bluuebunny/crossref_metadata_2025_split huggingface dataset:
Down Regulation of Macrophage Activation inBrugia pahangi-Infected Jirds (Meriones unguiculatus)
Authors: Nasarre C. , Krahenbuhl J. L. , Klei T. R. 
Published: December 2019

ABSTRACTThe macrophage is a major component of the inflammatory response induced by lymphatic tissue-dwelling filariae. Intraperitoneal (i.p.) infections withBrugia pahangiin Mongolian gerbils, or jirds (Meriones unguiculatus), induce a peritoneal inflammatory response characterized by accumulation of numerous macrophages and fewer eosinophils. This inflammatory response is associated with the release of microfilariae by female worms. The aim of this study was to investigate the activation state of the peritoneal macrophages during the course of i.p. infections with either male or female worms. Activation was determined by a toxoplasmacidal assay and assays which measured the production of tumor necrosis factor (TNF)-like activity and nitric oxide (NO) production. The development of these assays with jirds was initially conducted in parallel with the mouse system, which served as a positive control. Jird macrophages became activated to killToxoplasma gondiiby in vivo immunization withMycobacterium bovisBCG in a pattern similar to that of mouse macrophages. However, unlike the mouse system, supernatants from purified protein derivative- or concanavalin A-stimulated jird splenocytes plus lipopolysaccharide failed to activate jird macrophages in vitro or induce NO production. These results indicate that factors involved in jird macrophage activation may differ from those demonstrated in the mouse system and other systems. i.p. infections of 15 days in duration with either male or female worms induced macrophage activation as measured byToxoplasmakilling and TNF production. These responses decreased as the infection progressed to the chronic period on a time course that parallels the down regulation of experimentalB. pahangigranulomas. There was no evidence of NO production by activated jird macrophages. These data indicate that macrophage function is down modulated during filarial infection and suggest that mechanisms involved in macrophage deactivation are related to those that induce down modulation of the systemic granulomatous inflammatory response in the jird. This response is not dependent on the microfilarial stage of the parasite and is also independent of mechanisms which induce peritoneal accumulations of macrophages.
Isolation and Characterization of the Outer Membrane of
Borrelia hermsii
Authors: Shang Ellen S. , Skare Jonathan T. , Exner Maurice M. , Blanco David R. , Kagan Bruce L. , Miller James N. , Lovett Michael A. 
Published: December 2019

ABSTRACT

The outer membrane of
Borrelia hermsii
has been shown by freeze-fracture analysis to contain a low density of membrane-spanning outer membrane proteins which have not yet been isolated or identified. In this study, we report the purification of outer membrane vesicles (OMV) from
B. hermsii
HS-1 and the subsequent identification of their constituent outer membrane proteins. The
B. hermsii
outer membranes were released by vigorous vortexing of whole organisms in low-pH, hypotonic citrate buffer and isolated by isopycnic sucrose gradient centrifugation. The isolated OMV exhibited porin activities ranging from 0.2 to 7.2 nS, consistent with their outer membrane origin. Purified OMV were shown to be relatively free of inner membrane contamination by the absence of measurable β-NADH oxidase activity and the absence of protoplasmic cylinder-associated proteins observed by Coomassie blue staining. Approximately 60 protein spots (some of which are putative isoelectric isomers) with 25 distinct molecular weights were identified as constituents of the OMV enrichment. The majority of these proteins were also shown to be antigenic with sera from
B. hermsii
-infected mice. Seven of these antigenic proteins were labeled with [
3
H]palmitate, including the surface-exposed glycerophosphodiester phosphodiesterase, the variable major proteins 7 and 33, and proteins of 15, 17, 38, 42, and 67 kDa, indicating that they are lipoprotein constituents of the outer membrane. In addition, immunoblot analysis of the OMV probed with antiserum to the
Borrelia garinii
surface-exposed p66/Oms66 porin protein demonstrated the presence of a p66 (Oms66) outer membrane homolog. Treatment of intact
B. hermsii
with proteinase K resulted in the partial proteolysis of the Oms66/p66 homolog, indicating that it is surface exposed. This identification and characterization of the OMV proteins should aid in further studies of pathogenesis and immunity of tick-borne relapsing fever.
Yersinia enterocolitica
-Induced Interleukin-8 Secretion by Human Intestinal Epithelial Cells Depends on Cell Differentiation
Authors: Schulte Ralf , Autenrieth Ingo B. 
Published: December 2019

ABSTRACT

In response to bacterial entry epithelial cells up-regulate expression and secretion of various proinflammatory cytokines, including interleukin-8 (IL-8). We studied
Yersinia enterocolitica
O:8-induced IL-8 secretion by intestinal epithelial cells as a function of cell differentiation. For this purpose, human T84 intestinal epithelial cells were grown on permeable supports, which led to the formation of tight monolayers of polarized intestinal epithelial cells. To analyze IL-8 secretion as a function of cell differentiation, T84 monolayers were infected from the apical or basolateral side at different stages of differentiation. Both virulent (plasmid-carrying) and nonvirulent (plasmid-cured)
Y. enterocolitica
strains invaded nondifferentiated T84 cells from the apical side.
Yersinia
invasion into T84 cells was followed by secretion of IL-8. After polarized differentiation of T84 cells
Y. enterocolitica
was no longer able to invade from the apical side or to induce IL-8 secretion by T84 cells. However,
Y. enterocolitica
invaded and induced IL-8 secretion by polarized T84 cells after infection from the basolateral side. Basolateral invasion required the presence of the
Yersinia
invasion locus,
inv
, suggesting β
1
integrin-mediated cell invasion. After basolateral infection,
Yersinia
-induced IL-8 secretion was not strictly dependent on cell invasion. Thus, although the plasmid-carrying
Y. enterocolitica
strain did not significantly invade T84 cells, it induced significant IL-8 secretion. Taken together, these data show that
Yersinia
-triggered IL-8 secretion by intestinal epithelial cells depends on cell differentiation and might be induced by invasion as well as by basolateral adhesion, suggesting that invasion is not essential for triggering IL-8 production. Whether IL-8 secretion is involved in the pathogenesis of
Yersinia
-induced abscess formation in Peyer’s patch tissue remains to be shown.
d
-Lactate Production and [
14
C]Succinic Acid Uptake by Adherent and Nonadherent
Escherichia coli
Authors: McCabe K. , Mann M. D. , Bowie M. D. 
Published: December 2019

ABSTRACT

Escherichia coli
isolates of different adherence phenotypes produced different amounts of
d
-lactate. Alterations of culture conditions did not influence the amount of
d
-lactate produced. The observed pH decreases in tissue culture medium corresponded with increases in
d
-lactate concentration. Very little [
14
C]succinic acid was incorporated into cells during the in vitro incubation of adherent and nonadherent
E. coli
with HeLa cells, but the amounts of tracer removed from the culture medium by adherent and nonadherent strains differed. The results are further evidence of a difference in the metabolic behavior of adherent and nonadherent
E. coli.
Structural Properties of Lipopolysaccharides fromRickettsia typhiandRickettsia prowazekiiand Their Chemical Similarity to the Lipopolysaccharide fromProteus vulgarisOX19 Used in the Weil-Felix Test
Authors: Amano Ken-ichi , Williams Jim C. , Dasch Gregory A. 
Published: December 2019

ABSTRACTThe lipopolysaccharides (LPSs) isolated from typhus group (TG) rickettsiaeRickettsia typhiandRickettsia prowazekiiwere characterized by chemical analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by silver staining. LPSs from two species of TG rickettsiae contained glucose, 3-deoxy-d-manno-octulosonic acid, glucosamine, quinovosamine, phosphate, and fatty acids (β-hydroxylmyristic acid and heneicosanoic acid) but not heptose. The O-polysaccharides of these LPSs were composed of glucose, glucosamine, quinovosamine, and phosphorylated hexosamine. Resolution of these LPSs by their apparent molecular masses by SDS-PAGE showed that they have a common ladder-like pattern. Based on the results of chemical composition and SDS-PAGE pattern, we suggest that these LPSs act as group-specific antigens. Furthermore, glucosamine, quinovosamine, and phosphorylated hexosamine were also found in the O-polysaccharide of the LPS fromProteus vulgarisOX19 used in the Weil-Felix test, suggesting that they may represent the antigens common to LPSs from TG rickettsiae andP. vulgarisOX19.
Identification of Linked
Legionella pneumophila
Genes Essential for Intracellular Growth and Evasion of the Endocytic Pathway
Authors: Andrews Helene L. , Vogel Joseph P. , Isberg Ralph R. 
Published: December 2019

ABSTRACT

Legionella pneumophila
replicates within a specialized phagosome in cultured cells, a function necessary for its pathogenicity. The replicative phagosome lacks membrane marker proteins, such as the glycoprotein LAMP-1, that are indicators of the normal endocytic pathway. We describe the isolation of several
Legionella
genes essential for intracellular growth and evasion of the endocytic pathway, using a genetic and cell biological approach. We screened 4,960 ethyl methanesulfonate-mutagenized colonies for defects in intracellular growth and trafficking to the replicative phagosome. Six mutant strains of
L. pneumophila
that had severe intracellular growth defects in mouse bone marrow-derived macrophages were identified. All six mutants were found in phagosomes that colocalized with LAMP-1, indicating defects in intracellular trafficking. The growth defects of two of these strains were complemented by molecular clones from a bank constructed from a wild-type
L. pneumophila
strain. The inserts from these clones are located in a region of the chromosome contiguous with several other genes essential for intracellular growth. Three mutants could be complemented by single open reading frames placed in
trans
, one mutant by a gene termed
dotH
and two additional mutants by a gene termed
dotO
. A deletion mutation was created in a third gene,
dotI
, which is located directly upstream of
dotH
. The Δ
dotI
strain was also defective for intracellular growth in macrophages, and this defect was complemented by a single open reading frame in
trans
. Based on sequence analysis and structural predictions, possible roles of
dotH
,
dotI
, and
dotO
in intracellular growth are discussed.
Phase Variation of Hemoglobin Utilization in
Neisseria gonorrhoeae
Authors: Chen Ching-Ju , Elkins Christopher , Sparling P. Frederick 
Published: December 2019

ABSTRACT

Most
Neisseria gonorrhoeae
isolates are unable to use human hemoglobin as the sole source of iron for growth (Hgb
−
), but a minor population is able to do so (Hgb
+
). This minor population grows luxuriously on hemoglobin, expresses two outer membrane proteins of 42 kDa (HpuA) and 89 kDa (HpuB), and binds hemoglobin under iron-stressed conditions. In addition to the previously reported HpuB, we identified and characterized HpuA, which is encoded by the gene
hpuA
, located immediately upstream of
hpuB
. Expression of both proteins was found to be controlled at the translational level by frameshift mutations in a run of guanine residues within the
hpuA
sequence encoding the mature HpuA protein. The “on-phase” hemoglobin-utilizing variants contained 10 G’s, while the “off-phase” variants contained 9 G’s. Insertional
hpuB
mutants of FA19 Hgb
+
and FA1090 Hgb
+
no longer expressed HpuB but still produced HpuA. A polar insertional mutation of the upstream
hpuA
gene in FA1090 Hgb
+
eliminated production of both HpuA and HpuB, whereas a nonpolar insertional mutant expressed HpuB only. Insertional mutagenesis of either
hpuA
or
hpuB
or both substantially decreased the hemoglobin binding ability of the FA1090 Hgb
+
variant and prevented growth on hemoglobin plates. Therefore, both HpuA and HpuB were required for the utilization of hemoglobin for growth.
Influence of Antibodies in Mother’s Milk on Antigenic Variation ofGiardia lambliain the Murine Mother-Offspring Model of Infection
Authors: Stäger S. , Gottstein B. , Sager H. , Jungi T. W. , Müller N. 
Published: December 2019

ABSTRACTIn the present study, neonatal ZU.ICR mice and their mothers were infected with trophozoites ofGiardia lambliaclone GS/M-83-H7 expressing the variant surface protein (VSP) H7. The infection experiments included a detailed analysis of the specificities of anti-Giardiaimmunoglobulin A (IgA) antibodies in mother’s milk and a determination of the effects of the milk antibodies on both the growth of the parasite during in vitro cultivation and colonization of the parasite within the intestine of suckling offspring. These investigations revealed that transiently emerging milk IgA antibodies against a variant-specific 314-amino-acid N-terminal region of VSP H7 exhibit a strong parasiticidal effect on VSP H7-type trophozoites both in vitro and in vivo. These findings indicated that parasiticidal effects of local IgA antibodies against the N-terminal part of VSP H7 select for new variant types within the intestinal parasite population of suckling mice. The selective influence of such antibodies promotes in vivo antigenic variation ofG. lambliaclone GS/M-83-H7 and modulates the early course of parasite infection in these animals.
Superoxide Dismutase-Dependent, Catalase-Sensitive Peroxides in Human Endothelial Cells Infected byRickettsia rickettsii
Authors: Hong June E. , Santucci Lisa A. , Tian Xiaojiang , Silverman David J. 
Published: December 2019

ABSTRACTThe generation and intracellular accumulation of reactive oxygen species have been shown to be associated with the infection of human umbilical vein endothelial cells (HUVEC) byRickettsia rickettsii. In response to the oxidant superoxide, the activity of the enzyme superoxide dismutase (SOD) increases following infection by this obligate intracellular bacterium. Other oxidants which are capable of oxidizing the fluorescent probe 2′,7′-dichlorofluorescin (DCFH) also accumulate intracellularly within infected cells. In the study reported here, we show that (i) an inhibitor of SOD, diethyldithiocarbamic acid, reduces the observed rise in SOD activity in infected cells by 40 to 60% and at the same time reduces the degree of intracellular oxidation of DCFH; (ii) catalase-sensitive peroxides can be detected in supernatants ofR. rickettsii-infected cells shortly after rickettsial exposure; and (iii) fluorescence-activated cell sorter analysis demonstrates significant intracellular oxidant activity in infected cells within 5 h after exposure toR. rickettsii. The results of these experiments indicate that hydrogen peroxide is a major oxidant associated with infection of HUVEC byR. rickettsiiand that intracellular oxidant activity sensitive to SOD inhibition is detectable early and prior to significant rickettsial multiplication and much earlier than the ultrastructural manifestations of cell injury seen by electron microscopy.
Expression and Bactericidal Activity of Nitric Oxide Synthase inBrucella suis-Infected Murine Macrophages
Authors: Gross Antoine , Spiesser Sandra , Terraza Annie , Rouot Bruno , Caron Emmanuelle , Dornand Jacques 
Published: December 2019

ABSTRACTWe examined the expression and activity of inducible nitric oxide synthase (iNOS) in both gamma interferon (IFN-γ)-treated and untreated murine macrophages infected with the gram-negative bacteriumBrucella suis. The bacteria were opsonized with a mouse serum containing specific antibrucella antibodies (ops-Brucella) or with a control nonimmune serum (c-Brucella). The involvement of the produced NO in the killing of intracellularB. suiswas evaluated.B. suissurvived and replicated within J774A.1 cells. Opsonization with specific antibodies increased the number of phagocytized bacteria but lowered their intramacrophage development. IFN-γ enhanced the antibrucella activity of phagocytes, with this effect being greater inops-Brucellainfection. Expression of iNOS, interleukin-6, and tumor necrosis factor alpha (TNF-α) mRNAs was induced in bothc-Brucella- andops-Brucella-infected cells and was strongly potentiated by IFN-γ. In contrast to that of cytokine mRNAs, iNOS mRNA expression was independent of opsonization. Similar levels of iNOS mRNAs were expressed in IFN-γ-treated cells infected withc-Brucellaorops-Brucella; however, expression of iNOS protein and production of NO were detected only in IFN-γ-treated cells infected withops-Brucella. These discrepencies between iNOS mRNA and protein levels were not due to differences in TNF-α production. The iNOS inhibitorNω-nitro-l-arginine methyl ester increasedB. suismultiplication specifically in IFN-γ-treated cells infected withops-Brucella, demonstrating a microbicidal effect of the NO produced. This observation was in agreement with in vitro experiments showing thatB. suiswas sensitive to NO killing. Together our data indicate that inB. suis-infected murine macrophages, the posttranscriptional regulation of iNOS necessitates an additive signal triggered by macrophage Fcγ receptors. They also support the possibility that in mice, NO favors the elimination ofBrucella, providing that IFN-γ and antibrucella antibodies are present, i.e., following expression of acquired immunity.
Intranasal Administration of a Meningococcal Outer Membrane Vesicle Vaccine Induces Persistent Local Mucosal Antibodies and Serum Antibodies with Strong Bactericidal Activity in Humans
Authors: Haneberg Bjørn , Dalseg Rolf , Wedege Elisabeth , Høiby E. Arne , Haugen Inger Lise , Oftung Fredrik , Andersen Svein Rune , Næss Lisbeth Meyer , Aase Audun , Michaelsen Terje E. , Holst Johan 
Published: December 2019

ABSTRACTA nasal vaccine, consisting of outer membrane vesicles (OMVs) from group BNeisseria meningitidis, was given to 12 volunteers in the form of nose drops or nasal spray four times at weekly intervals, with a fifth dose 5 months later. Each nasal dose consisted of 250 μg of protein, equivalent to 10 times the intramuscular dose that was administered twice with a 6-week interval to 11 other volunteers. All individuals given the nasal vaccine developed immunoglobulin A (IgA) antibody responses to OMVs in nasal secretions, and eight developed salivary IgA antibodies which persisted for at least 5 months. Intramuscular immunizations did not lead to antibody responses in the secretions. Modest increases in serum IgG antibodies were obtained in 5 volunteers who had been immunized intranasally, while 10 individuals responded strongly to the intramuscular vaccine. Both the serum and secretory antibody responses reached a maximum after two to three doses of the nasal vaccine, with no significant booster effect of the fifth dose. The pattern of serum antibody specificities against the different OMV components after intranasal immunizations was largely similar to that obtained with the intramuscular vaccine. Five and eight vaccinees in the nasal group developed persistent increases in serum bactericidal titers to the homologous meningococcal vaccine strain expressing low and high levels, respectively, of the outer membrane protein Opc. Our results indicate that meningococcal OMVs possess the structures necessary to initiate systemic as well as local mucosal immune responses when presented as a nasal vaccine. Although the serum antibody levels were less conspicuous than those after intramuscular vaccinations, the demonstration of substantial bactericidal activity indicates that a nonproliferating nasal vaccine might induce antibodies of high functional quality.
Molecular Cloning and Sequencing of Three GranulocyticEhrlichiaGenes Encoding High-Molecular-Weight Immunoreactive Proteins
Authors: Storey James R. , Doros-Richert Linda A. , Gingrich-Baker Cindy , Munroe Kenneth , Mather Thomas N. , Coughlin Richard T. , Beltz Gerald A. , Murphy Cheryl I. 
Published: December 2019

ABSTRACTGranulocyticEhrlichiawas isolated from canine blood obtained from animals challenged with field-collectedIxodes scapularisand propagated in HL60 cells. PCR primers specific for the 16S ribosomal DNA (rDNA) of theEhrlichiagenogroup comprisingE. equi,E. phagocytophila, and the agent of human granulocytic ehrlichiosis (HGE) amplified DNA from extracts of these cells. Sequence analysis of this amplified DNA revealed that it is identical to the 16S rDNA sequence of the HGE agent. A genomic library was constructed with DNA from granulocyticEhrlichiaand screened with pooled sera from tick-challenged, granulocyticEhrlichia-infected dogs. Several clones were isolated and sequenced. Three complete genes encoding proteins with apparent molecular masses of 100, 130, and 160 kDa were found. The recombinant proteins reacted with convalescent-phase sera from dogs and human patients recovering from HGE. This approach will be useful for identifying candidate diagnostic and vaccine antigens for granulocytic ehrlichiosis and aid in the classification of genogroup members.
Characterization of a Strain of
Chlamydia pneumoniae
Isolated from a Coronary Atheroma by Analysis of the
omp1
Gene and Biological Activity in Human Endothelial Cells
Authors: Molestina Robert E. , Dean Deborah , Miller Richard D. , Ramirez Julio A. , Summersgill James T. 
Published: December 2019

ABSTRACT

Chlamydia pneumoniae
is a respiratory pathogen that has been associated with chronic inflammatory diseases such as asthma and atherosclerosis. Recent isolation of
C. pneumoniae
from human carotid and coronary atheromas provides additional support for a role of this organism in atherogenesis. We characterized the coronary strain
C. pneumoniae
A-03 by sequence analysis of the major outer membrane protein gene (
omp1
). In addition, the in vitro activities of A-03 and three respiratory strains of
C. pneumoniae
(BAL-16, TW-183, and T-2634) were examined in infected human umbilical vein endothelial cells (HUVEC) by analysis of the production of interleukin-8 (IL-8), monocyte chemotactic protein 1 (MCP-1), and soluble intercellular cell adhesion molecule 1 (sICAM-1). Sequence analysis of
omp1
of
C. pneumoniae
A-03, compared to prototype strains TW-183 and AR-39, revealed five nucleotide changes resulting in nonsynonymous codons. Of interest was a nonconservative amino acid substitution (Ser to Pro) in position 61 of variable segment 1. In vitro, the extent of MCP-1, IL-8, and sICAM-1 production was dependent on the
C. pneumoniae
strain examined at low multiplicities of infection following 24 h of incubation. Strain A-03 displayed the lowest stimulatory activity in infected HUVEC, while T-2634 induced the highest levels of MCP-1, IL-8, and sICAM-1 among all strains examined. Heat-inactivated
C. pneumoniae
failed to stimulate production of these proteins by all strains tested. In contrast, only partial inhibition was observed by UV-inactivated organisms. Results from this study demonstrate that unlike prototype respiratory strains of
C. pneumoniae
, the coronary strain A-03 displays divergence in the
omp1
gene. In addition, the stimulation of chemokines and adhesion molecules involved in the recruitment of leukocytes to sites of inflammation by
C. pneumoniae
may be important in the pathogenesis of diseases associated with this organism, including atherosclerosis.