bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of plant density on grain yield, root–length density and Orobanche crenata infestation in two faba bean genotypes
Authors: MANSCHADI A. M. , SAUERBORN J. , KROSCHEL J. , SAXENA M. C.
Published: July 2006

The effect of host plant cultivar and sowing density on Orobanche crenata Forsk. L. infestation in Vicia faba was studied in a field experiment in north–west Syria. Two faba bean genotypes. ILB 1814 (Syrian Local Large) and 402/29/84 (new breeding line from Egypt), were planted at four sowing densities. Whereas ILB 1814 was severely affected by O. crenata, 402/29/84 proved to be highly resistant. Sowing density did not have a significant effect on O. crenata dry weight in either genotype. However, the number of O. crenata attachments in ILB 1814 was positively correlated with plant density. The resistance of faba bean genotype 402/29/84 to O. crenata is due to: (a) less plant vigour and root–length density; (b) necrosis of host cells preventing O. crenata attack either before or just after penetration into the host root, or developing a barrier in the host root after the formation of a small tubercle: (c) early flowering and pod setting.
Wild onion (Asphodelus tenuifolius Cav.) interference in lentil and chickpea crops and its management through competitive cropping
Authors: MISHRA JANKI S. , SINGH VED P. , YADURAJU NANJAPUR T.
Published: July 2006

The interference of wild onion with various densities of lentil and chickpea and its management through competitive cropping were studied under field conditions from 2001–2002 and 2002–2003 at Jabalpur, India. The observed yield loss and predicted yield loss related to wild onion indicated that wild onion was less competitive with chickpea than with lentil. As a result of intraspecies competition, the dry weight and number of seeds per plant for wild onion were reduced with increasing density. The suppressing effect of different crops on the seed rain of wild onion was in the order of pea > mustard > wheat > chickpea > linseed > lentil > French bean. Wheat, pea, and mustard were the most competitive crops against wild onion. The high shading ability of these crops was thought to contribute to the suppression of wild onion. French bean offered the least suppression while chickpea, linseed, and lentil showed moderate weed suppression.
Effects of Shelf‐Life Enhancers on E. coli K12 Survival in Solutions Used to Enhance Beef Strip Steaks
Authors: Wicklund R.A. , Paulson D.D. , Rojas M.C. , Brewer M.S.
Published: July 2006

ABSTRACT:  The objective of this study was to evaluate the effects of enhancement solutions containing sodium lactate or sodium lactate/sodium diacetate on E. coli K12 transmission to beef strip steaks and in purge. Solutions containing salt, phosphate, and shelf‐life enhancers were injected to 10% over initial weight of the steaks. Lactate or lactate/diacetate addition to a solution inoculated with 6 log10E. coli K12 CFU/mL was equally effective in limiting growth resulting in a 1‐2 log10 CFU/g reduction when compared to salt/phosphate in steaks. When inoculation level was 3 log10 CFU/mL in the enhancement solution, microbial growth was detectable only in the purge of steaks enhanced with salt/phosphate only. Lactate increased CIE L* value and b* and decreased a* values when compared to the control. Lactate‐/diacetate‐containing solutions decreased L* values when compared to lactate alone. Lactate/diacetate also reduced purge loss from steaks compared to lactate and salt/phosphate solutions.
Streptococcus pneumoniaeInfection Aggravates Experimental Autoimmune Encephalomyelitis via Toll-Like Receptor 2
Authors: Herrmann Isabel , Kellert Markus , Schmidt Hauke , Mildner Alexander , Hanisch Uwe K. , Brück Wolfgang , Prinz Marco , Nau Roland
Published: July 2006

The course of autoimmune inflammatory diseases of the central nervous system (CNS) can be influenced by infections. Here we assessed the disease-modulating effects of the most frequent respiratory pathogenStreptococcus pneumoniaon the course of experimental autoimmune encephalomyelitis (EAE). Mice were immunized with myelin oligodendrocyte glycoprotein 35-55 (MOG35-55) peptide, challenged intraperitoneally with liveS. pneumoniaetype 3, and then treated with ceftriaxone. EAE was monitored by a clinical score for 35 days after immunization. EAE was unaltered in mice infected withS. pneumoniae2 days before and 21 days after the first MOG35-55injection but was more severe in animals infected 7 days after the first MOG35-55injection. The antigen-driven systemic T-cell response was unaltered, and the intraspinal Th1 cytokine mRNA concentrations at the peak of disease were unchanged. The composition of CNS-infiltrating cells and subsequent tissue destruction were only slightly increased afterS. pneumoniaeinfection. In contrast, the serum levels of tumor necrosis factor alpha and interleukin-6 and spinal interleukin-6 levels were elevated, and the expression of major histocompatibility complex class II molecules, CD80, and CD86 on splenic dendritic cells were enhanced early after infection. Serum cytokine concentrations were not elevated, and EAE was not aggravated byS. pneumoniaeinfection in Toll-like receptor 2 (TLR2)-deficient mice. In conclusion, infection withS. pneumoniaeworsens EAE probably by elevation of proinflammatory cytokines and activation of dendritic cells in the systemic circulation via TLR2 and cross talk through the blood-brain barrier.
Cj1496c Encodes a
Campylobacter jejuni
Glycoprotein That Influences Invasion of Human Epithelial Cells and Colonization of the Chick Gastrointestinal Tract
Authors: Kakuda Tsutomu , DiRita Victor J.
Published: July 2006

Campylobacter jejuni
has an N-linked protein glycosylation pathway that is required for efficient cell invasion and chick gastrointestinal colonization by the microbe. In this study, we constructed insertion mutants of 22 putative glycoprotein genes and examined the ability of each to invade the human intestinal epithelial cell line INT-407. Among the mutants tested, one carrying an insertion in Cj1496c was defective for invasion into INT-407 cells; this defect was also observed in an in-frame deletion mutant of Cj1496c (ΔCj1496c). The ΔCj1496c mutant
C. jejuni
also showed a reduced ability to colonize chick ceca. Site-specific mutagenesis combined with Western blot analysis suggested that the Cj1496c protein is glycosylated at N73 and N169. However, the ΔCj1496c mutant expressing a nonglycosylated form of Cj1496c exhibited levels of invasion and colonization equivalent to those of the parent strain, suggesting that glycans are not directly involved in the function of Cj1496c.
Diversity of the T-Cell Response to PulmonaryCryptococcus neoformansInfection
Authors: Lindell Dennis M. , Ballinger Megan N. , McDonald Roderick A. , Toews Galen B. , Huffnagle Gary B.
Published: July 2006

Cell-mediated immunity plays an important role in immunity to the pathogenic fungusCryptococcus neoformans. However, the antigen specificity of the T-cell response toC. neoformansremains largely unknown. In this study, we used two approaches to determine the antigen specificity of the T-cell response toC. neoformans. We report here that a diverse T-cell receptor (TCR) Vβ repertoire was maintained throughout the primary response to pulmonaryC. neoformansinfection in immunocompetent mice. CD4+T-cell deficiency resulted in relative expansion of all CD8+T-cell subsets. During a secondary immune response, preferential usage of a TCR Vβ subset in CD4+T cells occurred in single individuals, but the preferences were “private” and not shared between individuals. Both CD4+and CD8+T cells from the secondary lymphoid tissues of immunized mice proliferated in response to a variety ofC. neoformansantigens, including heat-killed wholeC. neoformans, culture filtrate antigen,C. neoformanslysate, and purified cryptococcal mannoprotein. CD4+and CD8+T cells from the secondary lymphoid tissues of mice undergoing a primary response toC. neoformansproliferated in response toC. neoformanslysate. In response to stimulation withC. neoformanslysate, lung CD4+and CD8+T cells produced the effector cytokines tumor necrosis factor alpha and gamma interferon. These results demonstrate that a diverse T-cell response is generated in response to pulmonaryC. neoformansinfection.
The Hypothetical Protein CT813 Is Localized in theChlamydia trachomatisInclusion Membrane and Is Immunogenic in Women Urogenitally Infected withC. trachomatis
Authors: Chen Chaoqun , Chen Ding , Sharma Jyotika , Cheng Wen , Zhong Youmin , Liu Kaiyang , Jensen Jani , Shain Rochelle , Arulanandam Bernard , Zhong Guangming
Published: July 2006

Using antibodies raised with chlamydial fusion proteins, we have localized a protein encoded by hypothetical open reading frame CT813 in the inclusion membrane ofChlamydia trachomatis. The detection of theC. trachomatisinclusion membrane by an anti-CT813 antibody was blocked by the CT813 protein but not unrelated fusion proteins. The CT813 protein was detected as early as 12 h after chlamydial infection and was present in the inclusion membrane during the entire growth cycle. All tested serovars fromC. trachomatisbut not other chlamydial species expressed the CT813 protein. Exogenously expressed CT813 protein in HeLa cells displayed a cytoskeleton-like structure similar to but not overlapping with host cell intermediate filaments, suggesting that the CT813 protein is able to either polymerize or associate with host cell cytoskeletal structures. Finally, women withC. trachomatisurogenital infection developed high titers of antibodies to the CT813 protein, demonstrating that the CT813 protein is not only expressed but also immunogenic during chlamydial infection in humans. In all, the CT813 protein is an inclusion membrane protein unique toC. trachomatisspecies and has the potential to interact with host cells and induce host immune responses during natural infection. Thus, the CT813 protein may represent an important candidate for understandingC. trachomatispathogenesis and developing intervention and prevention strategies for controllingC. trachomatisinfection.
Gamma Interferon Secretion by Human Vγ2Vδ2 T Cells after Stimulation with Antibody against the T-Cell Receptor plus the Toll-Like Receptor 2 Agonist Pam3Cys
Authors: Deetz Carl O. , Hebbeler Andrew M. , Propp Nadia A. , Cairo Cristiana , Tikhonov Illia , Pauza C. David
Published: July 2006

Circulating Vγ2Vδ2 T-cell populations in healthy human beings are poised for rapid responses to bacterial or viral pathogens. We asked whether Vγ2Vδ2 T cells use the Toll-like receptor (TLR) family to recognize pathogen-associated molecular pattern molecules and to regulate cell functions. Analysis of expanded Vγ2Vδ2 T-cell lines showed the abundant presence of TLR2 mRNA, implying that these receptors are important for cell differentiation or function. However, multiple efforts to detect TLR2 protein on the cell surface or in cytoplasmic compartments gave inconsistent results. Functional assays confirmed that human Vγ2Vδ2 T cells could respond to the TLR2 agonist (S)-(2,3-bis(palmitoyloxy)-(2RS)-propyl)-N-palmitoyl-(R)-Cys-(S)-Ser(S)-Lys4-OH trihydrochloride (Pam3Cys), but the response required coincident stimulation through the γδ T-cell receptor (TCR). Dually stimulated cells produced higher levels of cytoplasmic or cell-free gamma interferon and showed increased expression of the lysosome-associated membrane protein CD107a on the cell surface. A functional TLR2 that requires coincident TCR stimulation may increase the initial potency of Vγ2Vδ2 T-cell responses at the site of infection and promote the rapid development of subsequent acquired antipathogen immunity.
Signature-Tagged Mutagenesis of
Klebsiella pneumoniae
To Identify Genes That Influence Biofilm Formation on Extracellular Matrix Material
Authors: Boddicker Jennifer D. , Anderson Rebecca A. , Jagnow Jennifer , Clegg Steven
Published: July 2006

Klebsiella pneumoniae
causes urinary tract infections, respiratory tract infections, and septicemia in susceptible individuals. Strains of
Klebsiella
frequently produce extended-spectrum beta-lactamases, and infections with these strains can lead to relatively high mortality rates (approximately 15%). Other virulence factors include production of an antiphagocytic capsule and outer membrane lipopolysaccharide (LPS), which mediates serum resistance, as well as fimbriae on the surface of the bacteria. Type 1 fimbriae mediate adherence to many types of epithelial cells and may facilitate adherence of the bacteria to the bladder epithelium. Type 3 fimbriae can bind in vitro to the extracellular matrix of urinary and respiratory tissues, suggesting that they mediate binding to damaged epithelial surfaces. In addition, type 3 fimbriae are required for biofilm formation by
Klebsiella pneumoniae
on plastics and human extracellular matrix; thus, they may facilitate the formation of treatment-resistant biofilm on indwelling plastic devices, such as catheters and endotracheal tubing. The presence of these devices may cause tissue damage, allowing
Klebsiella
to grow as a biofilm on exposed tissue basement membrane components. Though in vivo biofilm growth may be an important step in the infection process, little is known about the genetic factors required for biofilm formation by
Klebsiella pneumoniae
. Thus, we performed signature-tagged mutagenesis to identify factors produced by
K. pneumoniae
strain 43816 that are required for biofilm formation. We identified mutations in the
cps
capsule gene cluster, previously unidentified transcriptional regulators, fimbrial, and sugar phosphotransferase homologues, as well as genetic loci of unknown function, that affect biofilm formation.
Intranasal Immunization with the Cholera Toxin B Subunit-Pneumococcal Surface Antigen A Fusion Protein Induces Protection against Colonization with
Streptococcus pneumoniae
and Has Negligible Impact on the Nasopharyngeal and Oral Microbiota of Mice
Authors: Pimenta F. C. , Miyaji E. N. , Arêas A. P. M. , Oliveira M. L. S. , de Andrade A. L. S. S. , Ho P. L. , Hollingshead S. K. , Leite L. C. C.
Published: July 2006

One of the candidate proteins for a mucosal vaccine antigen against
Streptococcus pneumoniae
is PsaA (pneumococcal surface antigen A). Vaccines targeting mucosal immunity may raise concerns as to possible alterations in the normal microbiota, especially in the case of PsaA, which was shown to have homologs with elevated sequence identity in other viridans group streptococci. In this work, we demonstrate that intranasal immunization with a cholera toxin B subunit-PsaA fusion protein is able to protect mice against colonization with
S. pneumoniae
but does not significantly alter the natural oral or nasopharyngeal microbiota of mice.
Cardiac Failure in C5-Deficient A/J Mice afterCandida albicansInfection
Authors: Mullick Alaka , Leon Zully , Min-Oo Gundula , Berghout Joanne , Lo Rita , Daniels Eugene , Gros Philippe
Published: July 2006

The effect of a deficiency in the C5 component of complement on the pathophyisology of infection with the fungal pathogenCandida albicanswas studied by using the A/J inbred mouse strain and the BcA17 congenic mouse strain. Acute infection caused by intravenous injection ofC. albicansblastospores is associated with rapid fungal replication in the heart, brain, and, in particular, kidneys of C5-deficient mice. Histological studies and analysis of markers for tissue damage indicated that the heart is the organ that is most affected and that it ultimately fails in C5-deficient mice. In A/J and BcA17 mice, tissue damage is associated with (i) cellular infiltration in the heart, which is not seen in the kidney despite the higher fungal load in the latter organ, and (ii) a very strong inflammatory response, including elevated levels of many cytokines and chemokines. This results in cardiomyopathy, which is associated with elevated levels of creatine kinase and cardiac troponin I in the circulation. Damage to the cardiac muscle is associated with metabolic changes, including hypoglycemia, decreased lipid utilization resulting in elevated levels of cardiac triglycerides, and unproductive glucose utilization linked to a dramatic increase in the level of pyruvate dehydrogenase kinase 4 (Pdk4), a negative regulator of the pyruvate dehydrogenase complex.
Regulation of Production of Mucosal Antibody to Pneumococcal Protein Antigens by T-Cell-Derived Gamma Interferon and Interleukin-10 in Children
Authors: Zhang Qibo , Bernatoniene Jolanta , Bagrade Linda , Paton James C. , Mitchell Timothy J. , Hammerschmidt Sven , Nunez Desmond A. , Finn Adam
Published: July 2006

Nasopharyngeal tonsils (adenoids) are part of human nasopharynx-associated lymphoid tissue, which may play an important role in local defense against pneumococci. Recent studies with animals have suggested that several pneumococcal proteins, including CbpA and pneumolysin (Ply), may be vaccine candidates. Our recent data obtained with children suggest that antibodies to these proteins may protect against carriage. This study was performed to investigate the regulation of the T-cell-dependent antibody responses to CbpA and pneumolysin by cytokines in adenoidal immune cells from children. Adenoidal mononuclear cells (MNC) were cultured with pneumococcal concentrated culture supernatants (CCS) or recombinant proteins. Cytokine expression profiles in adenoidal MNC after antigen stimulation were analyzed by reverse transcription-PCR, protein array analysis, and an immunoassay, along with an antibody production analysis. The roles, interactions, and cellular sources of the main cytokines identified were evaluated further. Pneumococcal CCS induced production of CbpA- and Ply-specific antibodies in association with several chemokines and cytokines, including gamma interferon (IFN-γ) and interleukin-10 (IL-10) in MNC. The antibody production correlated well with the concentrations of these two cytokines. Addition of recombinant IFN-γ or IL-10 enhanced antibody production, and monoclonal antibodies to these two cytokines and T-cell depletion significantly reduced antibody production. Intracellular cytokine staining showed that T cells are a major source of IFN-γ and IL-10. Recombinant Ply and, to a lesser extent, recombinant CbpA induced significant production of IFN-γ and IL-10 in MNC. T-cell-derived IFN-γ and IL-10 may be key regulators of production of mucosal antibody to pneumococcal protein antigens in the nasopharynx and may play an important role in local protection against pneumococcal infection in children.
Staphyloxanthin Plays a Role in the Fitness of
Staphylococcus aureus
and Its Ability To Cope with Oxidative Stress
Authors: Clauditz Alexandra , Resch Alexandra , Wieland Karsten-Peter , Peschel Andreas , Götz Friedrich
Published: July 2006

Staphyloxanthin is a membrane-bound carotenoid of
Staphylococcus aureus
. Here we studied the interaction of staphyloxanthin with reactive oxygen substances (ROS) and showed by comparative analysis of the wild type (WT) and an isogenic
crtM
mutant that the WT is more resistant to hydrogen peroxide, superoxide radical, hydroxyl radical, hypochloride, and neutrophil killing.
Unique Features of a Highly Pathogenic
Campylobacter jejuni
Strain
Authors: Hofreuter Dirk , Tsai Jennifer , Watson Robert O. , Novik Veronica , Altman Bill , Benitez Michelle , Clark Christina , Perbost Clotilde , Jarvie Thomas , Du Lei , Galán Jorge E.
Published: July 2006

Campylobacter jejuni
, a major human enteric pathogen, exhibits significant strain-to-strain differences which result in differences in pathogenic potential.
C. jejuni
81-176 is a highly virulent strain that exhibits unique pathogenic features and is used by many research laboratories. We have determined the nucleotide sequence of its genome and compared it to the genomes of other sequenced
C. jejuni
strains. We identified a number of unique genetic features which may confer specific metabolic and pathogenic properties on this strain. We have also identified regions of the
C. jejuni
genome that are hot spots for the integration of horizontally acquired genetic material. This information should help the understanding of the pathogenesis of
C. jejuni
and, in particular, the unique features of this highly pathogenic strain.
Effect of Lung Surfactant Collectins on Bronchoalveolar Macrophage Interaction withBlastomyces dermatitidis: Inhibition of Tumor Necrosis Factor Alpha Production by Surfactant Protein D
Authors: Lekkala Madhavi , LeVine Ann Marie , Linke Michael J. , Crouch Erika C. , Linders Bruce , Brummer Elmer , Stevens David A.
Published: July 2006

Alveolar surfactant modulates the antimicrobial function of bronchoalveolar macrophages (BAM). Little is known about the effect of surfactant-associated proteins in bronchoalveolar lavage fluid (BALF) on the interaction of BAM andBlastomyces dermatitidis. We investigated BALF enhancement or inhibition of TNF-α production by BAM stimulated byB. dermatitidis. BAM from CD-1 mice were stimulated withB. dermatitidiswithout or with normal BALF, surfactant protein A-deficient (SP-A−/−) or surfactant protein D-deficient (SP-D−/−) BALF, or a mixture of SP-A−/−and SP-D−/−BALF. An enzyme-linked immunosorbent assay was used to measure tumor necrosis factor alpha (TNF-α) in culture supernatants. BALFs were standardized in protein concentration. BAM plusB. dermatitidis(BAM-B. dermatitidis) TNF-α production was inhibited ≥47% by BALF or SP-A−/−BALF (at 290 or 580 μg of protein/ml,P< 0.05 to 0.01); in contrast, SP-D−/−BALF did not significantly inhibit TNF-α production. If SP-A−/−BALF was mixed in equal amounts with SP-D−/−BALF, TNF-α production by BAM-B. dermatitidiswas inhibited (P< 0.01). Finally, pure SP-D added to SP-D−/−BALF inhibited TNF-α production by BAM-B. dermatitidis(P< 0.01).B. dermatitidisincubated with BALF and washed, plus BAM, stimulated 63% less production of TNF-α than did unwashedB. dermatitidis(P< 0.05). SP-D was detected by anti-SP-D antibody on BALF-treated unwashedB. dermatitidisin an immunofluorescence assay (IFA). The BALF depleted by a coating ofB. dermatitidislost the ability to inhibit TNF-α production (P < 0.05). 1,3-β-Glucan was a good stimulator of BAM for TNF-α production and was detected onB. dermatitidisby IFA. β-Glucan incubated with BALF inhibited the binding of SP-D in BALF toB. dermatitidisas demonstrated by IFA. Our data suggest that SP-D in BALF binds β-glucan onB. dermatitidis, blocking BAM access to β-glucan, thereby inhibiting TNF-α production. Thus, whereas BALF constituents commonly mediate antimicrobial activity,B. dermatitidismay utilize BALF constituents, such as SP-D, to blunt the host defensive reaction; this effect could reduce inflammation and tissue destruction but could also promote disease.
An Intradermal Environment Promotes a Protective Type-1 Response against Lethal Systemic Monocytotropic Ehrlichial Infection
Authors: Stevenson Heather L. , Jordan Jeffrey M. , Peerwani Ziad , Wang Hui-Qun , Walker David H. , Ismail Nahed
Published: July 2006

Immune responses against monocytotropic ehrlichiosis during infection with a strain of
Ehrlichia
from
Ixodes ovatus
(IOE) were evaluated using a model that closely reproduces the pathology and immunity associated with tick-transmitted human monocytotropic ehrlichiosis. C57BL/6 mice were inoculated intradermally or intraperitoneally with high-dose highly virulent IOE or intraperitoneally with mildly virulent
Ehrlichia muris
. Intradermal (i.d.) infection with IOE established mild, self-limited disease associated with minimal hepatic apoptosis, and all mice survived past 30 days. Intraperitoneal (i.p.) infection with IOE resulted in acute, severe toxic shock-like syndrome and severe multifocal hepatic apoptosis and necrosis, and all mice succumbed to disease. Compared to i.p. infection with IOE, intradermally infected mice had a 100- to 1,000-fold lower bacterial load in the spleen with limited dissemination. Compared to mice infected intraperitoneally with IOE, i.d. infection stimulated a stronger protective type-1 cell-mediated response on day 7 of infection, characterized by increased percentages of both CD4
+
and CD8
+
splenic T cells, generation of a greater number of IOE-specific, gamma interferon-producing CD4
+
Th1 cells, and higher levels of tumor necrosis factor (TNF-α) in the spleen but lower concentrations of serum TNF-α and interleukin-10. These data suggest that under the conditions of natural route of challenge (i.e., i.d. inoculation), the immune response has the capacity to confer complete protection against monocytotropic ehrlichiosis, which is associated with a strong cell-mediated type-1 response and decreased systemic production of pro- and anti-inflammatory cytokines.
The
yjeQ
Gene Is Required for Virulence of
Staphylococcus aureus
Authors: Campbell Tracey L. , Henderson James , Heinrichs David E. , Brown Eric D.
Published: July 2006

Gene products required for in vivo growth and survival of
Staphylococcus aureus
and other pathogens represent new targets for antimicrobial chemotherapy. In this study we created a
Staphylococcus aureus yjeQ
deletion strain and tested its virulence using a mouse kidney abscess infection model. The
yjeQ
deletion strain was compromised for growth in vitro and severely attenuated for virulence. We concluded that
yjeQ
is an attractive and novel new drug target.
Characterization of the T-Cell Receptor Vβ Repertoire in the Human Immune Response againstLeishmaniaParasites
Authors: Clarêncio Jorge , de Oliveira Camila I. , Bomfim Glória , Pompeu Margarida M. , Teixeira Maria Jania , Barbosa Theolis C. , Souza-Neto Sebastião , Carvalho Edgar M. , Brodskyn Cláudia , Barral Aldina , Barral-Netto Manoel
Published: July 2006

In order to explore a possible presence of hyperreactive T-cell clones in human cutaneous leishmaniasis (CL), we have investigated, by flow cytometry, the expression of Vβ chains of T-cell receptors (TCRs) in the following types of cells: (i) peripheral blood mononuclear cells (PBMCs) from CL patients, which were then compared to those from normal volunteers; (ii) unstimulated and solubleLeishmaniaantigen-stimulated draining lymph node cells from CL patients; (iii) PBMCs from volunteers before versus afterLeishmaniaimmunization; and (iv) PBMCs from healthy volunteers that were primed in vitro with liveLeishmaniaparasites. Our results show a modulation in the TCR Vβ repertoire during CL and after antigen stimulation of patients' cells. Vaccination, however, leads to a broad expansion of different Vβ TCRs. We also observed an association between TCR Vβ12 expression, T-cell activation, and gamma interferon production upon in vitro priming withLeishmania.Collectively, these results both indicate that infection with live parasites or exposure to parasite antigen can modulate the TCR Vβ repertoire and suggest that TCR Vβ12 may be implicated in the response toLeishmania.
The Circadian ClockPeriod 2Gene Regulates Gamma Interferon Production of NK Cells in Host Response to Lipopolysaccharide-Induced Endotoxic Shock
Authors: Liu Jianguo , Mankani Guantham , Shi Xiaoyan , Meyer Mark , Cunningham-Runddles Susana , Ma Xiaojing , Sun Zhong Sheng
Published: July 2006

ThePeriod 2(Per2) gene is a key molecular component in controlling mammalian circadian rhythms at the levels of gene expression, physiology, and pathogenesis. Although many immune parameters, such as the number of different subtypes of circulating immune cells and the level of cytokine production in response to infection with bacteria and viruses, have been well documented to display a circadian pattern in mammals, the basic features of molecular clock components in the immune system and the role of clock genes in regulating host immune defenses remain uncharacterized. Previously, we have reported that circadian clock genes oscillate in human mononuclear cells. Here we report that Per2-deficient mice were more resistant to lipopolysaccharide (LPS)-induced endotoxic shock than control wild-type mice. We further demonstrate that the levels of the proinflammatory cytokines gamma interferon (IFN-γ) and interleukin-1β (IL-1β) in the serum were dramatically decreased inPer2−/−mice following LPS challenge, while production of tumor necrosis factor alpha, IL-6, and IL-10 was approximately normal, compared to that in control wild-type mice. Flow cytometric analyses confirmed that the cellularity of most of the immune cell subsets in the spleens of LPS-challenged mice was normal and that the impaired IFN-γ production inPer2−/−mice was attributable to defective NK and NKT cell function. Our data suggest that Per2 is an important regulator of NK cell function, therefore providing the first direct link between the circadian clock system and innate immune responses.
Regulation of Murine Dendritic Cell Immune Responses byHelicobacter felisAntigen
Authors: Drakes Maureen L. , Czinn Steven J. , Blanchard Thomas G.
Published: July 2006

Helicobacterinfections are present in approximately 50% of humans, causing severe illnesses such as gastritis and malignancies. Dendritic cells (DC) are critical antigen-presenting cells which link innate and adaptive immune responses. The mechanism of dendritic cell regulation inHelicobacter-induced gastritis is poorly understood. These studies characterized DC isolated from the lamina propria ofHelicobacter-infected mice and analyzed innate and adaptive immune responses elicited byHelicobacterantigen (Ag)-pulsed DC. The presence of DC was elevated in the gastric lamina propria infiltrate of infected mice in comparison with controls. After treatment withHelicobacter felisAg, DC were polarized to secrete interleukin-6 as the dominant cytokine. In the presence of DC andHelicobacterAg, responder allogeneic T cells in culture exhibited limited cell division. We suggest that the response of DC and T cells toHelicobacterAg is critical to the chronic persistence ofHelicobacter-induced gastritis.
The Presence of Peptidoglycan
O
-Acetyltransferase in Various Staphylococcal Species Correlates with Lysozyme Resistance and Pathogenicity
Authors: Bera Agnieszka , Biswas Raja , Herbert Silvia , Götz Friedrich
Published: July 2006

Human-pathogenic bacteria that are able to cause persistent infections must have developed mechanisms to resist the immune defense system. Lysozyme, a cell wall-lytic enzyme, is one of the first defense compounds induced in serum and tissues after the onset of infection. Recently, we showed that
Staphylococcus aureus
is resistant to lysozyme by O acetylating its peptidoglycan (PG) by
O
-acetyltransferase (OatA). We asked the question of which staphylococcal species PG is O acetylated. We applied various methods, such as genome analysis, PCR, Southern blotting, lysozyme sensitivity assay, and verification of O acetylation of PG by high-performance liquid chromatography (HPLC) analysis. PCR analysis using
S. aureus
-derived
oatA
primers and Southern blotting did not yield reliable results with other staphylococcal species. Therefore, we used the HPLC-based assay to directly detect PG O acetylation. Our studies revealed that the muramic acid was O acetylated only in pathogenic, lysozyme-resistant staphylococci (e.g.,
S. aureus
,
S. epidermidis
,
S. lugdunensis
, and others). All nonpathogenic species were lysozyme sensitive. They can be divided into sensitive species (e.g.,
S. carnosus
,
S. gallinarum
, and
S. xylosus
) and hypersensitive species (e.g.,
S. equorum
,
S. lentus
, and
S. arlettae
). In all lysozyme-sensitive species, the analyzed PG was de-O-acetylated. When we transformed the
oatA
gene from lysozyme-resistant
S. aureus
into
S. carnosus
, the corresponding transformants also became lysozyme resistant.
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

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

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

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

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

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

Caspase-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

FhSAP-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

Contact 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

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.