bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Mycobacterial Heparin-Binding Hemagglutinin Is a Protective Antigen in the Mouse Aerosol Challenge Model of Tuberculosis
Authors: Parra Marcela , Pickett Thames , Delogu Giovanni , Dheenadhayalan Veerabadran , Debrie Anne-Sophie , Locht Camille , Brennan Michael J. 
Published: November 2004

ABSTRACT

The heparin-binding hemagglutinin (HBHA) of
Mycobacterium tuberculosis
is a surface-expressed adhesin that can affect binding to host cells via a unique, methylated, carboxyl-terminal, lysine-, alanine-, and proline-rich repeat region. It has been implicated in extrapulmonary dissemination of
M. tuberculosis
from the lung following the initial infection of the host. To assess the vaccine potential of this protein, purified preparations of HBHA were emulsified in a dimethyldioctadecylammonium bromide-monophosphoryl lipid A adjuvant and tested for the ability to reduce
M. tuberculosis
infection in the mouse aerosol challenge model for tuberculosis. The HBHA-containing vaccine gave a ∼0.7-log reduction in CFU in both mouse lungs and spleens compared to adjuvant controls 28 days following challenge. Although a notable level of serum antibody to HBHA was elicited after three immunizations and the antibodies were able to bind to the surface of
M. tuberculosis
, passive immunization with monoclonal antibodies directed against HBHA did not protect in the challenge model. Compared to adjuvant controls, an elevated gamma interferon response was generated by splenic and lymph node-derived T cells from immunized mice in the presence of macrophages pulsed with purified HBHA or infected with live
M. tuberculosis
, suggesting that the effective immunity may be cell mediated. Efforts to construct effective recombinant HBHA vaccines in fast-growing
Mycobacterium smegmatis
have been unsuccessful so far, which indicates that distinctive posttranslational modifications present in the HBHA protein expressed by
M. tuberculosis
are critical for generating effective host immune responses. The vaccine studies described here demonstrate that HBHA is a promising new vaccine candidate for tuberculosis.
Vesicular Transport Is Not Required for the Cytoplasmic Pool of Cholera Toxin To Interact with the Stimulatory Alpha Subunit of the Heterotrimeric G Protein
Authors: Teter Ken , Jobling Michael G. , Holmes Randall K. 
Published: November 2004

ABSTRACT
Cholera toxin (CT) moves from the cell surface to the endoplasmic reticulum (ER) by retrograde vesicular transport. The catalytic A1 polypeptide of CT (CTA1) then crosses the ER membrane, enters the cytosol, ADP-ribosylates the stimulatory α subunit of the heterotrimeric G protein (Gsα) at the cytoplasmic face of the plasma membrane, and activates adenylate cyclase. The cytosolic pool of CTA1 may reach the plasma membrane and its Gsα target by traveling on anterograde-directed transport vesicles. We examined this possibility with the use of a plasmid-based transfection system that directed newly synthesized CTA1 to either the ER lumen or the cytosol of CHO cells. Such a system allowed us to bypass the CT retrograde trafficking itinerary from the cell surface to the ER. Previous work has shown that the ER-localized pool of CTA1 is rapidly exported from the ER to the cytosol. Expression of CTA1 in either the ER or the cytosol led to the activation of Gsα, and Gsα activation was not inhibited in transfected cells exposed to drugs that inhibit vesicular traffic. Thus, anterograde transport from the ER to the plasma membrane is not required for the cytotoxic action of CTA1.
Analysis of the Immune Response toMycobacterium aviumsubsp.paratuberculosisin Experimentally Infected Calves
Authors: Koo Hye Cheong , Park Yong Ho , Hamilton Mary Jo , Barrington George M. , Davies Christopher J. , Kim Jong Bae , Dahl John L. , Waters W. Ray , Davis William C. 
Published: November 2004

ABSTRACTJohne's disease of cattle is widespread and causes significant economic loss to producers. Control has been hindered by limited understanding of the immune response to the causative agent,Mycobacterium aviumsubsp.paratuberculosis, and lack of an effective vaccine and sensitive specific diagnostic assays. The present study was conducted to gain insight into factors affecting the immune response toM. aviumsubsp.paratuberculosis. A persistent proliferative response toM. aviumsubsp.paratuberculosispurified protein derivative and solubleM. aviumsubsp.paratuberculosisantigens was detected in orally infected neonatal calves 6 months postinfection (p.i.) by flow cytometry (FC). CD4+T cells with a memory phenotype (CD45R0+) expressing CD25 and CD26 were the predominant cell type responding to antigens. Few CD8+T cells proliferated in response to antigens until 18 months p.i. γδ T cells did not appear to respond to antigen until 18 months p.i. The majority of WC1+CD2−and a few WC1−CD2+γδ T cells expressed CD25 at time zero. By 18 months, however, subsets of γδ T cells from both control and infected animals showed an increase in expression of CD25, ACT2, and CD26 in the presence of the antigens. Two populations of CD3−non-T non-B null cells, CD2+and CD2−, proliferated in cell cultures from some control and infected animals during the study, with and without antigen. The studies clearly show multicolor FC offers a consistent reliable way to monitor the evolution and changes in the immune response toM. aviumsubsp.paratuberculosisthat occur during disease progression.
Fine Mapping of the N-Terminal Cytotoxicity Region of
Clostridium perfringens
Enterotoxin by Site-Directed Mutagenesis
Authors: Smedley James G. , McClane Bruce A. 
Published: November 2004

ABSTRACT

Clostridium perfringens
enterotoxin (CPE) has a unique mechanism of action that results in the formation of large, sodium dodecyl sulfate-resistant complexes involving tight junction proteins; those complexes then induce plasma membrane permeability alterations in host intestinal epithelial cells, leading to cell death and epithelial desquamation. Previous deletion and point mutational studies mapped CPE receptor binding activity to the toxin's extreme C terminus. Those earlier analyses also determined that an N-terminal CPE region between residues D45 and G53 is required for large complex formation and cytotoxicity. To more finely map this N-terminal cytotoxicity region, site-directed mutagenesis was performed with recombinant CPE (rCPE). Alanine-scanning mutagenesis produced one rCPE variant, D48A, that failed to form large complexes or induce cytotoxicity, despite having normal ability to bind and form the small complex. Two saturation variants, D48E and D48N, also had a phenotype resembling that of the D48A variant, indicating that both size and charge are important at CPE residue 48. Another alanine substitution rCPE variant, I51A, was highly attenuated for large complex formation and cytotoxicity, but rCPE saturation variants I51L and I51V displayed a normal large complex formation and cytotoxicity phenotype. Collectively, these mutagenesis results identify a core CPE sequence extending from residues G47 to I51 that directly participates in large complex formation and cytotoxicity.
TheLeishmania majorLACK Antigen with an Immunodominant Epitope at Amino Acids 156 to 173 Is Not Required for Early Th2 Development in BALB/c Mice
Authors: Kelly Ben L. , Locksley Richard M. 
Published: November 2004

ABSTRACTTheLeishmania majorLACK antigen contains an immunodominant epitope at amino acids 156 to 173 (LACK156-173) that is believed to nucleate the pathological Th2 immune response in susceptible BALB/c mice. To test this hypothesis, we generatedL. majorparasites that express a mutated LACK that fails to activate Vβ4/Vα8 T-cell receptor transgenic T cells specific for this epitope. Although mutant parasites attenuated the expansion of endogenous LACK-specific, interleukin-4 (IL-4)-expressing, CD4 T cells compared to wild-type parasites in vivo, the overall frequency of IL-4 and gamma interferon-secreting lymphocytes was similar to that elicited by wild-typeL. major. Mutant parasites demonstrated diminished amastigote viability and delayed lesion development in mice, although parasites could be recovered over 200 days after infection. Complementation with a wild-typelackfusion construct partially rescued these defects, indicating a role for endogenous LACK in parasitism. Mice inoculated with mutant parasites were not protected against subsequent infection with wild-typeL. major.
Hemozoin Differentially Regulates Proinflammatory Cytokine Production in Human Immunodeficiency Virus-Seropositive and -Seronegative Women with Placental Malaria
Authors: Moore Julie M. , Chaisavaneeyakorn Sujittra , Perkins Douglas J. , Othoro Caroline , Otieno Juliana , Nahlen Bernard L. , Shi Ya Ping , Udhayakumar Venkatachalam 
Published: November 2004

ABSTRACT

Pregnant women are at an increased risk for malarial infection.
Plasmodium falciparum
accumulates in the placenta and is associated with dysregulated immune function and poor birth outcomes. Malarial pigment (hemozoin) also accumulates in the placenta and may modulate local immune function. In this study, the impact of hemozoin on cytokine production by intervillous blood mononuclear cells from malaria-infected placentas was investigated. There was a dose-dependent, suppressive effect of hemozoin on production of gamma interferon (IFN-γ), with less of an effect on tumor necrosis factor alpha (TNF-α) and interleukin-10, in human immunodeficiency virus-seronegative (HIV
−
) women. In contrast, IFN-γ and TNF-α production tended to increase in HIV-seropositive women with increasing hemozoin levels. Production patterns of cytokines, especially IFN-γ in HIV
−
women, followed different trends as a function of parasite density and hemozoin level. The findings suggest that the influences of hemozoin accumulation and high-density parasitemia on placental cytokine production are not equivalent and may involve different mechanisms, all of which may operate differently in the context of HIV infection. Cytokine production dysregulated by accumulation of hemozoin or high-density parasitemia may induce pathology and impair protective immunity in HIV-infected and -uninfected women.
Yersinia enterocoliticaInduces Apoptosis and Inhibits Surface Molecule Expression and Cytokine Production in Murine Dendritic Cells
Authors: Erfurth Stella E. , Gröbner Sabine , Kramer Uwe , Gunst Dani S. J. , Soldanova Irena , Schaller Martin , Autenrieth Ingo B. , Borgmann Stefan 
Published: November 2004

ABSTRACTYersinia enterocoliticaevades innate immunity by expression of a variety of pathogenicity factors. Therefore, adaptive immunity including CD4+T cells plays an important role in defense againstY. enterocolitica. We investigated whetherY. enterocoliticamight target dendritic cells (DC) involved in adaptive T-cell responses. For this purpose, murine DC were infected withY. enterocoliticawild-type and mutant strains prior to incubation with ovalbumin (OVA) as antigen and 5-(6)-carboxyfluorescein diacetateN-succinimidyl ester-labeled OVA-specific T cells from DO11.10 mice. While T-cell proliferation was partially affected by infection of DC with plasmid-cured and YopP-deficientYersiniamutant strains, no T-cell proliferation occurred after infection of DC with wild-typeY. enterocolitica. Infection of DC withY. enterocoliticawild type resulted in decreased up-regulation of major histocompatibility complex class II, CD54 (intercellular adhesion molecule 1), CD 80, and CD86 expression. Experiments with plasmid-curedY. enterocoliticaor a YopP-deficient mutant strain revealed that YopP accounts for inhibition of surface molecule expression. Wild-typeY. enterocoliticasuppressed the release of KC, tumor necrosis factor alpha, interleukin-10 (IL-10), and IL-12 by DC, while infection of DC with plasmid-curedY. enterocoliticaor with the YopP-deficient mutant resulted in the production of these cytokines. Moreover, infection with wild-typeY. enterocoliticainduced apoptosis in DC mediated by YopP. Apoptosis occurred despite translocation of NF-κB to the nucleus, as demonstrated by electromobility shift assays. Together, these data demonstrate thatY. enterocoliticatargets functions of murine DC that are required for T-cell activation. This might contribute to evasion of adaptive immune responses byY. enterocolitica.
Antigenicity and Immunogenicity of a Synthetic Oligosaccharide-Protein Conjugate Vaccine against
Haemophilus influenzae
Type b
Authors: Fernández-Santana V. , Cardoso Félix , Rodriguez Arlene , Carmenate Tania , Peña Luis , Valdés Yuri , Hardy Eugenio , Mawas Fatme , Heynngnezz Lazaro , Rodríguez Maria C. , Figueroa Ignacio , Chang Janoi , Toledo Maria E. , Musacchio Alexis , Hernández Ibis , Izquierdo Mabel , Cosme Karelia , Roy Rene , Verez-Bencomo V. 
Published: November 2004

ABSTRACT

Polysaccharide-protein conjugates as vaccines have proven to be very effective in preventing
Haemophilus influenzae
type b infections in industrialized countries. However, cost-effective technologies need to be developed for increasing the availability of anti-
H. influenzae
type b vaccines in countries from the developing world. Consequently, vaccine production with partially synthetic antigens is a desirable goal for many reasons. They may be rigidly controlled for purity and effectiveness while at the same time being cheap enough that they may be made universally available. We describe here the antigenicity and immunogenicity of several
H. influenzae
type b synthetic oligosaccharide-protein conjugates in laboratory animals. The serum of
H. influenzae
type b-immunized animals recognized our synthetic
H. influenzae
type b antigens to the same extent as the native bacterial capsular polysaccharide. Compared to the anti-
H. influenzae
type b vaccine employed, these synthetic versions induced similar antibody response patterns in terms of titer, specificity, and functional capacity. The further development of synthetic vaccines will meet urgent needs in the less prosperous parts of the world and remains our major goal.
Diversity and Host Range of Shiga Toxin-Encoding Phage
Authors: Gamage Shantini D. , Patton Angela K. , Hanson James F. , Weiss Alison A. 
Published: November 2004

ABSTRACT

Shiga toxin 2 (Stx2) from the foodborne pathogen
Escherichia coli
O157:H7 is encoded on a temperate bacteriophage. Toxin-encoding phages from C600::933W and from six clinical
E. coli
O157:H7 isolates were characterized for PCR polymorphisms, phage morphology, toxin production, and lytic and lysogenic infection profiles on O157 and non-O157 serotype
E. coli
. The phages were found to be highly variable, and even phages isolated from strains with identical pulsed-field gel electrophoresis profiles differed. Examination of cross-plaquing and lysogeny profiles further substantiated that each phage is distinct; reciprocal patterns of susceptibility and resistance were not observed and it was not possible to define immunity groups. The interaction between Shiga toxin-encoding phage and intestinal
E. coli
was examined. Lytic infection was assessed by examining Shiga toxin production following overnight incubation with phage. While not common, lytic infection was observed, with a more-than-1,000-fold increase in Stx2 seen in one case, demonstrating that commensal
E. coli
cells can amplify Shiga toxin if they are susceptible to infection by the Shiga toxin-encoding phages. Antibiotic-resistant derivatives of the Stx2-encoding phages were used to examine lysogeny. Different phages were found to lysogenize different strains of intestinal
E. coli
. Lysogeny was found to occur more commonly than lytic infection. The presence of a diverse population of Shiga toxin-encoding phages may increase the pathogenic fitness of
E. coli
O157:H7.
Characterization of a Defensin from the Sand Fly
Phlebotomus duboscqi
Induced by Challenge with Bacteria or the Protozoan Parasite
Leishmania major
Authors: Boulanger Nathalie , Lowenberger Carl , Volf Petr , Ursic Raul , Sigutova Lucie , Sabatier Laurence , Svobodova Milena , Beverley Stephen M. , Späth Gerald , Brun Reto , Pesson Bernard , Bulet Philippe 
Published: November 2004

ABSTRACT

Antimicrobial peptides are major components of the innate immune response of epithelial cells. In insect vectors, these peptides may play a role in the control of gut pathogens. We have analyzed antimicrobial peptides produced by the sand fly
Phlebotomus duboscqi
, after challenge by injected bacteria or feeding with bacteria or the protozoan parasite
Leishmania major
. A new hemolymph peptide with antimicrobial activity was identified and shown to be a member of the insect defensin family. Interestingly, this defensin exhibits an antiparasitic activity against the promastigote forms of
L. major
, which reside normally within the sand fly midgut.
P. duboscqi
defensin could be induced by both hemolymph or gut infections. Defensin mRNA was induced following infection by wild-type
L. major
, and this induction was much less following infections with
L. major
knockout mutants that survive poorly in sand flies, due to specific deficiencies in abundant cell surface glycoconjugates containing phosphoglycans (including lipophosphoglycan). The ability of gut pathogens to induce gut as well as fat body expression of defensin raises the possibility that this antimicrobial peptide might play a key role in the development of parasitic infections.
BBE02 Disruption Mutants of
Borrelia burgdorferi
B31 Have a Highly Transformable, Infectious Phenotype
Authors: Kawabata Hiroki , Norris Steven J. , Watanabe Haruo 
Published: November 2004

ABSTRACT

We constructed highly transformable and infectious
Borrelia burgdorferi
B31 by inactivating BBE02, a putative restriction-modification gene on the linear plasmid lp25. The low-passage-number B31 clones 5A4 (containing all plasmids) and 5A18 (lp28-4
−
lp56
−
) were used for this study, and BBE02 was disrupted by homologous recombination. The transformation efficiency with the shuttle vector pBSV2
C03
::
gntΔkan
was increased from <1 to ∼10 colonies per μg of DNA for 5A4 and 5A4 BBE02::Kan
r
and from 14 to approximately 600 colonies per μg of DNA for 5A18 and 5A18 BBE02::Kan
r
. lp25, which is required for infectivity in mice, was retained in BBE02 mutants transformed with pBSV2
C03
::
gntΔkan
, but lp25 was not detected in transformants of the parental clones 5A4 and 5A18. BBE02 disruptants and pBSV2
C03
::
gntΔkan
transformants of these clones remained infectious in C3H/HeN mice, and the 50% infective doses of the BBE02 disruptants were <10
2
organisms per mouse. The inactivation of BBE02 thus eliminates a transformation barrier for infectious
B. burgdorferi
B31 and will provide a valuable tool for studying the virulence factors of Lyme disease.
Distinct Roles of Reactive Nitrogen and Oxygen Species To Control Infection with the Facultative Intracellular BacteriumFrancisella tularensis
Authors: Lindgren Helena , Stenmark Stephan , Chen Wangxue , Tärnvik Arne , Sjöstedt Anders 
Published: November 2004

ABSTRACTReactive nitrogen species (RNS) and reactive oxygen species (ROS) are important mediators of the bactericidal host response. We investigated the contribution of these two mediators to the control of infection with the facultative intracellular bacteriumFrancisella tularensis. When intradermally infected with the live vaccine strainF. tularensisLVS, mice deficient in production of RNS (iNOS−/−mice) or in production of ROS by the phagocyte oxidase (p47phox−/−mice) showed compromised resistance to infection. The 50% lethal dose (LD50) for iNOS−/−mice was <20 CFU, and the LD50for p47phox−/−mice was 4,400 CFU, compared to an LD50of >500,000 CFU for wild-type mice. The iNOS−/−mice survived for 26.4 ± 1.8 days, and the p47phox−/−mice survived for 10.1 ± 1.3 days. During the course of infection, the serum levels of gamma interferon (IFN-γ) and interleukin-6 were higher in iNOS−/−and p47phox−/−mice than in wild-type mice. Histological examination of livers of iNOS−/−mice revealed severe liver pathology. Splenocytes obtained 5 weeks after primary infection from antibiotic-treated iNOS−/−mice showed an in vitro recall response that was similar in magnitude and greater secretion of IFN-γ compared to cells obtained from wild-type mice. In summary, mice lacking expression of RNS or ROS showed extreme susceptibility to infection withF. tularensisLVS. The roles of RNS and ROS seemed to be distinct since mice deficient in production of ROS showed dissemination of infection and died during the early phase of infection, whereas RNS deficiency led to severe liver pathology and a contracted course of infection.
Synovial Fibroblasts Infected with
Salmonella enterica
Serovar Typhimurium Mediate Osteoclast Differentiation and Activation
Authors: Zhang Xiang , Aubin Jane E. , Kim Tae-Hwan , Payne Ursula , Chiu Basil , Inman Robert D. 
Published: November 2004

ABSTRACT

The mechanisms whereby arthritogenic organisms may induce cartilage and bone erosions in infection-triggered arthritis remain unknown. In this study, we asked whether an arthritogenic organism could contribute to osteoclast differentiation and activation through regulation of the receptor activator of NF-κB ligand (RANKL) in synovial fibroblasts. Rat synovial fibroblasts were infected in vitro with
Salmonella enterica
serovar Typhimurium and monitored over time. The expression of RANKL in resting and infected synovial fibroblasts was quantified by reverse transcription-PCR and Western blotting. Osteoclast progenitors, isolated from femurs of 8-week-old rats and cultured in the presence of macrophage colony-stimulating factor, were cocultured with either infected or noninfected synovial fibroblasts for 2 to 4 days. Differentiation and maturation of osteoclasts were determined by morphology and tartrate-resistant acid phosphatase (TRAP) staining and by a bone resorption bioassay. RANKL expression was undetectable in resting synovial fibroblasts but was dose-dependently upregulated in cells after
Salmonella
infection. Osteoprotegerin was constitutively expressed by synovial fibroblasts and was not upregulated by infection. Further, we observed the formation of multinucleated TRAP-positive cells and formation of bone resorption pits in cocultures of bone marrow-derived osteoclast precursors with synovial fibroblasts infected with
Salmonella
but not with heat-killed
Salmonella
or noninfected cells. Arthritogenic bacteria may alter bone structure via synovial fibroblast intermediaries, since infected synovial fibroblasts (i) upregulate RANKL expression and (ii) enhance osteoclast precursor maturation into multinucleated, TRAP-positive, bone-resorbing, osteoclast-like cells. These data provide a link between infection and osteoclastogenesis. A better understanding of infection-mediated osteoclast differentiation and activation may provide new therapeutic strategies for inflammatory joint disease.
Intranasal Vaccination with Streptococcal Fibronectin Binding Protein Sfb1 Fails To Prevent Growth and Dissemination ofStreptococcus pyogenesin a Murine Skin Infection Model
Authors: McArthur J. , Medina E. , Mueller A. , Chin J. , Currie B. J. , Sriprakash K. S. , Talay S. R. , Chhatwal G. S. , Walker M. J. 
Published: November 2004

ABSTRACTFibronectin binding protein F1 (Sfb1) ofStreptococcus pyogenes(group A streptococcus [GAS]) is a well-characterized adhesin that has been shown to induce protection in mice against a lethal intranasal GAS challenge after intranasal immunization with cholera toxin B subunit (CTB) as adjuvant. With a murine skin infection model, we have shown that Sfb1/CTB vaccination neither elicits opsonizing antibodies nor prevents systemic bacterial growth and dissemination to internal organs after a subcutaneous GAS challenge. These results indicate that an Sfb1-based vaccine should be complemented with additional protective antigens in order to be used in areas such as the tropical north of Australia, where the skin is the primary route of entry for invasive streptococcal diseases.