bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shiga Toxin Binds Human Platelets via Globotriaosylceramide (PkAntigen) and a Novel Platelet Glycosphingolipid
Authors: Cooling Laura L. W. , Walker Katherine E. , Gille Theresa , Koerner Theodore A. W. 
Published: March 2020

ABSTRACTHemolytic-uremic syndrome is a clinical syndrome characterized by acute renal failure, microangiopathic hemolytic anemia, and thrombocytopenia that often follows infection by Shiga toxin- or verotoxin-producing strains ofEscherichia coli. Because thrombocytopenia and platelet activation are hallmark features of hemolytic-uremic syndrome, we examined the ability of Shiga toxin to bind platelets by flow cytometry and high-performance thin-layer chromatography (HPTLC) of isolated platelet glycosphingolipids. By HPTLC, Shiga toxin was shown to bind globotriaosylceramide (Gb3) and a minor platelet glycolipid with anRfof 0.03, band 0.03. In a survey of 20 human tissues, band 0.03 was identified only in platelets. In individuals, band 0.03 was expressed by 20% of donors and was specifically associated with increased platelet Gb3expression. Based on glycosidase digestion and epitope mapping, band 0.03 was hypothesized to represent a novel glycosphingolipid, IV3-β-Galα1-4galactosylglobotetraosylceramide. Based on incidence, structure, and association with increased Gb3expression, band 0.03 may represent the antithetical Luke blood group antigen. By flow cytometry, Shiga toxin bound human platelets, although the amount of Shiga toxin bound varied in donors. Differences in Shiga toxin binding to platelet membranes did not reflect differences in platelet Gb3expression. In contrast, there was a loose association between Shiga toxin binding and decreasing forward scatter, suggesting that Shiga toxin and verotoxins bind more efficiently to smaller, older platelets. In summary, Shiga and Shiga-like toxins may bind platelets via specific glycosphingolipid receptors. Such binding may contribute to the thrombocytopenia, platelet activation, and microthrombus formation observed in hemolytic-uremic syndrome.
Importance of Interleukin-10 in Genetic Susceptibility of Mice toCoccidioides immitis
Authors: Fierer Joshua , Walls Lorraine , Eckmann Lars , Yamamoto Tomoko , Kirkland Theo N. 
Published: March 2020

ABSTRACTInbred strains of mice vary in their susceptibility toCoccidioides immitis. We infected resistant DBA/2 (D2) mice and three susceptible strains of mice (C57BL/6 [B6], BALB/c, and CAST/Ei) by intraperitoneal injection of arthroconidia and determined the severity of infection based on colony counts of fungus in the spleens and lungs 14 days after infection. We used quantitative reverse transcription-PCR to measure the amounts of cytokines made in the spleens and lungs of infected mice. Susceptible mice made 1,000-fold more interleukin-10 (IL-10) than resistant D2 mice and about 10-fold more IL-4. In contrast, D2 mice had more IL-12 p40 in their lungs than did B6 mice. Resistant and susceptible mice made equivalent amounts of gamma interferon, IL-6, and IL-2. In order to determine whether IL-10 adversely affected the response toC. immitis, we infected IL-10-deficient mice, and they were found to be as resistant as D2 mice. This result indicates that IL-10 plays a crucial role in determining susceptibility toC. immitisin inbred mice. Because IL-4 mRNA levels were higher in most strains of susceptible mice, we also infected IL-4-deficient B6 mice. They were more resistant than B6 controls but not as resistant as IL-10-deficient mice. Thus, both IL-10 and IL-4 adversely affect the ability of C57BL mice to resist infection withC. immitis, but IL-10 has a larger effect and is the cytokine that is consistently associated with susceptibility in all strains of inbred mice.
Immunological Relationship between the Class I Epitope of Streptococcal M Protein and Myosin
Authors: Quinn Anthony , Ward Kent , Fischetti Vincent A. , Hemric Mark , Cunningham Madeleine W. 
Published: March 2020

ABSTRACTThe class I epitope of streptococcal M protein is an epidemiological marker for acute rheumatic fever (ARF)-associated serotypes of group A streptococci and is recognized by anti-M protein monoclonal antibody (MAb) 10B6. Using MAb 10B6, we determined the relationship between the class I epitope of M protein and the α-helical coiled-coil protein myosin. MAb 10B6 reacted by enzyme-linked immunosorbent assay and Western blotting with human cardiac myosin and rabbit skeletal myosin and its heavy meromyosin (HMM) subfragment. Overlapping synthetic peptides of M5 protein were used to identify the region of M5 protein recognized by MAb 10B6. Two C repeat peptides (C2A and C3) containing the amino acid sequence KGLRRDLDASREAK reacted with MAb 10B6. Partial sequence identity, RRDL, was found in the HMM fragment of myosin, which reacted with MAb 10B6. However, not all peptides of M5 protein and myosin containing the RRDL sequence reacted with MAb 10B6. ARF sera and sera from uncomplicated pharyngitis (UNC) reacted with C repeat region peptides of M protein, while acute glomerulonephritis sera were not as reactive. Affinity-purified human antibody to peptide C3 reacted with myosin. The data demonstrate that the class I epitope of M protein is immunologically cross-reactive with myosin and the HMM subfragment, and antibodies to peptide C3 and myosin were present in ARF and UNC sera.
Antibody Responses in Humans against Coli Surface Antigen 6 of Enterotoxigenic
Escherichia coli
Authors: Helander Anna , Wennerås Christine , Qadri Firdausi , Svennerholm Ann-Mari 
Published: March 2020

ABSTRACT

Enterotoxigenic
Escherichia coli
(ETEC) strains expressing only coli surface antigen 6 (CS6) have previously been isolated from patients with diarrhea, but the immunogenicity of CS6 has not been established in humans. We have detected CS6-specific immunoglobulin A responses in the feces and blood of patients convalescing from natural ETEC disease and of volunteers given an oral ETEC vaccine.
Elevated Concentrations of Eotaxin and Interleukin-5 in Human Neurocysticercosis
Authors: Evans Carlton A. W. , Garcia Hector H. , Hartnell Adele , Gilman Robert H. , Jose Peter J. , Martinez Manuel , Remick Daniel G. , Williams Timothy J. , Friedland Jon S. 
Published: March 2020

ABSTRACTSymptomatic neurocysticercosis, a major cause of epilepsy worldwide, results from inflammation aroundTaenia soliumlarvae, but the mechanisms are unknown. Eotaxin, not previously reported in cases of human infection, and interleukin-5 (IL-5) but not IL-8 concentrations were elevated in patient serum, and IL-5 levels were also elevated in cerebrospinal fluid (CSF). Eosinophil-selective mediators may be involved in the pathogenesis of cysticercosis. IL-6 concentrations were also elevated in patient CSF, possibly indicative of an acute-phase response.
Clostridium perfringensType E Animal Enteritis Isolates with Highly Conserved, Silent Enterotoxin Gene Sequences
Authors: Billington Stephen J. , Wieckowski Eva U. , Sarker Mahfuzur R. , Bueschel Dawn , Songer J. Glenn , McClane Bruce A. 
Published: March 2020

ABSTRACTSeveralClostridium perfringensgenotype E isolates, all associated with hemorrhagic enteritis of neonatal calves, were identified by multiplex PCR. These genotype E isolates were demonstrated to express α and ι toxins, but, despite carrying sequences for the gene (cpe) encodingC. perfringensenterotoxin (CPE), were unable to express CPE. These silentcpesequences were shown to be highly conserved among type E isolates. However, relative to the functionalcpegene of type A isolates, these silent type Ecpesequences were found to contain nine nonsense and two frameshift mutations and to lack the initiation codon, promoters, and ribosome binding site. The type E animal enteritis isolates carrying these silentcpesequences do not appear to be clonally related, and their silent type Ecpesequences are always located, near the ι toxin genes, on episomal DNA. These findings suggest that the highly conserved, silentcpesequences present in most or all type E isolates may have resulted from the recent horizontal transfer of an episome, which also carries ι toxin genes, to several different type AC. perfringensisolates.
The Macrophage-Induced Gene
mig
as a Marker for Clinical Pathogenicity and In Vitro Virulence of
Mycobacterium avium
Complex Strains
Authors: Meyer Martin , von Grünberg Philipp W. R. , Knoop Tim , Hartmann Pia , Plum Georg 
Published: March 2020

ABSTRACT

The capacity of 20
Mycobacterium avium
complex isolates to multiply intracellularly in human monocyte-derived macrophages was assessed and correlated to the clinical relevance of each isolate and its reactivity with several candidate genetic virulence markers. The strongest correlation with a virulence phenotype was found for a conserved coding sequence of the macrophage-induced gene
mig
identified by a specific
mig
restriction fragment length polymorphism type.
Chemokine Secretion of Human Cells in Response toToxoplasma gondiiInfection
Authors: Denney Carolyn F. , Eckmann Lars , Reed Sharon L. 
Published: March 2020

ABSTRACTThe ubiquitous protozoan parasiteToxoplasma gondiiis a major cause of morbidity and mortality in neonates and immunocompromised hosts. Both acute invasion and reactivation of latent infection result in an inflammatory reaction with lymphocytes, macrophages, and neutrophils. The mechanisms responsible for triggering the local host response to toxoplasmosis are not fully understood. Infection of monolayers of human HeLa epithelial cells and fibroblasts withT. gondiiresulted in a marked increase in the expression of interleukin-8 (IL-8)-specific mRNA and secretion of the proinflammatory and chemoattractant cytokines interleukin-8 (IL-8), GROα, and MCP-1. Host cell invasion and lysis were required for this response, as tachyzoite lysates alone had no effect on IL-8 secretion. IL-8 release was dependent on the release of soluble host cell factors: IL-1α in HeLa cells and an additional mediator in fibroblasts. HT-29 epithelial cells, which lack IL-1α or another IL-8-inducing activity, did not release IL-8 after infection, although they were efficiently infected withT. gondiiand increased IL-8 secretion in response to added IL-1α. These data suggest that proinflammatory chemokine secretion is an important host cell response to toxoplasmosis and that the release of IL-1α and other mediators from lysed host cells is critical for this chemokine response.
Immunity toChlamydia trachomatisMouse Pneumonitis Induced by Vaccination with Live Organisms Correlates with Early Granulocyte-Macrophage Colony-Stimulating Factor and Interleukin-12 Production and with Dendritic Cell-Like Maturation
Authors: Zhang Dongji , Yang Xi , Lu Hang , Zhong Guangming , Brunham Robert C. 
Published: March 2020

ABSTRACTAs is true for other intracellular pathogens, immunization with liveChlamydia trachomatisgenerally induces stronger protective immunity than does immunization with inactivated organism. To investigate the basis for such a difference, we studied immune responses in BALB/c mice immunized with viable or UV-killedC. trachomatismouse pneumonitis (MoPn). Strong, acquired resistance toC. trachomatisinfection was elicited by immunization with viable but not dead organisms. Immunization with viable organisms induced high levels of antigen-specific delayed-type hypersensitivity (DTH), gamma interferon production, and immunoglobulin A (IgA) responses. Immunization with inactivated MoPn mainly induced interleukin-10 (IL-10) production and IgG1 antibody without IgA or DTH responses. Analysis of local early cytokine and cellular events at days 3, 5, and 7 after peritoneal cavity immunization showed that high levels of granulocyte-macrophage colony-stimulating factor and IL-12 were detected with viable but not inactivated organisms. Furthermore, enrichment of a dendritic cell (DC)-like population was detected in the peritoneal cavity only among mice immunized with viable organisms. The results suggest that early differences in inducing proinflammatory cytokines and activation and differentiation of DCs may be the key mechanism underlying the difference between viable and inactivated organisms in inducing active immunity toC. trachomatisinfection.
TransformedToxoplasma gondiiTachyzoites Expressing the Circumsporozoite Protein ofPlasmodium knowlesiElicit a Specific Immune Response in Rhesus Monkeys
Authors: di Cristina Manlio , Ghouze Firman , Kocken Clemens H. M. , Naitza Silvia , Cellini Pamela , Soldati Dominique , Thomas Alan W. , Crisanti Andrea 
Published: March 2020

ABSTRACTToxoplasma gondiitachyzoites were transformed with the coding sequence of the circumsporozoite (CS) protein of the primate malaria parasitePlasmodium knowlesi. A single inoculation of live transformed tachyzoites elicited an antibody response directed against the immunodominant repeat epitope (EQPAAGAGG)2of theP. knowlesiCS protein in rhesus monkeys. Notably, these animals failed to show a positive serum conversion againstT. gondii. Antibodies againstToxoplasmaantigens were detected only after a second inoculation with a higher number of transformed tachyzoites. This boost induced an increased antibody response against theP. knowlesiCS protein associated with immunoglobulin class switching, thus demonstrating the establishment of immunological memory. These results indicate that theToxoplasma-derived CS protein is efficiently recognized by the monkey immune system and represents an immunodominant antigen in transformed parasites.
Identification of Pneumococcal Surface Protein A as a Lactoferrin-Binding Protein of
Streptococcus pneumoniae
Authors: Hammerschmidt Sven , Bethe Gesina , H. Remane Petra , Chhatwal Gursharan S. 
Published: March 2020

ABSTRACT

Lactoferrin (Lf), an iron-sequestering glycoprotein, predominates in mucosal secretions, where the level of free extracellular iron (10
−18
M) is not sufficient for bacterial growth. This represents a mechanism of resistance to bacterial infections by prevention of colonization of the host by pathogens. In this study we were able to show that
Streptococcus pneumoniae
specifically recognizes and binds the iron carrier protein human Lf (hLf). Pretreatment of pneumococci with proteases reduced hLf binding significantly, indicating that the hLf receptor is proteinaceous. Binding assays performed with 63 clinical isolates belonging to different serotypes showed that 88% of the tested isolates interacted with hLf. Scatchard analysis showed the existence of two hLf-binding proteins with dissociation constants of 5.7 × 10
−8
and 2.74 × 10
−7
M. The receptors were purified by affinity chromatography, and internal sequence analysis revealed that one of the
S. pneumoniae
proteins was homologous to pneumococcal surface protein A (PspA). The function of PspA as an hLf-binding protein was confirmed by the ability of purified PspA to bind hLf and to competitively inhibit hLf binding to pneumococci.
S. pneumoniae
may use the hLf-PspA interaction to overcome the iron limitation at mucosal surfaces, and this might represent a potential virulence mechanism.
Interleukin-12 Production Is Required for Chlamydial Antigen-Pulsed Dendritic Cells To Induce Protection against LiveChlamydia trachomatisInfection
Authors: Lu Hang , Zhong Guangming 
Published: March 2020

ABSTRACTImmunization with dendritic cells pulsed ex vivo with antigens has been successfully used to elicit primary antigen-specific immune responses. We report that mouse bone marrow-derived dendritic cells pulsed with inactivated chlamydial organisms induced strong protection against live chlamydial infection in a mouse lung infection model. Either the dendritic cells or chlamydial organisms alone or macrophages similarly pulsed with chlamydial organisms failed to induce any significant protection. These observations suggest that dendritic cells can efficiently process and present chlamydial antigens to naive T cells in vivo. Mice immunized with the chlamydia-pulsed dendritic cells preferentially developed a Th1 cell-dominant response while mice immunized with the other immunogens did not, suggesting a correlation between a Th1 cell-dominant response and protection against chlamydial infection. We further found that dendritic cells produced a large amount of interleukin 12 (IL-12) upon ex vivo pulsing with inactivated chlamydial organisms, which may allow the dendritic cells to direct a Th1 cell-dominant response. Dendritic cells from mice deficient in the IL-12 p40 gene failed to produce IL-12 after a similar ex vivo pulse with chlamydial organisms, and more importantly, immunization with these dendritic cells failed to induce a Th1 cell-dominant response and did not induce strong protection against chlamydial infection. Thus, the ability of dendritic cells to efficiently process and present chlamydial antigens and to produce IL-12 upon chlamydial-organism stimulation are both required for the induction of protection against chlamydial infection. This information may be useful for the further design of effective chlamydial vaccines.
Rapid Local Expression of Interleukin-12, Tumor Necrosis Factor Alpha, and Gamma Interferon after CutaneousFrancisella tularensisInfection in Tularemia-Immune Mice
Authors: Stenmark Stephan , Sunnemark Dan , Bucht Anders , Sjöstedt Anders 
Published: March 2020

ABSTRACTFrancisella tularensisLVS is an effective live vaccine strain used for cutaneous vaccination against tularemia in man. In mice, injection of LVS causes invasive disease and subsequent development of immunity that is characterized by effective control of otherwise lethal doses of the organism. In the present investigation, it is shown that LVS-immune mice controlled an intradermal infection much more effectively than did naive mice; bacterial counts in skin samples were 1.5 to 2.0 log10lower 24 h after injection and 6 log10lower 72 h after injection in immune mice. Moreover, in contrast to naive mice, no bacteria were demonstrated in samples from livers and spleens of immune mice. By immunohistochemistry, skin samples from immune mice showed an intense staining for interleukin-12 (IL-12) and a moderate staining for tumor necrosis factor alpha (TNF-α) at 24 h postinoculation, after which staining for both cytokines faded. In naive mice, the staining for IL-12 was weak at all time points and no staining for TNF-α was observed. No staining for gamma interferon (IFN-γ) was observed in any group before 72 h. At that time point, skin samples from immune mice showed moderate staining and skin samples from naive mice showed weak staining. Reverse transcriptase PCR showed an induction of mRNA of the three cytokines in the skin within the first day after injection. A quantitative analysis demonstrated higher IFN-γ and TNF-α mRNA levels in immune mice at 24 h postinoculation. In conclusion, immunization withF. tularensisLVS conferred a capability to respond to cutaneous reinfection, with rapid local expression of IL-12, TNF-α, and IFN-γ, and this expression was paralleled by containment and mitigation of the infection. The cytokine response may be part of a local barrier function of the skin, important to host protection against tularemia.
Identification of a Receptor-Binding Region within Domain 4 of the Protective Antigen Component of Anthrax Toxin
Authors: Varughese Mini , Teixeira Avelino V. , Liu Shihui , Leppla Stephen H. 
Published: March 2020

ABSTRACT

Anthrax toxin from
Bacillus anthracis
is a three-component toxin consisting of lethal factor (LF), edema factor (EF), and protective antigen (PA). LF and EF are the catalytic components of the toxin, whereas PA is the receptor-binding component. To identify residues of PA that are involved in interaction with the cellular receptor, two solvent-exposed loops of domain 4 of PA (amino acids [aa] 679 to 693 and 704 to 723) were mutagenized, and the altered proteins purified and tested for toxicity in the presence of LF. In addition to the intended substitutions, novel mutations were introduced by errors that occurred during PCR. Substitutions within the large loop (aa 704 to 723) had no effect on PA activity. A mutated protein, LST-35, with three substitutions in the small loop (aa 679 to 693), bound weakly to the receptor and was nontoxic. A mutated protein, LST-8, with changes in three separate regions did not bind to receptor and was nontoxic. Toxicity was greatly decreased by truncation of the C-terminal 3 to 5 aa, but not by their substitution with nonnative residues or the extension of the terminus with nonnative sequences. Comparison of the 28 mutant proteins described here showed that the large loop (aa 704 to 722) is not involved in receptor binding, whereas residues in and near the small loop (aa 679 to 693) play an important role in receptor interaction. Other regions of domain 4, in particular residues at the extreme C terminus, appear to play a role in stabilizing a conformation needed for receptor-binding activity.
CD40 Ligation PreventsTrypanosoma cruziInfection through Interleukin-12 Upregulation
Authors: Chaussabel Damien , Jacobs Frédérique , de Jonge Jan , de Veerman Marijke , Carlier Yves , Thielemans Kris , Goldman Michel , Vray Bernard 
Published: March 2020

ABSTRACTBecause of the critical role of the CD40-CD40 ligand (CD40L) pathway in the induction and effector phases of immune responses, we investigated the effects of CD40 ligation on the control ofTrypanosoma cruziinfection. First, we observed that supernatants of murine spleen cells stimulated by CD40L-transfected 3T3 fibroblasts (3T3-CD40L transfectants) prevent the infection of mouse peritoneal macrophages (MPM) byT. cruzi. This phenomenon depends on de novo production of nitric oxide (NO) as it is prevented by the addition ofN-nitro-l-arginine methyl ester, a NO synthase inhibitor. NO production requires interleukin (IL)-12-mediated gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α) synthesis as demonstrated by inhibition experiments using neutralizing anti-IL-12, anti-IFN-γ, and anti-TNF-α monoclonal antibodies (MAb). We found that an activating anti-CD40 MAb also directly stimulates IFN-γ-activated MPM to produce NO and thereby to controlT. cruziinfection. To determine the in vivo relevance of these in vitro findings, mice were injected with 3T3-CD40L transfectants or 3T3 control fibroblasts at the time ofT. cruziinoculation. We observed that in vivo CD40 ligation dramatically reduced both parasitemia and the mortality rate ofT. cruzi-infected mice. A reduced parasitemia was still observed when the injection of 3T3-CD40L transfectants was delayed 8 days postinfection. It was abolished by injection of anti-IL-12 MAb. Taken together, these data establish that CD40 ligation facilitates the control ofT. cruziinfection through a cascade involving IL-12, IFN-γ, and NO.
Vaccinated Mice Remain More Susceptible to
Mycobacterium tuberculosis
Infection Initiated via the Respiratory Route than via the Intravenous Route
Authors: North Robert J. , LaCourse Ronald , Ryan Lynn 
Published: March 2020

ABSTRACT

Mice given
Mycobacterium tuberculosis
bacilli via the respiratory route succumbed much sooner to infection than mice given 1,000 times more bacilli via the intravenous route. Vaccination provided increased protection to an
M. tuberculosis
challenge infection; however, mice infected via the respiratory route remained much more susceptible.
β
1
-Chain Integrins Are Not Essential for Intimin-Mediated Host Cell Attachment and Enteropathogenic
Escherichia coli
-Induced Actin Condensation
Authors: Liu Hui , Magoun Loranne , Leong John M. 
Published: March 2020

ABSTRACT

Intimin is a bacterial outer membrane protein required for intimate attachment of enterohemorrhagic and enteropathogenic
Escherichia coli
(EHEC and EPEC) to mammalian cells. β
1
-chain integrins have been proposed as candidate receptors for intimin. We found that binding of mammalian cells to immobilized intimin was not detectable unless mammalian cells were preinfected with EPEC or EHEC. β
1
-chain integrin antagonists or inactivation of the gene encoding the β
1
-chain did not affect binding of preinfected mammalian cells to intimin or the actin condensation associated with the attachment of EPEC. The results indicate that β
1
-chain integrins are not essential for intimin-mediated cell attachment or EPEC-mediated actin polymerization.