bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human Intestinal Epithelial Cells Respond toCryptosporidium parvumInfection with Increased Prostaglandin H Synthase 2 Expression and Prostaglandin E2and F2αProduction
Authors: Laurent Fabrice , Kagnoff Martin F. , Savidge Tor C. , Naciri Muriel , Eckmann Lars 
Published: December 2019

ABSTRACTCryptosporidium parvumis an important cause of diarrhea in humans and several animal species. Prostaglandins play a central role in regulating intestinal fluid secretion in animal models of cryptosporidiosis, but their cellular sources and mechanisms of induction are unclear. Here, we show thatC. parvuminfection directly activates prostaglandin H synthase 2 expression and prostaglandin E2and F2αproduction in human intestinal epithelial cells.
Granulocytic Ehrlichiosis in Tick-Immune Guinea Pigs
Authors: Das Subrata , Deponte Kathleen , Marcantonio Nancy L. , Ijdo Jacob W. , Hodzic Emir , Katavolos Paula , Barthold Stephen W. , Telford Sam R. , Kantor Fred S. , Fikrig Erol 
Published: December 2019

ABSTRACT

We investigated whether
Ixodes scapularis
-mediated host immunity interrupts transmission of the agent of human granulocytic ehrlichiosis (aoHGE) to guinea pigs. Ticks infected with aoHGE readily transmitted aoHGE to tick-immune guinea pigs, despite incomplete tick engorgement and host attachment. Although tick immunity can prevent Lyme borreliosis, protection is not afforded against granulocytic ehrlichiosis.
Molecular Characterization of the
Aeromonas hydrophila aroA
Gene and Potential Use of an Auxotrophic
aroA
Mutant as a Live Attenuated Vaccine
Authors: Hernanz Moral Carmen , del Castillo Emilio Flaño , Fierro Pilar López , Cortés Alberto Villena , Castillo Juan Anguita , Soriano Alberto Cascón , Salazar María Sánchez , Peralta Blanca Razquín , Carrasco Germán Naharro 
Published: December 2019

ABSTRACT

The
aroA
gene of
Aeromonas hydrophila
SO2/2, encoding 5-enolpyruvylshikimate 3-phosphate synthase, was cloned by complementation of the
aroA
mutation in
Escherichia coli
K-12 strain AB2829, and the nucleotide sequence was determined. The nucleotide sequence of the
A. hydrophila aroA
gene encoded a protein of 440 amino acids which showed a high degree of homology to other bacterial AroA proteins. To obtain an effective attenuated live vaccine against
A. hydrophila
infections in fish, the
aroA
gene was inactivated by the insertion of a DNA fragment containing a kanamycin resistance determinant and reintroduced by allelic exchange into the chromosome of
A. hydrophila
AG2 by means of the suicide vector pSUP202. The
A. hydrophila
mutant AG2
aroA
::Ka
r
was highly attenuated when inoculated intraperitoneally into a rainbow trout, with a 50% lethal dose of >2 × 10
8
CFU. The mutants were not recoverable from the internal organs after 48 h postinoculation. Immunohistochemical studies demonstrated that immunopositive materials, but not whole cells, reacting with a polyclonal antiserum against
A. hydrophila
were present in the kidney and spleen 9 days postinjection. Vaccination of rainbow trout with the AroA mutant as a live vaccine conferred significant protection against the wild-type strain of
A. hydrophila.
cagA
-Positive
Helicobacter pylori
Populations in China and The Netherlands Are Distinct
Authors: van der Ende Arie , Pan Zhi-Jun , Bart Aldert , van der Hulst René W. M. , Feller Monique , Xiao Shu-Dong , Tytgat Guido N. J. , Dankert Jacob 
Published: December 2019

ABSTRACT

The aim of this research was to study whether and to what extent Chinese
cagA
-positive
Helicobacter pylori
isolates differ from those in The Netherlands. Analysis of random amplified polymorphic DNA (RAPD)-PCR-assessed DNA fingerprints of chromosomal DNA of 24
cagA
-positive
H. pylori
isolates from Dutch (
n
= 12) and Chinese (
n
= 10) patients yielded the absence of clustering. Based on comparison of the sequence of a 243-nucleotide part of
cagA
, the Dutch (group I) and Chinese (group II)
H. pylori
isolates formed two separate branches with high confidence limits in the phylogenetic tree. These two clusters were not observed when the sequence of a 240-bp part of
glmM
was used in the comparison. The number of nonsynonymous substitutions was much higher in
cagA
than in
glmM
, indicating positive selection. The average levels of divergence of
cagA
at the nucleotide and protein levels between group I and II isolates were found to be high, 13.3 and 17.9%, respectively. Possibly, the pathogenicity island (PAI) that has been integrated into the chromosome of the ancestor of
H. pylori
now circulating in China contained a different
cagA
than the PAI that has been integrated into the chromosome of the ancestor of
H. pylori
now circulating in The Netherlands. We conclude that in China and The Netherlands, two distinct
cagA
-positive
H. pylori
populations are circulating.
Cytopathic Effects of the Major Surface Protein and the Chymotrypsinlike Protease ofTreponema denticola
Authors: Fenno J. Christopher , Hannam Pauline M. , Leung W. Keung , Tamura Muneaki , Uitto Veli-Jukka , McBride Barry C. 
Published: December 2019

ABSTRACTProminent antigens ofTreponema denticolahave been suggested to be mediators of the cytopathic effects typically seen in periodontal disease. In the present study of theT. denticolamajor surface protein (Msp) and the surface-expressed chymotrypsinlike protease complex (CTLP), we characterized the ability of these proteins to adhere to and lyse epithelial cells. Msp and CTLP were closely associated in spirochete outer membranes. Purified Msp, both native and recombinant, and CTLP bound to glutaraldehyde-fixed periodontal ligament epithelial cells. Adherence of Msp was partially blocked by specific antibodies. Adherence of CTLP was partially blocked by serine protease inhibitors and was further inhibited by specific antibodies. Both native Msp and CTLP were cytotoxic toward periodontal ligament epithelial cells, and their cytotoxicity was inhibited by the same treatments that inhibited adherence. Msp, but not CTLP, lysed erythrocytes. Msp complex (partially purified outer membranes free of protease activity) was cytotoxic toward a variety of different cell types. Pore-forming activities of recombinant Msp in black lipid model membrane assays and in HeLa cell membranes were similar to those reported for the native protein, supporting the hypothesis that Msp cytotoxicity was due to its pore-forming activity.
Role of YopP in Suppression of Tumor Necrosis Factor Alpha Release by Macrophages duringYersiniaInfection
Authors: Boland Anne , Cornelis Guy R. 
Published: December 2019

ABSTRACTTheYersiniaplasmid-encoded Yop virulon enables extracellular adhering bacteria to deliver toxic effector proteins inside their target cells. It includes a type III secretion system (Ysc), at least two translocator proteins (YopB, YopD), and a set of intracellular Yop effectors (YopE, YopH, YopO, YopM, and YopP). Infection of macrophages with a wild-type strain leads to low levels of tumor necrosis factor alpha (TNF-α) release compared to infection with plasmid-cured strains, suggesting that the virulence plasmid encodes a factor impairing the normal TNF-α response of infected macrophages. This effect is correlated with the inhibition of the macrophage mitogen-activated protein kinase (MAPK) activities. To identify the Yop protein responsible for the suppression of TNF-α release, we infected J774A.1 and PU5-1.8 macrophages with a battery of knockoutYersinia enterocoliticamutants and we quantified the TNF-α released. Mutants affected in secretion (yscN), in translocation (yopBandyopD), or in synthesis of all the known Yop effectors (yopH,yopO,yopP,yopE, andyopMpolymutants) were unable to block the TNF-α response of the macrophages. In contrast, singleyopE,yopH,yopO, andyopMmutants behaved like the wild-type strain. AyopPmutant elicited elevated TNF-α release, and complementation of theyopPmutant or theyopeffector polymutant strain withyopPalone led to a drop in TNF-α release. In addition, YopP was also responsible for the inhibition of the extracellular signal-regulated kinase2 (ERK2) and p38 MAPK activities. These results show that YopP is the Yop effector responsible for theYersinia-induced suppression of TNF-α release by infected macrophages.
Validation of a Volunteer Model of Cholera with Frozen Bacteria as the Challenge
Authors: Sack David A. , Tacket Carol O. , Cohen Mitchell B. , Sack R. Bradley , Losonsky Genevieve A. , Shimko Janet , Nataro James P. , Edelman Robert , Levine Myron M. , Giannella Ralph A. , Schiff Gilbert , Lang Dennis 
Published: December 2019

ABSTRACT

To evaluate a standardized inoculum of
Vibrio cholerae
for volunteer challenge studies, 40 healthy adult volunteers were challenged at three different institutions with a standard inoculum prepared directly from vials of frozen, virulent, El Tor Inaba
V. cholerae
N16961, with no further incubation. Groups of 5 volunteers, with each group including 2 volunteers with blood group O, were given a dose of 10
5
CFU, and 34 of the 40 volunteers developed diarrhea (mean incubation time, 28 h). Transient fevers occurred in 15 (37.5%) of the volunteers.
V. cholerae
was excreted by 36 of 40 volunteers. Five additional volunteers received 10
4
CFU, and four developed diarrhea but with a lower average purging rate than required for the model. Of the 40 volunteers, 37 developed rises in their vibriocidal and antitoxin titers similar to those in previous groups challenged with freshly harvested bacteria. We conclude that challenge with frozen bacteria results in a reproducible illness similar to that induced by freshly harvested bacteria. Use of this model should minimize differences in attack rates or severity when groups are challenged at different times and in different institutions.
Adherence of Human Vaginal Lactobacilli to Vaginal Epithelial Cells and Interaction with Uropathogens
Authors: Boris Soledad , Suárez Juan E. , Vázquez Fernando , Barbés Covadonga 
Published: December 2019

ABSTRACT

Three strains of
Lactobacillus
, identified as
Lactobacillus acidophilus
,
Lactobacillus gasseri
, and
Lactobacillus jensenii
, were selected from among 70 isolates from the vaginas of healthy premenopausal women for properties relevant to mucosal colonization or antagonism. All three self-aggregated and adhered to epithelial vaginal cells, displacing well-known vaginal pathogens, such as
G. vaginalis
, and inhibiting the growth in vitro of
Escherichia coli
and
Streptococcus agalactiae
. The surface components involved in self-aggregation appeared to be proteins for
L. gasseri
and lipoproteins for
L. acidophilus
and
L. jensenii
, as judged by susceptibility to treatment with appropriate degrading enzymes. The factors responsible for adherence to epithelial vaginal cells seemed to be glycoproteins (
L. acidophilus
and
L. gasseri
) and carbohydrate (
L. jensenii
). The receptors of the vaginal cells were glycolipids, which presumably were the targets of the competition observed between the lactobacilli and the pathogenic microbes.
Defined Deletion Mutants Demonstrate that the Major Secreted Toxins Are Not Essential for the Virulence of
Aeromonas salmonicida
Authors: Vipond Richard , Bricknell Ian R. , Durant Emma , Bowden Timothy J. , Ellis Anthony E. , Smith Mary , MacIntyre Sheila 
Published: December 2019

ABSTRACT

The importance of the two major extracellular enzymes of
Aeromonas salmonicida
, glycerophospholipid:cholesterol acyltransferase (GCAT) and a serine protease (AspA), to the pathology and mortality of salmonid fish with furunculosis had been indicated in toxicity studies. In this study, the genes encoding GCAT (
satA
) and AspA (
aspA
) have been cloned and mutagenized by marker replacement of internal deletions, and the constructs have been used for the creation of isogenic
satA
and
aspA
mutants of
A. salmonicida
. A pSUP202 derivative (pSUP202sac) carrying the
sacRB
genes was constructed to facilitate the selection of mutants. The requirement of serine protease for processing of pro-GCAT was demonstrated. Processing involved the removal of a short internal fragment. Surprisingly, pathogenicity trials revealed no major decrease in virulence of the
A. salmonicida ΔsatA
::
kan
or
A. salmonicida ΔaspA
::
kan
mutants compared to the wild-type parent strains when Atlantic salmon (
Salmo salar
L.) were challenged by intraperitoneal injection. Moreover, using a cohabitation model, which more closely mimics the natural disease, there was also no significant decrease in the relative cumulative mortality following infection with either of the deletion mutants compared to the parent strain. Thus, although these two toxins may confer some competitive advantage to
A. salmonicida
, neither toxin is essential for the very high virulence of
A. salmonicida
in Atlantic salmon. This first report of defined deletion mutations within any proposed extracellular virulence factor of
A. salmonicida
raises crucial questions about the pathogenesis of this important fish pathogen.
Binding of
Porphyromonas gingivalis
Fimbriae to Proline-Rich Glycoproteins in Parotid Saliva via a Domain Shared by Major Salivary Components
Authors: Amano Atsuo , Shizukuishi Satoshi , Horie Hiroshi , Kimura Shigenobu , Morisaki Ichijiro , Hamada Shigeyuki 
Published: December 2019

ABSTRACT

Porphyromonas gingivalis
, a putative periodontopathogen, can bind to human saliva through its fimbriae. We previously found that salivary components from the submandibular and sublingual glands bind to
P. gingivalis
fimbriae and that acidic proline-rich protein (PRP) and statherin function as receptor molecules for fimbriae. In this study, we investigated the fimbria-binding components in parotid saliva. Fractionated human parotid saliva by gel-filtration chromatography was immobilized onto nitrocellulose membranes for the overlay assay following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The salivary components on the membrane were allowed to interact with fimbriae purified from
P. gingivalis
ATCC 33277, and the interacted fimbriae were probed with anti-fimbria antibodies. The fimbriae were shown to bind to two forms of proline-rich glycoproteins (PRGs) as well as to acidic PRPs and statherin. Moreover, fimbriae bound to several components of smaller molecular size which appeared to be acidic PRP variants and basic PRPs. Fimbriae bound strongly to the purified PRGs adsorbed onto hydroxyapatite (HAP) beads. In contrast, PRGs in solution failed to inhibit the fimbrial binding to the immobilized PRGs on the HAP beads. These findings suggest that the appearance of binding site(s) of PRGs can be ascribed to their conformational changes. We previously identified the distinct segments within PRP and statherin molecules that are involved in fimbrial binding. The peptides analogous to the binding regions of PRP and statherin (i.e., PRP-C and STN-C) markedly inhibit the binding of fimbriae to PRP and statherin immobilized on the HAP beads, respectively. The PRP-C significantly inhibited the binding of fimbriae to PRG-coated HAP beads as well as to PRP on HAP beads. The peptide did not affect the binding of fimbriae to statherin, whereas the STN-C showed no effect on the fimbrial binding to PRPs or PRGs. In the overlay assay, the PRP-C clearly diminished the interactions between the fimbriae and the various salivary components, including PRPs, the PRGs, and the components with smaller molecular sizes but not statherin. These results strongly suggest that fimbriae bind to salivary components (except statherin) via common peptide segments. It is also suggested that fimbriae bind to saliva through the two distinct binding domains of receptory salivary components: (i) PRGs and PRPs and (ii) statherin.
A 70-Kilodalton Recombinant Heat Shock Protein ofCandida albicansIs Highly Immunogenic and Enhances Systemic Murine Candidiasis
Authors: Bromuro Carla , La Valle Roberto , Sandini Silvia , Urbani Francesca , Ausiello Clara M. , Morelli Luisella , Féd’ostiani Cristiana , Romani Luigina , Cassone Antonio 
Published: December 2019

ABSTRACTThe 70-kDa recombinantCandida albicansheat shock protein (CaHsp70) and its 21-kDa C-terminal and 28-kDa N-terminal fragments (CaHsp70-Cter and CaHsp70-Nter, respectively) were studied for their immunogenicity, including proinflammatory cytokine induction in vitro and in vivo, and protection in a murine model of hematogenous candidiasis. The whole protein and its two fragments were strong inducers of both antibody (Ab; immunoglobulin G1 [IgG1] and IgG2b were the prevalent isotypes) and cell-mediated immunity (CMI) responses in mice. CaHsp70 preparations were also recognized as CMI targets by peripheral blood mononuclear cells of healthy human subjects. Inoculation of CaHsp70 preparations into immunized mice induced rapid production of interleukin-6 (IL-6) and tumor necrosis factor alpha, peaking at 2 to 5 h and declining within 24 h. CaHsp70 and CaHsp70-Cter also induced gamma interferon (IFN-γ), IL-12, and IL-10 but not IL-4 production by CD4+lymphocytes cocultured with splenic accessory cells from nonimmunized mice. In particular, the production of IFN-γ was equal if not superior to that induced in the same cells by whole, heat-inactivated fungal cells or the mitogenic lectin concanavalin A. In immunized mice, however, IL-4 but not IL-12 was produced in addition to IFN-γ upon in vitro stimulation of CD4+cells with CaHsp70 and CaHsp70-Cter. These animals showed a decreased median survival time compared to nonimmunized mice, and their mortality was strictly associated with organ invasion by fungal hyphae. Their enhanced susceptibility was attributable to the immunization state, as it did not occur in congenitally athymic nude mice, which were unable to raise either Ab or CMI responses to CaHsp70 preparations. Together, our data demonstrate the elevated immunogenicity of CaHsp70, with which, however, no protection against but rather some enhancement ofCandidainfection seemed to occur in the mouse model used.
Use of a
Mycobacterium tuberculosis
H37Rv Bacterial Artificial Chromosome Library for Genome Mapping, Sequencing, and Comparative Genomics
Authors: Brosch Roland , Gordon Stephen V. , Billault Alain , Garnier Thierry , Eiglmeier Karin , Soravito Catherine , Barrell Bart G. , Cole Stewart T. 
Published: December 2019

ABSTRACT

The bacterial artificial chromosome (BAC) cloning system is capable of stably propagating large, complex DNA inserts in
Escherichia coli
. As part of the
Mycobacterium tuberculosis
H37Rv genome sequencing project, a BAC library was constructed in the pBeloBAC11 vector and used for genome mapping, confirmation of sequence assembly, and sequencing. The library contains about 5,000 BAC clones, with inserts ranging in size from 25 to 104 kb, representing theoretically a 70-fold coverage of the
M. tuberculosis
genome (4.4 Mb). A total of 840 sequences from the T7 and SP6 termini of 420 BACs were determined and compared to those of a partial genomic database. These sequences showed excellent correlation between the estimated sizes and positions of the BAC clones and the sizes and positions of previously sequenced cosmids and the resulting contigs. Many BAC clones represent linking clones between sequenced cosmids, allowing full coverage of the H37Rv chromosome, and they are now being shotgun sequenced in the framework of the H37Rv sequencing project. Also, no chimeric, deleted, or rearranged BAC clones were detected, which was of major importance for the correct mapping and assembly of the H37Rv sequence. The minimal overlapping set contains 68 unique BAC clones and spans the whole H37Rv chromosome with the exception of a single gap of ∼150 kb. As a postgenomic application, the canonical BAC set was used in a comparative study to reveal chromosomal polymorphisms between
M. tuberculosis
,
M. bovis
, and
M. bovis
BCG Pasteur, and a novel 12.7-kb segment present in
M. tuberculosis
but absent from
M. bovis
and
M. bovis
BCG was characterized. This region contains a set of genes whose products show low similarity to proteins involved in polysaccharide biosynthesis. The H37Rv BAC library therefore provides us with a powerful tool both for the generation and confirmation of sequence data as well as for comparative genomics and other postgenomic applications. It represents a major resource for present and future
M. tuberculosis
research projects.
Isolation of the Third Capsule-Associated Gene,
CAP60
, Required for Virulence in
Cryptococcus neoformans
Authors: Chang Y. C. , Kwon-Chung K. J. 
Published: December 2019

ABSTRACT

A polysaccharide capsule is one of the most important virulence factors for the pathogenic fungus
Cryptococcus neoformans
. We previously characterized two capsule-associated genes,
CAP59
and
CAP64
. To further dissect the molecular mechanism of capsule synthesis, 16 acapsular mutants induced by 4-nitroquinoline-1-oxide were obtained. The acapsular phenotype of one of these mutants was complemented. The cloned gene was designated
CAP60
, and deletion of this newly described capsule-associated gene resulted in an acapsular phenotype. The proposed 67-kDa Cap60p contains 592 amino acids and appears to have a putative transmembrane domain close to the N terminus. DNA sequence analysis revealed that
CAP60
has similarity to
CAP59
at the center portion of its coding regions. Contour-clamped homogeneous electric field blot analysis suggested that these two genes are on the same chromosome.
CAP60
and
CAP59
, however, could not be functionally substituted for each other by direct complementation or by domain swap experiments. In addition,
CAP60
is closely linked to a gene which is similar to a cellulose growth-specific gene of
Agaricus bisporus
,
CEL1
. Immunogold electron microscopy studies of the epitope-tagged
CAP60
gene revealed that Cap60p was primarily localized to the nuclear membrane. Animal model studies indicated that
CAP60
is essential for virulence. Thus,
CAP60
is required for both capsule formation and virulence.
Potential of a Novel Protein, OMP26, from Nontypeable
Haemophilus influenzae
To Enhance Pulmonary Clearance in a Rat Model
Authors: Kyd Jennelle M. , Cripps Allan W. 
Published: December 2019

ABSTRACT

A major outer membrane protein band of approximately 25 to 27 kDa is commonly observed in strains of
Haemophilus influenzae
. This study has investigated the potential of a 26-kDa protein (OMP26) from nontypeable
H. influenzae
(NTHI) as a vaccine candidate. OMP26 was used to immunize rats via intestinal Peyer’s patches, followed by an intratracheal boost. Immunization was found to significantly enhance bacterial clearance following pulmonary challenge with both the homologous NTHI strain and a different NTHI strain. Significant levels of anti-OMP26 were found in the serum and bronchoalveolar lavage from immunized rats, and isotypes of immunoglobulin G (IgG) were also measured in serum. Analysis of IgG isotypes present in serum following OMP26-immunization suggest that predominantly a T-helper 1-type response was induced. The OMP26 protein was amino-terminally sequenced and found to have no homology with the P5 of
H. influenzae
type b P5 or the fimbrin protein of NTHI, both can migrate upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis at similar molecular masses but OMP26 has 100% homology with a segment of the
H. influenzae
Rd genome. The results of this study suggest that OMP26 may be a suitable vaccine candidate against NTHI infection and warrants continued investigation and characterization.
Differential Effects of Gamma Interferon onChlamydia trachomatisGrowth in Polarized and Nonpolarized Human Epithelial Cells in Culture
Authors: Kane Colleen D. , Byrne Gerald I. 
Published: December 2019

ABSTRACTThe effects of gamma interferon (IFN-γ) onChlamydia trachomatisgrowth in polarized epithelial cells were examined. The range of IFN-γ concentrations causing aberrant chlamydial growth was wider in polarized than in nonpolarized cultures. Results indicate that chlamydial growth modulation in polarized cells readily leads to persistence and better reflects in vivo conditions.