bluuebunny/crossref_metadata_2025_split huggingface dataset:
Double-Stranded RNA Mycovirus from
Fusarium graminearum
Authors: Chu Yeon-Mee , Jeon Jae-Jin , Yea Sang-Jin , Kim Yong-Ho , Yun Sung-Hwan , Lee Yin-Won , Kim Kook-Hyung 
Published: July 2002

ABSTRACT

Double-stranded RNA (dsRNA) viruses in some fungi are associated with hypovirulence and have been used or proposed as biological control agents. We isolated 7.5-kb dsRNAs from 13 of 286 field strains of
Fusarium graminearum
isolated from maize in Korea. One of these strains, DK21, was examined in more detail. This strain had pronounced morphological changes, including reduction in mycelial growth, increased pigmentation, reduced virulence towards wheat, and decreased (60-fold) production of trichothecene mycotoxins. The presence or absence of the 7.5-kb dsRNA was correlated with the changes in pathogenicity and morphology. The dsRNA could be transferred to virus-free strains by hyphal fusion, and the recipient strain acquired the virus-associated phenotype of the donor strain. The dsRNA was transmitted to approximately 50% of the conidia, and only colonies resulting from conidia carrying the mycovirus had the virus-associated phenotype. Partial nucleotide sequences of the purified dsRNA identify an RNA-dependent RNA polymerase sequence and an ATP-dependent helicase that are closely related to those of
Cryphonectria
hypovirus and
Barley yellow mosaic virus
. Collectively, these results suggest that this dsRNA isolated from
F. graminearum
encodes traits for hypovirulence.
Reversible and Irreversible Adhesion of Motile
Escherichia coli
Cells Analyzed by Total Internal Reflection Aqueous Fluorescence Microscopy
Authors: Vigeant Margot A.-S. , Ford Roseanne M. , Wagner Michael , Tamm Lukas K. 
Published: July 2002

ABSTRACT

The initial events in bacterial adhesion are often explained as resulting from electrostatic and van der Waals forces between the cell and the surface, as described by DLVO theory (developed by Derjaguin, Landau, Verwey, and Overbeek). Such a theory predicts that negatively charged bacteria will experience greater attraction toward a negatively charged surface as the ionic strength of the medium is increased. In the present study we observed both smooth-swimming and nonmotile
Escherichia coli
bacteria close to plain, positively, and hydrophobically coated quartz surfaces in high- and low-ionic-strength media by using total internal reflection aqueous fluorescence microscopy. We found that reversibly adhering cells (cells which continue to swim along the surface for extended periods) are too distant from the surface for this behavior to be explained by DLVO-type forces. However, cells which had become immobilized on the surface did seem to be affected by electrostatic interactions. We propose that the “force” holding swimming cells near the surface is actually the result of a hydrodynamic effect, causing the cells to swim at an angle along the glass, and that DLVO-type forces are responsible only for the observed immobilization of irreversibly adhering cells. We explain our observations within the context of a conceptual model in which bacteria that are interacting with the surface may be thought of as occupying one of three compartments: bulk fluid, near-surface bulk, and near-surface constrained. A cell in these compartments feels either no effect of the surface, only the hydrodynamic effect of the surface, or both the hydrodynamic and the physicochemical effects of the surface, respectively.
New Automated Immunoassay Measuring Immunoglobulin A Antigliadin Antibodies for Prediction of Celiac Disease in Childhood
Authors: Grodzinsky E. , Ivarsson A. , Juto P. , Olcén P. , Fälth-Magnusson K. , Persson L. Å. , Hernell O. 
Published: July 2002

ABSTRACT
The prevalence of celiac disease (CD) in Sweden is about 4 cases per 1,000 people. Screening for CD with serological tests indicates similar high prevalences in many other countries. Between 1 November 1992 and 30 April 1995, 133 children (9 months to 16.7 years of age) with suspected CD were studied. The predictive value (PV) of immunoglobulin A antigliadin antibodies (IgA-AGA) in the serum as assayed with two new commercial automated immunoassays—the Pharmacia CAP System Gliadin IgA FEIA (CAP) and the UNICAP-100 (UNICAP)—and with three “in-house” methods was evaluated using assessment of the small intestinal mucosa morphology as the “gold standard.” All serum samples were analyzed for total serum IgA. At presentation the diagnostic sensitivities and specificities of the different tests varied from 0.72 to 0.88 and 0.67 to 0.87, respectively. All methods showed a higher sensitivity for CD in younger children. The area under each assay's receiver operating characteristic curve was calculated and varied between 0.82 and 0.89. The positive and negative PVs for the CAP and UNICAP, which were assays with a high sensitivity and a high specificity, respectively, were estimated. In the clinically selected population (prevalence of CD, 1 in 3) the positive PV was about 55%, and in the general population (prevalence, 1 in 250) it was about 1%. The negative PVs for both CAP and UNICAP were close to 100%; thus, when the AGA test was negative, the risk for CD was small. Interestingly, five children had serum IgA levels below the detection limit (<0.07 g/liter) when on a gluten-free diet, whereas they had normal levels at the time of the first biopsy. In conclusion, the automated immunoassays—based on ImmunoCAP technology—for analysis of IgA-AGA had a reliability comparable to that of the in-house methods.
Peptide Mimic of Phosphorylcholine, a Dominant Epitope Found onStreptococcus pneumoniae
Authors: Harris Shannon L. , Park Moon K. , Nahm Moon H. , Diamond Betty 
Published: July 2002

ABSTRACTEven in the age of antibiotics,Streptococcus pneumoniaecauses significant morbidity, especially in the young, the elderly, and the immunocompromised. While a carbohydrate-based vaccine exists, it is poorly immunogenic in the at-risk populations. In mice, antibodies directed against phosphorylcholine (PC), an epitope present on the cell wall C polysaccharide of all pneumococcal serotypes, protect against infection. However, PC itself is a poor vaccine candidate. We report here peptide mimics of PC based on the anti-idiotypic interaction of T15 anti-PC antibodies. T15 antibodies, the dominant and protective idiotype induced in mice by PC immunization, self-associate via a 24-amino-acid region in the PC binding site (ASRNKANDYTTEYSASVKGRFIVS; peptide 1). Peptide 1 has been shown to bind in the PC binding site. We demonstrated that amino acid sequences derived from peptide 1 starting at amino acid 9, 11, or 13 inhibit PC binding. Therefore, we immunized mice with bovine serum albumin (BSA) conjugates of peptide 1 or either of two selected 12-mers. The 12-mer peptides were not immunogenic. Mice immunized with peptide 1-BSA developed an anti-PC response consisting mainly immunoglobulin G1 and expressed the T15 heavy chain. Nonetheless, neither BALB/c nor CBA/N mice were protected from lethal pneumococcal infections by immunization with peptide 1-BSA. Preliminary data suggest that peptide 1-BSA is not able to elicit the canonical T15 light chain, explaining the absence of protection. This idiotype-derived mimotope of PC is a useful tool for understanding immunologic cross-reactivity and learning to design T-cell-dependent vaccines forS. pneumoniae.
Isolation and Characterization of a
Shigella flexneri
Invasin Complex Subunit Vaccine
Authors: Turbyfill K. Ross , Hartman Antoinette B. , Oaks Edwin V. 
Published: July 2002

ABSTRACT

The invasiveness and virulence of
Shigella
spp. are largely due to the expression of plasmid-encoded virulence factors, among which are the invasion plasmid antigens (Ipa proteins). After infection, the host immune response is directed primarily against lipopolysaccharide (LPS) and the virulence proteins (IpaB, IpaC, and IpaD). Recent observations have indicated that the Ipa proteins (IpaB, IpaC, and possibly IpaD) form a multiprotein complex capable of inducing the phagocytic event which internalizes the bacterium. We have isolated a complex of invasins and LPS from water-extractable antigens of virulent shigellae by ion-exchange chromatography. Western blot analysis of the complex indicates that all of the major virulence antigens of
Shigella
, including IpaB, IpaC, and IpaD, and LPS are components of this macromolecular complex. Mice or guinea pigs immunized intranasally with purified invasin complex (invaplex), without any additional adjuvant, mounted a significant immunoglobulin G (IgG) and IgA antibody response against the
Shigella
virulence antigens and LPS. The virulence-specific response was very similar to that previously noted in primates infected with shigellae. Guinea pigs (keratoconjunctivitis model) or mice (lethal lung model) immunized intranasally on days 0, 14, and 28 and challenged 3 weeks later with virulent shigellae were protected from disease (
P
< 0.01 for both animal models).
The CD40/CD40 Ligand Interaction Is Required for Resistance to Toxoplasmic Encephalitis
Authors: Reichmann Gaby , Walker William , Villegas Eric N. , Craig Linden , Cai Guifang , Alexander James , Hunter Christopher A. 
Published: July 2002

ABSTRACTSince the CD40/CD40 ligand (CD40L) interaction is involved in the regulation of macrophage production of interleukin 12 (IL-12) and T-cell production of gamma interferon (IFN-γ), effector cell functions associated with resistance toToxoplasma gondii, the role of CD40L in immunity to this parasite was assessed. Infection of C57BL/6 mice withT. gondiiresults in an upregulation of CD40 expression on accessory cell populations at local sites of infection as well as in lymphoid tissues. Splenocytes from C57BL/6 mice infected withT. gondiifor 5 days produced high levels of IL-12 and IFN-γ when stimulated with toxoplasma lysate antigen, and blocking CD40L did not significantly alter the production of IFN-γ or IL-12 by these cells. Similar results were observed with splenocytes and mononuclear cells isolated from the brains of chronically infected mice. Interestingly, although CD40L−/−mice infected withT. gondiiproduced less IL-12 than wild-type mice, they produced comparable levels of IFN-γ but succumbed to toxoplasmic encephalitis 4 to 5 weeks after infection. The inability of CD40L−/−mice to control parasite replication in the brain correlated with the ability of soluble CD40L, in combination with IFN-γ, to activate macrophages in vitro to control replication ofT. gondii. Together, these results identify an important role for the CD40/CD40L interaction in resistance toT. gondii. However, this interaction may be more important in the control of parasite replication in the brain rather than the generation of protective T-cell responses during toxoplasmosis.
ankA
: an
Ehrlichia phagocytophila
Group Gene Encoding a Cytoplasmic Protein Antigen with Ankyrin Repeats
Authors: Caturegli Patrizio , Asanovich Kristin M. , Walls Jennifer J. , Bakken Johan S. , Madigan John E. , Popov Vsevolod L. , Dumler J. Stephen 
Published: July 2002

ABSTRACT

Human granulocytic ehrlichiosis (HGE) is a potentially fatal, tick-borne disease caused by a bacterium related or identical to
Ehrlichia phagocytophila
. To identify and characterize
E. phagocytophila
group-specific protein antigen genes, we prepared and screened HGE agent and
Ehrlichia equi
genomic DNA expression libraries using polyclonal equine
E. equi
antibodies. Two clones, one each from HGE agent and
E. equi
, that were recognized specifically by antibodies to the
E. phagocytophila
group ehrlichiae had complete open reading frames of 3,693 and 3,615 nucleotides, respectively. The two clones were 96.6% identical and predicted a protein with at least 11 tandemly repeated ankyrin motifs. Thus, the gene was named
ank
(for ankyrin). When the encoded protein, named AnkA, was expressed in
Escherichia coli
, it was recognized by antibodies from rabbits and mice immunized with the HGE agent, sera from humans convalescent from HGE, and sera from horses convalescent from HGE and
E. equi
infection. Monospecific AnkA antibodies reacted with proteins in HGE agent immunoblots, and AnkA monoclonal antibodies detected cytoplasmic antigen in
E. phagocytophila
group bacteria and also detected antigen associated with chromatin in infected but not uninfected HL-60 cell cultures. These results suggest that this
Ehrlichia
protein may influence host cell gene expression.
The
toxR
Gene of
Vibrio
(
Listonella
)
anguillarum
Controls Expression of the Major Outer Membrane Proteins but Not Virulence in a Natural Host Model
Authors: Okuda Jun , Nakai Toshihiro , Chang Park Se , Oh Takanori , Nishino Takeshi , Koitabashi Tsutomu , Nishibuchi Mitsuaki 
Published: July 2002

ABSTRACT

To examine the hypothesis that the ancestral role of the
toxR
gene in the family
Vibrionaceae
is control of the expression of outer membrane protein (OMP)-encoding genes for adaptation to environmental change, we investigated the role of the
toxR
gene in
Vibrio anguillarum
, an important fish pathogen. The
toxR
gene of
V. angullarum
(Va-
toxR
) was cloned from strain PT-87050 isolated from diseased ayu (
Plecoglossus altivelis
), and the sequence was analyzed. The
toxR
sequence was 63 to 51% identical to those reported for other species of the family
Vibrionaceae
. Distribution of the Va-
toxR
gene sequence in
V. anguillarum
strains of various serotypes was confirmed by using DNA probe and PCR methods. An isogenic
toxR
mutant of
V. anguillarum
PT-24, isolated from diseased ayu, was constructed by using an allelic exchange method. The wild-type strain and the
toxR
mutant did not differ in the ability to produce a protease(s) and a hemolysin(s) or in pathogenicity for ayu when examined by the intramuscular injection and immersion methods. A 35-kDa major OMP was not produced by the
toxR
mutant. However, a 46-kDa OMP was hardly detected in the wild-type strain but was produced as the major OMP by the
toxR
mutant. For the
toxR
mutant, the MICs of two β-lactam antibiotics were higher and the minimum bactericidal concentration of sodium dodecyl sulfate was lower than for the wild-type strain. Analysis of the N-terminal amino acid sequences of the 35- and 46-kDa OMPs indicated that these proteins are the porin-like OMPs and are related to the
toxR
-regulated major OMPs of the family
Vibrionaceae
. The results indicate that the
toxR
gene is not involved in virulence expression in
V. anguillarum
PT-24 and that
toxR
regulation of major OMPs is universal in the family
Vibrionaceae
. These results support the hypothesis that the ancestral role of the
toxR
gene is regulation of OMP gene expression and that only in some
Vibrio
species has ToxR been appropriated for the regulation of a virulence gene(s).
Macrophage Nitric Oxide Synthase Associates with Cortical Actin but Is Not Recruited to Phagosomes
Authors: Webb J. L. , Harvey M. W. , Holden David W. , Evans T. J. 
Published: July 2002

ABSTRACT

Nitric oxide (NO) produced from inducible NO synthase (iNOS) is an important component of host defense against intracellular pathogens. To understand how phagocytes deliver NO to ingested microorganisms while avoiding cytotoxicity, we set out to study the subcellular localization of iNOS within macrophages following phagocytosis. Confocal microscopy of immunostained cells showed that iNOS was located not only diffusely within cytoplasm but also in vesicles, as well as immediately adjacent to the peripheral cell membrane. This peripheral iNOS colocalized with the cortical actin cytoskeleton and was removed by the actin-depolymerizing drug cytochalasin B. Biochemical fractionation of RAW 264 macrophages showed that 32.75% (±5.11%;
n
= 3) of iNOS was present in a particulate fraction, which cosedimented with low-density cellular vesicles. Following phagocytosis of latex beads, zymosan, immunoglobulin G-coated beads, or complement-coated zymosan, submembranous cortical iNOS was not recruited to phagosomes, nor was there any relocalization of intracellular iNOS. Similarly, following phagocytosis of
Salmonella enterica
serovar Typhimurium there was no recruitment of iNOS to the
Salmonella
vacuole at any stage after internalization. NO mediated significant killing of intracellular
S. enterica
serovar Typhimurium in RAW macrophages treated with lipopolysaccharide and gamma interferon; this was evident 4 h after infection. Although not recruited to phagosomes, iNOS association with the submembranous cortical actin cytoskeleton is ideally suited to deliver NO to microbes in contact with the cell surface and may contribute to early killing of ingested
Salmonella.
Intranasal Immunization with SAG1 and Nontoxic Mutant Heat-Labile Enterotoxins Protects Mice againstToxoplasma gondii
Authors: Bonenfant C. , Dimier-Poisson I. , Velge-Roussel F. , Buzoni-Gatel D. , Del Giudice G. , Rappuoli R. , Bout D. 
Published: July 2002

ABSTRACTEffective protection against intestinal pathogens requires both mucosal and systemic immune responses. Intranasal administration of antigens induces these responses but generally fails to trigger a strong protective immunity. Mucosal adjuvants can significantly enhance the immunogenicities of intranasally administered antigens. Cholera toxin (CT) and heat-labile enterotoxin (LT) are strong mucosal adjuvants with a variety of antigens. Moreover, the toxicities of CT and LT do not permit their use in humans. Two nontoxic mutant LTs, LTR72 and LTK63, were tested withToxoplasma gondiiSAG1 protein in intranasal vaccination of CBA/J mice. Vaccination with SAG1 plus LTR72 or LTK63 induced strong systemic (immunoglobulin G [IgG]) and mucosal (IgA) humoral responses. Splenocytes and mesenteric lymph node cells from mice immunized with LTR72 plus SAG1, but not those from mice immunized with LTK63 plus SAG1, responded to restimulation with aT. gondiilysate antigen in vitro. Gamma interferon and interleukin 2 (IL-2) production by splenocytes and IL-2 production by mesenteric lymph node cells were observed in vitro after antigen restimulation, underlying a Th1-like response. High-level protection as assessed by the decreased load of cerebral cysts after a challenge with the 76K strain ofT. gondiiwas obtained in the group immunized with LTR72 plus SAG1 and LTK63 plus SAG1. They were as well protected as the mice immunized with the antigen plus native toxins. This is the first report showing protection against a parasite by using combinations of nontoxic mutant LTs and SAG1 antigen. These nontoxic mutant LTs are now attractive candidates for the development of mucosally delivered vaccines.
Reduced Virulence of aBordetella bronchisepticaSiderophore Mutant in Neonatal Swine
Authors: Register Karen B. , Ducey Thomas F. , Brockmeier Susan L. , Dyer David W. 
Published: July 2002

ABSTRACTOne means by whichBordetella bronchisepticascavenges iron is through production of the siderophore alcaligin. A nonrevertible alcaligin mutant derived from the virulent strain 4609, designated DBB25, was constructed by insertion of a kanamycin resistance gene intoalcA, one of the genes essential for alcaligin biosynthesis. The virulence of thealcAmutant in colostrum-deprived, caesarean-delivered piglets was compared with that of the parent strain in two experiments. At 1 week of age, piglets were inoculated with phosphate-buffered saline, 4609, or DBB25. Two piglets in each group were euthanatized on day 10 postinfection. The remainder were euthanatized at 21 days postinfection. Clinical signs, including fever, coughing, and sneezing, were present in both groups. Nasal washes performed 7, 14, and 21 days postinoculation demonstrated that strain DBB25 colonized the nasal cavity but did so at levels that were significantly less than those achieved by strain 4609. Analysis of colonization based on the number of CFU per gram of tissue recovered from the turbinate, trachea, and lung also demonstrated significant differences between DBB25 and 4609, at both day 10 and day 21 postinfection. Mild to moderate turbinate atrophy was apparent in pigs inoculated with strain 4609, while turbinates of those infected with strain DBB25 developed no or mild atrophy. We conclude from these results that siderophore production byB. bronchisepticais not essential for colonization of swine but is required for maximal virulence.B. bronchisepticamutants with nonrevertible defects in genes required for alcaligin synthesis may be candidates for evaluation as attenuated, live vaccine strains in conventionally reared pigs.
Protective Efficacy of H Antigen fromHistoplasma capsulatumin a Murine Model of Pulmonary Histoplasmosis
Authors: Deepe George S. , Gibbons Reta 
Published: July 2002

ABSTRACTWe previously reported that immunization with H antigen fromHistoplasma capsulatumdid not protect mice against an intravenous challenge with yeasts. Here, we investigated the utility of H antigen to protect mice in a model of pulmonary histoplasmosis. Mice immunized with H antigen and challenged intranasally 4 weeks postvaccination were protected against sublethal and lethal challenges withH. capsulatumyeasts. If the challenge was performed 3 months after vaccination, there was a reduction in fungal burden following sublethal challenge and a modest delay in mortality in mice given a lethal inoculum. Vaccination was associated with production of gamma interferon, granulocyte-macrophage colony-stimulating factor, interleukin-4, and interleukin-10 by splenocytes. Vaccination with H antigen was not accompanied by a major expansion of CD4+or CD8+cells in spleens of mice. These results demonstrate that H antigen may be useful as a protective immunogen against pulmonary exposure toH. capsulatum.
Visualizing Pneumococcal Infections in the Lungs of Live Mice Using Bioluminescent
Streptococcus pneumoniae
Transformed with a Novel Gram-Positive
lux
Transposon
Authors: Francis Kevin P. , Yu Jun , Bellinger-Kawahara Carolyn , Joh Danny , Hawkinson Matthew J. , Xiao Grace , Purchio Tony F. , Caparon Michael G. , Lipsitch Marc , Contag Pamela R. 
Published: July 2002

ABSTRACT

Animal studies with
Streptococcus pneumoniae
have provided valuable models for drug development. In order to monitor long-term pneumococcal infections noninvasively in living mice, a novel gram-positive
lux
transposon cassette, Tn
4001 luxABCDE
Km
r
, that allows random integration of
lux
genes onto the bacterial chromosome was constructed. The cassette was designed so that the
luxABCDE
and kanamycin resistance genes were linked to form a single promoterless operon. Bioluminescence and kanamycin resistance only occur in a bacterial cell if this operon has transposed downstream of a promoter on the bacterium's chromosome.
S. pneumoniae
D39 was transformed with plasmid pAUL-A Tn
4001 luxABCDE
Km
r
, and a number of highly bioluminescent colonies were recovered. Genomic DNA from the brightest D39 strain was used to transform a number of clinical
S. pneumoniae
isolates, and several of these strains were tested in animal models, including a pneumococcal lung infection model. Strong bioluminescent signals were seen in the lungs of the animals containing these pneumococci, allowing the course and antibiotic treatment of the infections to be readily monitored in real time in the living animals. Recovery of the bacteria from the animals showed that the bioluminescent signal corresponded to the number of CFU and that the
lux
construct was highly stable even after several days in vivo. We believe that this
lux
transposon will greatly expand the ability to evaluate drug efficacy against gram-positive bacteria in living animals using bioluminescence.