bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of Lethal Shock and Tolerance byPorphyromonas gingivalisLipopolysaccharide ind-Galactosamine-Sensitized C3H/HeJ Mice
Authors: Tanamoto Ken-Ichi 
Published: December 2019

ABSTRACTLipopolysaccharide (LPS) obtained fromPorphyromonas gingivaliswas found to exhibit marked lethal toxicity in galactosamine-sensitized C3H/HeJ mice. Although no lethality was observed in mice intraperitoneally challenged with 1 mg ofP. gingivalisLPS without galactosamine, when they were sensitized with 30 mg of galactosamine, challenge with 1 and 10 μg of LPS resulted in 67 and 100% lethality, respectively. The lethal dose of LPS was almost the same in LPS-responsive C57BL/6 mice and non-LPS-responsive C3H/HeJ mice. Furthermore, when 1 μg ofP. gingivalisLPS was administered to each mouse 90 min before the challenge with the same LPS with galactosamine, tolerance to the lethal action of LPS was induced, and the mice were completely protected from death, even at a dose 100-fold greater than the lethal dose of LPS. Neither a lethal effect nor induction of tolerance to the lethality ofP. gingivalisLPS was exhibited bySalmonellaLPS in galactosamine-sensitized C3H/HeJ mice. A protein-LPS complex derived fromPseudomonas aeruginosa, which exhibited strong lethality and induced tolerance to a subsequent challenge with a lethal dose of LPS in galactosamine-sensitized LPS-responsive mice, did not exhibit lethal toxicity in galactosamine-sensitized C3H/HeJ mice and failed to induce tolerance in these mice to the lethality ofP. gingivalisLPS. These results indicate thatP. gingivalisLPS plays the central role in the activation of non-LPS-responsive C3H/HeJ mice.
Analysis of a Capsular Polysaccharide Biosynthesis Locus ofBacteroides fragilis
Authors: Comstock Laurie E. , Coyne Michael J. , Tzianabos Arthur O. , Pantosti Annalisa , Onderdonk Andrew B. , Kasper Dennis L. 
Published: December 2019

ABSTRACTA major clinical manifestation of infection withBacteroides fragilisis the formation of intra-abdominal abscesses, which are induced by the capsular polysaccharides of this organism. Transposon mutagenesis was used to locate genes involved in the synthesis of capsular polysaccharides. A 24,454-bp region was sequenced and found to contain a 15,379-bp locus (designatedwcf) with 16 open reading frames (ORFs) encoding products similar to those encoded by genes of other bacterial polysaccharide biosynthesis loci. Four genes encode products that are similar to enzymes involved in nucleotide sugar biosynthesis. Seven genes encode products that are similar to sugar transferases. Two gene products are similar toO-acetyltransferases, and two products are probably involved in polysaccharide transport and polymerization. The product of one ORF, WcfH, is similar to a set of deacetylases of the NodB family. Deletion mutants demonstrated that thewcflocus is necessary for the synthesis of polysaccharide B, one of the two capsular polysaccharides ofB. fragilis9343. The virulence of the polysaccharide B-deficient mutant was comparable to that of the wild type in terms of its ability to induce abscesses in a rat model of intra-abdominal infection.
Genetic Basis for Lipopolysaccharide O-Antigen Biosynthesis in Bordetellae
Authors: Preston Andrew , Allen Andrew G. , Cadisch Joanna , Thomas Richard , Stevens Kim , Churcher Carol M. , Badcock K. L. , Parkhill Julian , Barrell Bart , Maskell Duncan J. 
Published: December 2019

ABSTRACT

Bordetella bronchiseptica
and
Bordetella parapertussis
express a surface polysaccharide, attached to a lipopolysaccharide, which has been called O antigen. This structure is absent from
Bordetella pertussis
. We report the identification of a large genetic locus in
B. bronchiseptica
and
B. parapertussis
that is required for O-antigen biosynthesis. The locus is replaced by an insertion sequence in
B. pertussis
, explaining the lack of O-antigen biosynthesis in this species. The DNA sequence of the
B. bronchiseptica
locus has been determined and the presence of 21 open reading frames has been revealed. We have ascribed putative functions to many of these open reading frames based on database searches. Mutations in the locus in
B. bronchiseptica
and
B. parapertussis
prevent O-antigen biosynthesis and provide tools for the study of the role of O antigen in infections caused by these bacteria.
Secretion of Functional Salivary Peptide by
Streptococcus gordonii
Which Inhibits Fimbria-Mediated Adhesion of
Porphyromonas gingivalis
Authors: Kataoka Kosuke , Amano Atsuo , Kawabata Shigetada , Nagata Hideki , Hamada Shigeyuki , Shizukuishi Satoshi 
Published: December 2019

ABSTRACT

Porphyromonas gingivalis
, a putative periodontopathogen, can bind to human salivary components with its fimbriae. We have previously shown that fimbriae specifically bind to a peptide domain shared by a major salivary component, i.e., proline-rich (glyco)proteins (PRPs). The synthetic domain peptide PRP-C (pPRP-C) significantly inhibits the fimbrial binding to PRPs. In this study, a recombinant strain of
Streptococcus gordonii
secreting pPRP-C was generated as a model of a possible approach to prevent the oral colonization by the pathogen. A duplicate DNA fragment (
prpC
) encoding pPRP-C was obtained by self-complementary annealing of synthetic oligonucleotides.
prpC
was connected downstream to a promoter and a gene encoding a signal peptide of
Streptococcus downei
glucosyltransferase I in frame. The linked fragments were inserted into the plasmid pMNK-4 derived from pVA838. The constructed plasmid was inserted to produce the transformant
S. gordonii
G9B, which then successfully secreted recombinant pPRP-C (r-pPRP-C) of the expected size. The concentrated bacterial culture supernatant containing r-pPRP-C inhibited the binding of
P. gingivalis
cells and fimbriae to PRP1 in a dose-dependent manner up to 72 and 77%, respectively. The r-pPRP-C concentrate also inhibited the coaggregation of
P. gingivalis
with various streptococcal strains as effectively as synthetic pPRP-C in a dose-dependent manner. Collectively, pPRP-C was found to be able to prevent
P. gingivalis
adherence to salivary receptor protein and plaque-forming bacteria. These results suggest that this recombination approach with a nonperiodontopathic bacterium may be suitable for the therapeutic prevention of
P. gingivalis
adherence to the oral cavity.
In Vitro Expansion of T-Cell-Receptor Vα2.3+CD4+T Lymphocytes in HLA-DR17(3), DQ2+Individuals upon Stimulation withMycobacterium tuberculosis
Authors: Esin Semih , Batoni Giovanna , Saruhan-Direskeneli Güher , Harris Robert A. , Grunewald Johan , Pardini Manuela , Svenson Stefan B. , Campa Mario , Wigzell Hans 
Published: December 2019

ABSTRACTThe T-cell receptor (TCR) Vα/β gene product expression upon in vitro stimulation with mycobacteria was investigated to assess whether T-cell proliferation was associated with any specific TCR V gene usage. T-cell-enriched populations from peripheral blood ofMycobacterium bovisBCG-vaccinated healthy blood donors were stimulated in vitro with live or killedM. tuberculosisor with a soluble extract thereof. TCR Vα/β repertoire analysis of reactive CD4+and CD8+T cells revealed a selective HLA-DR17(3), DQ2-restricted expansion of Vα2.3+CD4+T cells upon stimulation with liveM. tuberculosisor its soluble extract. Third-complementarity-determining-region (CDR3) length analysis of the expanded Vα2.3+T cells indicated an oligoclonal pattern with short CDR3 lengths in six of seven HLA-DR17(3), DQ2+individuals tested. In addition, Vα/Vβ repertoire analysis of T lymphocytes from a DR17(3), DQ2+donor before and after BCG vaccination revealed that positivity of skin test reactivity was associated with expansion of Vα2.3+CD4+T lymphocytes with preferential use of a short CDR3 peak length after in vitro stimulation. Separation ofM. tuberculosissoluble extract by fast protein liquid chromatography (FPLC) purification indicated that fractions corresponding to molecular masses of 60 to 70 and 15 to 25 kDa were particularly effective in eliciting Vα2.3+CD4+T-cell expansion.
Antigenic Variation of the Class I Outer Membrane Protein in Hyperendemic
Neisseria meningitidis
Strains in The Netherlands
Authors: Bart Aldert , Dankert Jacob , van der Ende Arie 
Published: December 2019

ABSTRACT

Since 1980, the number of cases of meningococcal disease caused by serogroup B isolates with the P1.4 serosubtype has greatly increased in The Netherlands. Screening for this serosubtype in the strain collection of The Netherlands Reference Laboratory for Bacterial Meningitis revealed that a low number of P1.4 strains had been present in the Dutch meningococcal population since 1965. Genotyping of P1.4 strains showed that one cluster of strains, the hyperendemic lineage III (D. A. Caugant et al., J. Infect. Dis. 162:867–874, 1990), is responsible for the increase since 1980. The diversity of the
porA
genes, which encode the P1 protein on which serosubtyping is based, was studied for genotypically different P1.4 strains and for lineage III strains expressing antigenically different P1 proteins. Sequence analysis showed that
porA
genes of genotypically distinct strains that express antigenically indistinguishable P1 proteins are identical only in the epitope-encoding region, suggesting that this region has spread through the meningococcal population via horizontal gene transfer. Analysis of
porA
genes of lineage III strains showed that both horizontal gene transfer and partial deletion of the epitope-encoding region may contribute to the different antigenic properties for P1 of these strains. Phase variation of expression of the
porA
gene seems to account for most nonreacting strains. These results show that serosubtyping may underestimate the rise of a hyperendemic clone.
Functional Analysis of the
Staphylococcus aureus
Collagen Adhesin B Domain
Authors: Snodgrass James L. , Mohamed Nehal , Ross Julia M. , Sau Subrata , Lee Chia Y. , Smeltzer Mark S. 
Published: December 2019

ABSTRACT

The
Staphylococcus aureus
collagen adhesin (CNA) occurs in at least four forms that differ in the number (one, two, three, or four) of B domains. The B domains contain 187 amino acids and are located between the domains that anchor CNA to the cell envelope and the ligand-binding A domain. To determine whether a B domain is required for functional expression of CNA, we cloned the 2B
cna
gene from
S. aureus
strain Phillips and then eliminated both B domains by overlapping PCR. The absence of a B domain did not affect processing of the collagen adhesin to the cell surface or the ability to bind collagen. Based on our recent demonstration that the capsule can mask CNA on the surface of
S. aureus
cells (A. F. Gillaspy et al., Infect. Immun. 66:3170–3178, 1998), we also investigated the possibility that multiple B domains can extend the ligand-binding A domain outward from the cell surface and thereby overcome the inhibitory effect of the capsule. Specifically, we cloned the naturally occurring 4B CNA variant from
S. aureus
UAMS-639 and, by successive elimination of B domains, generated 1, 2, and 3B variants that are isogenic with respect to the 4B clone. After introducing each variant into microencapsulated and heavily encapsulated strains of
S. aureus
and growing cells under conditions known to affect capsule production (e.g., growth on Columbia agar), we correlated capsule production with exposure of CNA on the cell surface and the ability to bind collagen. Under no circumstance was the masking effect of the capsule reduced by the presence of multiple B domains. These results indicate that the B domains do not extend the ligand-binding A domain outward in a fashion that can overcome the inhibition of collagen binding associated with capsule production.
Decay-Accelerating Factor and Cytoskeleton Redistribution Pattern in HeLa Cells Infected with RecombinantEscherichia coliStrains Expressing Dr Family of Adhesins
Authors: Goluszko Pawel , Selvarangan Rangaraj , Popov Vsevolod , Pham Tuan , Wen Julie W. , Singhal Jyotsana 
Published: December 2019

ABSTRACTEscherichia colistrains expressing Dr fimbriae are able to enter epithelial cells by interacting with a complement-regulatory protein, decay-accelerating factor. This model of bacterial internalization, with a well-characterized bacterial ligand and host receptor, provides a unique opportunity to investigate the early stages of invasion. We used immunofluorescence staining techniques to examine the distribution of receptor and cytoskeletal proteins in HeLa cells infected withE. colirecombinant strains that expressed Dr family of adhesins: Dr, Dr-II, F1845, AFA-I, and AFA-III. A major rearrangement of decay-accelerating factor was found at the adherence sites of recombinant strains expressing Dr, Dr-II, and F1845 adhesins. The changes in the distribution of receptor were significantly smaller on HeLa cells infected withE. colibearing AFA-I or AFA-III afimbrial adhesins. Receptor aggregation was associated with the redistribution of cytoskeleton-associated proteins such as actin, α-actinin, ezrin, and occasionally tropomyosin. Purified Dr fimbriae coated on polystyrene beads were capable of triggering clustering of receptor and accumulating actin at the adhesion sites of beads to HeLa cells. Using scanning and transmission electron microscopic techniques, we have shown that beads coated with Dr fimbriae, as opposed to beads coated with bovine serum albumin, were enwrapped by cellular microvilli and ultimately internalized into HeLa cells. This indicates that interaction of Dr fimbriae with decay-accelerating factor is associated with redistribution of receptor and is sufficient to promote bacterial internalization.
Cloning, Expression, and Immunological Evaluation of Two Putative Secreted Serine Protease Antigens ofMycobacterium tuberculosis
Authors: Skeiky Yasir A. W. , Lodes Michael J. , Guderian Jeffrey A. , Mohamath Raodoh , Bement Teresa , Alderson Mark R. , Reed Steven G. 
Published: December 2019

ABSTRACTCulture filtrate proteins (CFP) ofMycobacterium tuberculosishave been shown to contain immunogenic components that elicit at least partial protective immunity againstMycobacteriuminfection. To clone genes encoding some of the immunogenic proteins, we made a high-titer rabbit anti-CFP serum and used it to screen anM. tuberculosisgenomic expression library inEscherichia coli. In this paper, we describe the molecular cloning of two new protein components of CFP and identified them as members of the serine protease gene family. Their open reading frames contain N-terminal hydrophobic secretory signals consistent with their detection in CFP. The predicted molecular masses of the mature, fully processed forms of both antigens are ∼32 kDa, in agreement with their observed sizes on immunoblots of CFP probed with polyclonal rabbit antisera made to the recombinant proteins. Thus, these proteins have been designated MTB32A and MTB32B. Interestingly, and despite 66% amino acid sequence homology between the two proteins, polyclonal rabbit antisera made to each of the recombinant proteins were found to be specific for the respective immunizing antigens. The recombinant proteins were also evaluated in in vitro assays with donor peripheral blood mononuclear cells (PBMC) from healthy purified protein derivative (PPD)-positive individuals of diverse ethnic backgrounds. MTB32A but not MTB32B stimulated PBMC from healthy PPD-positive donors but not from PPD-negative donors to proliferate and secrete gamma interferon. MTB32A is encoded by a single-copy gene which is present in both virulent and avirulent strains of theM. tuberculosiscomplex and the BCG strain ofMycobacterium bovisbut absent in the environmental mycobacterial species tested. In addition, nucleotide sequence comparison ofmtb32aof the avirulent H37Ra strain and the virulent Erdman strain, as well as with the corresponding sequences (identified in the databases) of strain H37Rv and the clinical isolate CSU93, revealed 100% identity. MTB32A, therefore, represents a candidate for inclusion in subunit vaccine development. Finally, the possible role of MTB32 serine proteases as a virulence factor(s) duringMycobacteriumspp. infection is discussed.
Roles of CD4+T Cells and Gamma Interferon in Protective Immunity againstBabesia microtiInfection in Mice
Authors: Igarashi Ikuo , Suzuki Reiko , Waki Seiji , Tagawa Yoh-Ichi , Seng Seyha , Tum Sothyra , Omata Yoshitaka , Saito Atsushi , Nagasawa Hideyuki , Iwakura Yohichiro , Suzuki Naoyoshi , Mikami Takeshi , Toyoda Yutaka 
Published: December 2019

ABSTRACTBabesia microtiproduces a self-limiting infection in mice, and recovered mice are resistant to reinfection. In the present study, the role of T cells in protective immunity against challenge infection was examined. BALB/c mice which recovered from primary infection showed strong protective immunity against challenge infection. In contrast, nude mice which failed to control the primary infection and were cured with an antibabesial drug did not show protection against challenge infection. Treatment of immune mice with anti-CD4 monoclonal antibody (MAb) diminished the protective immunity against challenge infection, but treatment with anti-CD8 MAb had no effect on the protection. Transfer of CD4+T-cell-depleted spleen cells resulted in higher parasitemia than transfer of CD8+T-cell-depleted spleen cells. A high level of gamma interferon (IFN-γ), which was produced by CD4+T cells, was observed for the culture supernatant of spleen cells from immune mice, and treatment of immune mice with anti-IFN-γ MAb partially reduced the protection. Moreover, no protection against challenge infection was found in IFN-γ-deficient mice. On the other hand, treatment of immune mice with MAbs against interleukin-2 (IL-2), IL-4, or tumor necrosis factor alpha did not affect protective immunity. These results suggest essential requirements for CD4+T cells and IFN-γ in protective immunity against challenge infection withB. microti.
Heat-Shocked Monocytes Are Resistant toStaphylococcus aureus-Induced Apoptotic DNA Fragmentation due to Expression of HSP72
Authors: Guzik Krzysztof , Bzowska Małgorzata , Dobrucki Jerzy , Pryjma Juliusz 
Published: December 2019

ABSTRACTHuman peripheral blood monocytes became apoptotic following phagocytosis ofStaphylococcus aureus. The consequences of heat stress for monocytes were studied with regard to the effect onS. aureus-induced apoptosis. Exposure of monocytes to 41.5°C for 1 h resulted in HSP72 expression and had no influence on phagocytosis of bacteria; moreover, phagocytosis ofS. aureusimmediately or shortly after heat shock had no effect on theS. aureus-induced monocyte apoptosis, as evidenced by DNA fragmentation assay. In contrast, cells which recovered from heat shock for 18 to 24 h, although active as phagocytes, were resistant to theS. aureus-induced apoptosis. The observed protective effect was related to the induction of HSP72, since blocking of HSP72 synthesis by an antisense oligomer abolished the protective effect of heat shock on bacterium-induced monocyte apoptosis.
Helicobacter pyloriInduces Gastric Epithelial Cell Apoptosis in Association with Increased Fas Receptor Expression
Authors: Jones Nicola L. , Day Andrew S. , Jennings Hilary A. , Sherman Philip M. 
Published: December 2019

ABSTRACTThe mechanisms involved in mediating the enhanced gastric epithelial cell apoptosis observed during infection withHelicobacter pyloriin vivo are unknown. To determine whetherH. pyloridirectly induces apoptosis of gastric epithelial cells in vitro and to define the role of the Fas-Fas ligand signal transduction cascade, human gastric epithelial cells were infected withH. pylorifor up to 72 h under microaerophilic conditions. As assessed by both transmission electron microscopy and fluorescence microscopy, incubation with acagA-positive,cagE-positive, VacA-positive clinicalH. pyloriisolate stimulated an increase in apoptosis compared to the apoptosis of untreated AGS cells (16.0% ± 2.8% versus 5.9% ± 1.4%,P< 0.05) after 72 h. In contrast, apoptosis was not detected following infection withcagA-negative,cagE-negative, VacA-negative clinical isolates or aCampylobacter jejunistrain. In addition to stimulating apoptosis, infection withH. pylorienhanced Fas receptor expression in AGS cells to a degree comparable to that of treatment with a positive control, gamma interferon (12.5 ng/ml) (148% ± 24% and 167% ± 24% of control, respectively). The enhanced Fas receptor expression was associated with increased sensitivity to Fas-mediated cell death. Ligation of the Fas receptor with an agonistic monoclonal antibody resulted in an increase in apoptosis compared to the apoptosis of cells infected with the bacterium alone (38.5% ± 7.1% versus 16.0% ± 2.8%,P< 0.05). Incubation with neutralizing anti-Fas antibody did not prevent apoptosis ofH. pylori-infected cells. Taken together, these findings demonstrate that the gastric pathogenH. pyloristimulates apoptosis of gastric epithelial cells in vitro in association with the enhanced expression of the Fas receptor. These data indicate a role for Fas-mediated signaling in the programmed cell death that occurs in response toH. pyloriinfection.
Identification of Genes Encoding Two-Component Lantibiotic Production in
Staphylococcus aureus
C55 and Other Phage Group II
S. aureus
Strains and Demonstration of an Association with the Exfoliative Toxin B Gene
Authors: Navaratna Maduwe A. D. B. , Sahl Hans-Georg , Tagg John R. 
Published: December 2019

ABSTRACT

The production of exfoliative toxin B (ET-B), but not ET-A, was shown to be specifically associated with production of a highly conserved two-component lantibiotic peptide system in phage group II
Staphylococcus aureus
. Two previously studied but incompletely characterized
S. aureus
bacteriocins, staphylococcins C55 and BacR1, were found to be members of this lantibiotic system, and considerable homology was also found with the two-component
Lactococcus lactis
bacteriocin, lacticin 3147.
sacαA
and
sacβA
, the structural genes of the lantibiotics staphylococcins C55α and C55β and two putative lantibiotic processing genes,
sacM1
and
sacT
, were localized together with the ET-B structural gene to a single 32-kb plasmid in strain C55. Irreversible loss of both ET-B and two-component lantibiotic production occurs during laboratory passage of ET-B-positive
S. aureus
strains, particularly at elevated temperatures.
Avirulence of
Candida albicans CaHK1
Mutants in a Murine Model of Hematogenously Disseminated Candidiasis
Authors: Calera José Antonio , Zhao Xiao-Jiong , De Bernardis Flavia , Sheridan Michael , Calderone Richard 
Published: December 2019

ABSTRACT

Deletion of both alleles of the
Candida albicans CaHK1
gene, which causes cells to flocculate when grown at pH 7.5, a pH comparable to that of mammalian blood, abolishes the ability of the yeast to establish a successful infection in a murine model of hematogenously disseminated candidiasis. Within 72 h all mice inoculated with the parental
C. albicans
strain had died. The mice infected with either the heterozygote or revertant strain, either of which harbors only one functional
CaHK1
allele, also succumbed to the infection, although survivors were observed for up to 16 days postinfection. However, mice inoculated with the
Δcahk1
null strain survived for the course of the infection. These results indicate that
CaHK1
is required for the virulence of
C. albicans
in a murine model of hematogenously disseminated candidiasis. In contrast,
CaHK1
is not required for the virulence of
C. albicans
in a rat model of vaginal candidiasis.