bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of Staphylococcal Enterotoxin B-Induced Lymphocyte Proliferation and Tumor Necrosis Factor Alpha Secretion by MAb5, an Anti-Toxic Shock Syndrome Toxin 1 Monoclonal Antibody
Authors: Pang Liwina T. Y. , Kum Winnie W. S. , Chow Anthony W. 
Published: July 2002

ABSTRACTToxic shock syndrome (TSS) is primarily caused by toxic shock syndrome toxin-1 (TSST-1) and staphylococcal enterotoxin B (SEB). These toxins belong to a family of pyrogenic toxin superantigens (PTSAgs) produced byStaphylococcus aureusand exhibit several shared biological properties, including the induction of massive cytokine release and Vβ-specific T-cell proliferation. The crystal structures of most PTSAgs are now published, and they demonstrate a striking similarity in conformational architecture even though their primary protein sequences are different. Despite these structural and immunobiological similarities, no cross-reactivity between TSST-1 and other PTSAgs has been demonstrated in serological or neutralization assays. Our laboratory has developed a neutralizing murine anti-TSST-1 monoclonal antibody (MAb5) which displayed cross-reactivity with SEB by enzyme-linked immunosorbent assay. The aim of the present study was to evaluate whether MAb5 can also cross-neutralize SEB-induced superantigenic activities in vitro. MAb5 was found to partially inhibit SEB-induced T-cell mitogenesis (63%) and tumor necrosis factor alpha (TNF-α) secretion (70%) in human peripheral blood mononuclear cells (PBMC) in a dose-dependent manner, while an isotypic anti-TSST-1 monoclonal antibody showed no effect. Epitope mapping revealed that MAb5 bound to TSST-1 residues 47 to 56 (47FPSPYYSPAF56) and to SEB residues 83 to 92 (83DVFGANYYYQ92), sequences that located in different regions of these toxins and are structurally dissimilar. SEB peptide83DVFGANYYYQ92was synthesized and found to also inhibit SEB-induced mitogenesis and TNF-α secretion in human PBMC. Our results demonstrate for the first time that MAb5 binds to different epitopes on TSST-1 and SEB that appear functionally important in inducing T-cell mitogenesis and TNF-α secretion in vitro.
Toll-Like Receptors Confer Responsiveness to Lipopolysaccharide fromPorphyromonas gingivalisin Human Gingival Fibroblasts
Authors: Tabeta Kouich , Yamazaki Kazuhisa , Akashi Sachiko , Miyake Kensuke , Kumada Hidefumi , Umemoto Toshio , Yoshie Hiromasa 
Published: July 2002

ABSTRACTGingival fibroblasts produce proinflammatory cytokines in response to lipopolysaccharide (LPS) from periodontopathic bacteria. Recently it has become evident that the human homologue ofDrosophilaToll can transduce intracellular signaling by LPS stimulation. Toll-like receptors (TLRs) have been identified in myeloid cells; however, their role in nonmyeloid cells such as gingival fibroblasts has not been fully elucidated. Here, we report that human gingival fibroblasts constitutively express TLR2 and TLR4 and that their levels of expression are increased by stimulation with LPS fromPorphyromonas gingivalis. Upregulated expression of interleukin-6 gene and protein in fibroblasts stimulated with LPS is inhibited by anti-TLR4 antibody. These findings suggest that TLRs may confer responsiveness to LPS in gingival fibroblasts.
Importance of Holotoxin Assembly in Ptl-Mediated Secretion of Pertussis Toxin from
Bordetella pertussis
Authors: Farizo Karen M. , Huang Theresa , Burns Drusilla L. 
Published: July 2002

ABSTRACT

We examined the structural components of pertussis toxin that are required for efficient export from
Bordetella pertussis
via the Ptl system, a member of the type IV family of macromolecular transporters. First, we constructed a strain of
B. pertussis
that contains a functional Ptl system but does not produce pertussis toxin. Plasmids which express either the S1 subunit or the B oligomer were then introduced into this strain. We found that the B oligomer of the toxin is not secreted in the absence of the S1 subunit. Conversely, the S1 subunit is also not secreted by a Ptl-mediated mechanism in the absence of the B oligomer. Thus, an assembled holotoxin is required for Ptl-mediated export of pertussis toxin from
B. pertussis
.
Characterization of a Multigene Family Undergoing High-Frequency DNA Rearrangements and Coding for Abundant Variable Surface Proteins in
Mycoplasma agalactiae
Authors: Glew M. D. , Papazisi L. , Poumarat F. , Bergonier D. , Rosengarten R. , Citti C. 
Published: July 2002

ABSTRACT

A family of abundant surface proteins (Vpmas [variable proteins of
Mycoplasma agalactiae
]) undergoing phase variation in
M. agalactiae
has been characterized using monoclonal antibodies and specific polyclonal sera. Two expressed members of 39 kDa (Vpma39) and 34 kDa (Vpma34), which varied in expression between clones of a lineage, shared a common amino-terminal sequence but were immunologically distinct. An amino-terminal oligonucleotide probe identified multiple
vpma
genes which were clustered within a 14-kb
Cla
I genomic fragment. Rearrangements were found to have occurred within the
vpma
locus between clones which correlated with changes in their Vpma phenotype. Two neighboring
vpma
genes were cloned and sequenced from one
M. agalactiae
clonal variant expressing Vpma39. The two genes,
vpmaX
and
vpmaY
, were orientated divergently and shared highly homologous 5′ untranslated regions, 25-amino-acid (aa) lipoprotein leader sequences, and amino-terminal sequences. The
vpmaY
gene coded for 346 aa and 84% of the open reading frame, comprised of 1.5 units of a large repeat of 186 aa. Although the sequence for an entire second
vpmaY
repeat was present, it was prematurely terminated by insertion of two nucleotides. The
vpmaX
gene encoded 221 aa and possessed 102 aa of the 186-aa repeat of
vpmaY
. Many of the features in common between the
vpma
genes were also found to be shared by the
vsp
genes of
M. bovis
, which also undergo DNA rearrangements concomitant with phenotypic changes. Since
M. bovis
is the closest phylogenetic relative to
M. agalactiae
, the
vpma
and
vsp
gene families most probably represent homologous systems.
Human Response to
Escherichia coli
O157:H7 Infection: Antibodies to Secreted Virulence Factors
Authors: Li Yuling , Frey Elizabeth , Mackenzie Andrew M. R. , Finlay B. Brett 
Published: July 2002

ABSTRACT

Vaccination has been proposed for the prevention of disease due to enterohemorrhagic
Escherichia coli
(EHEC), but the immune response following human infection, including the choice of potential antigens, has not been well characterized. To study this, sera were obtained from five pediatric patients with acute diarrhea caused by
E. coli
O157:H7 0, 8, and 60 days after hospitalization. These sera were used to examine the immune response to four different EHEC virulence factors: Tir (translocated intimin receptor, which is inserted into the host cell membrane), intimin (bacterial outer membrane protein which binds to Tir), EspA (secreted protein which forms filamentous structures on EHEC surface), and EspB (inserted into the host membrane and cytoplasm). The response to O157:H7 lipopolysaccharide was also examined. Sera were assayed against purified recombinant proteins using immunoblot analysis and by enzyme-linked immunosorbent assay to determine the sera's titers to each of the antigens in all patients. We found that there was little reaction to EspA, EspB, and intimin in the acute-phase sera, although there was some reactivity to Tir. By day 8, titers of antibody to all four virulence factors were present in all patients, with a very strong response against Tir (up to a titer of 1:256,000), especially in hemolytic-uremic syndrome patients, and lesser strong responses to the other three antigens. The titer to the antigens 60 days after hospitalization was decreased but was still highest for Tir. These results suggest that there is a strong immune response to Tir, and to a lesser extent to the other three virulence factors, following EHEC disease, indicating that these bacterial molecules are potential vaccine candidates for preventing EHEC disease. They also suggest that bacterial virulence factors that are inserted into host cells during infection by type III secretion systems (Tir or EspB) are still recognized by the host immune response.
Intranasal Vaccination with Pneumococcal Surface Protein A and Interleukin-12 Augments Antibody-Mediated Opsonization and Protective Immunity againstStreptococcus pneumoniaeInfection
Authors: Arulanandam Bernard P. , Lynch Joyce M. , Briles David E. , Hollingshead Susan , Metzger Dennis W. 
Published: July 2002

ABSTRACTStreptococcus pneumoniaeis a major pathogen in humans that enters the host primarily through the respiratory tract. Targeting mucosal surfaces directly may therefore be an optimal approach for vaccination to prevent bacterial colonization and invasive disease. We have previously demonstrated the effectiveness of interleukin-12 (IL-12) delivered intransally (i.n.) as an antiviral respiratory adjuvant. In this study, we examined the effects of i.n. IL-12 treatment on induction of protective humoral immunity againstS. pneumoniae. Immunization i.n. with pneumococcal surface protein A (PspA) and IL-12 resulted in enhanced lung IL-10 mRNA expression and marked augmentation of respiratory and systemic immunoglobulin G1 (IgG1), IgG2a, and IgA antibody levels compared to those in animals receiving PspA alone. In addition, i.n. vaccination with PspA and IL-12 provided increased protection against nasopharyngeal carriage. Flow cytometric analysis revealed a threefold increase in antibody-mediated, complement-independent opsonic activity in the sera of PspA- and IL-12-treated animals, which was mainly contributed by IgG2a and, to a lesser extent, IgA. Passive transfer of these immune sera conferred complete protection from death upon systemic pneumococcal challenge. These findings demonstrate the effectiveness of combining PspA and IL-12 at mucosal sites to achieve optimal antibody-mediated opsonization and killing ofS. pneumoniae.
Dynamic Nature of Host-Pathogen Interactions inMycobacterium marinumGranulomas
Authors: Bouley Donna M. , Ghori Nafisa , Mercer K. Lynne , Falkow Stanley , Ramakrishnan Lalita 
Published: July 2002

ABSTRACTMycobacterium marinumcauses long-term subclinical granulomatous infection in immunocompetent leopard frogs (Rana pipiens). These granulomas, organized collections of activated macrophages, share many morphological features with persistent human tuberculous infection. We examined organs of frogs with chronicM. marinuminfection using transmission electron microscopy in conjunction with immunohistochemistry and acid phosphatase cytochemistry to better define the bacterium-host interplay during persistent infection. Bacteria were always found within macrophage phagosomes. These phagosomes were often fused to lysosomes, in sharp contrast to those formed during in vitro infection of J774 macrophage-like cells byM. marinum. The infected macrophages in frog granulomas showed various levels of activation, as evidenced by morphological changes, including epithelioid transformation, recent phagocytic events, phagolysosomal fusion, and disintegration of bacteria. Our results demonstrate that even long-term granulomas are dynamic environments with regard to the level of host cell activation and bacterial turnover and suggest a continuum between constantly replicating bacteria and phagocytic killing that maintains relatively constant bacterial numbers despite an established immune response. Infection with a mutant bacterial strain with a reduced capacity for intracellular replication shifted the balance, leading to a greatly reduced bacterial burden and inflammatory foci that differed from typical granulomas.
Trehalose 6,6′-Dimycolate (Cord Factor) ofMycobacterium tuberculosisInduces Foreign-Body- and Hypersensitivity-Type Granulomas in Mice
Authors: Yamagami Hirokazu , Matsumoto Takayuki , Fujiwara Nagatoshi , Arakawa Tetsuo , Kaneda Kenji , Yano Ikuya , Kobayashi Kazuo 
Published: July 2002

ABSTRACTGranulomatous inflammation is characterized morphologically by a compact organized collection of macrophages and their derivatives. It is classified as either a hypersensitivity type or a foreign-body type. Lipid components of theMycobacterium tuberculosiscell wall participate in the pathogenesis of infection. Strains ofM. tuberculosishave cord factor (trehalose 6,6′-dimycolate [TDM]) on their surface. To clarify host responses to TDM, including immunogenicity and pathogenicity, we have analyzed the footpad reaction, histopathology, and cytokine profiles of experimental granulomatous lesions in immunized and unimmunized mice challenged with TDM. In the present study, we have demonstrated for the first time that TDM can induce both foreign-body-type (nonimmune) and hypersensitivity-type (immune) granulomas by acting as a nonspecific irritant and T-cell-dependent antigen. Immunized mice challenged with TDM developed more severe lesions than unimmunized mice. At the active lesion, we found monocyte chemotactic, proinflammatory, and immunoregulatory cytokines. The level was enhanced in immunized mice challenged with TDM. This result implies that both nonimmune and immune mechanisms participate in granulomatous inflammation induced by mycobacterial infection. Taken together with a previous report, this study shows that TDM is a pleiotropic molecule against the host and plays an important role in the pathogenesis of tuberculosis.
Immune Response to Infection withMycobacterium ulcerans
Authors: Gooding Travis M. , Johnson Paul D. R. , Campbell Dianne E. , Hayman John A. , Hartland Elizabeth L. , Kemp Andrew S. , Robins-Browne Roy M. 
Published: July 2002

ABSTRACTMycobacterium ulceransis a slow-growing, acid-fast bacillus that causes chronic necrotizing skin ulcers known as Buruli ulcers. Previously reported information on immunity to this mycobacterium is limited. We examined immune responses toM. ulceransandM. bovisBCG in patients withM. ulceransdisease and in 20 healthy control subjects (10 tuberculin test positive and 10 tuberculin test negative). Cell-mediated immunity was assessed by stimulating peripheral blood mononuclear cells (PBMC) with whole mycobacteria and then measuring PBMC proliferation and the production of gamma interferon (IFN-γ). Humoral immunity was assessed by immunoblotting. PBMC from all subjects showed significantly greater proliferation and IFN-γ production in response to stimulation with living mycobacteria compared with killed cells. However, PBMC from subjects with past or currentM. ulceransdisease showed significantly reduced proliferation and production of IFN-γ in response to stimulation with liveM. ulceransorM. bovisthan PBMC from healthy, tuberculin test-positive subjects (P< 0.001) and showed results in these assays comparable to those of tuberculin test-negative subjects (P> 0.2). Serum from 9 of 11 patients withM. ulceransdisease, but no control subject, contained antibodies toM. ulcerans. The results indicate that patients withM. ulceransinfection mount an immune response toM. ulceransas evidenced by antibody production, but they demonstrate profound systemic T-cell anergy to mycobacterial antigens. These findings may explain some of the distinct clinical and pathological features ofM. ulcerans-induced disease.
Aberrant Macrophage and Neutrophil Population Dynamics and Impaired Th1 Response toListeria monocytogenesin Colony-Stimulating Factor 1-Deficient Mice
Authors: Guleria Indira , Pollard Jeffrey W. 
Published: July 2002

ABSTRACTListeria monocytogenes, a facultative intracellular bacterium, has been used extensively to study innate immune responses. Macrophages act as hosts for this bacterium as well as a major defense against it. Using mice homozygous for a null mutation (Csf1op) in the gene for the mononuclear phagocytic growth factor colony-stimulating factor 1 (CSF-1), we have demonstrated that CSF-1-regulated macrophages were essential to defend against a listerial infection. In the absence of CSF-1, monocytes were not recruited to the sites of infection due to the lack of synthesis of the macrophage chemoattractant chemokine MCP-1. In addition, there was no burst of interleukin-10 (IL-10) synthesis that has been shown to result in the egress of neutrophils from sites of infection. Consequently, neutrophils were not replaced by macrophages, and numerous neutrophil-filled microabscesses developed, followed by tissue destruction and death of the mice. In the CSF-1 nullizygous mice compared to wild-type mice, there was also a very low synthesis of gamma interferon (IFN-γ), resulting in reduced macrophage activation. However, the concentrations of the IFN-γ-inducing cytokines IL-12 and IL-18 at this bacterial load were similar in these mutant mice. In contrast, IL-6 concentrations were dramatically reduced. Administration of IL-6 toCsf1op/Csf1opmice significantly increased the synthesis of IFN-γ and reduced the bacterial burden to a greater extent than treatment with IFN-γ alone. These data indicate that IL-6 occupies a central role in the CSF-1-regulated macrophage response toL. monocytogenes.
Recognition of Multiple Antibody Epitopes throughout
Borrelia burgdorferi
p66, a Candidate Adhesin, in Patients with Early or Late Manifestations of Lyme Disease
Authors: Ntchobo Hyacinthe , Rothermel Holly , Chege Wambui , Steere Allen C. , Coburn Jenifer 
Published: July 2002

ABSTRACT

Antibody responses to p66, a candidate integrin ligand of
Borrelia burgdorferi
, were studied in 79 patients with early or late manifestations of Lyme disease. The central portion of p66 was previously shown to contain all of the information required for specific recognition of β
3
-chain integrins, but work by others had suggested that the C-terminal portion of the protein contains a single surface-exposed, immunodominant loop. In examining antibody responses to full-length p66 and to three overlapping fragments of the protein, we found that the majority of Lyme disease patients had immunoglobulin M (IgM) and/or IgG responses to p66 and that, particularly early in the disease, epitopes throughout p66 were recognized. Among patients with later manifestations of the illness, antibody responses to the C-terminal portion of the protein were more prominent. These results demonstrate that Lyme disease patient sera recognize epitopes throughout p66.
Clostridium perfringens
Iota-Toxin: Mapping of Receptor Binding and Ia Docking Domains on Ib
Authors: Marvaud Jean-Christophe , Smith Theresa , Hale Martha L. , Popoff Michel R. , Smith Leonard A. , Stiles Bradley G. 
Published: July 2002

ABSTRACT

Clostridium perfringens
iota-toxin is a binary toxin consisting of iota a (Ia), an ADP-ribosyltransferase that modifies actin, and iota b (Ib), which binds to a cell surface protein and translocates Ia into a target cell. Fusion proteins of recombinant Ib and truncated variants were tested for binding to Vero cells and docking with Ia via fluorescence-activated cytometry and cytotoxicity experiments. C-terminal residues (656 to 665) of Ib were critical for cell surface binding, and truncated Ib variants containing ≥200 amino acids of the C terminus were effective Ib competitors and prevented iota cytotoxicity. The N-terminal domain (residues 1 to 106) of Ib was important for Ia docking, yet this region was not an effective competitor of iota cytotoxicity. Further studies showed that Ib lacking just the N-terminal 27 residues did not facilitate Ia entry into a target cell and subsequent cytotoxicity. Five monoclonal antibodies against Ib were also tested with each truncated Ib variant for epitope and structural mapping by surface plasmon resonance and an enzyme-linked immunosorbent assay. Each antibody bound to a linear epitope within the N terminus (residues 28 to 66) or the C terminus (residues 632 to 655). Antibodies that target the C terminus neutralized in vitro cytotoxicity and delayed the lethal effects of iota-toxin in mice.
Trypanosome-Derived Oligopeptidase B Is Released into the Plasma of Infected Rodents, Where It Persists and Retains Full Catalytic Activity
Authors: Morty Rory E. , Lonsdale-Eccles John D. , Mentele Reinhardt , Auerswald Ennes A. , Coetzer Theresa H. T. 
Published: July 2002

ABSTRACT

A trypsin-like serine peptidase activity, levels of which correlate with blood parasitemia levels, is present in the plasma of rats acutely infected with
Trypanosoma brucei brucei
. Antibodies to a trypanosome peptidase with a trypsin-like substrate specificity (oligopeptidase B [OP-Tb]) cross-reacted with a protein in the plasma of trypanosome-infected rats on a Western blot. These antibodies also abolished 80% of the activity in the plasma of trypanosome-infected rats, suggesting that the activity may be attributable to a parasite-derived peptidase. We purified the enzyme responsible for the bulk of this activity from parasite-free
T. b. brucei
-infected rat plasma and confirmed its identity by protein sequencing. We show that live trypanosomes do not release OP-Tb in vitro and propose that disrupted parasites release it into the host circulation, where it is unregulated and retains full catalytic activity and may thus play a role in the pathogenesis of African trypanosomiasis.
Characterization of Binding of Human Lactoferrin to Pneumococcal Surface Protein A
Authors: Håkansson Anders , Roche Hazeline , Mirza Shaper , McDaniel Larry S. , Brooks-Walter Alexis , Briles David E. 
Published: July 2002

ABSTRACTHuman lactoferrin is an iron-binding glycoprotein that is particularly prominent in exocrine secretions and leukocytes and is also found in serum, especially during inflammation. It is able to sequester iron from microbes and has immunomodulatory functions, including inhibition of both complement activation and cytokine production. This study used mutants lacking pneumococcal surface protein A (PspA) and PspC to demonstrate that the binding of human lactoferrin to the surface ofStreptococcus pneumoniaewas entirely dependent on PspA. Lactoferrin bound both family 1 and family 2 PspAs. Binding of lactoferrin to PspA was shown by surface colocalization with PspA and was verified by the lack of binding to PspA-negative mutants. Lactoferrin was expressed on the body of the cells but was largely absent from the poles. PspC showed exactly the same distribution on the pneumococcal surface as PspA but did not bind lactoferrin. PspA's binding site for lactoferrin was mapped using recombinant fragments of PspA of families 1 and 2. Binding of human lactoferrin was detected primarily in the C-terminal half of the α-helical domain of PspA (amino acids 167 to 288 of PspA/Rx1), with no binding to the N-terminal 115 amino acids in either strain. The interaction was highly specific. As observed previously, bovine lactoferrin bound poorly to PspA. Human transferrin did not bind PspA at all. The binding of lactoferrin toS. pneumoniaemight provide a way for the bacteria to interfere with host immune functions or to aid in the acquisition of iron at the site of infection.