bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tuberculin-Purified Protein Derivative-, MPT-64-, and ESAT-6-Stimulated Gamma Interferon Responses in Medical Students before and afterMycobacterium bovisBCG Vaccination and in Patients with Tuberculosis
Authors: Johnson P. D. R. , Stuart R. L. , Grayson M. L. , Olden D. , Clancy A. , Ravn P. , Andersen P. , Britton W. J. , Rothel J. S. 
Published: December 2019

ABSTRACTQuantiFERON-TB(QIFN) (CSL Limited) is a whole-blood assay for the recognition of infection withMycobacterium tuberculosis. QIFN measures gamma interferon (IFN-γ) production when purified protein derivatives (PPDs) of mycobacteria are incubated with venous blood samples. The specificity of QIFN in medical students before and after BCG immunization was assessed, and sensitivity in patients with tuberculosis was assessed. Antigens were PPD derived fromM. tuberculosisand twoM. tuberculosis-specific proteins, ESAT-6 and MPT-64. Of 60 medical students, all of whom had 0-mm tuberculin skin tests (TSTs) at study entry, 58 (97%) were initially classified as negative forM. tuberculosisinfection by PPD QIFN. Five months after BCG immunization, 7 of 54 students (13%) had a TST result of ≥10 mm and 11 of 54 students (20%) tested positive by PPD QIFN. ESAT-6- and MPT-64-stimulated IFN-γ responses in the medical students were negative prior to and after BCG immunization. For patients with active tuberculosis, 12 of 19 (63%) were positive by PPD QIFN, 11 of 19 (58%) were positive by ESAT-6 QIFN, and 0 of 12 were positive by MPT-64 QIFN. In conclusion, PPD QIFN was negative in 97% of a low-risk population who had not received BCG and who had negative TSTs. The specificities of both the TST and PPD QIFN were reduced following BCG immunization. PPD QIFN and ESAT-6 QIFN were of similar and moderate sensitivity in patients with active tuberculosis, but ESAT-6 QIFN is likely to be more specific because it is not influenced by past BCG exposure.
Specificity and Prevalence of Natural Bovine Antimannan Antibodies
Authors: Srinivasan Abhay , Ni Yawei , Tizard Ian 
Published: December 2019

ABSTRACTImmune responses to the carbohydrate components of microorganisms, mediated both by antibodies and by lectins, are an important part of host defense. In the present experiments, the specificity and presence of natural bovine antibodies against mannan, a common fungal antigen, were examined by enzyme-linked immunosorbent assay (ELISA), usingSaccharomyces cerevisiaemannan as an antigen. The results showed that all serum samples from animals of three age groups (newborn, calf, and adult) tested contained antimannan antibodies, and the titer of these antibodies increased significantly in adults. However, titers among individual adult cattle differed widely. Inhibition assays showed that yeast mannan was the strongest inhibitor.d-Mannose exhibited only a minor inhibitory effect at high concentrations. This suggests that most of these antibodies recognize an oligosaccharide-based epitope(s) different from those recognized by lectins. Cattle possess three serum C-type lectins (collectins) capable of recognizing mannan in a calcium-dependent manner. Addition of EDTA to the reaction did not reduce antibody binding, suggesting that the binding of these antibodies to mannan was not affected by the presence of collectin. The antibodies purified from either calf or adult serum by mannan-Sepharose affinity chromatography consisted of mainly immunoglobulin G (IgG) and a smaller amount of IgM. IgG1 was shown to be the dominant antimannan IgG isotype by isotype-specific ELISA. Together, these results demonstrate the production of natural antimannan antibodies in cattle in an age-dependent manner. These antibodies might be involved in defending the host against mannan-containing pathogens as a specific line of defense in conjunction with the innate response by lectins.
Comparison and Characterization of Immunoglobulin G Subclasses among Primate Species
Authors: Shearer Michael H. , Dark Robyn D. , Chodosh James , Kennedy Ronald C. 
Published: December 2019

ABSTRACTLittle information is available on the immunoglobulin G (IgG) subclasses expressed in the sera of nonhuman primate species. To address this issue, we compared the IgG subclasses found in humans (IgG1, IgG2, IgG3, and IgG4) to those of nonhuman primates, such as baboons and macaques. Cross-reactive antihuman IgG subtype-specific reagents were identified and used to analyze purified IgG from sera by solid-phase enzyme-linked immunosorbent assay. Protein A-purified human IgG obtained from sera was composed of IgG1, IgG2, IgG3, and IgG4, whereas baboon and macaque IgG was composed of IgG1, IgG2, and IgG4. Protein G-purified human IgG was composed of IgG1, IgG2, IgG3, and IgG4, whereas baboon and macaque IgG was composed of IgG1, IgG2, and IgG4. To test the possibility that baboon and macaque IgG3 is actually present, but is outcompeted for binding to proteins A and G by the other more abundant IgG subclasses, we repurified the IgG from sera that did not bind either protein A or protein G. We found a baboon IgG3 population in the sera that did not bind protein A, but bound protein G. No IgG3 subtype was detectable in macaque sera. These data suggest that baboon sera, like human sera, contain four IgG subtypes, whereas macaque sera exhibit only three of the human subclass analogs. In addition, the IgG subtype-specific reagents were shown to be useful in determining the IgG subclass distribution following vaccination of baboons with hepatitis B surface antigen.
Binding of
Candida albicans
to Immobilized Amino Acids and Bovine Serum Albumin
Authors: Hawser Stephen P. , Islam Khalid 
Published: December 2019

ABSTRACT

In this study, we examined the binding of
Candida albicans
synchronized yeast-phase cells to plastic, immobilized amino acids and bovine serum albumin (BSA) and quantified the binding by using an XTT tetrazolium salt assay and absorbance determination. Our results show that
C. albicans
binds efficiently and specifically to several nonpolar aliphatic amino acids and positively charged amino acids and to BSA immobilized on tissue culture plastic but not to polar uncharged, negatively charged, or aromatic amino acids. Adhesion of yeasts to immobilized amino acids was not affected by preincubation of cells with BSA, whereas binding to immobilized BSA was affected by preincubation of yeasts with alanine, proline, and leucine but not by arginine or lysine. The ability to distinguish the chirality of these amino acids was also examined by using both the
d
and
l
amino acid configurations, and the results show that
C. albicans
yeasts recognize only the
l
configuration of these amino acids. The observations that
C. albicans
specifically binds to certain amino acids indicate that these amino acids may prove useful tools for studying the binding interactions of
C. albicans
yeasts with host proteins such as components of the extracellular matrix.
Interleukin-15 Augments Superoxide Production and Microbicidal Activity of Human Monocytes againstCandida albicans
Authors: Vázquez Nancy , Walsh Thomas J. , Friedman Daphne , Chanock Stephen J. , Lyman Caron A. 
Published: December 2019

ABSTRACTInterleukin-15 (IL-15) is a newly described cytokine that shares biological activities with IL-2. We report here results demonstrating the ability of IL-15 to enhance superoxide production and antifungal activity of human monocytes. After 18 and 48 h of treatment with IL-15, human elutriated monocytes manifested enhanced superoxide production in response to either phorbol myristate acetate or opsonizedCandida albicansblastoconidia. Similar results were obtained when monocytes were treated with IL-2, but to a lesser extent. Combination studies with IL-15 and IL-2 showed no additive or synergistic effects. Following incubation of monocytes with IL-15 for 18 h, there was no significant increase in mRNA transcripts for components of the NADPH oxidase complex, p40-phox, p47-phox, and gp91-phox, suggesting a posttranscriptional modulation of enhanced superoxide production. Antibodies against the γ chain of the IL-2 receptor and, to a lesser extent, against the β chain partially abrogated the IL-15-mediated enhanced superoxide production. Additionally, human monocytes showed enhanced killing activity againstC. albicansafter 18 h of incubation with IL-15 or IL-2, but this treatment did not enhance the ability of these cells to phagocytose the organism. In addition, the enhanced fungicidal activity seen after 18 h of treatment was no longer detectable after 48 h of cytokine treatment. Culture supernatants from the IL-15-treated monocytes were assayed for the presence of other proinflammatory cytokines. IL-15 treatment did not induce the release of detectable levels of tumor necrosis factor alpha, IL-1β, or IL-12. Our results indicate that IL-15 upregulates the microbicidal activity of human monocytes againstC. albicans.
Aggregation and Binding Substances Enhance Pathogenicity in Rabbit Models ofEnterococcus faecalisEndocarditis
Authors: Schlievert Patrick M. , Gahr Pamala J. , Assimacopoulos Aris P. , Dinges Martin M. , Stoehr Jennifer A. , Harmala John W. , Hirt Helmut , Dunny Gary M. 
Published: December 2019

ABSTRACTWe investigated the importance of enterococcal aggregation substance (AS) and enterococcal binding substance (EBS) in rabbit models ofEnterococcus faecaliscardiac infections. First, American Dutch belted rabbits were injected intraventricularly with 108CFU and observed for 2 days. No clinical signs of illness developed in animals given AS−EBS−organisms, and all survived. All rabbits given AS−EBS+organisms developed signs of illness, including significant pericardial inflammation, but only one of six died. All animals given AS+EBS−organisms developed signs of illness, including pericardial inflammation, and survived. All rabbits given AS+EBS+organisms developed signs of illness and died. None of the rabbits receiving AS+EBS+organisms showed gross pericardial inflammation. The lethality and lack of inflammation are consistent with the presence of a superantigen. Rabbit and human lymphocytes were highly stimulated in vitro by cell extracts, but not cell-free culture fluids, of AS+EBS+organisms. In contrast, cell extracts from AS−EBS−organisms weakly stimulated lymphocyte proliferation. Culture fluids from human lymphocytes stimulated with AS+/EBS+enterococci contained high levels of gamma interferon and tumor necrosis factor alpha (TNF-α) and TNF-β, which is consistent with functional stimulation of T-lymphocyte proliferation and macrophage activation. Subsequent experiments examined the abilities of the same strains to cause endocarditis in a catheterization model. New Zealand White rabbits underwent transaortic catheterization for 2 h, at which time catheters were removed and animals were injected with 2 × 109CFU of test organisms. None of the animals given AS−EBS−organisms developed vegetations or showed autopsy evidence of tissue damage. Rabbits given AS−EBS+or AS+EBS−organisms developed small vegetations and had splenomegaly at autopsy. All rabbits given AS+EBS+organisms developed large vegetations and had splenomegaly and lung congestion at autopsy. Similar experiments that left catheters in place for 3 days revealed that all rabbits given AS−EBS−or AS+EBS+organisms developed vegetations, but animals given AS+EBS+organisms had larger vegetations and autopsy evidence of lung congestion. These experiments provide direct evidence that these two cell wall components play an important role in the pathogenesis of endocarditis as well as in conjugative plasmid transfer.
Modulation of Murine Lyme Borreliosis by Interruption of the B7/CD28 T-Cell Costimulatory Pathway
Authors: Shanafelt Marie-Claude , Kang Insoo , Barthold Stephen W. , Bockenstedt Linda K. 
Published: December 2019

ABSTRACTRecent studies have implicated cytokines associated with Th2 cells in the genetic resistance to murine Lyme borreliosis. Because the B7/CD28 costimulatory pathway has been shown to influence the differentiation of Th-cell subsets, we investigated the contribution of the B7 molecules CD80 and CD86 to the Th2 cytokine profile and development of arthritis in BALB/c mice infected withBorrelia burgdorferi. Effective blockade of CD86/CD28 interaction was demonstrated by elimination of interleukin 4 (IL-4) and upregulation of gamma interferon (IFN-γ) responses byB. burgdorferi-specific T cells and by reduction ofB. burgdorferi-specific immunoglobulin G. Despite the shift toward a Th1 cytokine pattern, which others have associated with disease susceptibility, the severity of arthritis was unchanged. Moreover, combined CD80/CD86 blockade by using anti-CD80 and anti-CD86 monoclonal antibodies or CTLA-4Ig enhanced IFN-γ production over that seen with CD86 blockade alone, yet augmentation of this Th1-associated cytokine did not enhance disease. These results demonstrate that IL-4 production by T cells inB. burgdorferi-infected BALB/c mice is dependent upon CD86/CD28 interaction and that this cytokine does not contribute significantly to host resistance to the development of arthritis. In addition, combined CD80/CD86 blockade resulted in preferential expansion of IFN-γ-producing T cells inB. burgdorferiinfection, suggesting that costimulatory pathways other than B7/CD28 may contribute to T-cell activation during continuous antigen stimulation. These studies may provide insight into the role of the B7/CD28 pathway in other infectious and autoimmune diseases in which deviation of Th cell immune responses occurs and antigen is persistently present.
Complementation Analysis of the
Dichelobacter nodosus fimN
,
fimO
, and
fimP
Genes in
Pseudomonas aeruginosa
and Transcriptional Analysis of the
fimNOP
Gene Region
Authors: Johnston Joanne L. , Billington Stephen J. , Haring Volker , Rood Julian I. 
Published: December 2019

ABSTRACT

The causative agent of ovine footrot, the gram-negative anaerobe
Dichelobacter nodosus
, produces polar type IV fimbriae, which are the major protective antigens. The
D. nodosus
genes
fimN
,
fimO
, and
fimP
are homologs of the
Pseudomonas aeruginosa
fimbrial assembly genes,
pilB
,
pilC
, and
pilD
, respectively. Both the
pilD
and
fimP
genes encode prepilin peptidases that are responsible for cleavage of the leader sequence from the immature fimbrial subunit. To investigate the functional similarity of the fimbrial biogenesis systems from these organisms, the
D. nodosus
genes were introduced into
P. aeruginosa
strains carrying mutations in the homologous genes. Analysis of the resultant derivatives showed that the
fimP
gene complemented a
pilD
mutant of
P. aeruginosa
for both fimbrial assembly and protein secretion. However, the
fimN
and
fimO
genes did not complement
pilB
or
pilC
mutants, respectively. These results suggest that although the PilD prepilin peptidase can be functionally replaced by the heterologous FimP protein, the function of the PilB and PilC proteins may require binding or catalytic domains specific for the
P. aeruginosa
fimbrial assembly system. The transcriptional organization and regulation of the
fimNOP
gene region were also examined. The results of reverse transcriptase PCR and primer extension analysis suggested that these genes form an operon transcribed from two ς
70
-type promoters located upstream of ORFM, an open reading frame proximal to
fimN
. Transcription of the
D. nodosus
fimbrial subunit was found to increase in cells grown on solid media, and it was postulated that this regulatory effect may be of significance in the infected footrot lesion.
Intracellular
Staphylococcus aureus
Escapes the Endosome and Induces Apoptosis in Epithelial Cells
Authors: Bayles Kenneth W. , Wesson Carla A. , Liou Linda E. , Fox Lawrence K. , Bohach Gregory A. , Trumble W. R. 
Published: December 2019

ABSTRACT

We examined the invasion of an established bovine mammary epithelial cell line (MAC-T) by a
Staphylococcus aureus
mastitis isolate to study the potential role of intracellular survival in the persistence of staphylococcal infections.
S. aureus
cells displayed dose-dependent invasion of MAC-T cells and intracellular survival. An electron microscopic examination of infected cells indicated that the bacteria induced internalization via a mechanism involving membrane pseudopod formation and then escaped into the cytoplasm following lysis of the endosomal membrane. Two hours after the internalization of
S. aureus
, MAC-T cells exhibited detachment from the matrix, rounding, a mottled cell membrane, and vacuolization of the cytoplasm, all of which are indicative of cells undergoing programmed cell death (apoptosis). By 18 h, the majority of the MAC-T cell population exhibited an apoptotic morphology. Other evidence for apoptosis was the generation of MAC-T cell DNA fragments differing in size by increments of approximately 180 bp and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling of the fragmented nuclear DNA of the infected host cells. These results demonstrate that after internalization
S. aureus
escapes the endosome and induces apoptosis in nonprofessional phagocytes.
The
Pseudomonas aeruginosa
Quorum-Sensing Signal Molecule
N
-(3-Oxododecanoyl)-
l
-Homoserine Lactone Has Immunomodulatory Activity
Authors: Telford Gary , Wheeler D. , Williams Paul , Tomkins P. T. , Appleby P. , Sewell Herbert , Stewart Gordon S. A. B. , Bycroft Barrie W. , Pritchard David I. 
Published: December 2019

ABSTRACT

Diverse gram-negative bacterial cells communicate with each other by using diffusible
N
-acyl homoserine lactone (AHL) signal molecules to coordinate gene expression with cell population density. Accumulation of AHLs above a threshold concentration renders the population “quorate,” and the appropriate target gene is activated. In pathogenic bacteria, such as
Pseudomonas aeruginosa
, AHL-mediated quorum sensing is involved in the regulation of multiple virulence determinants. We therefore sought to determine whether the immune system is capable of responding to these bacterial signal molecules. Consequently the immunomodulatory properties of the AHLs
N
-(3-oxododecanoyl)-
l
-homoserine lactone (OdDHL) and
N
-(3-oxohexanoyl)-
l
-homoserine lactone (OHHL) were evaluated in murine and human leukocyte immunoassays in vitro. OdDHL, but not OHHL, inhibited lymphocyte proliferation and tumor necrosis factor alpha production by lipopolysaccharide-stimulated macrophages. Furthermore, OdDHL simultaneously and potently down-regulated the production of IL-12, a Th-1-supportive cytokine. At high concentrations (>7 × 10
−5
M) OdDHL inhibited antibody production by keyhole limpet hemocyanin-stimulated spleen cells, but at lower concentrations (<7 × 10
−5
M), antibody production was stimulated, apparently by increasing the proportion of the immunoglobulin G1 (IgG1) isotype. OdDHL also promoted IgE production by interleukin-4-stimulated human peripheral blood mononuclear cells. These data indicate that OdDHL may influence the Th-1–Th-2 balance in the infected host and suggest that, in addition to regulating the expression of virulence determinants, OdDHL may contribute to the pathogenesis of
P. aeruginosa
infections by functioning as a virulence determinant per se.
Phase Variation in
Helicobacter pylori
Lipopolysaccharide
Authors: Appelmelk B. J. , Shiberu B. , Trinks C. , Tapsi N. , Zheng P. Y. , Verboom T. , Maaskant J. , Hokke C. H. , Schiphorst W. E. C. M. , Blanchard D. , Simoons-Smit I. M. , van den Eijnden D. H. , Vandenbroucke-Grauls C. M. J. E. 
Published: December 2019

ABSTRACT

Helicobacter pylori
NCTC 11637 lipopolysaccharide (LPS) expresses the human blood group antigen Lewis x (Le
x
) in a polymeric form. Le
x
is β-
d
-galactose-(1-4)-[α-
l
-fucose-(1-3)]-β-
d
-acetylglucosamine. Schematically the LPS structure is (Le
x
)

n

-core-lipid A. In this report, we show that Le
x
expression is not a stable trait but that LPS displays a high frequency (0.2 to 0.5%) of phase variation, resulting in the presence of several LPS variants in one bacterial cell population. One type of phase variation implied the loss of α1,3-linked fucose, resulting in variants that expressed nonsubstituted polylactosamines (also called the i antigen), i.e., Le
x
minus fucose; LPS: (lactosamine)

n

-core-lipid A. The switch of Le
x
to i antigen was reversible. A second group of variants arose by loss of polymeric main chain which resulted in expression of monomeric Le
y
; LPS: (Le
y
)-core-lipid A. A third group of variants arose by acquisition of α1,2-linked fucose which hence expressed Le
x
plus Le
y
; LPS: (Le
y
)(Le
x
)

n

-core-lipid A. The second and third group of variants switched back to the parental phenotype [(Le
x
)

n

-core-lipid A] in lower frequencies. Part of the variation can be ascribed to altered expression levels of glycosyltransferase levels as assessed by assaying the activities of galactosyl-, fucosyl-, and
N
-acetylglucosaminyltransferases. Clearly phase variation increases the heterogeneity of
H. pylori
, and this process may be involved in generating the very closely related yet genetically slightly different strains that have been isolated from one patient.
A Second Two-Component Regulatory System of
Bordetella bronchiseptica
Required for Bacterial Resistance to Oxidative Stress, Production of Acid Phosphatase, and In Vivo Persistence
Authors: Jungnitz Heidrun , West Nicholas P. , Walker Mark J. , Chhatwal Gursharan S. , Guzmán Carlos A. 
Published: December 2019

ABSTRACT

Random minitransposon mutagenesis was used to identify genes involved in the survival of
Bordetella bronchiseptica
within eukaryotic cells. One of the mutants which exhibited a reduced ability to survive intracellularly harbored a minitransposon insertion in a locus (
ris
) which displays a high degree of homology to two-component regulatory systems. This system exhibited less than 25% amino acid sequence homology to the only other two-component regulatory system described in
Bordetella
spp., the
bvg
locus. A
risA′-′lacZ
translational fusion was constructed and integrated into the chromosome of
B. bronchiseptica
. Determination of β-galactosidase activity under different environmental conditions suggested that
ris
is regulated independently of
bvg
and is optimally expressed at 37°C, in the absence of Mg
2+
, and when bacteria are in the intracellular niche. This novel regulatory locus, present in all
Bordetella
spp., is required for the expression of acid phosphatase by
B. bronchiseptica
. Although catalase and superoxide dismutase production were unaffected, the
ris
mutant was more sensitive to oxidative stress than the wild-type strain. Complementation of
bvg
-positive and
bvg
-negative
ris
mutants with the intact
ris
operon incorporated as a single copy into the chromosome resulted in the reestablishment of the ability of the bacterium to produce acid phosphatase and to resist oxidative stress. Mouse colonization studies demonstrated that the
ris
mutant is cleared by the host much earlier than the wild-type strain, suggesting that
ris
-regulated products play a significant role in natural infections. The identification of a second two-component system in
B. bronchiseptica
highlights the complexity of the regulatory network needed for organisms with a life cycle requiring adaptation to both the external environment and a mammalian host.
Cytotoxic T-Lymphocyte-Mediated Lysis ofToxoplasma gondii-Infected Target Cells Does Not Lead to Death of Intracellular Parasites
Authors: Yamashita Keizo , Yui Katsuyuki , Ueda Masakatsu , Yano Akihiko 
Published: December 2019

ABSTRACTCD8+T cells play a crucial role in the control of infection with intracellular microbes. The mechanisms underlying the CD8+T-cell-mediated clearance of the intracellular pathogenToxoplasma gondiiare, however, not completely understood. The effect of CD8+cytotoxic T-lymphocyte (CTL)-mediated lysis of host cells on the viability of intracellularT. gondiiwas investigated. Quantitative competitive PCR of the gene encodingT. gondiimajor surface antigen (SAG-1) was combined with treatment of the parasites with DNase, which removed the DNA template of nonviable parasites. The induction by CD8+CTLs of apoptosis in cells infected withT. gondiidid not result in the reduction of live parasites, indicating that intracellularT. gondiiremains alive after lysis of host cells by CTLs.