bluuebunny/crossref_metadata_2025_split huggingface dataset:
Additional Conjugation Methods and Immunogenicity of
Bacillus anthracis
Poly-γ-
d
-Glutamic Acid-Protein Conjugates
Authors: Kubler-Kielb Joanna , Liu Teh-Yung , Mocca Christopher , Majadly Fathy , Robbins John B. , Schneerson Rachel 
Published: July 2006

ABSTRACT

The capsule of
Bacillus anthracis
, composed of poly-γ-
d
-glutamic acid (γDPGA), is an essential virulence factor of
B. anthracis
. The capsule inhibits innate host defense through its antiphagocytic action. γDPGA is a poor immunogen, but when covalently bound to a carrier protein, it elicits serum antibodies. To identify the optimal construct for clinical use, synthetic γDPGAs of different lengths were bound to carrier proteins at different densities. The advantages of the synthetic over the natural polypeptide are the homogeneous chain length and end groups, allowing conjugates to be accurately characterized and standardized and their chemical compositions to be related to their immunogenicities. In the present study, we evaluated, in addition to methods reported by us, hydrazone, oxime, and thioether linkages between γDPGA and several proteins, including bovine serum albumin, recombinant
Pseudomonas aeruginosa
exotoxin A, recombinant
B. anthracis
protective antigen (rPA), and tetanus toxoid (TT). The effects of the dosage and formulation on the immunogenicities of the conjugates were evaluated in mice. All conjugates were immunogenic. The optimal γDPGA chain length of 10 to 15 amino acids and the density, an average of 15 mol γDPGA per mol of protein, were confirmed. The thioether bond was the optimal linkage type, and TT and rPA were the best carriers. The optimal dosage was 1.2 to 2.5 μg of γDPGA per mouse, and adsorption of the conjugates onto aluminum hydroxide significantly increased the antibody response to the protein with a lesser effect on anti-γDPGA levels.
Identification of a Candidate
Streptococcus pneumoniae
Core Genome and Regions of Diversity Correlated with Invasive Pneumococcal Disease
Authors: Obert Caroline , Sublett Jack , Kaushal Deepak , Hinojosa Ernesto , Barton Theresa , Tuomanen Elaine I. , Orihuela Carlos J. 
Published: July 2006

ABSTRACT

Streptococcus pneumoniae
is a leading cause of community-acquired pneumonia and gram-positive sepsis. While multiple virulence determinants have been identified, the combination of features that determines the propensity of an isolate to cause invasive pneumococcal disease (IPD) remains unknown. In this study, we determined the genetic composition of 42 invasive and 30 noninvasive clinical isolates of serotypes 6A, 6B, and 14 by comparative genomic hybridization. Comparison of the present/absent gene matrix (i.e., comparative genomic analysis [CGA]) identified a candidate core genome consisting of 1,553 genes (73% of the TIGR4 genome), 154 genes whose presence correlated with the ability to cause IPD, and 176 genes whose presence correlated with the noninvasive phenotype. Genes identified by CGA were cross-referenced with the published signature-tagged mutagenesis studies, which served to identify core and IPD-correlated genes required for in vivo passage. Among these, two pathogenicity islands, region of diversity 8a (RD8a), which encodes a neuraminidase and V-type sodium synthase, and RD10, which encodes PsrP, a protein homologous to the platelet adhesin GspB in
Streptococcus gordonii
, were identified. Mice infected with a PsrP mutant were delayed in the development of bacteremia and demonstrated reduced mortality versus wild-type-infected controls. Finally, the presence of seven RDs was determined to correlate with the noninvasive phenotype, a finding that suggests some RDs may contribute to asymptomatic colonization. In conclusion, RDs are unequally distributed between invasive and noninvasive isolates, RD8a and RD10 are correlated with the propensity of an isolate to cause IPD, and PsrP is required for full virulence in mice.
Inactivation of a Two-Component Signal Transduction System, SaeRS, Eliminates Adherence and Attenuates Virulence of
Staphylococcus aureus
Authors: Liang Xudong , Yu Chuanxin , Sun Junsong , Liu Hong , Landwehr Christina , Holmes David , Ji Yinduo 
Published: July 2006

ABSTRACT

Staphylococcus aureus
is a major human and animal pathogen. During infection, this organism not only is able to attach to and enter host cells by using its cell surface-associated factors but also exports toxins to induce apoptosis and kill invaded cells. In this study, we identified the regulon of a two-component signal transduction system, SaeRS, and demonstrated that the SaeRS system is required for
S. aureus
to cause infection both in vitro and in vivo. Using microarray and real-time reverse transcriptase PCR analyses, we found that SaeRS regulates the expression of genes involved in adhesion and invasion (such as those encoding fibronectin-binding proteins and fibrinogen-binding proteins) and genes encoding α-, β-, and γ-hemolysins. Surprisingly, we found that SaeRS represses the Agr regulatory system since the mutation of
saeS
up-regulates
agrA
expression, which was confirmed by using an
agr
promoter-reporter fusion system. More importantly, we demonstrated that inactivation of the SaeRS system significantly decreases the bacterium-induced apoptosis and/or death of lung epithelial cells (A549) and attenuates virulence in a murine infection model. Moreover, we found that inactivation of the SaeRS system eliminates staphylococcal adhesion and internalization of lung epithelial cells. We also found that both a novel hypothetical protein (the SA1000 protein) and a bifunctional protein (Efb), which binds to extracellular fibrinogen and complement factor C3, might partially contribute to bacterial adhesion to and invasion of epithelial cells. Our results indicate that activation of the SaeRS system may be required for
S. aureus
to adhere to and invade epithelial cells.
Maturation of Intracellular
Escherichia coli
Communities Requires SurA
Authors: Justice Sheryl S. , Lauer Scott R. , Hultgren Scott J. , Hunstad David A. 
Published: July 2006

ABSTRACT

Escherichia coli
is the most common cause of community-acquired urinary tract infection (UTI). During murine cystitis, uropathogenic
E. coli
(UPEC) utilizes type 1 pili to bind and invade superficial bladder epithelial cells. UPEC then replicates within to form intracellular bacterial communities (IBCs), a process whose genetic determinants are as yet undefined. In this study, we investigated the role of SurA in the UPEC pathogenic cascade. SurA is a periplasmic prolyl isomerase/chaperone that facilitates outer membrane protein biogenesis and pilus assembly in
E. coli
. Invasion into bladder epithelial cells was disproportionately reduced when
surA
was genetically disrupted in the UPEC strain UTI89, demonstrating that binding alone is not sufficient for invasion. In a murine cystitis model, UTI89
surA
::
kan
was unable to persist in the urinary tract. Complementation of UTI89
surA
::
kan
with a plasmid (pDH15) containing
surA
under the control of an arabinose-inducible promoter restored in vivo binding and invasion events. However, the absence of arabinose within the mouse bladder resulted in depletion of SurA after invasion of the bacteria into the superficial epithelial cells. Under these conditions, invasion by UTI89/pDH15
surA
::
kan
was normal, but in contrast to UTI89, UTI89/pDH15
surA
::
kan
formed intracellular collections that contained fewer bacteria, were loosely organized, and lacked the normal transition to a densely packed, coccoid morphology. Our data argue that SurA is required within bladder epithelial cells for UPEC to undergo the morphological changes that underlie IBC maturation and completion of the UTI pathogenic cascade.
Immunological and Molecular Analyses of the
Borrelia hermsii
Factor H and Factor H-Like Protein 1 Binding Protein, FhbA: Demonstration of Its Utility as a Diagnostic Marker and Epidemiological Tool for Tick-Borne Relapsing Fever
Authors: Hovis Kelley M. , Schriefer Martin E. , Bahlani Sonia , Marconi Richard T. 
Published: July 2006

ABSTRACT

It has been demonstrated that
Borrelia hermsii
, a causative agent of relapsing fever, produces a factor H (FH) and FH-like protein 1 (FHL-1) binding protein. The binding protein has been designated FhbA. To determine if FH/FHL-1 binding is widespread among
B. hermsii
isolates, a diverse panel of strains was tested for the FH/FHL-1 binding phenotype and FhbA production. Most isolates (23/24) produced FhbA and bound FH/FHL-1. Potential variation in FhbA among isolates was analyzed by DNA sequence analyses. Two genetically distinct FhbA types, designated
fhbA1
and
fhbA2
, were delineated, and type-specific PCR primers were generated to allow for rapid differentiation. Pulsed-field gel electrophoresis and hybridization analyses demonstrated that all isolates that possess the gene carry it on a 200-kb linear plasmid (lp200), whereas isolates that lack the gene lack lp200 and instead carry an lp170. To determine if FhbA is antigenic during infection and to assess the specificity of the response, recombinant FhbA1 (rFhbA1) and rFhbA2 were screened with serum from infected mice and humans. FhbA was found to be expressed and antigenic and to elicit a potentially type-specific FhbA response. To localize the epitopes of FhbA1 and FhbA2, truncations were generated and screened with infection serum. The epitopes were determined to be conformationally defined. Collectively, these analyses indicate that FH/FHL-1 binding is a widespread virulence mechanism for
B. hermsii
and provide insight into the genetic and antigenic structure of FhbA. The data also have potential implications for understanding the epidemiology of relapsing fever in North America and can be applied to the future development of species-specific diagnostic tools.
Caspase-1-Mediated Activation of Interleukin-1β (IL-1β) and IL-18 Contributes to Innate Immune Defenses againstSalmonella entericaSerovar Typhimurium Infection
Authors: Raupach Bärbel , Peuschel Soo-Kyung , Monack Denise M. , Zychlinsky Arturo 
Published: July 2006

ABSTRACTCaspase-1 (Casp-1) mediates the processing of the proinflammatory cytokines interleukin-1β (IL-1β) and IL-18 to their mature forms. Casp-1-deficient mice succumb more rapidly toSalmonellachallenge than do wild-type animals. Both Casp-1 substrates, IL-18 and IL-1β, are relevant for control ofSalmonella entericaserovar Typhimurium. We used IL-18−/−and IL-1β−/−mice in addition to administration of recombinant IL-18 to Casp-1−/−mice to demonstrate that IL-18 is important for resistance to the systemic infection but not for resistance to the intestinal phase of the infection. This suggests that IL-1β is critical for the intestinal phase of the disease. Thus, we show that Casp-1 is essential for host innate immune defense againstS. entericaserovar Typhimurium and that Casp-1 substrates are required at distinct times and anatomical sites.
Mapping of B-Cell Epitopes on a Novel 11.5-KilodaltonFasciola hepatica-Schistosoma mansoniCross-Reactive Antigen Belonging to a Member of theF. hepaticaSaposin-Like Protein Family
Authors: Torres Daricel , Espino Ana M. 
Published: July 2006

ABSTRACTFhSAP-2 is a novel member of theFasciola hepaticasaposin-like protein family that induces protection in rabbits against a challenge infection. We investigated the presence of lineal B-cell epitopes within this protein using a set of overlapping synthetic peptides. Peptides were tested in enzyme-linked immunosorbent assays against sera from rabbits infected withF. hepatica. Two dominant epitopes were identified, which were also highly reactive with sera from mice infected withSchistosoma mansoni. These peptides may be suitable to incorporate into a polyepitope-based vaccine formulation againstF. hepatica.
Bacillus anthracisSpores Stimulate Cytokine and Chemokine Innate Immune Responses in Human Alveolar Macrophages through Multiple Mitogen-Activated Protein Kinase Pathways
Authors: Chakrabarty Kaushik , Wu Wenxin , Booth J. Leland , Duggan Elizabeth S. , Coggeshall K. Mark , Metcalf Jordan P. 
Published: July 2006

ABSTRACTContact with the human alveolar macrophage plays a key role in the innate immune response toBacillus anthracisspores. Because there is a significant delay between the initial contact of the spore with the host and clinical evidence of disease, there appears to be temporary containment of the pathogen by the innate immune system. Therefore, the early macrophage response toBacillus anthracisexposure is important in understanding the pathogenesis of this disease. In this paper, we studied the initial events after exposure to spores, beginning with the rapid internalization of spores by the macrophages. Spore exposure rapidly activated the mitogen-activated protein kinase signaling pathways extracellular signal-regulated kinase, c-Jun-NH2-terminal kinase, and p38. This was followed by the transcriptional activation of cytokine and primarily monocyte chemokine genes as determined by RNase protection assays. Transcriptional induction is reflected at the translational level, as interleukin-1α (IL-1α), IL-1β, IL-6, and tumor necrosis factor alpha (TNF-α) cytokine protein levels were markedly elevated as determined by enzyme-linked immunosorbent assay. Induction of IL-6 and TNF-α, and, to a lesser extent, IL-1α and IL-1β, was partially inhibited by the blockade of individual mitogen-activated protein kinases, while the complete inhibition of cytokine induction was achieved when multiple signaling pathway inhibitors were used. Taken together, these data clearly show activation of the innate immune system in human alveolar macrophages byBacillus anthracisspores. The data also show that multiple signaling pathways are involved in this cytokine response. This report is the first comprehensive examination of this process in primary human alveolar macrophages.
Serial Propagation of the Microsporidian
Enterocytozoon bieneusi
of Human Origin in Immunocompromised Rodents
Authors: Feng Xiaochuan , Akiyoshi Donna E. , Sheoran Abhineet , Singh Inderpal , Hanawalt Joel , Zhang Quanshun , Widmer Giovanni , Tzipori Saul 
Published: July 2006

ABSTRACT

Enterocytozoon bieneusi
, a microsporidian, is clinically one of the most significant opportunistic causes of diarrhea and wasting associated with profound human immunodeficiencies. The lack of an animal model for
E. bieneusi
hinders serious investigations and limits the availability of spores to individuals with severe human immunodeficiency virus/AIDS disease who are infected with
E. bieneusi
. The development of procedures for purification and concentration of spores from stools of infected humans has led to the production of immune reagents and provided a source of spores to conduct research, including attempts to develop and serially propagate
E. bieneusi
in rodent models. We have evaluated and successfully infected six different immunodeficient and/or immunosuppressed rodent models and have demonstrated persistent infections lasting at least 18 weeks in SCID mice and in nude rats. To enhance the intensity and duration of infection in these two models, animals were given anti-gamma interferon monoclonal antibody injections at regular intervals. Of the six models evaluated, nude rats and gerbils immunosuppressed with dexamethasone excreted the highest number of spores and for longer time periods. Four different
E. bieneusi
isolates were equally infectious, and one of them was serially propagated in nude rats six times over a period of 10 months. Typically, rats challenged orally with 10
4
spores yielded 2 × 10
7
to 6.3 × 10
7
spores per single fecal sample when the level of spores was measured 2 weeks later. Rodent models and a nonhuman source of fresh spores will considerably enhance future investigations on this important opportunistic pathogen, including the screening and evaluation of urgently needed chemotherapeutic agents.
Comparison and Correlation of
Neisseria meningitidis
Serogroup B Immunologic Assay Results and Human Antibody Responses following Three Doses of the Norwegian Meningococcal Outer Membrane Vesicle Vaccine MenBvac
Authors: Findlow Jamie , Taylor Stephen , Aase Audun , Horton Rachel , Heyderman Robert , Southern Jo , Andrews Nick , Barchha Rita , Harrison Ewan , Lowe Ann , Boxer Emma , Heaton Charlotte , Balmer Paul , Kaczmarski Ed , Oster Philipp , Gorringe Andrew , Borrow Ray , Miller Elizabeth 
Published: July 2006

ABSTRACT

The prediction of efficacy of
Neisseria meningitidis
serogroup B (MenB) vaccines is currently hindered due to the lack of an appropriate correlate of protection. For outer membrane vesicle (OMV) vaccines, immunogenicity has primarily been determined by the serum bactericidal antibody (SBA) assay and OMV enzyme-linked immunosorbent assay (ELISA). However, the opsonophagocytic assay (OPA), surface labeling assay, whole blood assay (WBA), and salivary antibody ELISA have been developed although correlation with protection is presently undetermined. Therefore, the aim of the study was to investigate further the usefulness of, and relationships between, MenB immunologic assays. A phase II trial of the OMV vaccine, MenBvac, with proven efficacy was initiated to compare immunologic assays incorporating the vaccine and six heterologous strains. Correlations were achieved between the SBA assay, OMV ELISA, and OPA using human polymorphonuclear leukocytes and human complement but not between an OPA using HL60 phagocytic cells and baby rabbit complement. Correlations between the surface labeling assay, the SBA assay, and the OMV ELISA were promising, although target strain dependent. Correlations between the salivary antibody ELISA and other assays were poor. Correlations to the WBA were prevented since many samples had results greater than the range of the assay. The study confirmed the immunogenicity and benefit of a third dose of MenBvac against the homologous vaccine strain using a variety of immunologic assays. These results emphasize the need for standardized methodologies that would allow a more robust comparison of assays between laboratories and promote their further evaluation as correlates of protection against MenB disease.
Interleukin-10 Inhibits Gram-Negative-Microbe-Specific Human Receptor Activator of NF-κB Ligand-Positive CD4
+
-Th1-Cell- Associated Alveolar Bone Loss In Vivo
Authors: Zhang Xiaoxia , Teng Yen-Tung A. 
Published: July 2006

ABSTRACT

To study anti-inflammatory cytokine effects on RANKL
+
-T-cell-mediated osteoclastogenesis in vivo, we injected human interleukin-10 (hIL-10) into pathogen-infected HuPBL-NOD/SCID mice. The results show significantly decreased RANKL
+
Th1-associated alveolar bone loss and coexpression of human gamma interferon (hIFN-γ) and human macrophage colony-stimulating factor, but not hIL-4, in RANKL
+
Th cells compatible with those from successfully treated aggressive periodontitis subjects. Thus, there are critical cytokine interactions linking hIFN-γ
+
Th1 cells to RANKL-RANK/OPG signaling for periodontal osteoclastogenesis in vivo.
Modulation of Host Immune Responses by the Cytolethal Distending Toxin of
Helicobacter hepaticus
Authors: Pratt Jason S. , Sachen Kacey L. , Wood Heather D. , Eaton Kathryn A. , Young Vincent B. 
Published: July 2006

ABSTRACT

Persistent murine infection with
Helicobacter hepaticus
leads to chronic gastrointestinal inflammation and neoplasia in susceptible strains. To determine the role of the virulence factor cytolethal distending toxin (CDT) in the pathogenesis of this organism, interleukin-10-deficient (IL-10
−/−
) mice were experimentally infected with wild-type
H. hepaticus
and a CDT-deficient isogenic mutant. Both wild-type
H. hepaticus
and the CDT-deficient mutant successfully colonized IL-10
−/−
mice, and they reached similar tissue levels by 6 weeks after infection. Only animals infected with wild-type type
H. hepaticus
developed significant typhlocolitis. However, by 4 months after infection, the CDT-deficient mutant was no longer detectable in IL-10
−/−
mice, whereas wild-type
H. hepaticus
persisted for the 8-month duration of the experiment. Animals infected with wild-type
H. hepaticus
exhibited severe typhlocolitis at 8 months after infection, while animals originally challenged with the CDT-deficient mutant had minimal cecal inflammation at this time point. In follow-up experiments, animals that cleared infection with the CDT-deficient mutant were protected from rechallenge with either mutant or wild-type
H. hepaticus
. Animals infected with wild-type
H. hepaticus
developed serum immunoglobulin G1 (IgG1) and IgG2c responses against
H. hepaticus
, while animals challenged with the CDT-deficient mutant developed significantly lower IgG2c responses and failed to mount IgG1 responses against
H. hepaticus
. These results suggest that CDT plays a key immunomodulatory role that allows persistence of
H. hepaticus
and that in IL-10
−/−
mice this alteration of the host immune response results in the development of colitis.
Identification of Antigenic Components of
Staphylococcus epidermidis
Expressed during Human Infection
Authors: Pourmand Mohammad R. , Clarke Simon R. , Schuman Richard F. , Mond James J. , Foster Simon J. 
Published: July 2006

ABSTRACT

A spectrum of in vivo-expressed
Staphylococcus epidermidis
antigens was identified by probing a bacteriophage lambda library of
S. epidermidis
genomic DNA with human serum from infected and uninfected individuals. This analysis resulted in identification of 53 antigen-encoding loci. Six antigenic polypeptides were expressed from these loci and purified. These polypeptides were the propeptide, mature amidase, and repeat sequence domains of the major autolysin AtlE, GehD (lipase), and two members of a conserved family of surface proteins (ScaA [AaE] and ScaB). AtlE, ScaA, and ScaB all exhibit human ligand binding capacity. Screening a bank of human serum samples revealed that there were significant increases in the amounts of reactive immunoglobulin G in infected individuals compared to the amounts in healthy individuals for the repeat sequence and mature amidase domains of AtlE, ScaB, and GehD. Vaccination of mice with recombinant antigens stimulated an immune response which in vitro opsonized
S. epidermidis
. In this study we identified prospective candidate antigens for prophylaxis or immunotherapy to control disease.
Mutational Analysis of RetS, an Unusual Sensor Kinase-Response Regulator Hybrid Required for
Pseudomonas aeruginosa
Virulence
Authors: Laskowski Michelle A. , Kazmierczak Barbara I. 
Published: July 2006

ABSTRACT

Pseudomonas aeruginosa
is an opportunistic pathogen capable of causing both acute and chronic infections in a wide range of hosts. Expression of the type III secretion system (T3SS) proteins is correlated with virulence in models of acute infection, while downregulation of the T3SS and upregulation of genes important for biofilm formation are observed during chronic infections. RetS, a hybrid sensor kinase-response regulator protein of
P. aeruginosa
, plays a key role in the reciprocal regulation of virulence factors required for acute versus chronic infection and is postulated to act in concert with two other sensor kinase-response regulator hybrids, GacS and LadS. This work examines the roles of the putative sensing and signal transduction domains of RetS in induction of the T3SS in vitro and in a murine model of acute pneumonia. We identify distinct signaling roles for the tandem receiver domains of RetS and present evidence suggesting that RetS may serve as a substrate for another sensor kinase. Phenotypes associated with RetS alleles lacking periplasmic and/or transmembrane domains further indicate that the periplasmic domain of RetS may transmit a signal that inhibits RetS activity during acute infections.