bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alterations in Frequency of Interleukin-2 (IL-2)-, Gamma Interferon-, or IL-4-Secreting Splenocytes Induced byCandida albicansMannan and/or Monophosphoryl Lipid A
Authors: Li Shaokang P. , Lee Sang-il , Domer Judith E. 
Published: December 2019

ABSTRACTWe have shown previously that intravenous injection ofCandida albicansmannan (MAN) into naive mice induced CD8+effector downregulatory cells and that such cells were not produced if mice were deficient in CD4+or I-A+cells during the early interval (≤30 h) following the introduction of MAN. Moreover, the nonspecific biological response modifier monophosphoryl lipid A (MPL), given in vivo or incubated with cells in vitro, can abrogate the MAN-specific immunomodulatory activity. The mechanism by which the abrogation is mediated is unknown, but it is hypothesized to involve cytokines. Therefore, we measured the number of cytokine-secreting cells for the Th1 cytokine interleukin-2 (IL-2) and the Th2 cytokine IL-4, as well as for gamma interferon (IFN-γ), in splenocyte populations from MAN and/or MPL-treated mice, using an enzyme-linked immunospot assay designed to detect individual cytokine-secreting cells (spot-forming cells [SFC]). Cytokine-secreting cells were demonstrated in cell suspensions enriched for CD4+cells, but no SFC could be demonstrated in populations enriched for CD8+cells. Both MAN and MPL, when administered to separate groups of animals, stimulated the production of increased numbers of cytokine-producing cells for each of the three cytokines tested. The response with respect to IL-4-secreting cells, however, was the most striking. Despite the fact that MAN and MPL independently caused increases in SFC to all three cytokines, when both MAN and MPL were administered to the same animal, all increases were reversed, and the numbers of SFC detected were at or below those detected in saline control animals. These data support the hypothesis that IL-4 is involved in MAN-specific immunoregulatory activities. The data also emphasize the fact that two immunomodulators, i.e., MAN and MPL, having similar effects when given in vivo independently, may be antagonistic when administered sequentially to the same animal.
The Protective Effects of Lactoferrin Feeding against Endotoxin Lethal Shock in Germfree Piglets
Authors: Lee Wang J. , Farmer Jeffrey L. , Hilty Milo , Kim Yoon B. 
Published: December 2019

ABSTRACTThe unique germfree, colostrum-deprived, immunologically “virgin” piglet model was used to evaluate the ability of lactoferrin (LF) to protect against lethal shock induced by intravenously administered endotoxin. Piglets were fed LF or bovine serum albumin (BSA) prior to challenge with intravenousEscherichia colilipopolysaccharide (LPS), and temperature, clinical symptoms, and mortality were tracked for 48 h following LPS administration. Prefeeding with LF resulted in a significant decrease in piglet mortality compared to feeding with BSA (16.7 versus 73.7% mortality,P< 0.001). Protection against the LPS challenge by LF was also correlated with both resistance to induction of hypothermia by endotoxin and an overall increase in wellness, as quantified by a toxicity score developed for these studies. In vitro studies using a flow cytometric assay system demonstrated that LPS binding to porcine monocytes was inhibited by LF in a dose-dependent fashion, suggesting that the mechanism of LF action in vivo may be inhibition of LPS binding to monocytes/macrophages and, in turn, prevention of induction of monocyte/macrophage-derived inflammatory-toxic cytokines.
Adherence of
Streptococcus pneumoniae
to Respiratory Epithelial Cells Is Inhibited by Sialylated Oligosaccharides
Authors: Barthelson Roger , Mobasseri Ali , Zopf David , Simon Paul 
Published: December 2019

ABSTRACT

To study carbohydrate-mediated adherence of
Streptococcus pneumoniae
to the human airway, we measured binding of live
S. pneumoniae
organisms to a cultured cell line derived from the lining of the conjunctiva and to primary monolayers of human bronchial epithelial cells in the presence and absence of oligosaccharide inhibitors. Both encapsulated and nonencapsulated strains of
S. pneumoniae
grown to mid-logarithmic phase in suspension culture adhered to cultured primary respiratory epithelial cells and the conjunctival cell line. Adherence of nine clinically prevalent
S. pneumoniae
capsular types studied was inhibited preferentially by sialylated oligosaccharides that terminate with the disaccharide NeuAcα2-3(or 6)Galβ1. Adherence of some strains also was weakly inhibited by oligosaccharides that terminate with lactosamine (Galβ1-4GlcNAcβ1). When sialylated oligosaccharides were covalently coupled to human serum albumin at a density of approximately 20 oligosaccharides per molecule of protein, the molar inhibitory potency of the oligosaccharide inhibitor was enhanced 500-fold. The above-mentioned experiments reveal a previously unreported dependence upon sialylated carbohydrate ligands for adherence of
S. pneumoniae
to human upper airway epithelial cells. Enhanced inhibitory potencies of polyvalent over monovalent forms of oligosaccharide inhibitors of adherence suggest that the putative adhesin(s) that recognizes the structure NeuAcα2-3(or 6)Galβ1 is arranged on the bacterial surface in such a manner that it may be cross-linked by oligosaccharides covalently linked to human serum albumin.
Effect of Group A Streptococcal Cysteine Protease on Invasion of Epithelial Cells
Authors: Tsai Pei-Jane , Kuo Chih-Feng , Lin Kuei-Yuan , Lin Yee-Shin , Lei Huan-Yao , Chen Fen-Fen , Wang Jen-Ren , Wu Jiunn-Jong 
Published: December 2019

ABSTRACT

Cysteine protease of group A streptococci (GAS) is considered an important virulence factor. However, its role in invasiveness of GAS has not been investigated. We demonstrated in this study that two strains of protease-producing GAS had the ability to invade A-549 human respiratory epithelial cells. Isogenic protease mutants were constructed by using integrational plasmids to disrupt the
speB
gene and confirmed by Southern hybridization and Western immunoblot analyses. No extracellular protease activity was produced by the mutants. The mutants had growth rates similar to those of the wild-type strains and produced normal levels of other extracellular proteins. When invading A-549 cells, the mutants had a two- to threefold decrease in activity compared to that of the wild-type strains. The invasion activity increased when the A-549 cells were incubated with purified cysteine protease and the mutant. However, blockage of the cysteine protease with a specific cysteine protease inhibitor, E-64, decreased the invasion activity of GAS. Intracellular growth of GAS was not found in A-549 cells. The presence or absence of protease activity did not affect the adhesive ability of GAS. These results suggested that streptococcal cysteine protease can enhance the invasion ability of GAS in human respiratory epithelial cells.
Evolution of the Primary Immune Response toHistoplasma capsulatumin Murine Lung
Authors: Cain Judith A. , Deepe George S. 
Published: December 2019

ABSTRACTHistoplasma capsulatuminduces a cell-mediated immune response in the lungs and lymphoid organs of mammals. In this study, we analyzed the progression of the cytokine and inflammatory reactions in the lungs of mice infected intranasally withH. capsulatum. We measured cytokine mRNA levels and determined the inflammatory cell populations during the active phase of infection (<3 weeks). Transcription of genes encoding interleukin-2 (IL-2), IL-4, and IL-12 and gamma interferon (IFN-γ) was detectable as early as day 3 of infection, whereas a signal for IL-10 was never observed. Competitive PCR analysis demonstrated that enhanced expression of IL-12 mRNA was observed by day 3 and that expression of mRNA for IL-2 and IFN-γ progressively increased from day 5 to day 10. All levels declined by day 14. Analysis of the inflammatory response revealed an initial elevation in myeloid cells (Mac-1+) and natural killer (NK) cells followed by a rise in T cells, predominantly CD4+cells. Since IFN-γ is a key factor in host defense, we performed cytoplasmic staining to determine the cell populations that produced this cytokine. The hierarchy of synthesis was CD4+> CD8+> NK cells. Thus,H. capsulatumprovokes an orderly modulation of the inflammatory and cytokine responses in murine lungs.
Baculovirus Merozoite Surface Protein 1 C-Terminal Recombinant Antigens Are Highly Protective in a Natural Primate Model for Human
Plasmodium vivax
Malaria
Authors: Perera K. L. R. Lakshman , Handunnetti Shiroma M. , Holm Inge , Longacre Shirley , Mendis Kamini 
Published: December 2019

ABSTRACT

A successful anti-blood stage malaria vaccine trial based on a leading vaccine candidate, the major merozoite surface antigen-1 (MSP1), is reported here. The trial was based on
Plasmodium cynomolgi
, which is a primate malaria parasite which is highly analogous to the human parasite
Plasmodium vivax
, in its natural host, the toque monkey,
Macaca sinica
. Two recombinant baculovirus-expressed
P. cynomolgi
MSP1 proteins, which are analogous to the 42- and 19-kDa C-terminal fragments of
P. falciparum
MSP1, were tested by immunizing three groups of three animals each with either p42, p19, or both together. The vaccines were delivered subcutaneously in three doses at 4-week intervals with complete and incomplete Freund’s adjuvants. Very high antibody titers were obtained against both vaccinating antigens as measured by enzyme-linked immunosorbent assay (10
6
and above) and against whole parasites as measured by indirect immunofluorescence assay (>10
5
), achieving, in most animals, about a 10-fold increase from the first to the last immunization. A blood stage challenge with
P. cynomolgi
parasites led, in three adjuvant-treated and three naive control animals, to blood infections which were patent for at least 44 days, reaching peak densities of 0.6 and 3.8%, respectively. In contrast, all except one of the nine animals in the three vaccinated groups were highly protected, showing either no parasitemia at all or transient parasitemias which were patent for only 1 or 2 days. When the three p19-vaccinated monkeys were rechallenged 6 months later, the protective efficacy was unchanged. The success of this trial, and striking analogies of this natural host-parasite system with human
P. vivax
malaria, suggests that it could serve as a surrogate system for the development of a human
P. vivax
malaria vaccine based on similar recombinant analogs of the
P. vivax
MSP1 antigen.
Inhibition of the Production of Anti-OspA Borreliacidal Antibody with T Cells from Hamsters Vaccinated againstBorrelia burgdorferi
Authors: Jensen Jani R. , Du Chateau Brian K. , Munson Erik L. , Callister Steven M. , Schell Ronald F. 
Published: December 2019

ABSTRACTThe serious morbidity associated with Lyme borreliosis has focused considerable effort on the development of a comprehensive vaccine for protection against infection withBorrelia burgdorferi. Induction of borreliacidal antibody by vaccination or infection has been shown to correlate with protection of humans and animals against infection with the Lyme spirochete. In this report, we showed that high levels of borreliacidal antibody (titer of 1,280) were produced in vitro when T and B cells from hamsters 14 days after vaccination were incubated with macrophages andB. burgdorferi. By contrast, T and B cells from hamsters 7 or 21 days after vaccination failed to initiate production of borreliacidal activity. Furthermore, the T cells from hamsters 7 or 21 days after vaccination inhibited the in vitro production of borreliacidal antibody when cocultured with T and B cells obtained from hamsters 14 days after vaccination. When cell-free supernatants from the suspensions of T and B cells from hamsters 14 days after vaccination were absorbed with recombinant OspA, they lost nearly all borreliacidal activity. The removal of anti-OspA antibody resulted in a decrease in borreliacidal titer from 1,280 to less than 4. These results demonstrate that T cells from vaccinated animals can prevent a sustained production of protective borreliacidal antibody.
Characterization of Anticapsular Monoclonal Antibodies That Regulate Activation of the Complement System by theCryptococcus neoformansCapsule
Authors: Kozel Thomas R. , deJong Bouke C. H. , Grinsell Matthew M. , MacGill Randall S. , Wall Kevin K. 
Published: December 2019

ABSTRACTIncubation of the encapsulated yeastCryptococcus neoformansin human serum leads to alternative pathway-mediated deposition of C3 fragments in the capsule. We examined the ability of monoclonal antibodies (MAbs) specific for different epitopes of the major capsular polysaccharide to alter the kinetics for classical and alternative pathway-mediated deposition of C3 onto a serotype A strain. We studied MAbs reactive with capsular serotypes A, B, C, and D (MAb group II); serotypes A, B, and D (MAb group III); and serotypes A and D (MAb group IV). The MAb groupings are based on antibody variable region usage which determines the antibody molecular structure. When both the classical and alternative pathways were operative, group II MAbs induced early classical pathway-mediated binding of C3 but reduced the overall rate of C3 accumulation and the amount of bound C3. Group III MAbs closely mimicked the effects of group II MAbs but exhibited reduced support of early classical pathway-facilitated accumulation of C3. Depending on the antibody isotype, group IV MAbs slightly or markedly enhanced early binding of C3 but had no effect on either the rate of C3 accumulation or the amount of bound C3. When the classical pathway was blocked, group II and III MAbs markedly suppressed C3 binding that normally would have occurred via the alternative pathway. In contrast, MAbs of group IV had no effect on alternative pathway-mediated C3 binding. These results indicate that anticapsular antibodies with different epitope specificities may have distinct regulatory effects on activation and binding of C3.
Bivalency Is Required for Anticapsular Monoclonal Antibodies To Optimally Suppress Activation of the Alternative Complement Pathway by theCryptococcus neoformansCapsule
Authors: Kozel Thomas R. , MacGill Randall S. , Wall Kevin K. 
Published: December 2019

ABSTRACTEncapsulated cells ofCryptococcus neoformansare potent activators of the alternative complement pathway. Previous studies found that monoclonal antibodies (MAbs) specific for the major capsular polysaccharide, termed glucuronoxylomannan (GXM), can markedly suppress the ability of the capsule to accumulate C3 from normal human serum via the alternative pathway. The present study examined the abilities of F(ab)2and Fab fragments of three MAbs (MAbs 439, 3C2, and 471) to mediate the suppressive effect. The results showed that F(ab)2fragments of all three MAbs suppressed activation and binding of C3 via the alternative pathway in a manner similar to that of intact antibodies. In contrast, Fab fragments of MAb 439 and MAb 3C2 showed no suppressive activity, and Fab fragments of MAb 471 were markedly reduced in suppressive activity. Indeed, there was an earlier accumulation of C3 on encapsulated cryptococci in the presence of the Fab fragments. Study of subclass switch families of MAb 439 and MAb 471 found that MAbs of an immunoglobulin G (IgG) subclass with increased flexibility in the hinge region (IgG2b) had less suppressive activity than MAbs of IgG subclasses with less flexibility (IgG1 or IgG2a). Taken together, these results indicate that cross-linking of the capsular matrix is an essential component in suppression of the alternative complement pathway by anti-GXM MAbs.
Characterization of the Carbohydrate Moiety of Intestinal Mucin-Type Sialoglycoprotein Receptors for the K88ac Fimbrial Adhesin of
Escherichia coli
Authors: Grange Philippe A. , Erickson Alan K. , Anderson Timothy J. , Francis David H. 
Published: December 2019

ABSTRACT

We have previously identified two mucin-type sialoglycoproteins from porcine intestinal epithelial cells with approximate molecular masses of 210 (intestinal mucin-type glycoprotein IMTGP-1) and 240 kDa (IMTGP-2) as receptors for the K88ab and K88ac fimbrial adhesins of
Escherichia coli
. These receptors are detected in intestinal brush border membrane preparations from pigs with adhesive phenotypes but not from pigs with nonadhesive phenotypes and are postulated to be important determinants of the susceptibility of pigs to K88ab
+
and K88ac
+
enterotoxigenic
E. coli
infections. Using exoglycosidase digestion studies, we have now determined that β-linked galactose is an important component in the recognition of IMTGP-1 and IMTGP-2 by the K88ac adhesin. In addition, we observed a differential distribution of the K88ac adhesin binding activity of IMTGP-1 and IMTGP-2 along the crypt-villus axis, suggesting that receptor activity is dependent on the maturation state of the intestinal epithelial cells. Brush borders from immature intestinal epithelial cells possessed the highest concentrations of IMTGP-1 and IMTGP-2 receptor activity, with a progressive decrease in receptor activity as the cells mature. To characterize the differences in the carbohydrate moieties of IMTGP-1 and IMTGP-2, we developed a procedure for purifying the receptors, using phenol extraction followed by serial lectin affinity chromatography. Carbohydrate compositional analysis of the purified receptors indicated that the carbohydrate moieties of IMTGP-1 and IMTGP-2 consist of both N- and O-glycans containing galactose, glucose, sialic acid, mannose,
N
-acetylgalactosamine,
N
-acetylglucosamine, and fucose. The major difference between the two receptors is that IMTGP-2 contains a higher percentage of monosaccharides (mannose and glucose) commonly found in N-glycans.
Expression of Multiple Pili by
Legionella pneumophila
: Identification and Characterization of a Type IV Pilin Gene and Its Role in Adherence to Mammalian and Protozoan Cells
Authors: Stone Barbara J. , Kwaik Yousef Abu 
Published: December 2019

ABSTRACT

Legionella pneumophila
expresses pili of variable lengths, either long (0.8 to 1.5 μm) or short (0.1 to 0.6 μm), that can be observed by transmission electron microscopy. We have identified a gene in
L. pneumophila
with homology to the type IV pilin genes (

pilE
L

). An insertion mutation was constructed in

pilE
L

and introduced into the
L. pneumophila
wild-type strain by allelic exchange. The pilin mutant is defective for expression of long pili. Reintroduction of the pilin locus on a cosmid vector restores expression of the long pili. The

L. pneumophila pilE
L

mutant exhibited approximately a 50% decrease in adherence to human epithelial cells (HeLa and WI-26 cells), macrophages (U937 cells), and
Acanthamoeba polyphaga
but had a wild-type phenotype for intracellular replication within these cells. Southern hybridization analysis showed that the

pilE
L

locus is present in
L. pneumophila
serogroups 1 through 13 but is variable in 16 other
Legionella
species. The presence of a type IV pilin gene and its expression by
L. pneumophila
may provide an advantage for colonization of lung tissues during Legionnaires’ disease and invasion of amoebas in the environment.
Binding to Human Extracellular Matrix by
Neisseria meningitidis
Authors: Eberhard Thomas , Virkola Ritva , Korhonen Timo , Kronvall Göran , Ullberg Måns 
Published: December 2019

ABSTRACT

Adhesion of
Neisseria meningitidis
strains to extracellular matrix (ECM) and purified matrix components was examined. Most strains bound to subendothelial ECM as well as to immobilized fibronectin and types I, III, and V collagen. Strains from healthy carriers adhered significantly better than isolates from patients. The binding site was localized to the central 75-kDa cell-binding domain of the fibronectin molecule. This domain has not been described previously to interact with bacterial structures.
Increased Leptin Expression in Mice with Bacterial Peritonitis is Partially Regulated by Tumor Necrosis Factor Alpha
Authors: Moshyedi Armin K. , Josephs Michael D. , Abdalla Eddie K. , MacKay Sally L. D. , Edwards Carl K. , Copeland Edward M. , Moldawer Lyle L. 
Published: December 2019

ABSTRACT

Plasma leptin and
ob
gene mRNA levels were increased in mice following bacterial peritonitis, and blocking an endogenous tumor necrosis factor alpha (TNF-α) response blunted the increase. However, plasma leptin concentrations did not correlate with the associated anorexia. We conclude that leptin expression is under partial regulatory control of TNF-α in peritonitis, but the anorexia is not dependent on increased leptin production.
Cloning and Sequencing of a
Candida albicans
Catalase Gene and Effects of Disruption of This Gene
Authors: Wysong Deborah R. , Christin Laurent , Sugar Alan M. , Robbins Phillips W. , Diamond Richard D. 
Published: December 2019

ABSTRACT

Catalase plays a key role as an antioxidant, protecting aerobic organisms from the toxic effects of hydrogen peroxide, and in some cases has been postulated to be a virulence factor. To help elucidate the function of catalase in
Candida albicans
, a single
C. albicans
-derived catalase gene, designated
CAT1
, was isolated and cloned. Degenerate PCR primers based on highly conserved areas of other fungal catalase genes were used to amplify a 411-bp product from genomic DNA of
C. albicans
ATCC 10261. By using this product as a probe, catalase clones were isolated from genomic libraries of
C. albicans
. Nucleotide sequence analysis revealed an open reading frame encoding a protein of 487 amino acid residues. Construction of a
CAT1
-deficient mutant was achieved by using the Ura-blaster technique for sequential disruption of multiple alleles by integrative transformation using
URA3
as a selectable marker. Resulting mutants exhibited normal morphology and comparable growth rates of both yeast and mycelial forms. Enzymatic analysis revealed an abundance of catalase in the wild-type strain but decreasing catalase activity in heterozygous mutants and no detectable catalase in a homozygous null mutant. In vitro assays showed the mutant strains to be more sensitive to damage by both neutrophils and concentrations of exogenous peroxide that were sublethal for the parental strain. Compared to the parental strain, the homozygous null mutant strain was far less virulent for mice in an intravenous infection model of disseminated candidiasis. Definitive linkage of
CAT1
with virulence would require restoration of activity by reintroduction of the gene into mutants. However, initial results in mice, taken together with the enhanced susceptibility of catalase-deficient hyphae to damage by human neutrophils, suggest that catalase may enhance the pathogenicity of
C. albicans.
Nonspecific Binding ofClostridium difficileToxin A to Murine Immunoglobulins Occurs via the Fab Component
Authors: Cooke Deborah L. , Borriello S. Peter 
Published: December 2019

ABSTRACTClostridium difficiletoxin A binds nonspecifically to a mouse monoclonal antibody (MAb) immunoglobulin G3 λ chain [IgG3(λ)], through the Fab component. This binding, which is retained even after boiling the MAb, is temperature dependent, with more toxin bound at 4 than 37°C (P= 0.0024). The nonspecific binding was decreased by incubation of the IgG3 λ MAb with α- or β-galactosidase (P= 0.0001 and 0.029, respectively), indicating that toxin A binds to a carbohydrate moiety on the Fab. However, binding was not blocked by theBandeiraea simplicifolialectin BS-1, indicating that a terminal α-galactose may not be involved. Binding was also not affected by competitive assays with Lewis X antigen. The dependence on carbohydrate moieties in nonspecific binding was also shown for two other MAbs, IgA(κ) and IgM(λ), with demonstration of a significant reduction in binding with α-galactosidase (P= 0.0001 and 0.0002, respectively) but not β-galactosidase (P= 0.27 and 0.25, respectively).