bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immune Destruction of LarvalTaenia crassicepsin Mice
Authors: Mooney K. A. , Spolski R. J. , See E. J. , Kuhn R. E. 
Published: July 2002

ABSTRACTImmune destruction of larvalTaenia crassicepswas examined by first injecting BALB/cJ mice subcutaneously with larval buds and 30 to 60 days later challenging the mice with larvae injected into the peritoneal cavity. The larvae injected intraperitoneally (i.p.) secondarily are killed by host cells that completely encase the larvae in a thick sheath. The peritoneal exudate cells and the cytokines they produced were characterized by flow cytometry, enzyme-linked immunosorbent assays (ELISAs), and reverse transcription PCR (RT-PCR). No changes in percentage of CD4+T cells, CD8+T cells, B1 cells, or macrophages were detected in the peritoneal cavities of mice that were killing larvae compared to mice with a primary 7-day infection i.p. Both RT-PCR and ELISA demonstrated a decrease in cytokines including gamma interferon (IFN-γ), interleukin-4 (IL-4), and IL-10 in mice that were killing the larvae compared to control mice infected for 30 to 60 days i.p. alone, although there was little difference compared to mice infected for 7 days i.p. alone. Serum cytokine levels in mice that were killing the larvae showed a decrease in IFN-γ and IL-4, an increase in IL-10 when compared to mice infected for 30 to 60 days i.p. alone, and increases in all cytokines compared to mice infected for 7 days i.p. alone. Inhibition of nitric oxide production did not significantly affect the number or the viability of larvae in the peritoneal cavity of mice that were killing larvae during secondary infection.
Characterization of an Isogenic Mutant of
Streptococcus pyogenes
Manfredo Lacking the Ability To Make Streptococcal Acid Glycoprotein
Authors: Degnan B. A. , Fontaine M. C. , Doebereiner A. H. , Lee J. J. , Mastroeni P. , Dougan G. , Goodacre J. A. , Kehoe M. A. 
Published: July 2002

ABSTRACT

An isogenic mutant of
Streptococcus pyogenes
Manfredo that lacks the ability to make streptococcal acid glycoprotein (SAGP) has been constructed by inserting a deletion in the
sagp
gene using the method of allelic exchange. An assay of cell extracts (CE) prepared from the wild-type and mutant Manfredo strains for the enzyme arginine deiminase (AD) showed that significant activity was present in wild-type CE but none could be detected in mutant CE. These findings confirm our earlier conclusion that SAGP has AD activity (B. A. Degnan, J. M. Palmer, T. Robson, C. E. D. Jones, M. Fischer, M. Glanville, G. D. Mellor, A. G. Diamond, M. A. Kehoe, and J. A. Goodacre, Infect. Immun. 66:3050–3058, 1998). Wild-type CE but not mutant CE potently inhibited human peripheral blood mononuclear cell proliferation in response to phytohemagglutinin, and this inhibition was overcome by the addition of
l
-arginine to proliferation assay mixtures. Invasion assays showed that the isogenic mutant organisms lacking SAGP, and thus AD activity, were between three and five times less able to enter epithelial cells (Hep-2C and A549) than were the wild-type streptococci. Both wild-type and mutant
S. pyogenes
bacteria were extremely sensitive to low pH. However,
l
-arginine (1 mM or above) significantly increased the viability of the wild type but not the isogenic mutant organisms under acidic conditions. The difference in acid susceptibility between wild-type and mutant bacteria may explain the reduced capacity of the isogenic mutant bacteria to invade and survive intracellularly.
Characterization of Binding of
Candida albicans
to Small Intestinal Mucin and Its Role in Adherence to Mucosal Epithelial Cells
Authors: de Repentigny Louis , Aumont Francine , Bernard Karine , Belhumeur Pierre 
Published: July 2002

ABSTRACT

In order to approximate and adhere to mucosal epithelial cells,
Candida
must traverse the overlying mucus layer. Interactions of
Candida
species with mucin and human buccal epithelial cells (BECs) were thus investigated in vitro. Binding of the
Candida
species to purified small intestinal mucin showed a close correlation with their hierarchy of virulence. Significant differences (
P
< 0.05) were found among three categories of
Candida
species adhering highly (
C. dubliniensis
,
C. tropicalis
, and
C. albicans
), moderately (
C. parapsilosis
and
C. lusitaniae
) or weakly (
C. krusei
and
C. glabrata
) to mucin. Adherence of
C. albicans
to BECs was quantitatively inhibited by graded concentrations of mucin. However, inhibition of adherence was reversed by pretreatment of mucin with pronase or
C. albicans
secretory aspartyl proteinase Sap2p but not with sodium periodate. Saturable concentration- and time-dependent binding of mucin to
C. albicans
was abrogated by pronase or Sap2p treatment of mucin but was unaffected by β-mercaptoethanol, sodium periodate, neuraminidase, lectins, or potentially inhibitory sugars. Probing of membrane blots of the mucin with
C. albicans
revealed binding of the yeast to the 66-kDa cleavage product of the 118-kDa C-terminal glycopeptide of mucin. Although no evidence was found for the participation of
C. albicans
cell surface mannoproteins in specific receptor-ligand binding to mucin, inhibition of binding by
p
-nitrophenol (1 mM) and tetramethylurea (0.36 M) revealed that hydrophobic interactions are involved in adherence of
C. albicans
to mucin. These results suggest that
C. albicans
may both adhere to and enzymatically degrade mucins by the action of Saps, and that both properties may act to modulate
Candida
populations in the oral cavity and gastrointestinal tract.
Induction of a Polarized Th1 Response by Insertion of Multiple Copies of a Viral T-Cell Epitope into Adenylate Cyclase ofBordetella pertussis
Authors: Dadaglio Gilles , Moukrim Zhora , Lo-Man Richard , Sheshko Valeria , Sebo Peter , Leclerc Claude 
Published: July 2002

ABSTRACTThe adenylate cyclase (CyaA) ofBordetella pertussisdelivers the N-terminal catalytic domain into the cytosol of a large number of eukaryotic cells, in particular, professional antigen-presenting cells. This allows the delivery of CD8+T-cell epitopes to the major histocompatibility complex class I presentation pathway. We have previously shown that immunization of mice with CyaA carrying a single CD8+T-cell epitope leads to antiviral protection as well as to protective and therapeutic antitumor immunity associated with the induction of specific cytotoxic T-lymphocyte (CTL) responses. Here, we evaluated the capacity of CyaA carrying one to four copies of the CD8+CD4+T-cell epitope from the nucleoprotein of the lymphocytic choriomeningitis virus to induce T-cell responses. Both CTL and Th1-like specific responses were detected in mice immunized with recombinant CyaA with or without adjuvant. Although the insertion of the larger peptides resulted in partial loss of the invasive capacity of recombinant CyaA, insertion of several copies of the same epitope led to a strong enhancement of Th1 responses and, to a lesser degree, CTL responses. These results underscore the potency of CyaA for vaccine design with a new impact on diseases in which the Th1 response has been described to have a beneficial effect.
Involvement of a Plasmid in Virulence of
Campylobacter jejuni
81-176
Authors: Bacon David J. , Alm Richard A. , Burr Don H. , Hu Lan , Kopecko Dennis J. , Ewing Cheryl P. , Trust Trevor J. , Guerry Patricia 
Published: July 2002

ABSTRACT

Campylobacter jejuni
strain 81-176 contains two, previously undescribed plasmids, each of which is approximately 35 kb in size. Although one of the plasmids, termed pTet, carries a
tetO
gene, conjugative transfer of tetracycline resistance to another strain of
C. jejuni
could not be demonstrated. Partial sequence analysis of the second plasmid, pVir, revealed the presence of four open reading frames which encode proteins with significant sequence similarity to
Helicobacter pylori
proteins, including one encoded by the
cag
pathogenicity island. All four of these plasmid-encoded proteins show some level of homology to components of type IV secretion systems. Mutation of one of these plasmid genes,
comB3
, reduced both adherence to and invasion of INT407 cells to approximately one-third that seen with wild-type strain 81-176. Mutation of
comB3
also reduced the natural transformation frequency. A mutation in a second plasmid gene, a
virB11
homolog, resulted in a 6-fold reduction in adherence and an 11-fold reduction in invasion compared to the wild type. The isogenic
virB11
mutant of strain 81-176 also demonstrated significantly reduced virulence in the ferret diarrheal disease model. The
virB11
homolog was detected on plasmids in 6 out of 58 fresh clinical isolates of
C. jejuni
, suggesting that plasmids are involved in the virulence of a subset of
C. jejuni
pathogens.
Growth ofMycobacterium tuberculosisin a Defined Medium Is Very Restricted by Acid pH and Mg2+Levels
Authors: Piddington Debra L. , Kashkouli Ali , Buchmeier Nancy A. 
Published: July 2002

ABSTRACTMycobacterium tuberculosisgrows within the phagocytic vacuoles of macrophages, where it encounters a moderately acidic and possibly nutrient-restricted environment. Other mycobacterial species encounter acidic conditions in soil and aquatic environments. We have evaluated the influence of pH and divalent cation levels on the growth ofM. tuberculosisand seven other mycobacterial species. In a defined medium, the growth ofM. tuberculosiswas very restricted by acidic pH. Higher levels of Mg2+were required for growth ofM. tuberculosisin mildly acidic media (pH 6.0 to 6.5) compared to pH 7.0 medium. The divalent cations Ca2+, Zn2+, or Mn2+could not replace Mg2+during growth at pH 6.25, but Ca2+could at least partially substitute for Mg2+during growth at pH 7.0. Among eight species of mycobacteria tested, there was a diversity of growth rates in media with acidic pH and low Mg2+levels.M. tuberculosiswas the most restricted in growth at pH 6.0, and all of this growth required elevated levels of Mg2+.M. kansasiiandM. smegmatisalso grew very poorly in acidic media with limiting Mg2+.M. fortuitum,M. marinum,M. scrofulaceum,M. avium, andM. chelonaegrew at pH 6.0 in an unrestricted manner. These results demonstrate thatM. tuberculosisis unique among the mycobacteria in its extreme sensitivity to acid and indicate thatM. tuberculosismust acquire sufficient Mg2+in order to grow in a mildly acidic environment such as within the phagosome of macrophages.
Novel Apoptosis-Inducing Activity in
Bacteroides forsythus
: a Comparative Study with Three Serotypes of
Actinobacillus actinomycetemcomitans
Authors: Arakawa Shinichi , Nakajima Takuma , Ishikura Hiroaki , Ichinose Shizuko , Ishikawa Isao , Tsuchida Nobuo 
Published: July 2002

ABSTRACT

Bacteroides forsythus
, which has been reported to be associated with periodontitis but has not been recognized as a key pathogen, was found to induce cytolytic activity against HL-60 and other human leukemic cells. This cytolytic activity was demonstrated according to three different criteria: (i) loss of both mitochondrial membrane potential and membrane integrity in cells treated with bacterial extracts and then with Rh123 and propidium iodide, respectively, as demonstrated by flow cytometry; (ii) damage to cytoplasmic membrane, as revealed by scanning electron microscopy (SEM); and (iii) DNA ladder formation and activation of caspase-3. These results indicate that
B. forsythus
produced an apoptosis-inducing factor(s) found to be composed of protein as judged by heat and trypsin sensitivity. In addition to extracts from
B. forsythus
, the culture supernatant of this bacterium has the ability to induce a cytolytic effect against peripheral white blood cells, especially lymphocytes. For comparison with
B. forsythus
, the same analyses were applied to two strains with different serotypes of
Actinobacillus actinomycetemcomitans
, serotypes a (ATCC 43717) and c (ATCC 43719), in addition to previously reported apoptosis-inducing serotype b (ATCC 43718), which was used as a positive control. The strains of
A. actinomycetemcomitans
serotypes a and b induced apoptosis in HL-60 cells as judged by the above three criteria but to a slightly lesser extent than did
B. forsythus
, while the serotype c strain produced apoptosis to a negligible extent. Detailed SEM images showed that the
A. actinomycetemcomitans
serotype a strain induced large-pore formation and the serotype b strain produced small pores with typical blebbing, while
B. forsythus
induced severe membrane ruffling. Further DNA ladder formation and caspase-3 activation were observed in the serotype a and b strains but not in the serotype c strain. The present paper is the first report of a protein factor(s) from
B. forsythus
and the
A. actinomycetemcomitans
serotype a strain which induces apoptotic cell death.
Identification of Saliva-Regulated Genes of
Streptococcus gordonii
DL1 by Differential Display Using Random Arbitrarily Primed PCR
Authors: Dû Laurence D. , Kolenbrander Paul E. 
Published: July 2002

ABSTRACT

Attachment of
Streptococcus gordonii
to the acquired pellicle of the tooth surface involves specific interactions between bacterial adhesins and adsorbed salivary components. To study saliva-regulated gene expression in
S. gordonii
, we used random arbitrarily primed PCR (RAP-PCR). Bacteria were incubated in either brain heart infusion medium or saliva. Total RNA from both conditions was purified and RAP fingerprinted and then PCR amplified with an arbitrary primer. The differentially displayed DNA fragments were cloned, sequenced, and analyzed using the BLAST search network service. Three DNA products were up-regulated. One was identified as that of the
sspA
and -
B
genes, which encode the salivary agglutinin glycoprotein-binding proteins SspA and SspB of
S. gordonii
; another had 79% identity with the
Lactococcus lactis clpE
gene, encoding a member of the Clp protease family; and the third product showed no significant homology to known genes. Five down-regulated genes were identified which encode proteins involved in bacterial metabolism. We have shown, for the first time, direct induction of
sspA
and -
B
in
S. gordonii
by human saliva.
In Vivo Genetic Analysis Indicates That PhoP-PhoQ and the
Salmonella
Pathogenicity Island 2 Type III Secretion System Contribute Independently to
Salmonella enterica
Serovar Typhimurium Virulence
Authors: Beuzón Carmen R. , Unsworth Kate E. , Holden David W. 
Published: July 2002

ABSTRACT

Many virulence factors are required for
Salmonella enterica
serovar Typhimurium to replicate intracellularly and proliferate systemically within mice. In this work, we have carried out genetic analyses in vivo to determine the functional relationship between two major virulence factors necessary for systemic infection by
S. enterica
serovar Typhimurium: the
Salmonella
pathogenicity island 2 (SPI-2) type III secretion system (TTSS) and the PhoP-PhoQ two-component regulatory system. Although previous work suggested that PhoP-PhoQ regulates SPI-2 TTSS gene expression in vitro, in vivo competitive analysis of mutant strains indicates that these systems contribute independently to
S. typhimurium
virulence. Our results also suggest that mutation of
phoP
may compensate partially for defects in the SPI-2 TTSS by deregulating SPI-1 TTSS expression. These results provide an explanation for previous reports showing an apparent functional overlap between these two systems in vitro.
Synergistic Effects of Alpha-Toxin and Perfringolysin O in
Clostridium perfringens
-Mediated Gas Gangrene
Authors: Awad Milena M. , Ellemor Darren M. , Boyd Richard L. , Emmins John J. , Rood Julian I. 
Published: July 2002

ABSTRACT

To examine the synergistic effects of alpha-toxin and perfringolysin O in clostridial myonecrosis, homologous recombination was used to construct an alpha-toxin deficient derivative of a perfringolysin O mutant of
Clostridium perfringens
. The subsequent strain was complemented with separate plasmids that carried the alpha-toxin structural gene (
plc)
, the perfringolysin O gene (
pfoA
), or both toxin genes, and the resultant isogenic strains were examined in a mouse myonecrosis model. Synergistic effects were clearly observed in these experiments. Infection with the control strain, which did not produce either toxin, resulted in very minimal gross pathological changes, whereas the isogenic strain that was reconstituted for both toxins produced a pathology that was clearly more severe than when alpha-toxin alone was reconstituted. These changes were most apparent in the rapid spread of the disease, the gross pathology of the footpad and in the rate at which the mice had to be euthanatized for ethical reasons. Elimination of both alpha-toxin and perfringolysin O production removed most of the histopathological features typical of clostridial myonecrosis. These effects were restored when the mutant was complemented with the alpha-toxin structural gene, but reconstituting only perfringolysin O activity produced vastly different results, with regions of coagulative necrosis, apparently enhanced by vascular disruption, being observed. Reconstitution of both alpha-toxin and perfringolysin O activity produced histopathology most similar to that observed with the alpha-toxin reconstituted strain. The spreading of myonecrosis was very rapid in these tissues, and coagulative necrosis appeared to be restricted to the lumen of the blood vessels. The results of these virulence experiments clearly support the hypothesis that alpha-toxin and perfringolysin O have a synergistic effect in the pathology of gas gangrene.
Innate Resistance toBabesiaInfection Is Influenced by Genetic Background and Gender
Authors: Aguilar-Delfin Irma , Homer Mary J. , Wettstein Peter J. , Persing David H. 
Published: July 2002

ABSTRACTInfection of severe combined immunodeficient mice withBabesiasp. strain WA1 was studied to assess the contributions of innate and adaptive immunity in resistance to acute babesiosis. Thescidmutation showed little effect in genetically susceptible C3H mice and did not decrease the inherent resistance of C57BL/6 mice to the infection, suggesting that innate immunity plays a central role in determining the course ofBabesiainfection in these strains. In contrast, thescidmutation dramatically impaired resistance in moderately susceptible BALB/c mice, suggesting that acquired immunity may play an important secondary role. In comparison to their female counterparts, male mice of different genetic backgrounds showed increased resistance to the infection, indicating that the gender of the host may influence protection against babesiosis.
Ammonia as an Accelerator of Tumor Necrosis Factor Alpha-Induced Apoptosis of Gastric Epithelial Cells in
Helicobacter pylori
Infection
Authors: Igarashi Muneki , Kitada Yukie , Yoshiyama Hironori , Takagi Atsushi , Miwa Takeshi , Koga Yasuhiro 
Published: July 2002

ABSTRACT

The mechanism by which
Helicobacter pylori
induces apoptosis remains unclear. In a previous study using biopsy samples, we found a significant correlation between the urease activity of an
H. pylori
strain and the apoptosis level induced by this strain. Therefore, in this study, we investigated whether urease and/or the ammonia generated by urease can induce apoptosis. Human gastric epithelial cell lines were cocultured with
H. pylori
, and the levels of apoptosis and ammonia production were measured. The medium was supplemented (or not supplemented) with urea and cytokines. While a large amount of ammonia (>30 mM) accumulated in the coculture containing urease-positive
H. pylori
and urea, no significant degree of apoptosis occurred. In the presence of tumor necrosis factor alpha (TNF-α), however, a marked acceleration of apoptosis was found in this coculture. Such enhancement of apoptosis was also induced by the addition of 4 to 8 mM ammonia to the cell culture without either
H. pylori
or urea but containing TNF-α. These results suggested that ammonia accelerates cytokine-induced apoptosis in gastric epithelial cells, while ammonia or urease molecules alone are unable to induce a significant degree of apoptosis.
Interleukin-8 and Intercellular Adhesion Molecule 1 Regulation in Oral Epithelial Cells by Selected Periodontal Bacteria: Multiple Effects ofPorphyromonas gingivalisvia Antagonistic Mechanisms
Authors: Huang George T.-J. , Kim Daniel , Lee Jonathan K.-H. , Kuramitsu Howard K. , Haake Susan Kinder 
Published: July 2002

ABSTRACTInteraction of bacteria with mucosal surfaces can modulate the production of proinflammatory cytokines and adhesion molecules produced by epithelial cells. Previously, we showed that expression of interleukin-8 (IL-8) and intercellular adhesion molecule 1 (ICAM-1) by gingival epithelial cells increases following interaction with several putative periodontal pathogens. In contrast, expression of IL-8 and ICAM-1 is reduced afterPorphyromonas gingivalisATCC 33277 challenge. In the present study, we investigated the mechanisms that govern the regulation of these two molecules in bacterially infected gingival epithelial cells. Experimental approaches included bacterial stimulation of gingival epithelial cells by either a brief challenge (1.5 to 2 h) or a continuous coculture throughout the incubation period. The kinetics of IL-8 and ICAM-1 expression following brief challenge were such that (i) secretion of IL-8 by gingival epithelial cells reached its peak 2 h followingFusobacterium nucleatuminfection whereas it rapidly decreased within 2 h afterP. gingivalisinfection and remained decreased up to 30 h and (ii) IL-8 and ICAM-1 mRNA levels were up-regulated rapidly 2 to 4 h postinfection and then decreased to basal levels 8 to 20 h after infection with eitherActinobacillus actinomycetemcomitans,F. nucleatum, orP. gingivalis. Attenuation of IL-8 secretion was facilitated by adherentP. gingivalisstrains. The IL-8 secreted from epithelial cells afterF. nucleatumstimulation could be down-regulated by subsequent infection withP. gingivalisor its culture supernatant. Although these results suggested that IL-8 attenuation at the protein level might be associated withP. gingivalisproteases, the Arg- and Lys-gingipain proteases did not appear to be solely responsible for IL-8 attenuation. In addition, whileP. gingivalisup-regulated IL-8 mRNA expression, this effect was overridden when the bacteria were continuously cocultured with the epithelial cells. The IL-8 mRNA levels in epithelial cells following sequential challenge withP. gingivalisandF. nucleatumand vice versa were approximately identical and were lower than those followingF. nucleatumchallenge alone and higher than control levels or those followingP. gingivalischallenge alone. Thus, together with the protease effect,P. gingivalispossesses a powerful strategy to ensure the down-regulation of IL-8 and ICAM-1.