bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transforming Growth Factor β-Induced Failure of Resistance to Infection with Blood-StagePlasmodium chabaudiin Mice
Authors: Tsutsui Naohisa , Kamiyama Tsuneo 
Published: December 2019

ABSTRACTThe role of transforming growth factor β (TGF-β) in infection withPlasmodium chabaudiwas investigated with resistant and susceptible mouse models. C57BL/10 mice produced gamma interferon (IFN-γ) and nitric oxide (NO) shortly after infection and cleared the parasite spontaneously. In contrast, BALB/c mice showed a transient enhancement of TGF-β production, followed by a relative lack of IFN-γ and NO production, and succumbed to the infection. However, there was no correlation between levels of serum TGF-β and splenic TGF-β mRNA in both mouse strains before and after infection. Administration of recombinant TGF-β (rTGF-β) rendered resistant mice susceptible because of suppression of subsequent production of IFN-γ and NO. Administration of anti-TGF-β antibody to the infected BALB/c mice resulted in remarkable increases in serum IFN-γ and NO, and the mice resisted the infection. Splenic CD4+T and CD11b+cells of C57BL/10 mice were significantly activated after infection, but this was completely abrogated by administration of rTGF-β. These results suggested that, in theP. chabaudi-susceptible but not resistant mice, production of TGF-β was promoted, and subsequent failure of IFN-γ- and NO-dependent resistance to the parasite was induced. This study is the first to indicate that TGF-β production was the key event in failure of resistance to mouse malaria.
Activation of Neutrophil Collagenase in Periodontitis
Authors: Romanelli Raquel , Mancini Sabrina , Laschinger Carol , Overall Christopher M. , Sodek Jaro , McCulloch Christopher A. G. 
Published: December 2019

ABSTRACT

Neutrophil collagenase (matrix metalloproteinase 8 [MMP-8]) is an important mediator of tissue destruction in inflammatory diseases. Studies of anaerobic periodontal infections have shown that active MMP-8 in gingival crevicular fluid is associated with the degradation of periodontal tissues in progressive periodontitis whereas the latent enzyme is predominant in gingivitis. Since the activation of MMP-8 appears to be a crucial step in periodontitis, we have examined the activation of MMP-8 in gingival crevicular fluid samples by using a soluble biotinylated collagen substrate. Analysis of gingival crevicular fluid in periodontitis, gingivitis, and controls revealed sixfold (
P
< 0.001)-higher levels of active collagenase in periodontitis (
n
= 12) samples compared to gingivitis (
n
= 17) samples, which exhibited low levels of activity, while controls (
n
= 25) showed no activity. After gingival crevicular fluid was collected, no further activation of latent collagenase occurred in vitro. Although both MMP-1 and MMP-8, but not MMP-13, could be detected by immunoblots, blocking antibodies to MMP-1 showed that collagenase activity was largely contributed by MMP-8, which was localized to the matrix of diseased tissues. The MMP-8 in gingival crevicular fluid migrated primarily as a 60-kDa form with smaller amounts of a 78-kDa species, whereas MMP-8 isolated from peripheral neutrophils migrated at 70 and 89 kDa, corresponding to active and latent forms of the enzyme, respectively. Most of the MMP-8 in the 60- and 70-kDa bands selectively bound to tissue inhibitor of metalloproteinase 2 and collagen, indicating that most, but not all, of the enzyme in these bands was in an activated form. However, the amounts of the 78- and 60-kDa forms from gingival crevicular fluid in different samples did not correlate (
r
2
= 0.028) with the latent and active enzyme measured by collagenase assay. Collectively, these studies have identified distinct forms of latent and active MMP-8 in gingival crevicular fluid that appear to result from a unique activation mechanism that occurs in periodontitis. The complexity of MMP-8 activation is further indicated by the presence of latent, activated, and superactivated forms of MMP-8 in the 60- and 70-kDa bands obtained from gingival crevicular fluid and neutrophil samples, respectively.
Genetic and Physiologic Characterization of Ferric/Cupric Reductase Constitutive Mutants ofCryptococcus neoformans
Authors: Nyhus Karin J. , Jacobson Eric S. 
Published: December 2019

ABSTRACTCryptococcus neoformansis a pathogenic yeast that causes meningitis in immunocompromised patients. Because iron acquisition is critical for growth of a pathogen in a host, we studied the regulation of the ferric reductase and ferrous uptake system of this organism. We isolated 18 mutants, representing four independent loci, with dysregulated ferric reductase. The mutant strains had >10-fold higher than wild-type WT reductase activity in the presence of iron. Two of the strains also had >7-fold higher than WT iron uptake in the presence of iron but were not markedly iron sensitive. Both were sensitive to the oxidative stresses associated with superoxide and hydrogen peroxide. One strain exhibited only 23% of the WT level of iron uptake in the absence of iron and grew poorly without iron supplementation of the medium, phenotypes consistent with an iron transport deficiency; it was sensitive to superoxide but not to hydrogen peroxide. The fourth strain had high reductase activity but normal iron uptake; it was not very sensitive to oxidative stress. We also demonstrated that the ferric reductase was regulated by copper and could act as a cupric reductase. Sensitivity to oxidants may be related to iron acquisition by a variety of mechanisms and may model the interaction of the yeast with the immune system.
SFS, a Novel Fibronectin-Binding Protein fromStreptococcus equi, Inhibits the Binding between Fibronectin and Collagen
Authors: Lindmark Hans , Guss Bengt 
Published: December 2019

ABSTRACTThe obligate parasitic bacteriumStreptococcus equisubsp.equiis the causative agent of strangles, a serious disease of the upper respiratory tract in horses. In this study we have, using shotgun phage display, cloned fromS. equisubsp.equiand characterized a gene, calledsfs, encoding a protein termed SFS, representing a new type of fibronectin (Fn)-binding protein. Thesfsgene was found to be present in all 50 isolates ofS. equisubsp.equitested and in 41 of 48S. equisubsp.zooepidemicusisolates tested. Thesfsgene is down-regulated during growth in vitro compared tofnz, a previously characterized gene encoding an Fn-binding protein fromS. equisubsp.zooepidemicus. Sequence comparisons revealed no similarities to previously characterized Fn-binding proteins, but high scores were obtained against collagen. Besides similarity due to the high content of glycine, serine, and proline residues present in both proteins, there was a nine-residue motif present both in collagen and in the Fn-binding domain of SFS. By searching the OklahomaS. pyogenesdatabase, we found that this motif is also present in a potential cell surface protein fromS. pyogenes. Protein SFS was found to inhibit the binding between Fn and collagen in a concentration-dependent way.
Molecular Interactions ofPorphyromonas gingivalisFimbriae with Host Proteins: Kinetic Analyses Based on Surface Plasmon Resonance
Authors: Amano Atsuo , Nakamura Takayuki , Kimura Shigenobu , Morisaki Ichijiro , Nakagawa Ichiro , Kawabata Shigetada , Hamada Shigeyuki 
Published: December 2019

ABSTRACTFimbriae ofPorphyromonas gingivalisare thought to play an important role in the colonization and invasion of periodontal tissues. In this study, we analyzed the interactions ofP. gingivalisfimbriae with human hemoglobin, fibrinogen, and salivary components (i.e., proline-rich protein [PRP], proline-rich glycoprotein [PRG], and statherin) based on surface plasmon resonance (SPR) spectroscopy with a biomolecular interaction analyzing system (BIAcore). The real-time observation showed that the fimbriae interacted more quickly with hemoglobin and PRG than with other proteins and more intensely with fibrinogen. The significant association constant (ka) values obtained by BIAcore demonstrated that the interactions between fimbriae and these host proteins are specific. These estimatedKavalues were not too different; however, theKavalues for hemoglobin (2.43 × 106) and fibrinogen (2.16 × 106) were statistically greater than those for the salivary proteins (1.48 × 106to 1.63 × 106). TheKavalue of anti-fimbriae immunoglobulin G for fimbriae was estimated to be 1.22 × 107, which was 6.55-fold higher than the meanKavalue of the host proteins. Peptide PRP-C, a potent inhibitor of PRP-fimbriae interaction, dramatically inhibited fimbrial association to PRP and PRG and was also inhibitory against other host proteins by BIAcore. The binding of fimbriae to these proteins was also evaluated by other methods with hydroxyapatite beads or polystyrene microtiter plates. The estimated binding abilities differed considerably, depending on the assay method that was used. It was noted that the binding capacity of PRP was strongly diminished by immobilization on a polystyrene surface. Taken together, these findings suggest thatP. gingivalisfimbriae possess a strong ability to interact with the host proteins which promote bacterial adherence to the oral cavity and that SPR spectroscopy is a useful method for analyzing specific protein-fimbriae interactions.
Structural and Evolutionary Inference from Molecular Variation in
Neisseria
Porins
Authors: Derrick Jeremy P. , Urwin Rachel , Suker Janet , Feavers Ian M. , Maiden Martin C. J. 
Published: December 2019

ABSTRACT

The porin proteins of the pathogenic
Neisseria
species,
Neisseria gonorrhoeae
and
Neisseria meningitidis
, are important as serotyping antigens, putative vaccine components, and for their proposed role in the intracellular colonization of humans. A three-dimensional structural homology model for
Neisseria
porins was generated from
Escherichia coli
porin structures and
N. meningitidis
PorA and PorB sequences. The
Neisseria
sequences were readily assembled into the 16-strand β-barrel fold characteristic of porins, despite relatively low sequence identity with the
Escherichia
proteins. The model provided information on the spatial relationships of variable regions of peptide sequences in the PorA and PorB trimers and insights relevant to the use of these proteins in vaccines. The nucleotide sequences of the porin genes from a number of other
Neisseria
species were obtained by PCR direct sequencing and from GenBank. Alignment and analysis of all available
Neisseria
porin sequences by use of the structurally conserved regions derived from the PorA and PorB structural models resulted in the recovery of an improved phylogenetic signal. Phylogenetic analyses were consistent with an important role for horizontal genetic exchange in the emergence of different porin classes and confirmed the close evolutionary relationships of the porins from
N. meningitidis
,
N. gonorrhoeae
,
Neisseria lactamica
, and
Neisseria polysaccharea
. Only members of this group contained three conserved lysine residues which form a potential GTP binding site implicated in pathogenesis. The model placed these residues on the inside of the pore, in close proximity, consistent with their role in regulating pore function when inserted into host cells.
Identification of Virulence Genes of
Helicobacter pylori
by Random Insertion Mutagenesis
Authors: Bijlsma J. J. E. , Vandenbroucke-Grauls C. M. J. E. , Phadnis S. H. , Kusters J. G. 
Published: December 2019

ABSTRACT

The complete genome of the gram-negative bacterial pathogen
Helicobacter pylori
, an important etiological agent of gastroduodenal disease in humans, has recently been published. This sequence revealed that the putative products of roughly one-third of the open reading frames (ORFs) have no significant homology to any known proteins. To be able to analyze the functions of all ORFs, we constructed an integration plasmid for
H. pylori
and used it to generate a random mutant library in this organism. This integration plasmid, designated pBCα3, integrated randomly into the chromosome of
H. pylori
. To test the capacity of this library to identify virulence genes, subsets of this library were screened for urease-negative mutants and for nonmotile mutants. Three urease-negative mutants in a subset of 1,251 mutants (0.25%) and 5 nonmotile mutants in a subset of 180 mutants (2.7%) were identified. Analysis of the disrupted ORFs in the urease-negative mutants revealed that two had disruptions of genes of the urease locus,
ureB
and
ureI
, and the third had a disruption of a unrelated gene; a homologue of
deaD
, which encodes an RNA helicase. Analysis of the disrupted ORFs in the nonmotile mutants revealed one ORF encoding a homologue of the paralyzed flagellar protein, previously shown to be involved in motility in
Campylobacter jejuni
. The other four ORFs have not been implicated in motility before. Based on these data, we concluded that we have generated a random insertion library in
H. pylori
that allows for the functional identification of genes in
H. pylori
.
Humoral Immune Responses toNeisseria meningitidisin Children
Authors: Pollard Andrew J. , Galassini Rachel , Rouppe van der Voort Eileene M. , Booy Robert , Langford Paul , Nadel Simon , Ison Catherine , Kroll J. Simon , Poolman Jan , Levin Michael 
Published: December 2019

ABSTRACTAn understanding of the nature of immunity to serogroup B meningococci in childhood is necessary in order to establish the reasons for poor responses to candidate vaccines in infancy. We sought to examine the nature of humoral immune responses following infection in relation to age. Serum bactericidal activity was poor in children under 12 months of age despite recent infection withNeisseria meningitidis. The highest levels of bactericidal activity were seen in children over 10 years of age. However, infants produced levels of total immunoglobulin G (IgG) and IgG subclass antibodies similar to those in older children in a meningococcal enzyme-linked immunosorbent assay. Most antibody was of the IgG1 and IgG3 subclasses. This striking age dependency of bactericidal antibody response following infection is not apparently due to failure of class switching in infants but might be due to qualitative differences in antibody specificity or affinity.
In Vivo Analysis of Secreted Aspartyl Proteinase Expression in Human Oral Candidiasis
Authors: Naglik Julian R. , Newport George , White Theodore C. , Fernandes-Naglik Lynette L. , Greenspan John S. , Greenspan Deborah , Sweet Simon P. , Challacombe Stephen J. , Agabian Nina 
Published: December 2019

ABSTRACTSecreted aspartyl proteinases are putative virulence factors inCandidainfections.Candida albicanspossesses at least nine members of aSAPgene family, all of which have been sequenced. Although the expression of theSAPgenes has been extensively characterized under laboratory growth conditions, no studies have analyzed in detail the in vivo expression of these proteinases in human oral colonization and infection. We have developed a reliable and sensitive procedure to detectC. albicansmRNA from whole saliva of patients with oralC. albicansinfection and those with asymptomaticCandidacarriage. The reverse transcription-PCR protocol was used to determine which of theSAP1toSAP7genes are expressed byC. albicansduring colonization and infection of the oral cavity.SAP2and theSAP4toSAP6subfamily were the predominant proteinase genes expressed in the oral cavities of bothCandidacarriers and patients with oral candidiasis;SAP4,SAP5, orSAP6mRNA was detected in all subjects.SAP1andSAP3transcripts were observed only in patients with oral candidiasis.SAP7mRNA expression, which has never been demonstrated under laboratory conditions, was detected in several of the patient samples. All sevenSAPgenes were simultaneously expressed in some patients with oral candidiasis. This is the first detailed study showing that theSAPgene family is expressed byC. albicansduring colonization and infection in humans and thatC. albicansinfection is associated with the differential expression of individualSAPgenes which may be involved in the pathogenesis of oral candidiasis.
Structural Requirements of the Major Protective Antibody toHaemophilus influenzaeType b
Authors: Hougs Lotte , Juul Lars , Svejgaard Arne , Barington Torben 
Published: December 2019

ABSTRACTProtective antibodies to the important childhood pathogenHaemophilus influenzaetype b (Hib) are directed against the capsular polysaccharide (HibCP). Most of the antibody is encoded by a well-defined set of (“canonical”) immunoglobulin genes, including the VκA2 gene, and expresses an idiotypic marker (HibId-1). In comparison to noncanonical antibodies, the canonical antibody is generally of higher avidity, shows higher levels of in vitro bactericidal activity, and is more protective in infant rats. Using site-directed mutagenesis, we here characterize canonical HibCP antibodies expressed as antigen-binding fragments (Fabs) inEscherichia coli, define amino acids involved in antigen binding and idiotype expression, and propose a three-dimensional structure for the variable domains. We found that canonical Fabs, unlike a noncanonical Fab, bound effectively to HibCP in the absence of somatic mutations. Nevertheless, pronounced mutation-based affinity maturation was demonstrated in vivo. An almost perfect correlation was found between unmutated gene segments that mediated binding in vitro and those encoding canonical HibCP antibodies in vivo. Thus, the VκA2a gene could be replaced by the A2c gene but not by the highly homologous sister gene, A18b, corresponding to the demonstrated usage of A2c but not of A18b in vivo. Similarly, only Jκ1 and Jκ3, which predominate in the response in vivo, were able to facilitate binding in vitro. These findings suggest that the restricted immunoglobulin gene usage in HibCP antibodies reflects strict structural demands ensuring relatively high affinity prior to somatic mutations—requirements met by only a limited spectrum of immunoglobulin gene combinations.
Towards aTaenia soliumCysticercosis Vaccine: an Epitope Shared byTaenia crassicepsandTaenia soliumProtects Mice against Experimental Cysticercosis
Authors: Toledo Andrea , Larralde Carlos , Fragoso Gladis , Gevorkian Goar , Manoutcharian Karen , Hernández Marisela , Acero Gonzalo , Rosas Gabriela , López-Casillas Fernando , Garfias Carlos Kubli , Vázquez Ricardo , Terrazas Ignacio , Sciutto Edda 
Published: December 2019

ABSTRACTTheTaenia crassicepsrecombinant antigen KETc7 has been shown to be effective as a vaccine against experimental murine cysticercosis, a laboratory model used to test potentially promising molecules against porcineTaenia soliumcysticercosis. Based on the deduced amino acid sequence of this proline-rich polypeptide, three fragments, GK-1, GK-2, and GK-3, were chemically synthesized in linear form. Of the three peptides, only GK-1 induced sterile protection againstT. crassicepscysticercosis in 40 to 70% of BALB/cAnN male mice. GK-1 is an 18-amino-acid peptide which contains at least one B-cell epitope, as demonstrated by its ability to induce an antibody response to the peptide andT. crassicepsantigen without need of a carrier protein. Immunofluorescence studies revealed that anti-GK1 antibodies strongly react with the native protein in the tegument ofT. crassicepsand also with anatomical structures ofT. soliumeggs, oncospheres, cysticercus, and tapeworm. GK-1 also contains at least one T-cell epitope, capable of stimulating the proliferation of CD8+and to a lower extent CD4+T cells primed either with the free peptide orT. crassicepstotal antigen. The supernatant of the stimulated cells contained high levels of gamma interferon and low levels of interleukin-4. Similar results were obtained with T cells tested for intracellular cytokine production, an indication of the peptide’s capacity to induce an inflammatory response. The remarkable protection induced by GK-1 immunization, its physicochemical properties, and its presence in all developmental stages ofT. soliumpoint to this synthetic peptide as a strong candidate in the construction of a synthetic vaccine againstT. soliumpig cysticercosis.
Comparative Physical and Genetic Maps of the Virulence Plasmids of
Salmonella enterica
Serovars Typhimurium, Enteritidis, Choleraesuis, and Dublin
Authors: Chu Chishih , Hong Seau-Feng , Tsai Chingju , Lin Wen-Shiun , Liu Tsui-Ping , Ou Jonathan T. 
Published: December 2019

ABSTRACT

Using fragment profiling, PCR, and Southern hybridization, we found that
Salmonella enterica
serovar Choleraesuis harbored virulence plasmids of various sizes, whereas serovars Typhimurium, Enteritidis, and Dublin carried a plasmid of a unique size. Also, the virulence plasmid of Typhimurium contained genes in the same order detected in the other three plasmids, all of which contained deletions.
Localization of
HArep
-Containing Genes on the Chromosome of
Porphyromonas gingivalis
W83
Authors: Lewis Janina P. , Macrina Francis L. 
Published: December 2019

ABSTRACT

We have mapped a group of virulence genes of
Porphyromonas gingivalis
to a single large fragment of the genome. These genes (
rgpA
,
kgp
, and
hagA
) all contain a consensus repeat sequence (
HArep
).
rgpA
and
kgp
encode cysteine proteases with Arg-X and Lys-X specificity, respectively, and
hagA
encodes a hemagglutinin. Genomic DNA fragments separated by pulse-field gel electrophoresis were blotted and probed in order to localize the genes to a 0.25-Mb
Nhe
I fragment of the
P. gingivalis
W83 genome. Further hybridization analyses with single- and double-restriction digestion allowed us to generate a physical map of the fragment and determine the precise locations of the protease and hemagglutinin genes. In addition, we found an insertion-like sequence, IS
195
, near the ends of the 0.25-Mb
Nhe
I fragment. A similarly sized fragment carrying
HArep
sequences was also demonstrated in the
P. gingivalis
W12 and W50 genomes.
Characterization of the Importance of Polysaccharide Intercellular Adhesin/Hemagglutinin ofStaphylococcus epidermidisin the Pathogenesis of Biomaterial-Based Infection in a Mouse Foreign Body Infection Model
Authors: Rupp Mark E. , Ulphani Joseph S. , Fey Paul D. , Bartscht Katrin , Mack Dietrich 
Published: December 2019

ABSTRACTThe production of biofilm is thought to be crucial in the pathogenesis of prosthetic-device infections caused byStaphylococcus epidermidis. An experimental animal model was used to assess the importance of biofilm production, which is mediated by polysaccharide intercellular adhesin/hemagglutinin (PIA/HA), in the pathogenesis of a biomaterial-based infection. Mice were inoculated along the length of a subcutaneously implanted intravenous catheter with either wild-typeS. epidermidis1457 or its isogenic PIA/HA-negative mutant. The wild-type strain was significantly more likely to cause a subcutaneous abscess than the mutant strain (P< 0.01) and was significantly less likely to be eradicated from the inoculation site by host defense (P< 0.05). In addition, the wild-type strain was found to adhere to the implanted catheters more abundantly than the PIA/HA-negative mutant (P< 0.05). The reliability of the adherence assay was assessed by scanning electron microscopy. To exclude contamination or spontaneous infection, bacterial strains recovered from the experimental animals were compared to inoculation strains by analysis of restriction fragment length polymorphism patterns by pulsed-field gel electrophoresis. In vitro binding of the wild-type strain and its isogenic mutant to a fibronectin-coated surface was similar. These results confirm the importance of biofilm production, mediated by PIA/HA, in the pathogenesis ofS. epidermidisexperimental foreign body infection.