmonella entericaserovar Dublin invade osteoblasts and are causative agents of human bone disease. In the present study, we examined the ability ofS. aureusandSalmonellaserovar Dublin to induce the production of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) by normal osteoblasts. Normal mouse and human osteoblasts were cocultured withS. aureusorSalmonellaserovar Dublin at different multiplicities of infection. Following initial incubation and examination of TRAIL expression, extracellular bacteria were killed by the addition of media containing the antibiotic gentamicin. Lysates and conditioned media from osteoblast cultures were then collected at various times following invasion and analyzed. The results demonstrated thatS. aureusandSalmonellaserovar Dublin are potent inducers of TRAIL expression by osteoblasts. Mouse and human TRAIL mRNA expression was induced by bacterial infection and demonstrated a dose-dependent response. Analysis of kinetics suggested that TRAIL mRNA was induced within 30 min after exposure to bacteria and that its level of expression remained relatively constant over the time period examined. mRNA molecules encoding TRAIL receptors were constitutively expressed by osteoblasts. Furthermore, TRAIL protein was detected as early as 45 min and up to 24 h following infection. The quantity of TRAIL protein produced also increased in a dose-dependent manner. Collectively, these findings suggest a mechanism whereby bacterial pathogens mediate bone destruction via osteoblast apoptosis.
Characterization of a Cell Surface Protein of
Clostridium difficile
with Adhesive Properties
Authors: Waligora Anne-Judith , Hennequin Claire , Mullany Peter , Bourlioux Pierre , Collignon Anne , Karjalainen Tuomo 
Published: July 2002

ABSTRACT

Our laboratory has previously shown that
Clostridium difficile
adherence to cultured cells is enhanced after heat shock at 60°C and that it is mediated by a proteinaceous surface component. The present study was undertaken to identify the surface molecules of this bacterium that could play a role in its adherence to the intestine. The
cwp66
gene, encoding a cell surface-associated protein of
C. difficile
79-685, was isolated by immunoscreening of a
C. difficile
gene library with polyclonal antibodies against
C. difficile
heated at 60°C. The Cwp66 protein (66 kDa) contains two domains, each carrying three imperfect repeats and one presenting homologies to the autolysin CwlB of
Bacillus subtilis
. A survey of 36 strains of
C. difficile
representing 11 serogroups showed that the 3′ portion of the
cwp66
gene is variable; this was confirmed by sequencing of
cwp66
from another strain, C-253. Two recombinant protein fragments corresponding to the two domains of Cwp66 were expressed in fusion with glutathione
S
-transferase in
Escherichia coli
and purified by affinity chromatography using gluthatione-Sepharose 4B. Antibodies raised against the two domains recognized Cwp66 in bacterial surface extracts. By immunoelectron microscopy, the C-terminal domain was found to be cell surface exposed. When used as inhibitors in cell binding studies, the antibodies and protein fragments partially inhibited adherence of
C. difficile
to cultured cells, confirming that Cwp66 is an adhesin, the first to be identified in clostridia.
Staphylococcus aureusagrandsarAFunctions Are Required for Invasive Infection but Not Inflammatory Responses in the Lung
Authors: Heyer Geoffrey , Saba Shahryar , Adamo Robert , Rush William , Soong Grace , Cheung Ambrose , Prince Alice 
Published: July 2002

ABSTRACTStaphylococcus aureusstrains lackingagr- andsarA-dependent gene products or specific MSCRAMM (microbial surface components recognizing adhesive matrix molecules) adhesins were compared for the ability to activate inflammatory responses in the lung. The mutants were evaluated for virulence in a mouse model of pneumonia and by quantifying their ability to stimulate interleukin-8 (IL-8) and granulocyte-macrophage colony-stimulating factor (GM-CSF) expression in respiratory epithelial cells. In a neonatal mouse, only strains with intactagrandsarAloci were consistently associated with invasive, fatal pulmonary infection (P< 0.001) andsarA was specifically required to cause bacteremia (P< 0.001). Theagrand/orsarAmutants were, nonetheless, fully capable of producing pneumonia and were as proficient as the wild-type strain in stimulating epithelial IL-8 expression, a polymorphonuclear leukocyte chemokine, in airway cells. In contrast,agrand especiallysarAmutants induced less epithelial GM-CSF expression, and MSCRAMM mutants lacking fibronectin binding proteins or clumping factor A, a ligand for fibrinogen, were unable to stimulate epithelial GM-CSF production. The ability to induce IL-8 expression was independent of the adherence properties of intact bacteria, indicating that shed and/or secreted bacterial components activate epithelial responses. While conserved staphylococcal components such as peptidoglycan are sufficient to evoke inflammation and cause pneumonia, theagrandsarAloci ofS. aureusare critical for the coordination of invasive infection of the lungs.