bluuebunny/crossref_metadata_2025_split huggingface dataset:
Type-Specific Contributions to Chromosome Size Differences in
Escherichia coli
Authors: Rode Christopher K. , Melkerson-Watson Lyla J. , Johnson Amanda T. , Bloch Craig A. 
Published: December 2019

ABSTRACT

The
Escherichia coli
genome varies in size from 4.5 to 5.5 Mb. It is unclear whether this variation may be distributed finely throughout the genome or is concentrated at just a few chromosomal loci or on plasmids. Further, the functional correlates of size variation in different genome copies are largely unexplored. We carried out comparative macrorestriction mapping using rare-restriction-site alleles (made with the Tn
10
dRCP2 family of elements, containing the
Not
I,
Bln
I, I-
Ceu
I, and ultra-rare-cutting I-
Sce
I sites) among the chromosomes of laboratory
E. coli
K-12, newborn-sepsis-associated
E. coli
RS218, and uropathogenic
E. coli
J96. These comparisons showed just a few large accessory chromosomal segments accounting for nearly all strain-to-strain size differences. Of 10 sepsis-associated and urovirulence genes, previously isolated from the two pathogens by scoring for function, all were colocalized exclusively with one or more of the accessory chromosomal segments. The accessory chromosomal segments detected in the pathogenic strains from physical, macrorestriction comparisons may be a source of new virulence genes, not yet isolated by function.
Influence of Outer Surface Protein A Antibody onBorrelia burgdorferiwithin Feeding Ticks
Authors: de Silva Aravinda M. , Zeidner Nordin S. , Zhang Yan , Dolan Marc C. , Piesman Joseph , Fikrig Erol 
Published: December 2019

ABSTRACTBorrelia burgdorferi, the spirochetal agent of Lyme disease, is transmitted byIxodesticks. When an infected nymphal tick feeds on a host, the bacteria increase in number within the tick, after which they invade the tick’s salivary glands and infect the host. Antibodies directed against outer surface protein A (OspA) ofB. burgdorferikill spirochetes within feeding ticks and block transmission to the host. In the studies presented here, passive antibody transfer experiments were carried out to determine the OspA antibody titer required to block transmission to the rodent host. OspA antibody levels were determined by using a competitive enzyme-linked immunosorbent assay that measured antibody binding to a protective epitope defined by monoclonal antibody C3.78. The C3.78 OspA antibody titer (>213 μg/ml) required to eradicate spirochetes from feeding ticks was considerably higher than the titer (>6 μg/ml) required to block transmission to the host. Although spirochetes were not eradicated from ticks at lower antibody levels, the antibodies reduced the number of spirochetes within the feeding ticks and interfered with the ability of spirochetes to induceospCand invade the salivary glands of the vector. OspA antibodies may directly interfere with the ability ofB. burgdorferito invade the salivary glands of the vector; alternately, OspA antibodies may lower the density of spirochetes within feeding ticks below a critical threshold required for initiating events linked to transmission.
Five Homologous Repeats of the Protein G-Related Protein MIG Cooperate in Binding to Goat Immunoglobulin G
Authors: Vasi József , Svensson Jan , Frick Inga-Maria , Müller Hans-Peter 
Published: December 2019

ABSTRACTProtein MIG, fromStreptococcus dysgalactiae, binds α2-macroglobulin and immunoglobulin G (IgG). MIG-derived fusion proteins with one to five IgG-binding repeats differed up to 72,000-fold in avidity for goat IgG, indicating a considerable cooperativity of the repeats. Significant sequence variation in the IgG-binding repeats was recognized. Protein MIG interacted with goat IgG1 via both the Fc and Fab parts.
Pseudomonas aeruginosa
Quorum-Sensing Signal Molecule
N
-(3-Oxododecanoyl)-
l
-Homoserine Lactone Inhibits Expression of P2Y Receptors in Cystic Fibrosis Tracheal Gland Cells
Authors: Saleh A. , Figarella C. , Kammouni W. , Marchand-Pinatel S. , Lazdunski A. , Tubul A. , Brun P. , Merten M. D. 
Published: December 2019

ABSTRACT

ATP and UTP have been proposed for use as therapeutic treatment of the abnormal ion transport in the airway epithelium in cystic fibrosis (CF), the most characteristic feature of which is permanent infection by
Pseudomonas aeruginosa
. As for diverse gram-negative bacteria, this pathogenic bacterium accumulates diffusible
N
-acylhomoserine lactone (AHL) signal molecules, and when a threshold concentration is reached, virulence factor genes are activated. Human submucosal tracheal gland serous (HTGS) cells are believed to play a major role in the physiopathology of CF. Since ATP and UTP stimulate CF epithelial cells through P2Y receptors, we sought to determine whether CF HTGS cells are capable of responding to the AHLs
N
-butanoyl-
l
-homoserine lactone (BHL),
N
-hexanoyl-
l
-homoserine lactone (HHL),
N
-(3-oxododecanoyl)-
l
-homoserine lactone (OdDHL), and
N
-(3-oxohexanoyl)-
l
-homoserine lactone (OHHL), with special reference to P2Y receptors. All AHLs inhibited ATP- and UTP-induced secretion by CF HTGS cells. The 50% inhibitory concentrations were as high as 10 and 5 μM for BHL and HHL, respectively, but were only 0.3 and 0.4 pM for OdDHL and OHHL, respectively. Furthermore, all AHLs down-regulated the expression of the P2Y2 and P2Y4 receptors. Ibuprofen and nordihydroguaiaretic acid were able to prevent AHL inhibition of the responses to nucleotides, but neither dexamethasone nor indomethacin was able to do this. These data indicate that AHLs may alter responsiveness to ATP and UTP by CF HTGS cells and suggest that, in addition to ATP and/or UTP analogues, ibuprofen may be of use for a combinational pharmacological therapy for CF.
Kinetics and Mechanisms of Extracellular Protein Release by
Helicobacter pylori
Authors: Schraw Wayne , McClain Mark S. , Cover Timothy L. 
Published: December 2019

ABSTRACT

To investigate the kinetics and mechanisms of extracellular protein release by
Helicobacter pylori
, we analyzed the entry of metabolically radiolabeled bacterial proteins into broth culture supernatant. At early time points, vacuolating cytotoxin (VacA) constituted a major extracellular protein. Subsequently, culture supernatants accumulated many proteins that were components of intact bacterial cells. This nonselective release of proteins was associated with a decreasing turbidity of cultures and loss of bacterial viability, indicative of an autolytic process. The rates of VacA secretion and autolysis were each influenced by medium composition, and therefore these may be regulated phenomena. Extracellular release of proteins by
H. pylori
may be an important adaptation that facilitates the persistence of
H. pylori
in the human gastric mucus layer. Moreover, entry of proinflammatory proteins into the gastric mucosa may contribute to the induction of a mucosal inflammatory response.
Role ofLeishmania donovaniand Its Lipophosphoglycan in CD4+T-cell Activation-Induced Human Immunodeficiency Virus Replication
Authors: Wolday Dawit , Akuffo Hannah , Demissie Abebech , Britton Sven 
Published: December 2019

ABSTRACTChronic immune activation by coinfecting pathogens has been suggested as a cofactor in human immunodeficiency virus (HIV) disease progression, particularly in the setting of developing countries. Here, we used in vivo-infected mononuclear cells to examine the role of the protozoan parasiteLeishmania donovaniand its major membrane constituent, lipophosphoglycan (LPG), in mediating CD4+T-lymphocyte activation-induced HIV replication and CD4+T-cell death. We found thatLeishmaniaantigens upregulated HIV replication in CD8-depleted peripheral blood mononuclear cells from asymptomatic HIV-infected donors compared to unstimulated cells.L. donovani-induced viral replication was associated with cellular proliferation, increased expression of the cellular immune activation markers CD25 and HLA-DR within the CD4+subpopulation, and enhanced secretion of tumor necrosis factor alpha (TNF-α), interleukin 2 (IL-2), and IL-6. LPG induced TNF-α secretion in the absence of increased expression of cellular activation markers. Moreover, in a few cases we observed thatL. donovaniinduced HIV replication without significant cellular activation but with cytokine secretion. The rate of apoptosis was accelerated in these latently infected CD4+T cells primed withLeishmaniaantigens compared to controls, and TNF-α production appeared to be the central event necessary for this effect. Furthermore, we demonstrate that thalidomide inhibitedLeishmania-induced virus replication coupled with abrogatedLeishmania-induced TNF-α secretion but not IL-2 or IL-6 production. Furthermore, thalidomide did not affectLeishmania-induced apoptosis. The results suggest thatLeishmaniaand its product, LPG, up-regulate HIV replication in latently infected cells through distinct antigen-specific and non-antigen-specific cellular immune activation mechanisms and that TNF-α secretion is pivotal in this process. The immunomodulatory role of thalidomide raises interest as a potential adjuvant to reduce HIV disease progression inLeishmania-HIV coinfected individuals.
Trapping and Immobilization ofNippostrongylus brasiliensisLarvae at the Site of Inoculation in Primary Infections of Interleukin-5 Transgenic Mice
Authors: Daly Christine M. , Mayrhofer Graham , Dent Lindsay A. 
Published: December 2019

ABSTRACTInterleukin-5 (IL-5) transgenic mice are highly resistant to primary infections with the intestinal nematodeNippostrongylus brasiliensis; few parasites are found in the intestines of infected animals, and egg production is minimal. While adult worms may be damaged in the intestine, larval migration, development, and viability may also be impaired in other tissues. This study addresses the migration ofN. brasiliensislarvae through the skin and lungs and associated cellular responses in primary infections of IL-5 transgenic mice. Although some larvae may have been trapped and killed in the lungs of IL-5 transgenic mice, most apparently failed to reach this site. Two or more hours after infection of IL-5 transgenic mice, eosinophils were a major component of the cellular infiltrate at the subcutaneous site of injection, and localized eosinophil degranulation was extensive. Seventy-five to ninety-five percent of the larvae injected into subcutaneous air pouches in IL-5 transgenic mice were retained there for at least 24 h. In contrast, in nontransgenic mice, less than 20% of larvae could be recovered from the skin 2 or more h postinjection, and eosinophil activity was modest at all times. The data strongly suggest that eosinophils can restrict the movement ofN. brasiliensislarvae in the first few hours of a primary infection and that this has profound effects on later stages of parasite development. Preexisting eosinophilia, due either to allergy or to infection with tissue-invasive helminth species, may therefore confer some degree of immediate and nonspecific resistance in primary infections with parasitic worms.
Fasciola hepaticaSuppresses a Protective Th1 Response againstBordetella pertussis
Authors: Brady Miriam T. , O’Neill Sandra M. , Dalton John P. , Mills Kingston H. G. 
Published: December 2019

ABSTRACTFasciolosis, like other helminth infections, is associated with the induction of T-cell responses polarized to the Th2 subtype. Respiratory infection withBordetella pertussisor immunization with a pertussis whole-cell vaccine (Pw) induces a potent Th1 response, which confers a high level of protection against bacterial challenge. We have used these two pathogens to examine bystander cross-regulation of Th1 and Th2 cells in vivo and provide evidence of immunomodulation of host T-cell responses toB. pertussisby a concomitant infection withFasciola hepatica. Mice with a coinfection ofF. hepaticaandB. pertussisexhibited a Th2 cytokine profile in response toF. hepaticaantigens, similar to those infected withF. hepaticaalone. By contrast, the Th1 response toB. pertussisantigens was markedly suppressed and the bacterial infection was exacerbated following infection withF. hepatica. Furthermore, an established Th1 response induced in mice by infection withB. pertussisor by parenteral immunization with Pw was also suppressed following infection withF. hepatica. This immunomodulatory effect ofB. pertussis-induced responses byF. hepaticainfection is significantly reduced, but not completely abrogated, in IL-4 knockout mice. Our findings demonstrate that Th2-inducing parasites can exert bystander suppression of protective Th1 responses to infection or vaccination with a bacterial pathogen and that the modulation is mediated in part by IL-4 and, significantly, is effective at both the induction and effector stages of the Th1 response.
Significance of Host Cell Kinesin in the Development of
Chlamydia psittaci
Authors: Escalante-Ochoa Cristina , Ducatelle Richard , Charlier Gerard , De Vos Kurt , Haesebrouck Freddy 
Published: December 2019

ABSTRACT

The influence of the microtubule-associated motor protein kinesin on
Chlamydia psittaci
inclusion development in epithelial and fibroblast cell lines was addressed. Kinesin was blocked early after chlamydial internalization (4 h postinfection [p.i.]) and before the initiation of active chlamydial multiplication (8 h p.i.). Chlamydia development was monitored by fluorescence and transmission electron microscopy at different times during the cycle. In both host cell lines, kinesin blockage restricted mitochondria from the chlamydial vacuole. The effects of kinesin blockage on the
C. psittaci
replication cycle included the presence of multiple inclusions up to late in the cycle, the presence of enlarged pleomorphic reticulate bodies, and a delayed reappearance of elementary bodies. The last effect seems to be greater when kinesin is blocked early after infection. Our results show that kinesin activity is required for optimal development of these microorganisms, most probably acting through the apposition of mitochondria to the
C. psittaci
inclusions.
Escherichia coli
Binding to and Invasion of Brain Microvascular Endothelial Cells Derived from Humans and Rats of Different Ages
Authors: Stins Monique F. , Nemani Prasadarao V. , Wass Carol , Kim Kwang Sik 
Published: December 2019

ABSTRACT

Escherichia coli
meningitis commonly occurs in the neonatal period, but the basis of this age dependency is unclear. We have previously identified two types of
E. coli
-brain microvascular endothelial cell (BMEC) interactions contributing to
E. coli
traversal of the blood-brain barrier (i.e., binding and invasion). The present study examined whether the age dependency of
E. coli
meningitis stemmed from differences in the capacities of neonatal and adult BMECs to interact with
E. coli
. BMECs were isolated from rats of different ages (10 days, 20 days and 3 months) as well as from humans of different ages (fetuses, 4- to 7-year-old children, and a 35-year-old adult, and 60- to 85-year-old geriatrics). The bindings of
E. coli
to young and old rat BMECs were similar. Also, the abilities of
E. coli
to invade BMECs were similar for BMECs derived from young and old rats and from human fetuses, children, adults, and geriatrics. These findings suggest that the predominance of
E. coli
meningitis in neonates is not likely due to greater binding and invasion capacities of newborn compared to adult BMECs.
Carrier Properties of a Protein Derived from Outer Membrane Protein A ofKlebsiella pneumoniae
Authors: Rauly Isabelle , Goetsch Liliane , Haeuw Jean-François , Tardieux Christine , Baussant Thierry , Bonnefoy Jean-Yves , Corvaia Nathalie 
Published: December 2019

ABSTRACTWe have recently cloned a new protein, recombinant P40 (rP40). When tested in vivo after conjugation to a B-cell epitope, rP40 induces an important antibody response without the need for adjuvant. To characterize its potency, this carrier protein was coupled to a peptide derived from respiratory syncytial virus attachment G protein (G1′). After immunization of mice with the rP40-G1′ conjugate, strong antipeptide antibodies were detected, whereas peptide alone was not immunogenic. To emphasize the carrier properties of rP40, a polysaccharide derived fromHaemophilus influenzaetype b (Hib) was coupled to it. Immunoglobulin G responses against the Hib polysaccharide were observed after coupling to rP40. Interestingly, an antipeptide antibody response was observed despite preexisting anti-rP40 antibodies generated by preimmunization with rP40. In addition, rP40 compares well with the reference carrier protein, tetanus toxoid (TT), since antibody responses of equal intensity were observed when a peptide or a polysaccharide was coupled to TT and rP40. Moreover, rP40 had advantages compared to TT; e.g., it induced a mixed Th1/Th2 response, whereas TT induced only a Th2 profile. Together, the results indicate that rP40 is a novel carrier protein with potential for use as an alternative carrier for human vaccination.
Identification by Subtractive Hybridization of a Novel Insertion Sequence Specific for Virulent Strains of
Porphyromonas gingivalis
Authors: Sawada Koichi , Kokeguchi Susumu , Hongyo Hiroshi , Sawada Satoko , Miyamoto Manabu , Maeda Hiroshi , Nishimura Fusanori , Takashiba Shogo , Murayama Yoji 
Published: December 2019

ABSTRACT

Subtractive hybridization was employed to isolate specific genes from virulent
Porphyromonas gingivalis
strains that are possibly related to abscess formation. The genomic DNA from the virulent strain
P. gingivalis
W83 was subtracted with DNA from the avirulent strain ATCC 33277. Three clones unique to strain W83 were isolated and sequenced. The cloned DNA fragments were 885, 369, and 132 bp and had slight homology with only
Bacillus stearothermophilus
IS
5377
, which is a putative transposase. The regions flanking the cloned DNA fragments were isolated and sequenced, and the gene structure around the clones was revealed. These three clones were located side-by-side in a gene reported as an outer membrane protein. The three clones interrupt the open reading frame of the outer membrane protein gene. This inserted DNA, consisting of three isolated clones, was designated IS
1598
, which was 1,396 bp (i.e., a 1,158-bp open reading frame) in length and was flanked by 16-bp terminal inverted repeats and a 9-bp duplicated target sequence. IS
1598
was detected in
P. gingivalis
W83, W50, and FDC 381 by Southern hybridization. All three
P. gingivalis
strains have been shown to possess abscess-forming ability in animal models. However, IS
1598
was not detected in avirulent strains of
P. gingivalis
, including ATCC 33277. The IS
1598
may interrupt the synthesis of the outer membrane protein, resulting in changes in the structure of the bacterial outer membrane. The IS
1598
isolated in this study is a novel insertion element which might be a specific marker for virulent
P. gingivalis
strains.
Analysis of Virulence of Clinical Isolates ofSalmonella enteritidisIn Vivo and In Vitro
Authors: Lu Sangwei , Manges Amee R. , Xu Yisheng , Fang Ferric C. , Riley Lee W. 
Published: December 2019

ABSTRACTSalmonella entericaserotype Enteritidis (S. enteritidis) is a major food-borne pathogen, and its incidence among allSalmonellaserotypes has increased dramatically in the last two decades. To study the virulence characteristics of clinical isolates ofS. enteritidis, we determined the 50% lethal doses (LD50) in mice of isolates of two major phage types (4 and 8). Isolates of both phage types showed a wide range of LD50after oral inoculation, varying from under 102organisms to over 108organisms. No significant difference in LD50was observed between the phage types. These observations indicated that clinical isolates ofS. enteritidisare highly heterogeneous in their ability to cause death in mice. We compared the LD50s of these isolates to the results observed from in vitro pathogenicity assays. We also analyzed these isolates for recognizedSalmonellavirulence loci (spv,sodCI,sopE, andsef). The in vitro phenotypes of the isolates showed no obvious correlation with their LD50in any given assay, and the virulence genes tested were present in all isolates. However, the isolate with the lowest LD50(isolate 97A 2472) was resistant to acidified sodium nitrite (ASN). Moreover, the most acid-susceptible, macrophage-susceptible, and ASN-susceptible isolates were attenuated for virulence in mice. These results, based on extensive analysis of clinical isolates ofS. enteritidis, demonstrate the complex nature ofSalmonellapathogenesis in mice. Our results also indicate the limitation of in vitro assays in predicting in vivo virulence.
Differences in Surface Expression of NspA amongNeisseria meningitidisGroup B Strains
Authors: Moe Gregory R. , Tan Siqi , Granoff Dan M. 
Published: December 2019

ABSTRACTNspA is a highly conserved membrane protein that is reported to elicit protective antibody responses againstNeisseria meningitidisserogroups A, B and C in mice (D. Martin, N. Cadieux, J. Hanel, and B. R. Brodeur, J. Exp. Med. 185:1173–1183, 1997). To investigate the vaccine potential of NspA, we produced mouse anti-recombinant NspA (rNspA) antisera, which were used to evaluate the accessibility of NspA epitopes on the surface of different serogroup B strains by an immunofluorescence flow cytometric assay and by susceptibility to antibody-dependent, complement-mediated bacteriolysis. Among 17 genetically diverse strains tested, 11 (65%) were positive for NspA cell surface epitopes and 6 (35%) were negative. All six negative strains also were resistant to bactericidal activity induced by the anti-rNspA antiserum. In contrast, of the 11 NspA surface-positive strains, 8 (73%;P< 0.05) were killed by the antiserum and complement. In infant rats challenged with one of these eight strains, the anti-rNspA antiserum conferred protection against bacteremia, whereas the antiserum failed to protect rats challenged by one of the six NspA cell surface-negative strains. Neither NspA expression nor protein sequence accounted for differences in NspA surface accessibility, since all six negative strains expressed NspA in outer membrane preparations and since their predicted NspA amino acid sequences were 99 to 100% identical to those of three representative positive strains. However, the six NspA cell surface-negative strains produced, on average, larger amounts of group B polysaccharide than did the 11 positive strains (reciprocal geometric mean titers, 676 and 224, respectively;P< 0.05), which suggests that the capsule may limit the accessibility of NspA surface epitopes. Given these strain differences in NspA surface accessibility, an rNspA-based meningococcal B vaccine may have to be supplemented by additional antigens.