bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat-KilledStreptococcus suisCapsular Type 2 Strains Stimulate Tumor Necrosis Factor Alpha and Interleukin-6 Production by Murine Macrophages
Authors: Segura Mariela , Stankova Jana , Gottschalk Marcelo 
Published: December 2019

ABSTRACTStreptococcus suiscapsular type 2 is an important etiological agent of swine meningitis, and it is also a zoonotic agent. Since mononuclear phagocytes have been suggested to play a central role in the pathogenesis of meningitis, the objective of the present study was to evaluate the capacity of whole killedS. suistype 2 organisms to induce the release of the proinflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) by murine macrophages. Induction of cytokines was evaluated in the presence or absence of phorbol ester (phorbol 12-myristate 13-acetate [PMA]) costimulation. Results showed thatS. suistype 2 stimulated the production of both cytokines in a concentration- and time-dependent fashion. Although large doses of bacteria were required for maximal cytokine release, titers were similar to those obtained with the lipopolysaccharide (LPS) positive control. An increase in cytokine release was observed with bothS. suisand LPS with PMA costimulation. Experiments with cytochalasin-treated macrophages showed that the stimulation of cytokine production was phagocytosis independent. When macrophages were stimulated with an unencapsulated mutant, an increase in TNF production was observed, but the absence of the capsule had no effect on IL-6 production. In fact, whereas purified capsular polysaccharide ofS. suisfailed to induce cytokine release, purifiedS. suiscell wall induced both TNF and, to a lesser extent, IL-6. IL-6 secretion probably requires some distinct stimuli which differ from those of TNF. Finally, theS. suisputative virulence factors suilysin and extracellular protein EF showed no cytokine-stimulating activity. The ability ofS. suisto trigger macrophages to produce proinflammatory cytokines may have an important role in the initiation and development of meningitis caused by this microorganism.
Preliminary Characterization of a
Mycobacterium abscessus
Mutant in Human and Murine Models of Infection
Authors: Byrd Thomas F. , Lyons C. Rick 
Published: December 2019

ABSTRACT

The ability to persist in the host after the establishment of infection is an important virulence determinant for mycobacteria.
Mycobacterium abscessus
is a rapidly growing mycobacterial species which causes a variety of clinical syndromes in humans. We have obtained a rough, wild-type human clinical isolate of
M. abscessus (M. abscessus-R)
and a smooth, attenuated mutant
(M. abscessus-S
) which spontaneously dissociated from the clinical isolate. We have found that
M. abscessus-R
is able to persist and multiply in a murine pulmonary infection model in contrast to
M. abscessus-S
, which is rapidly cleared. To understand the basis for this difference, we characterized the behavior of these variants in human tissue culture models of infection.
M. abscessus-R
is able to persist and multiply in human monocytes, while
M. abscessus-S
is deficient in this ability. Both of these variants are phagocytized by human monocytes.
M. abscessus-R
resides in a phagosome typical for pathogenic mycobacteria with a tightly adherent phagosomal membrane. In contrast,
M. abscessus-S
resides in a “loose” phagosome with the phagosomal membrane separated from the bacterial cell wall. Both
M. abscessus
variants also have distinctive growth patterns in a recently described fibroblast-mycobacterium microcolony assay, with
M. abscessus-R
exhibiting growth characteristics similar to those previously reported for virulent
M. tuberculosis
and
M. abscessus-S
exhibiting growth characteristics similar to those previously reported for avirulent
M. tuberculosis
. In both the monocyte infection assay and the murine pulmonary infection model, numerous infected mononuclear phagocyte aggregates develop at sites of
M. abscessus-R
infection, but are absent with
M. abscessus-S
infection. We conclude that a mutation has occurred in the
M. abscessus-S
variant which has altered the ability of this organism to persist and multiply in host cells and that this may be related to the phenotypic changes we have observed in our tissue culture models of infection.
Isolation of Recombinant Protective
Helicobacter pylori
Antigens
Authors: Hocking D. , Webb E. , Radcliff F. , Rothel L. , Taylor S. , Pinczower G. , Kapouleas C. , Braley H. , Lee A. , Doidge C. 
Published: December 2019

ABSTRACT

A total of seven clones producing both new and previously described
Helicobacter pylori
proteins were isolated from a library of
H. pylori
genomic DNA. The screening approach by which these proteins were detected relied on the use of antisera raised in mice vaccinated with
Helicobacter felis
sonicate plus cholera toxin, a regimen which protects mice from
H. pylori
challenge. This strategy was designed to maximize the possibility of obtaining antigens which might be capable of conferring protection from
H. pylori
infection. Two of the clones were shown to encode the urease enzyme and the heat shock protein HspB, which have already been identified as protective antigens. The other five clones were sequenced, protein coding regions were deduced, and these sequences were amplified by PCR for incorporation into
Escherichia coli
expression vectors. The proteins produced from these expression systems were purified to allow testing for protective efficacy in an
H. pylori
mouse model. All five proteins were able to facilitate the clearance of a challenge with
H. pylori
, as judged by an assay of gastric urease activity and light microscopy on stomach sections. These results clearly indicate that the screening strategy has successfully identified candidate vaccine antigens.
Pulmonary Outcome in Cystic Fibrosis Is Influenced Primarily by Mucoid
Pseudomonas aeruginosa
Infection and Immune Status and Only Modestly by Genotype
Authors: Parad Richard B. , Gerard Craig J. , Zurakowski David , Nichols David P. , Pier Gerald B. 
Published: December 2019

ABSTRACT

Whether allelic variants of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) independently contribute to pulmonary outcome in CF patients has not been resolved. We used both cross-sectional and mixed-model longitudinal analyses of data from CF patients that were at least 12 years old to determine the influence on pulmonary function (percent predicted forced expiratory volume [FEV
1
]) of the CFTR gene genotype, gender, mucoid
Pseudomonas aeruginosa
(MPA) infection status, presence of total opsonic antibody to MPA, and, separately, the opsonic antibody activity specific to the mucoid exopolysaccharide (MEP) surface antigen. Two different factors were independently associated with the lack of MPA infection: a high level of MEP-specific opsonic activity (MSOA), implicating an immunologically based mechanism of resistance to infection, and a lack of any type of opsonic antibody to MPA, indicative of no significant exposure or infection. This latter phenotype was found in a subset of CF patients who carried at least one uncommon CFTR gene allele suggestive of a genetic basis for resistance to infection in this group of older CF patients. For CF patients in whom both CFTR gene alleles were identified by screening for the 12 most common variants (75% of alleles), cross-sectional analysis showed that MPA infection was best correlated with lower percent predicted FEV
1
, while genotype (two versus one ΔF508 CFTR gene allele) and a low level of MSOA were associated with increased risk of infection. A mixed-model analysis of longitudinal spirometric measurements that considered multiple risk factors to derive regression equations was used to determine which clinical parameters had the greatest effect on the annual rate of decline in percent predicted FEV
1
. This analysis showed that the CFTR gene genotype only modestly modified the constant (
y
intercept) of the derived equations, while gender and MPA infection status had the largest effects on annual rates of decline in percent predicted FEV
1
. These results indicate that the CFTR genotype is usually not a primary determinant of pulmonary function in most CF patients, but gender and MPA infection status are. Infection status is potentially influenced by both immunologic (a high level of MSOA) and genetic factors, such as carriage of a CFTR gene allele that leads to a diagnosis of CF but still confers resistance to infection that is comparable to that of the wild-type CFTR gene.
Porin fromPseudomonas aeruginosaInduces Apoptosis in an Epithelial Cell Line Derived from Rat Seminal Vesicles
Authors: Buommino Elisabetta , Morelli Francesco , Metafora Salvatore , Rossano Fabio , Perfetto Brunella , Baroni Adone , Tufano Maria Antonietta 
Published: December 2019

ABSTRACTMicromolar concentrations of porin, purified from the outer membranes ofPseudomonas aeruginosa, induced in vitro the classic morphological and biochemical signs of apoptosis in an epithelial cell line (SVC1) derived from the rat seminal vesicle secretory epithelium. The programmed cell death (PCD) was p53 independent and associated with significant decrease ofbcl-2expression, a marked increase of c-myctranscriptional activity, and an absence of the mRNA coding for tissue transglutaminase. The Ca2+influx, caused by the porin treatment of SVC1 cells, appears to play an important role in the triggering of apoptosis in our biological model. The possibility that the porin property of inducing PCD plays a role in the infertility of individuals chronically infected by gram-negative bacteria is discussed.
Human β-Defensin-1 mRNA Is Transcribed in Tympanic Membrane and Adjacent Auditory Canal Epithelium
Authors: Bøe Roald , Silvola Juha , Yang Jinghui , Moens Ugo , McCray Paul B. , Stenfors Lars-Eric , Seljfelid Rolf 
Published: December 2019

ABSTRACT
The external auditory canal is less susceptible to infections than the sensitive middle-ear cavity. Since recent research has provided insight to the production of potent antimicrobial peptides from various surface epithelia, we wanted to investigate whether protection of the external auditory canal in part could be explained by the production of human β-defensin-1 (HBD-1). This particular peptide is known to be constitutively expressed in various surface epithelia, such as airway, skin, and urogenital tissues. By reverse transcriptase PCR we demonstrate HBD-1 mRNA in the pars tensa and pars flaccida of the tympanic membrane and in the meatal skin. In situ hybridization studies localized the HBD-1 mRNA to the epidermal layer of these tissues. The HBD-1 transcripts were also evident in the sebaceous glands and in hair follicles of the meatal skin. In contrast, HBD-1 mRNA was not detected in the tympanal epithelium of the eardrum. The widespread presence of mRNA encoding for this broad-spectrum antimicrobial peptide in the meatal skin and tympanic membrane suggests that HBD-1 participates in the innate antimicrobial defense of the external auditory canal and middle-ear cavity.
B- and T-Cell Immune Responses to Pneumococcal Conjugate Vaccines: Divergence between Carrier- and Polysaccharide-Specific Immunogenicity
Authors: McCool Tera L. , Harding Clifford V. , Greenspan Neil S. , Schreiber John R. 
Published: December 2019

ABSTRACTConjugation of various serotypes of pneumococcal polysaccharide (PnPS) to carrier protein enhances the magnitude of the polysaccharide-specific antibody response, presumably by eliciting T-cell help. However, variability in PnPS serotype-specific immunogenicity has been observed. CBA/J mice immunized with either 6B or 19F PnPS conjugated to the protein carrier Cross Reactive Material197(CRM197) produce a strong anti-PnPS antibody response; however, when mice are immunized with 23F PnPS conjugated to CRM197, they fail to produce a significant anti-PnPS response. In order to determine whether this difference was related to alterations in antigen processing of the carrier protein and the subsequent T-cell responses, we studied proliferation of lymphocytes from CBA/J mice immunized with CRM197alone or conjugated to 6B, 19F, or 23F PnPS. T-cell proliferative responses to synthetic peptides demonstrated that lymph node cells elicited by the poorly immunogenic conjugate 23F-CRM197recognized many, but not all, of the epitopes recognized by lymph node cells elicited by 6B- and 19F-CRM197as well as additional epitopes. Despite marked differences in PnPS-specific immunogenicity, all mice made high titers of CRM197antibodies of the immunoglobulin G1isotype. Cells from mice immunized with any of the conjugates yielded vigorous T-cell responses to whole antigen. We conclude that the serotype of PnPS can alter the peptide specificities of T-cell responses, but even a poorly immunogenic PnPS conjugate can elicit a significant T-cell response. Thus, conjugation of PnPS to a carrier protein that elicits carrier-specific T- and B-cell responses does not necessarily enhance PnPS immunogenicity.
Observed Differences in Virulence-Associated Phenotypes between a Human Clinical Isolate and a Veterinary Isolate ofMycobacterium avium
Authors: Birkness Kristin A. , Swords W. Edward , Huang Pei-Hsiu , White Elizabeth H. , Dezzutti Charlene S. , Lal Renu B. , Quinn Frederick D. 
Published: December 2019

ABSTRACTMycobacterium avium, the most common opportunistic pathogen in patients with AIDS, is frequently isolated from a variety of environmental sources, but rarely can these environmental isolates be epidemiologically linked with isolates known to cause human disease. Using a number of in vitro tissue culture assays, we found significant pathogenic differences between a serotype 4 human clinicalM. aviumisolate and a serotype 2 veterinary isolate. Cell association of the patient strain with a human intestinal cell line was 1.7 times that of the veterinary strain. Growth of this clinical strain in human peripheral blood mononuclear cell-derived macrophages increased from 12-fold higher than that of the veterinary isolate after 2 days to 200-fold higher after 4 days. By the conclusion of each experiment, lysis of all examined host cell types and accumulation of cell debris were observed in infections with the human isolate, but monolayers remained relatively intact in the presence of the animal isolate. The two strains also differed in the ability to stimulate human immunodeficiency virus replication in coinfected host cells, with p24 antigen levels after 6 days threefold higher in the cells coinfected with the clinical strain than in those infected with the veterinary strain. If the genetic differences responsible for the phenotypes observed in these assays can be identified and characterized, it may be possible to determine whichM. aviumstrains in the environment are potential human pathogens.
Differential Regulation of Enteric and Systemic Salmonellosis by
slyA
Authors: Watson Patricia R. , Paulin Sue M. , Bland A. Patricia , Libby Stephen J. , Jones Philip W. , Wallis Tim S. 
Published: December 2019

ABSTRACT

Mutation of
slyA
, which reduces
Salmonella typhimurium
virulence in mice, caused only minor attenuation of
S. typhimurium
virulence in orally inoculated calves. This correlated with modest reductions in intestinal invasion and enteropathogenic responses in bovine ligated ileal loops.
slyA
appears to regulate virulence genes involved in systemic, but not enteric, salmonellosis.
Molecular Cloning of thePasteurella haemolytica pomAGene and Identification of Bovine Antibodies against PomA Surface Domains
Authors: Zeng Hui , Pandher Karamjeet , Murphy George L. 
Published: December 2019

ABSTRACTThe gene (pomA) encoding PomA, an OmpA-like major outer membrane protein of the bovine respiratory pathogenPasteurella haemolytica, was cloned, and its nucleotide sequence was determined. The deduced amino acid sequence of PomA has significant identity with the sequences of other OmpA family proteins. Absorption of three different bovine immune sera with wholeP. haemolyticacells resulted in a reduction of bovine immunoglobulin G reactivity with recombinant PomA in Western immunoblots, suggesting the presence of antibodies against PomA surface domains.
Substrate Ambiguity of 3-Deoxy-
d
-
manno
-Octulosonate 8-Phosphate Synthase from
Neisseria gonorrhoeae
in the Context of Its Membership in a Protein Family Containing a Subset of 3-Deoxy-
d
-
arabino
-Heptulosonate 7-Phosphate Synthases
Authors: Subramaniam Prem S. , Xie Gang , Xia Tianhui , Jensen Roy A. 
Published: December 2019

ABSTRACT

3-Deoxy-
d
-
manno
-octulosonate 8-phosphate (KDOP) synthase and 3-deoxy-
d
-
arabino
-heptulosonate 7-phosphate (DAHP) synthase catalyze similar phosphoenolpyruvate-utilizing reactions. The genome of
Neisseria gonorrhoeae
contains one gene encoding KDOP synthase and one gene encoding DAHP synthase. Of the two nonhomologous DAHP synthase families known, the
N. gonorrhoeae
protein belongs to the family I assemblage. KDOP synthase exhibited an ability to replace arabinose-5-P with either erythrose-4-P or ribose-5-P as alternative substrates. The results of periodate oxidation studies suggested that the product formed by KDOP synthase with erythrose-4-P as the substrate was 3-deoxy-
d
-
ribo
-heptulosonate 7-P, an isomer of DAHP. As expected, this product was not utilized as a substrate by dehydroquinate synthase. The significance of the ability of KDOP synthase to substitute erythrose-4-P for arabinose-5-P is (i) recognition of the possibility that the KDOP synthase might otherwise be mistaken for a species of DAHP synthase and (ii) the possibility that the broad-specificity type of KDOP synthase might be a relatively vulnerable target for antimicrobial agents which mimic the normal substrates. An analysis of sequences in the database indicates that the family I group of DAHP synthase has a previously unrecognized membership which includes the KDOP synthases. The KDOP synthases fall into a subfamily grouping which includes a small group of DAHP synthases. Thus, family I DAHP synthases separate into two subfamilies, one of which includes the KDOP synthases. The two subfamilies appear to have diverged prior to the acquisition of allosteric-control mechanisms for DAHP synthases. These allosteric control specificities are highly diverse and correlate with the presence of N-terminal extensions which lack homology with one another.
Identification and Characterization of
aarF
, a Locus Required for Production of Ubiquinone in
Providencia stuartii
and
Escherichia coli
and for Expression of 2′-
N
-Acetyltransferase in
P. stuartii
Authors: Macinga David R. , Cook Gregory M. , Poole Robert K. , Rather Philip N. 
Published: December 2019

ABSTRACT

Providencia stuartii
contains a chromosomal 2′-
N
-acetyltransferase [AAC(2′)-Ia] involved in the O acetylation of peptidoglycan. The AAC(2′)-Ia enzyme is also capable of acetylating and inactivating certain aminoglycosides and confers high-level resistance to these antibiotics when overexpressed. We report the identification of a locus in
P. stuartii
, designated
aarF
, that is required for the expression of AAC(2′)-Ia. Northern (RNA) analysis demonstrated that
aac(2′)-Ia
mRNA levels were dramatically decreased in a
P. stuartii
strain carrying an
aarF
::Cm disruption. The
aarF
::Cm disruption also resulted in a deficiency in the respiratory cofactor ubiquinone. The
aarF
locus encoded a protein that had a predicted molecular mass of 62,559 Da and that exhibited extensive amino acid similarity to the products of two adjacent open reading frames of unknown function (YigQ and YigR), located at 86 min on the
Escherichia coli
chromosome. An
E. coli yigR
::Kan mutant was also deficient in ubiquinone content. Complementation studies demonstrated that the
aarF
and the
E. coli yigQR
loci were functionally equivalent. The
aarF
or
yigQR
genes were unable to complement
ubiD
and
ubiE
mutations that are also present at 86 min on the
E. coli
chromosome. This result indicates that
aarF
(
yigQR
) represents a novel locus for ubiquinone production and reveals a previously unreported connection between ubiquinone biosynthesis and the regulation of gene expression.
Diacylglycerol Kinase Is Involved in Regulation of Expression of the Lantibiotic Mutacin II of
Streptococcus mutans
Authors: Chen Ping , Novak Jan , Qi Fengxia , Caufield Page W. 
Published: December 2019

ABSTRACT

Genetic characterization of a Tn
916
transposon mutant,
Streptococcus mutans
T8-1, defective in mutacin II production, revealed that the transposon was inserted into the 3′ region of a diacylglycerol kinase (
dgk
) gene. The insertion occurred in the same region as described for another
S. mutans
mutant, GS5Tn1, which was altered in its ability to respond to environmental stress (Y. Yamashita, T. Takehara, and H. K. Kuramitsu, J. Bacteriol. 175:6220–6228, 1993). Quantitative primer extension from the mutacin structural gene
mutA
showed a decreased level (about eightfold) of
mutA
transcription for mutant T8-1. Mutacin production was restored by transforming mutant T8-1 with integration vector pVA891 containing an intact
dgk
gene. These data indicated that the full-length
dgk
gene product along with the mutacin biosynthetic operon are required for the production of the mutacin II lantibiotic.
Ammonification in
Bacillus subtilis
Utilizing Dissimilatory Nitrite Reductase Is Dependent on
resDE
Authors: Hoffmann Tamara , Frankenberg Nicole , Marino Marco , Jahn Dieter 
Published: December 2019

ABSTRACT

During anaerobic nitrate respiration
Bacillus subtilis
reduces nitrate via nitrite to ammonia. No denitrification products were observed.
B. subtilis
wild-type cells and a nitrate reductase mutant grew anaerobically with nitrite as an electron acceptor. Oxygen-sensitive dissimilatory nitrite reductase activity was demonstrated in cell extracts prepared from both strains with benzyl viologen as an electron donor and nitrite as an electron acceptor. The anaerobic expression of the discovered nitrite reductase activity was dependent on the regulatory system encoded by
resDE
. Mutation of the gene encoding the regulatory Fnr had no negative effect on dissimilatory nitrite reductase formation.
The Capsule and S-Layer: Two Independent and Yet Compatible Macromolecular Structures in
Bacillus anthracis
Authors: Mesnage Stéphane , Tosi-Couture Evelyne , Gounon Pierre , Mock Michèle , Fouet Agnès 
Published: December 2019

ABSTRACT

Bacillus anthracis
, the etiological agent of anthrax, is a gram-positive spore-forming bacterium. Fully virulent bacilli are toxinogenic and capsulated. Two abundant surface proteins, including the major antigen, are components of the
B. anthracis
surface layer (S-layer). The
B. anthracis
paracrystalline S-layer has previously only been found in noncapsulated vegetative cells. Here we report that the S-layer proteins are also synthesized under conditions where the poly-γ-
d
-glutamic acid capsule is present. Structural and immunological analyses show that the capsule is exterior to and completely covers the S-layer proteins. Nevertheless, analysis of single and double S-layer protein mutants shows that the presence of these proteins is not required for normal capsulation of the bacilli. Similarly, the S-layer proteins assemble as a two-dimensional crystal, even in the presence of the capsule. Thus, both structures are compatible, and yet neither is required for the correct formation of the other.