bluuebunny/crossref_metadata_2025_split huggingface dataset:
Therapeutic Vaccination againstHelicobacter pyloriin the Beagle Dog Experimental Model: Safety, Immunogenicity, and Efficacy
Authors: Rossi Giacomo , Ruggiero Paolo , Peppoloni Samuele , Pancotto Laura , Fortuna Damiano , Lauretti Laura , Volpini Gianfranco , Mancianti Silvia , Corazza Michele , Taccini Ennio , Di Pisa Francesco , Rappuoli Rino , Del Giudice Giuseppe 
Published: May 2004

ABSTRACTHelicobacter pyloriis a gram-negative bacterium that colonizes the human gastric mucosa causing gastritis and peptic ulcer and increasing the risk of gastric cancer. The efficacy of current antibiotic-based therapies can be limited by problems of patient compliance and increasing antibiotic resistance; the vaccine approach can overcome these limits. The present study describes the therapeutic vaccination of experimentallyH. pylori-infected beagle dogs, an animal model that reproduces several aspects of the human infection withH. pylori. The vaccine consisted of three recombinantH. pyloriantigens, CagA, VacA, and NAP, formulated at different doses (10, 25, or 50 μg each) with alum and administered intramuscularly either weekly or monthly. No adverse effects were observed after vaccination and a good immunoglobulin G response was generated against each of the three antigens. Bacterial colonization and gastritis were decreased after the completion of the vaccination cycle, especially in the case of the monthly immunization schedule. In conclusion, therapeutic vaccination in the beagle dog model was safe and immunogenic and was able to limitH. pyloricolonization and the related gastric pathology.
Binding and Internalization of
Clostridium perfringens
Iota-Toxin in Lipid Rafts
Authors: Nagahama Masahiro , Yamaguchi Akiwo , Hagiyama Tohko , Ohkubo Noriko , Kobayashi Keiko , Sakurai Jun 
Published: May 2004

ABSTRACT

Clostridium perfringens
iota-toxin is a binary toxin composed of an enzymatic component (Ia) and a binding component (Ib). The oligomer of Ib formed in membranes induces endocytosis. We examined the binding and internalization of Ib by using Cy3-labeled Ib. Labeled Ib was retained at the membranes of MDCK cells for 60 min of incubation at 37°C, and later it was detected in cytoplasmic vesicles. To determine whether Ib associates with lipid rafts, we incubated MDCK cells with Ib at 4 or 37°C and fractionated the Triton-insoluble membranes. An Ib complex of 500 kDa was localized at 37°C to the insoluble fractions that fulfilled the criteria of lipid rafts, but it did not form at 4°C. The amount of complex in the raft fraction reached a maximum after 60 min of incubation at 37°C. When the cells that were preincubated with Ib at 4°C were incubated at 37°C, the complex was detected in the raft fraction. The treatment of MDCK cells with methyl-β-cyclodextrin reduced the localization of the Ib complex to the rafts and the rounding of the cells induced by Ia plus Ib. When
125
I-labeled Ia was incubated with the cells in the presence of Ib at 37°C, it was localized in the raft fraction. Surface plasmon resonance analysis revealed that Ia binds to the oligomer of Ib. We conclude that Ib binds to a receptor in membranes and then moves to rafts and that Ia bound to the oligomer of Ib formed in the rafts is internalized.
Tyrosine Kinase Inhibition Reduces Inflammation in the Acute Stage of Experimental Pneumococcal Meningitis
Authors: Angstwurm Klemens , Hanisch Uwe-Karsten , Gassemi Tarraneh , Bille Margrethe Bastholm , Prinz Marco , Dirnagl Ulrich , Kettenmann Helmut , Weber Joerg R. 
Published: May 2004

ABSTRACTBacterial meningitis is an acute inflammatory disease of the central nervous system with a mortality rate of up to 30%. Excessive stimulation of the host immune system by bacterial surface components contributes to this devastating outcome. In vitro studies have shown that protein tyrosine kinase inhibitors are highly effective in preventing the release of proinflammatory cytokines induced by pneumococcal cell walls in microglia. In a well-established rat model, intracisternal injection of purified pneumococcal cell walls induced meningitis characterized by increases in the regional cerebral blood flow and intracranial pressure, an influx of leukocytes, and high concentrations of tumor necrosis factor alpha (TNF-α) in the cerebrospinal fluid. Compared with the values at the beginning of the experiment, intraperitoneal injection of tyrphostin AG 126 reduced the increases in regional cerebral blood flow (at 6 h, 127% ± 14% versus 222% ± 51% of the baseline value;P< 0.05) and intracranial pressure (at 6 h, 0.8 ± 2.4 versus 5.4 ± 2.0 mm of Hg;P< 0.05), the influx of leukocytes (at 6 h, 1,336 ± 737 versus 4,350 ± 2,182 leukocytes/μl;P< 0.05), and the TNF-α concentration (at 6 h, 261 ± 188 versus 873 ± 135 pg/μl;P< 0.05). These results demonstrate that inhibition of AG 126-sensitive tyrosine kinase pathways may provide new approaches for preventing excessive inflammation and reducing the increases in blood flow and intracranial pressure in the acute phase of bacterial meningitis.
Bacterial Probiotic Modulation of Dendritic Cells
Authors: Drakes Maureen , Blanchard Thomas , Czinn Steven 
Published: May 2004

ABSTRACTIntestinal dendritic cells are continually exposed to ingested microorganisms and high concentrations of endogenous bacterial flora. These cells can be activated by infectious agents and other stimuli to induce T-cell responses and to produce chemokines which recruit other cells to the local environment. Bacterial probiotics are of increasing use against intestinal disorders such as inflammatory bowel disease. They act as nonpathogenic stimuli within the gut to regain immunologic quiescence. This study was designed to determine the ability of a bacterial probiotic cocktail VSL#3 to alter cell surface antigen expression and cytokine production in bone marrow-derived dendritic cell-enriched populations. Cell surface phenotype was monitored by monoclonal fluorescent antibody staining, and cytokine levels were quantitated by enzyme-linked immunosorbent assay. High-dose probiotic upregulated the expression of C80, CD86, CD40, and major histocompatibility complex class II I-Ad. Neither B7-DC or B7RP-1 was augmented after low-dose probiotic orLactobacillus caseitreatment, but B7RP-1 showed increased expression on dendritic cells stimulated with the gram-negative bacteriumEscherichia coli. Functional studies showed that probiotic did not enhance the ability of dendritic cells to induce allogeneic T-cell proliferation, as was observed forE. coli. Substantial enhancement of interleukin-10 release was observed in dendritic cell-enriched culture supernatants after 3 days of probiotic stimulation. These results demonstrate that probiotics possess the ability to modulate dendritic cell surface phenotype and cytokine release in granulocyte-macrophage colony-stimulating factor-stimulated bone marrow-derived dendritic cells. Regulation of dendritic cell cytokines by probiotics may contribute to the benefit of these molecules in treatment of intestinal diseases.
Associations between Responses to the Rhoptry-Associated Membrane Antigen of
Plasmodium falciparum
and Immunity to Malaria Infection
Authors: Topolska Agnieszka E. , Richie Thomas L. , Nhan Doan Hanh , Coppel Ross L. 
Published: May 2004

ABSTRACT

Rhoptry proteins participate in the invasion of red blood cells by merozoites during the malaria parasite's asexual-stage cycle. Interference with the rhoptry protein function has been shown to prevent invasion, and three rhoptry proteins have been suggested as potential components of a vaccine against malaria. Rhoptry-associated membrane antigen (RAMA) is a 170-kDa protein of
Plasmodium falciparum
which is processed to a 60-kDa mature form in the rhoptries. p60/RAMA is discharged from rhoptries of free merozoites and binds to the red-cell membrane before being internalized to form part of the parasitophorous vacuole of the newly developing ring. We examined the range of anti-RAMA responses in individuals living in an area of endemicity for malaria and determined its association with clinical immunity. RAMA is immunogenic during infections, and at least three epitopes within RAMA are recognized by hyperimmune sera in immunoblots. Sera from individuals living in a region of Vietnam where malaria is endemic possessed strong antibody responses toward two C-terminal regions of RAMA. Cytophilic antibody isotypes (immunoglobulin G1 [IgG1] and IgG3) predominated in humoral responses to both C-terminal epitopes. Acute episodes of
P. falciparum
infection result in significant boosting of levels of antibody to an epitope at the extreme C terminus of RAMA that harbors the red-cell-binding domain. Immunity to
P. falciparum
infection was linked to elevated levels of IgG3 responses to this functional domain of RAMA, suggesting that the region may contain a protective epitope useful for inclusion in a multiepitope vaccine against malaria.
Mucosal Vaccine Made from Live, RecombinantLactococcus lactisProtects Mice against Pharyngeal Infection withStreptococcus pyogenes
Authors: Mannam Praveen , Jones Kevin F. , Geller Bruce L. 
Published: May 2004

ABSTRACTA novel vaccine (LL-CRR) made from live, nonpathogenicLactococcus lactisthat expresses the conserved C-repeat region (CRR) of M protein fromStreptococcus pyogenesserotype 6 was tested in mice. Nasally vaccinated mice produced CRR-specific salivary immunoglobulin A (IgA) and serum IgG. Subcutaneously vaccinated mice produced CRR-specific serum IgG but not salivary IgA. A combined regimen produced responses similar to the salivary IgA of nasally vaccinated mice and serum IgG of subcutaneously vaccinated mice. Mice vaccinated nasally or with the combined regimen were significantly protected against pharyngeal infection following a nasal challenge withS. pyogenesM serotype 14. Mice vaccinated subcutaneously were not protected against pharyngeal infection. Mice in all three LL-CRR vaccination groups were significantly protected against the lethal effects ofS. pyogenes. Only 1 of 77 challenged mice that were vaccinated with LL-CRR died, whereas 60 of 118 challenged mice that were vaccinated with a control strain or phosphate-buffered saline died. In conclusion, mucosal vaccination with LL-CRR produced CRR-specific salivary IgA and serum IgG, prevented pharyngeal infection withS. pyogenes, and promoted survival.
Surface Plasmon Resonance Analysis of Antipolysaccharide Antibody Specificity: Responses to Meningococcal Group C Conjugate Vaccines and Bacteria
Authors: García-Ojeda Pablo A. , Hardy Sharon , Kozlowski Steven , Stein Kathryn E. , Feavers Ian M. 
Published: May 2004

ABSTRACTAntibody (Ab) responses to polysaccharides (PS), such asNeisseria meningitidisgroup C PS (MCPS), are characterized as being thymus independent and are restricted with regard to clonotype and isotype expression. PS conjugated to proteins, e.g., MCPS coupled with tetanus toxoid or the diphtheria toxin derivative CRM197, elicit thymus-dependent responses. The present study developed a surface plasmon resonance approach to evaluate Ab responses to MCPS conjugate vaccines, including either O-acetylated (OAc+) or de-O-acetylated (OAc−) forms of the PS. The results were generally consistent with those obtained by enzyme-linked immunosorbent assay and showed that sera from mice immunized with conjugate vaccines contain Abs that bind more effectively to OAc+and OAc−MCPS than sera from mice immunized with fixed bacteria. The data suggest a critical shared or overlapping epitope recognized by all the conjugate vaccine immune sera and strategies for assessing polyclonal Ab avidity.
Role of Transferrin Receptor from a
Neisseria meningitidis tbpB
Isotype II Strain in Human Transferrin Binding and Virulence
Authors: Renauld-Mongénie Geneviève , Poncet David , Mignon Michèle , Fraysse Sophie , Chabanel Christophe , Danve Bernard , Krell Tino , Quentin-Millet Marie-José 
Published: May 2004

ABSTRACT

Neisseria meningitidis
acquires iron through the action of the transferrin (Tf) receptor, which is composed of the Tf-binding proteins A and B (TbpA and TbpB). Meningococci can be classified into isotype I and II strains depending on whether they harbor a type I or II form of TbpB. Both types of TbpB have been shown to differ in their genomic, biochemical, and antigenic properties. Here we present a comparative study of isogenic mutants deficient in either or both Tbps from the isotype I strain B16B6 and isotype II strain M982. We show that TbpA is essential in both strains for iron uptake and growth with iron-loaded human Tf as a sole iron source. No growth has also been observed for the TbpB
−
mutant of strain B16B6, as shown previously, whereas the growth of the analogous mutant in M982 was similar to that in the wild type. This indicates that TbpB in the latter strain plays a facilitating but not essential role in iron uptake, which has been observed previously in similar studies of other bacteria. These data are discussed in relation to the fact that isotype II strains represent more than 80% of serogroup B meningococcal strains. The contribution of both subunits in the bacterial virulence of strain M982 has been assessed in a murine model of bacteremia. Both the TbpB
−
TbpA
−
mutant and the TbpA
−
mutant are shown to be nonvirulent in mice, whereas the virulence of the TbpB
−
mutant is similar to that of the wild type.
Contribution of Immunological Memory to Protective Immunity Conferred by a
Bacillus anthracis
Protective Antigen-Based Vaccine
Authors: Marcus Hadar , Danieli Rachel , Epstein Eyal , Velan Baruch , Shafferman Avigdor , Reuveny Shaul 
Published: May 2004

ABSTRACT

Protective antigen (PA)-based vaccination is an effective countermeasure to anthrax infection. While neutralizing anti-PA antibody titers elicited by this vaccine serve as good correlates for protection against anthrax (S. Reuveny, M. D. White, Y. Y. Adar, Y. Kafri, Z. Altboum, Y. Gozes, D. Kobiler, A. Shafferman, and B. Velan, Infect. Immun.
69:
2888-2893, 2001), no data are available on the contribution of the immunological memory for PA itself to protection. We therefore developed a guinea pig model in which a primary immunization with threshold levels of PA can induce a long-term T-cell immunological memory response without inducing detectable anti-PA antibodies. A revaccination of primed animals with the same threshold PA levels was effective for memory activation, yielding a robust and rapid secondary response. A challenge with a lethal dose (40 50% lethal doses; 2,000 spores) of spores after the booster vaccinations indicated that animals were not protected at days 2, 4, and 6 postboosting. Protection was achieved only from the 8th day postboosting, concomitant with the detection of protective levels of neutralizing antibody titers in the circulation. The practical implications from the studies reported herein are that, as expected, the protective capacity of memory depends on the PA dose used for the primary immunization and that the effectiveness of booster immunizations for the postexposure treatment of anthrax may be very limited when no detectable antibodies are present in primed animals prior to
Bacillus anthracis
spore exposure. Therefore, to allow for the establishment of memory-dependent protection prior to the expected onset of disease, booster immunizations should not be used without concomitant antimicrobial treatment in postexposure scenarios.
Identification of a Novel Two-Component System inStreptococcus gordoniiV288 Involved in Biofilm Formation
Authors: Zhang Yongshu , Lei Yu , Khammanivong Ali , Herzberg Mark C. 
Published: May 2004

ABSTRACTStreptococcus gordoniiis a pioneer colonizer of the teeth, contributing to the initiation of the oral biofilm called dental plaque. To identify genes that may be important in biofilm formation, a plasmid integration library ofS. gordoniiV288 was used. After screening for in vitro biofilm formation on polystyrene, a putative biofilm-defective mutant was isolated. In this mutant, pAK36 was inserted into a locus encoding a novel two-component system (bfr[biofilm formation related]) with two cotranscribed genes that form an operon.bfrAencodes a putative response regulator, whilebfrBencodes a receptor histidine kinase. Thebfrmutant and wild-type strain V288 showed similar growth rates in Todd-Hewitt broth (THB). Abfr-catfusion strain was constructed. During growth in THB, the reporter activity (chloramphenicol acetyltransferase) was first detected in mid-log phase and reached a maximum in stationary phase, suggesting that transcription ofbfrwas growth stage dependent. After being harvested from THB, thebfrmutant adhered less effectively than did wild-type strain V288 to saliva-coated hydroxyapatite (sHA). To simulate pioneer colonization of teeth,S. gordoniiV288 was incubated with sHA for 4 h in THB with 10% saliva to develop biofilms. RNA was isolated, and expression ofbfrABwas estimated. In comparison to that of cells grown in suspension (free-growing cells),bfrmRNA expression by sessile cells on sHA was 1.8-fold greater and that by surrounding planktonic cells was 3.5-fold greater. Therefore,bfrABis a novel two-component system regulated in association withS. gordoniibiofilm formation in vitro.
The Novel Fibrinogen-Binding Protein FbsB PromotesStreptococcus agalactiaeInvasion into Epithelial Cells
Authors: Gutekunst Heike , Eikmanns Bernhard J. , Reinscheid Dieter J. 
Published: May 2004

ABSTRACTStreptococcus agalactiaeis a major cause of bacterial sepsis and meningitis in human newborns. The interaction ofS. agalactiaewith host proteins and the entry into host cells thereby represent important virulence traits of these bacteria. The present report describes the identification of thefbsBgene, encoding a novel fibrinogen-binding protein that plays a crucial role in the invasion ofS. agalactiaeinto human cells. In Western blots and enzyme-linked immunosorbent assay (ELISA) experiments, the FbsB protein was demonstrated to interact with soluble and immobilized fibrinogen. Binding studies showed the N-terminal 388 residues of FbsB and the Aα-subunit of human fibrinogen to recognize each other. By reverse transcription (RT)-PCR, thefbsBgene was shown to be cotranscribed with thegbs0851gene inS. agalactiae. Deletion of thefbsBgene in the genome ofS. agalactiaedid not influence the binding of the bacteria to fibrinogen, suggesting that FbsB does not participate in the attachment ofS. agalactiaeto fibrinogen. In tissue culture experiments, however, thefbsBdeletion mutant was severely impaired in its invasion into lung epithelial cells. Bacterial invasion could be reestablished by introducing thefbsBgene on a shuttle plasmid into thefbsBdeletion mutant. Furthermore, treatment of lung epithelial cells with FbsB fusion protein blockedS. agalactiaeinvasion of epithelial cells in a dose-dependent fashion. These results suggest an important role of the FbsB protein in the overall process of host cell entry byS. agalactiae.
Effect of Antibody on the Rickettsia-Host Cell Interaction
Authors: Feng Hui-Min , Whitworth Ted , Popov Vsevolod , Walker David H. 
Published: May 2004

ABSTRACTA recent study demonstrated that polyclonal antibodies toRickettsia conoriiand monoclonal antibodies to outer membrane proteins A (OmpA) and B (OmpB) provided effective, Fc-dependent, passive immunity, even in severe combined immunodeficient mice with an established infection. In order to determine the mechanism of protection, mouse endothelial and macrophage-like cell lines were infected withR. conoriithat had been exposed to polyclonal antibodies, monoclonal antibodies to OmpA or OmpB, Fab fragments of the polyclonal antibodies, or normal serum or that were left untreated. At 0 h, Fc-dependent antibody enhancement ofR. conoriiadherence to endothelial and macrophage-like cell lines was inhibited by the presence of normal serum, suggesting Fc receptor-mediated adherence of opsonized rickettsiae. At 3 h, the opsonized rickettsiae had been internalized. After 72 h, inhibited survival of rickettsiae exposed to polyclonal antibodies or monoclonal antibodies to OmpA or OmpB was evident compared with growth of untreated and normal serum-treated and polyclonal Fab antibody-treatedR. conorii. Polyclonal antibodies and an anti-OmpB monoclonal antibody inhibited the escape ofR. conoriifrom the phagosome, resulting in intraphagolysosomal rickettsial death. At 48 h of infection, rickettsicidal activity of macrophages by opsonized rickettsiae was inhibited by NG-monomethyl-l-arginine, superoxide dismutase, mannitol, or supplementall-tryptophan, and endothelial rickettsicidal activity against opsonized rickettsiae was inhibited by NG-monomethyl-l-arginine, superoxide dismutase, catalase, or supplementall-tryptophan. Thus, Fc-dependent antibodies protected againstR. conoriiinfection of endothelium and macrophages by opsonization that inhibited phagosomal escape and resulted in phagolysosomal killing mediated by nitric oxide, reactive oxygen intermediates, andl-tryptophan starvation.
Geographical and Temporal Conservation of Antibody Recognition of
Plasmodium falciparum
Variant Surface Antigens
Authors: Nielsen Morten A. , Vestergaard Lasse S. , Lusingu John , Kurtzhals Jørgen A. L. , Giha Haider A. , Grevstad Berit , Goka Bamenla Q. , Lemnge Martha M. , Jensen James B. , Akanmori Bartholomew D. , Theander Thor G. , Staalsoe Trine , Hviid Lars 
Published: May 2004

ABSTRACT

The slow acquisition of protection against
Plasmodium falciparum
malaria probably reflects the extensive diversity of important antigens. The variant surface antigens (VSA) that mediate parasite adhesion to a range of host molecules are regarded as important targets of acquired protective immunity, but their diversity makes them questionable vaccine candidates. We determined levels of VSA-specific immunoglobulin G (IgG) in human plasma collected at four geographically distant and epidemiologically distinct localities with specificity for VSA expressed by
P. falciparum
isolates from three African countries. Plasma levels of VSA-specific IgG recognizing individual parasite isolates depended on the transmission intensity at the site of plasma collection but were largely independent of the geographical origin of the parasites. The total repertoire of immunologically distinct VSA thus appears to be finite and geographically conserved, most likely due to functional constraints. Furthermore, plasma samples frequently had high IgG reactivity to VSA expressed by parasites isolated more than 10 years later, showing that the repertoire is also temporally stable. Parasites from patients with severe malaria expressed VSA (VSA
SM
) that were better recognized by plasma IgG than VSA expressed by other parasites, but importantly, VSA
SM
-type antigens also appeared to show substantial antigenic homogeneity. Our finding that the repertoire of immunologically distinct VSA in general, and in particular that of VSA
SM
, is geographically and temporally conserved raises hopes for the feasibility of developing VSA-based vaccines specifically designed to accelerate naturally acquired immunity, thereby enhancing protection against severe and life-threatening
P. falciparum
malaria.
CpG Oligodeoxynucleotides Improve the Survival of Pregnant and Fetal Mice followingListeria monocytogenesInfection
Authors: Ito Shu-ichi , Ishii Ken J. , Shirota Hidekazu , Klinman Dennis M. 
Published: May 2004

ABSTRACTListeria infection during pregnancy can cause the death of both mother and fetus. Previous studies established that immunostimulatory CpG oligodeoxynucleotides (ODN) increase the resistance of healthy adult mice to many infectious pathogens, includingListeria monocytogenes. This study examines whether the innate immune response elicited by CpG ODN can reduce the susceptibility of pregnant mice to lethal listeria challenge. The results indicate that CpG ODN treatment significantly improves maternal survival and reduces pathogen transmission to offspring. CpG ODN administered during pregnancy did not induce abortion, birth defects, or reduce the size or health of litters. These findings suggest that CpG ODN may provide a safe and effective means of improving the health of mothers and fetuses during pregnancy.