bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Cellular Form of Human Fibronectin as an Adhesion Target for the S Fimbriae of Meningitis-Associated
Escherichia coli
Authors: Sarén Anne , Virkola Ritva , Hacker Jörg , Korhonen Timo K. 
Published: December 2019

ABSTRACT

The adhesion of the S fimbriae of meningitis-associated
Escherichia coli
O18ac:K1:H7 to the cellular and the plasma forms of human fibronectin was studied.
E. coli
HB101(pAZZ50) expressing the complete S-fimbria II gene cluster of
E. coli
O18 adhered to cellular fibronectin (cFn) on glass but not to plasma fibronectin (pFn). Adhesion to cFn was specifically inhibited by neuraminidase treatment of cFn as well as by incubation of the bacteria with sialyl-α2-3-lactose, a receptor analog of the S fimbriae. No significant adhesion to cFn or pFn was detected with
E. coli
HB101(pAZZ50-67) expressing S fimbriae lacking the SfaS lectin subunit. Strain HB101(pAZZ50) also adhered to a human fibroblast cell culture known to be rich in cFn, and the adhesion was specifically inhibited in the presence of polyclonal antibodies to cFn. The results show that the SfaS lectin of the S fimbriae mediates the adherence of meningitis-associated
E. coli
to sialyl oligosaccharide chains of cFn.
Gamma Interferon and Interleukin-10 Gene Expression in Synovial Tissues from Patients with Early Stages ofChlamydia-Associated Arthritis and Undifferentiated Oligoarthritis and from Healthy Volunteers
Authors: Kotake Shigeru , Schumacher H. Ralph , Arayssi Thurayya K. , Gérard Herve C. , Branigan Patrick J. , Hudson Alan P. , Yarboro Cheryl H. , Klippel John H. , Wilder Ronald L. 
Published: December 2019

ABSTRACTGenetically determined differences in interleukin-10 (IL-10) and gamma interferon (IFN-γ) responses in mice correlate with clearance ofChlamydiapneumonitis infection. We measured the synovial expression of IL-10 and IFN-γ and additional cytokine genes in patients who had recent-onsetChlamydia-associated arthritis (Chl-AA). IL-10 and IFN-γ mRNA were relatively abundant in recent-onset Chl-AA.
Molecular Characterization of Equine Isolates of
Streptococcus pneumoniae
: Natural Disruption of Genes Encoding the Virulence Factors Pneumolysin and Autolysin
Authors: Whatmore Adrian M. , King Samantha J. , Doherty Neil C. , Sturgeon Daniel , Chanter Neil , Dowson Christopher G. 
Published: December 2019

ABSTRACT

Although often considered a strict human pathogen,
Streptococcus pneumoniae
has been reported to infect and cause pneumonia in horses, although the pathology appears restricted compared to that of human infections. Here we report on the molecular characterization of a group of
S. pneumoniae
isolates obtained from horses in England and Ireland. Despite being obtained from geographically distinct locations, the isolates were found to represent a tight clonal group, virtually identical to each other but genetically distinguishable from more than 120 divergent isolates of human
S. pneumoniae
. A comprehensive analysis of known pneumococcal virulence determinants was undertaken in an attempt to understand the pathogenicity of equine pneumococci. Surprisingly, equine isolates appear to lack activities associated with both the hemolytic cytotoxin pneumolysin, often considered a major virulence factor of pneumococci, and the major autolysin gene
lytA
, also considered an important virulence factor. In support of phenotypic data, molecular studies demonstrated a deletion of parts of the coding sequences of both
lytA
and
ply
genes in equine pneumococci. The implications of these findings for the evolution and pathogenicity of equine
S. pneumoniae
are discussed.
Environmental Modulation of Oral Treponeme Virulence in a Murine Model
Authors: Kesavalu Lakshmyya , Holt Stanley C. , Ebersole Jeffrey L. 
Published: December 2019

ABSTRACTThis investigation examined the effects of environmental alteration on the virulence of the oral treponemesTreponema denticolaandTreponema pectinovorum. The environmental effects were assessed by using a model of localized inflammatory abscesses in mice. In vitro growth ofT. denticolaandT. pectinovorumas a function of modification of the cysteine concentration significantly enhanced abscess formation and size. In contrast, growth ofT. denticolaorT. pectinovorumunder iron-limiting conditions (e.g., dipyridyl chelation) had no effect on abscess induction in comparison to that when the strains were grown under normal iron conditions. In vivo modulation of the microenvironment at the focus of infection with Cytodex beads demonstrated that increasing the local inflammation had no effect on lesion induction or size. In vivo studies involved the determination of the effects of increased systemic iron availability (e.g., iron dextran or phenylhydrazine) on the induction, kinetics, and size of lesions.T. denticolainduced significantly larger lesions in mice with iron pretreatment and demonstrated systemic manifestations of the infectious challenge and an accompanying spreading lesion with phenylhydrazine pretreatment (e.g., increases in circulating free hemoglobin). In contrast,T. pectinovorumvirulence was minimally affected by this in vivo treatment to increase iron availability.T. denticolavirulence, as evaluated by lesion size, was increased additively by in vivo iron availability, and cysteine modified growth of the microorganism. Additionally, galactosamine sensitized mice to a lethal outcome following infection with bothT. denticolaandT. pectinovorum, suggesting an endotoxin-like activity in these treponemes. These findings demonstrated the ability to modify the virulence capacity ofT. denticolaandT. pectinovorumby environmental conditions which can be evaluated by using in vivo murine models.
Inhibition of Osteoblastic Cell Differentiation by Lipopolysaccharide Extract fromPorphyromonas gingivalis
Authors: Kadono Hiroyuki , Kido Jun-Ichi , Kataoka Masatoshi , Yamauchi Noriyuki , Nagata Toshihiko 
Published: December 2019

ABSTRACTLipopolysaccharide fromPorphyromonas gingivalis(P-LPS), an important pathogenic bacterium, is closely associated with inflammatory destruction of periodontal tissues. P-LPS induces the release of cytokines and local factors from inflammatory cells, stimulates osteoclastic-cell differentiation, and causes alveolar bone resorption. However, the effect of P-LPS on osteoblastic-cell differentiation remains unclear. In this study, we investigated the effect of P-LPS extract prepared by the hot-phenol–water method, on the differentiation of primary fetal rat calvaria (RC) cells, which contain a subpopulation of osteoprogenitor cells, into osteoblastic cells. P-LPS extract significantly inhibited bone nodule (BN) formation and the activity of alkaline phosphatase (ALPase), an osteoblastic marker, in a dose-dependent manner (0 to 100 ng of P-LPS extract per ml). P-LPS extract (100 ng/ml) significantly decreased BN formation to 27% of the control value and inhibited ALPase activity to approximately 60% of the control level on days 10 to 21 but did not affect RC cell proliferation and viability. P-LPS extract time-dependently suppressed the expression of ALPase mRNA, with an inhibitory pattern similar to that of enzyme activity. The expression of mRNAs for osteocalcin and osteopontin, matrix proteins related to bone metabolism, was markedly suppressed by P-LPS extract. Furthermore, P-LPS extract increased the expression of mRNAs for CD14, LPS receptor, and interleukin-1β in RC cells. These results indicate that P-LPS inhibits osteoblastic-cell differentiation and suggest that LPS-induced bone resorption in periodontal disease may be mediated by effects on osteoblastic as well as osteoclastic cells.
Chlamydia pneumoniae
Infection of Human Endothelial Cells Induces Proliferation of Smooth Muscle Cells via an Endothelial Cell-Derived Soluble Factor(s)
Authors: Coombes Brian K. , Mahony James B. 
Published: December 2019

ABSTRACT

An association of
Chlamydia pneumoniae
with atherosclerosis and coronary heart disease has been determined epidemiologically and by the detection of
C. pneumoniae
organisms in atherosclerotic lesions in both humans and animal models of atherosclerosis. Previously, it has been shown that
C. pneumoniae
is capable of replicating in cell types found within atheromatous lesions, viz., endothelial cells, smooth muscle cells (SMC), and macrophages, yet the role of
C. pneumoniae
in the pathogenesis of atherosclerosis has not been determined. Since intimal thickening is a hallmark of atherosclerosis, we investigated whether
C. pneumoniae
infection of human umbilical vein endothelial cells (HUVEC) could induce the expression of a soluble factor(s) with mitogenic potential for SMC by using [
3
H]thymidine incorporation and direct cell counting. Conditioned medium harvested from HUVEC infected with
C. pneumoniae
stimulated SMC replication in a time- and dose-dependent fashion. Infection studies using various multiplicities of infection (MOIs) ranging from 0.001 to 1 demonstrated a dose-dependent production of the soluble factor(s). At an MOI of 1, SMC stimulation indices were 8.4 (
P
< 0.01) and 12.2 (
P
< 0.01) for conditioned media harvested at 24 and 48 h, respectively. To determine whether viable
C. pneumoniae
was required for production of the soluble factor(s), HUVEC were infected with heat-inactivated
C. pneumoniae
or with viable organisms in the presence of chloramphenicol. Both treatments produced stimulation indices similar to those for live
C. pneumoniae
in the absence of chloramphenicol (
P
> 0.05), indicating that the factor(s) was produced by HUVEC and not by
C. pneumoniae
and that signal transduction events following chlamydia endocytosis may be important in the production of a soluble factor(s). The ability of
C. pneumoniae
to elicit an endothelial cell-derived soluble factor(s) that stimulates SMC proliferation may be important in the pathogenesis of atherosclerosis.
Lipopolysaccharide Complexes withPasteurella haemolyticaLeukotoxin
Authors: Li Jun , Clinkenbeard Kenneth D. 
Published: December 2019

ABSTRACTThe presence of lipopolysaccharide (LPS) in gram-negative bacterial repeats-in-toxin (RTX) toxin preparations, as well as the harsh conditions required to remove it, suggests that LPS may complex with RTX toxins. Concentrated culture supernatant (CCS) preparations of the RTX toxinPasteurella haemolyticaleukotoxin (LKT) contained LKT and LPS as the most prominent components, with LKT and LPS constituting ≈30 and 50% of the density of the silver-stained fraction on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), respectively. CCS LKT contained 3.69 ± 0.46 mg of LPS per mg of protein, which was estimated to indicate an LPS/LKT molar ratio of ≈60:1. Subjection of the CCS LKT to preparative SDS-PAGE resulted in separation of LPS from LKT as detected by silver-stained analytical SDS-PAGE; however, the LKT fraction (SDS-PAGE LKT) contained significant endotoxin activity as detected by theLimulusamebocyte lysate assay. Subjection of the SDS-PAGE LKT to a second preparative SDS-PAGE run resulted in a reduction of the LPS/LKT molar ratio to 1:20. The target cell specificity of LKT for bovine leukocytic cells was retained by the SDS-PAGE LKT, and isolated LPS at comparable concentrations to that in CCS LKT exhibited no leukolytic activity. Addition of isolated LPS back to SDS-PAGE LKT resulted in reconstitution of an LPS-LKT complex. Immediately following reconstitution of the LPS-LKT complex, there was minimal change in leukolytic activity of the complex, but following 9.5 h at temperatures from −135 to 37°C, the LPS-LKT complex exhibited increased leukolytic activity and thermal stability compared to SDS-PAGE LKT. Therefore, it appears that LPS complexes with LKT, resulting in enhanced and stabilized leukolytic activity.
Molecular Characterization and Human T-Cell Responses to a Member of a NovelMycobacterium tuberculosis mtb39Gene Family
Authors: Dillon Davin C. , Alderson Mark R. , Day Craig H. , Lewinsohn David M. , Coler Rhea , Bement Teresa , Campos-Neto Antonio , Skeiky Y. A. W. , Orme Ian M. , Roberts Alan , Steen Sean , Dalemans Wilfried , Badaro Roberto , Reed Steven G. 
Published: December 2019

ABSTRACTWe have used expression screening of a genomicMycobacterium tuberculosislibrary with tuberculosis (TB) patient sera to identify novel genes that may be used diagnostically or in the development of a TB vaccine. Using this strategy, we have cloned a novel gene, termedmtb39a, that encodes a 39-kDa protein. Molecular characterization revealed thatmtb39ais a member of a family of three highly related genes that are conserved among strains ofM. tuberculosisandMycobacterium bovisBCG but not in other mycobacterial species tested. Immunoblot analysis demonstrated the presence of Mtb39A inM. tuberculosislysate but not in culture filtrate proteins (CFP), indicating that it is not a secreted antigen. This conclusion is strengthened by the observation that a human T-cell clone specific for purified recombinant Mtb39A protein recognized autologous dendritic cells infected with TB or pulsed with purified protein derivative (PPD) but did not respond toM. tuberculosisCFP. Purified recombinant Mtb39A elicited strong T-cell proliferative and gamma interferon responses in peripheral blood mononuclear cells from 9 of 12 PPD-positive individuals tested, and overlapping peptides were used to identify a minimum of 10 distinct T-cell epitopes. Additionally, mice immunized withmtb39aDNA have shown increased protection fromM. tuberculosischallenge, as indicated by a reduction of bacterial load. The human T-cell responses and initial animal studies provide support for further evaluation of this antigen as a possible component of a subunit vaccine forM. tuberculosis.
Chitinase Secretion by Encysting
Entamoeba invadens
and Transfected
Entamoeba histolytica
Trophozoites: Localization of Secretory Vesicles, Endoplasmic Reticulum, and Golgi Apparatus
Authors: Ghosh Sudip K. , Field Jessica , Frisardi Marta , Rosenthal Benjamin , Mai Zhiming , Rogers Rick , Samuelson John 
Published: December 2019

ABSTRACT

Entamoeba histolytica
, the protozoan parasite that phagocytoses bacteria and host cells, has a vesicle/vacuole-filled cytosol like that of macrophages. In contrast, the infectious cyst form has four nuclei and a chitin wall. Here, anti-chitinase antibodies identified hundreds of small secretory vesicles in encysting
E. invadens
parasites and in
E. histolytica
trophozoites overexpressing chitinase under an
actin
gene promoter. Abundant small secretory vesicles were also identified with antibodies to the surface antigen Ariel and with a fluorescent substrate of cysteine proteinases. Removal of an N-terminal signal sequence directed chitinase to the cytosol. Addition of a C-terminal KDEL peptide, identified on amebic BiP, retained chitinase in a putative endoplasmic reticulum, which was composed of a few vesicles of mixed sizes. A putative Golgi apparatus, which was Brefeldin A sensitive and composed of a few large, perinuclear vesicles, was identified with antibodies to ADP-ribosylating factor and to ɛ-COP. We conclude that the amebic secretory pathway is similar to those of other eukaryotic cells, even if its appearance is somewhat different.
Variation in the
Bordetella pertussis
Virulence Factors Pertussis Toxin and Pertactin in Vaccine Strains and Clinical Isolates in Finland
Authors: Mooi Frits R. , He Qiushui , van Oirschot Hans , Mertsola Jussi 
Published: December 2019

ABSTRACT

There is evidence that pertussis is reemerging in vaccinated populations. We have proposed, and provided evidence for, one explanation for this phenomenon in The Netherlands: antigenic divergence between vaccine strains and circulating strains. Finland has a pertussis vaccination history very similar to that of The Netherlands, and yet there is no evidence for an increase in the incidence of pertussis to the extent that it was observed in The Netherlands. A comparison of the
Bordetella pertussis
strains circulating in the two countries may shed light on the differences in pertussis epidemiology. Here we investigated whether temporal changes had occurred in pertussis toxin and pertactin types produced by the Finnish
B. pertussis
population. We show that strains isolated before 1964 produced the same pertussis toxin and pertactin variants as the vaccine strains. However, these vaccine types were replaced in later years, and in the 1990s most strains were distinct from the vaccine strains with respect to the two proteins. These trends are similar to those found in the Dutch
B. pertussis
population. An interesting difference between the contemporary Finnish and Dutch
B. pertussis
populations was found in the frequencies of pertactin variants, possibly explaining the distinct epidemiology of pertussis in the two countries.
Stability of
erp
Loci during
Borrelia burgdorferi
Infection: Recombination Is Not Required for Chronic Infection of Immunocompetent Mice
Authors: El Hage Nazira , Lieto Louis D. , Stevenson Brian 
Published: December 2019

ABSTRACT

Borrelia burgdorferi
can persistently infect mammals despite their production of antibodies directed against bacterial proteins, including the Erp lipoproteins. We sequenced
erp
loci of bacteria reisolated from laboratory mice after 1 year of infection and found them to be identical to those of the inoculant bacteria. We conclude that recombination of
erp
genes is not essential for chronic mammalian infection.
Sequence Conservation of Glycerophosphodiester Phosphodiesterase amongTreponema pallidumStrains
Authors: Cameron Caroline E. , Castro Christa , Lukehart Sheila A. , Van Voorhis Wesley C. 
Published: December 2019

ABSTRACTPrevious investigations have demonstrated that immunization withTreponema pallidumsubsp.pallidumglycerophosphodiester phosphodiesterase significantly protects rabbits from subsequent treponeme challenge. In this report, we show that the glycerophosphodiester phosphodiesterase amino acid sequence is conserved among 12 strains from a total of five pathogenic treponemes. The invariant nature of this immunoprotective antigen makes it an attractive candidate for inclusion in a universal subunit vaccine againstT. palliduminfection. In addition, these studies show a silent nucleotide substitution at position 579 of thegpdopen reading frame which is consistently observed in the non-T. pallidumsubsp.pallidumstrains. This sequence alteration introduces aPleI restriction site in the nonsyphilis strains and thus allows genetic differentiation fromT. pallidumsubsp.pallidumstrains.
Effects of Environmental pH on Membrane Proteins in
Borrelia burgdorferi
Authors: Carroll James A. , Garon Claude F. , Schwan Tom G. 
Published: December 2019

ABSTRACT

Borrelia burgdorferi
, the causative agent of Lyme disease, alternates between the microenvironments of the tick vector,
Ixodes scapularis
, and a mammalian host. The environmental conditions the spirochete encounters during its infectious cycle are suspected to differ greatly in many aspects, including available nutrients, temperature, and pH. Here we identify alterations in the membrane protein profile, as determined by immunoblotting and two-dimensional nonequilibrium pH gradient gel electrophoresis (2D-NEPHGE), that occur in virulent
B. burgdorferi
B31 as the pH of the medium is altered. Initial comparisons of cultures incubated at pHs 6.0, 7.0, and 8.0 yielded alterations in the expression of seven membrane proteins as determined by probing with hyperimmune rabbit serum. Six of these membrane proteins (54, 45, 44, 43, 35, and 24 kDa) were either present in increased amounts in or solely expressed by cultures incubated at pHs 6.0 and 7.0. The 24-kDa protein that decreased in expression at pH 8.0 was identified as outer surface protein C (OspC). In addition, a 42-kDa membrane protein increased in amount in cultures incubated at pH 8.0. Similar changes were observed with serum from a mouse infected by tick bite, with the recognition of two additional bands (48 and 46 kDa) unique to pHs 6.0 and 7.0. When membrane fractions were analyzed by 2D-NEPHGE, at least 37 changes in the membrane protein profile between cells incubated at pHs 6.0, 7.0, and 8.0 were observed by immunoblotting and silver staining. Environmental cues such as pH may prove important in the regulation of virulence determinants and factors necessary for the adaptation of
B. burgdorferi
to the tick or mammalian microcosm.
Pili Binding to Asialo-GM1 on Epithelial Cells Can Mediate Cytotoxicity or Bacterial Internalization by
Pseudomonas aeruginosa
Authors: Comolli James C. , Waite Leslie L. , Mostov Keith E. , Engel Joanne N. 
Published: December 2019

ABSTRACT

The interaction of
Pseudomonas aeruginosa
type IV pili and the glycosphingolipid asialo-GM1 (aGM1) can mediate bacterial adherence to epithelial cells, but the steps subsequent to this adherence have not been elucidated. To investigate the result of the interaction of pili and aGM1, we used polarized epithelial monolayers of Madin-Darby canine kidney (MDCK) cells in culture, which contained little detectable aGM1 on their apical surface but were able to incorporate exogenous aGM1. Compared to an untreated monolayer,
P. aeruginosa
PA103 displayed an eightfold increase in association with and fivefold more cytotoxicity toward MDCK cells pretreated with aGM1. Cytotoxicity of either carrier-treated or aGM1-treated monolayers required the type III secreted protein ExoU. Asialo-GM1 pretreatment of MDCK monolayers likewise augmented bacterial internalization of an isogenic invasive strain approximately fourfold. These increases were not seen in monolayers treated with GM1, the sialyated form of the glycolipid, and were inhibited by treatment with an antibody to aGM1. Also, the aGM1-mediated adhesion, cytotoxicity, and internalization required intact type IV pili since nonpiliated PA103 mutants were unaffected by aGM1 pretreatment of MDCK cells. These results demonstrate that epithelial cell injury and bacterial internalization can proceed from the same adhesin-receptor interaction, and they indicate that
P. aeruginosa
exoproducts solely determine the steps subsequent to adhesion.