bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Bactericidal Immune Responses following Vaccination with Acellular Pertussis Vaccines in Adults
Authors: Weingart Christine L. , Keitel Wendy A. , Edwards Kathryn M. , Weiss Alison A. 
Published: July 2002

ABSTRACTSera from six adults, collected before and after acellular pertussis vaccination, and from a placebo control were examined for the ability to elicit two bactericidal immune defenses, (i) antibody-dependent complement-mediated bacterial lysis and (ii) opsonization and phagocytosis by human neutrophils. The samples were chosen based on low preimmunization titers and strong postimmunization responses to various combinations of vaccine antigens. All but two prevaccination samples demonstrated activity indicative of complement-mediated lysis. Preimmunization activity could have been due to prior infection or childhood immunization. Immunization did not result in improved bactericidal activity for any of the individuals, and in two cases immunization caused a statistically significant decrease in complement-mediated lysis. Similarly, opsonization with the postimmunization sera failed to enhance attachment or phagocytosis of bacteria by neutrophils, and one postimmunization sample with a strong response to filamentous hemagglutinin caused an inhibition of phagocytosis that was statistically significant compared to that observed for the no-serum control. In summary, booster immunization of adults with acellular pertussis vaccines was not found to increase bactericidal activity over preimmunization levels. Identifying ways to promote bactericidal immune responses might improve the efficacy of acellular pertussis vaccines.
Metalloprotease Activity in a Small Heat Shock Protein of the Human Malaria Parasite
Plasmodium vivax
Authors: Fakruddin J. Mohamed , Biswas Sukla , Sharma Yagya D. 
Published: July 2002

ABSTRACT

The malaria parasite affects millions of people each year, lives and multiplies in two different hosts, and synthesizes a large number of proteases and heat shock proteins (HSPs) for its survival. We describe here the characterization of a metalloprotease activity which resides in the small HSP (PVHSP28) of the common but noncultivable human malaria parasite
Plasmodium vivax
. The protein is expressed by erythrocytic stages of the parasite. It is expressed as a ∼55-kDa polypeptide which is then processed to the 28-kDa mature protein. The latter was found to be an active protease in gelatin zymography. This protease showed its optimal activity at 37°C (pH 7.6). It also retained its proteolytic activity at higher temperatures of up to 55°C. The enzyme belongs to the metalloprotease class, as its proteolytic activity was most effectively blocked by 1,10-phenanthroline and was restored to a maximal level by the addition of zinc metal ions. Inhibitors for the cysteine, serine, and aspartate classes of proteases were ineffective against this enzyme. A homology search indicates that PVHSP28 probably belongs to a new class of HSPs which possess the metalloprotease signature sequence.
Pathogenic Mycobacteria Disrupt the Macrophage Actin Filament Network
Authors: Guérin Isabelle , de Chastellier Chantal 
Published: July 2002

ABSTRACTPhagosomes with pathogenic mycobacteria retain fusion and intermingling characteristics of early endosomes indefinitely. The time course of acquisition of newly endocytosed tracers becomes, however, atypical (lag instead of immediate acquisition) starting from day 1 postinfection (p.i.), thereby suggesting that additional factors affect this process. Disruption of the actin filament (F-actin) network by cytochalasin D perturbs the movement of early endosomes and probably fusion events among early endosomes and phagosomes. Here we compare, by immunofluorescence microscopy, the morphology and distribution of F-actin in macrophages infected with virulentMycobacterium avium, in uninfected macrophages, or in macrophages after phagocytosis of nonpathogenic bacteria (Mycobacterium smegmatisorBacillus subtilis) or hydrophobic latex particles. In uninfected cells, F-actin appeared as a network of small filaments distributed throughout the cell; about 80% of the cells also displayed one or two small patches of F-actin at the cell periphery. VirulentM. aviumcaused a marked disorganization of the F-actin network starting from day 1 p.i. The most salient features were the formation of several large patches, the progressive disappearance of the small filaments, and the appearance of large numbers of tiny punctate structures starting from day 2 p.i. With the three other particles, the F-actin network was unmodified compared to that in uninfected cells. The atypical lag in acquisition of newly endocytosed tracers byM. avium-containing phagosomes, therefore, seems to coincide with the disorganization of the F-actin network.
Serum Immunoglobulin G (IgG) and IgG Subclass Responses to the RgpA-Kgp Proteinase-Adhesin Complex ofPorphyromonas gingivalisin Adult Periodontitis
Authors: O'Brien-Simpson Neil M. , Black Catherine L. , Bhogal Peter S. , Cleal Steven M. , Slakeski Nada , Higgins Thomas J. , Reynolds Eric C. 
Published: July 2002

ABSTRACTSerum immunoglobulin G (IgG), IgM, and IgG subclass responses to the RgpA-Kgp proteinase-adhesin complex ofPorphyromonas gingivaliswere examined by enzyme-linked immunosorbent assay using adult periodontitis patients and age- and sex-matched controls. Twenty-five sera from subjects with adult periodontitis (diseased group) and 25 sera from healthy subjects (control group) were used for the study. Sera and subgingival plaque samples from 10 sites were collected from each patient at the time of clinical examination. The level ofP. gingivalisin the plaque samples was determined using a DNA probe. Highly significant positive associations between the percentage of sites positive forP. gingivalisand measures of disease severity (mean pocket depth, mean attachment loss, and percentage of sites that bled on probing) were found. The diseased group had significantly higher specific IgG responses to the RgpA-Kgp complex than did the control group, and the responses were significantly associated with mean probing depths and percentage of sites positive forP. gingivalis. Analysis of the IgG subclass responses to the RgpA-Kgp complex revealed that the subclass distribution for both the diseased and control groups was IgG4 > IgG2 > IgG3 = IgG1. The IgG2 response to the complex was positively correlated with mean probing depth, whereas the IgG4 response was negatively correlated with this measure of disease severity. Immunoblot analysis of the RgpA-Kgp complex showed that sera from healthy subjects and those with low levels of disease, with high IgG4 and low IgG2 responses, reacted with the RgpA27, Kgp39, and RgpA44 adhesins; however, sera from diseased subjects with low IgG4 and high IgG2 responses reacted only with the RgpA44 and/or Kgp44 adhesins. Epitope mapping of the RgpA27 adhesin localized a major epitope recognized by IgG4 antibodies in sera from subjects with high IgG4 and low IgG2 responses to the RgpA-Kgp complex which was not recognized by sera from diseased subjects with low IgG4 and high IgG2 responses.
Passive Transfer of Antiserum Specific for Immunogens Derived from a Nontypeable
Haemophilus influenzae
Adhesin and Lipoprotein D Prevents Otitis Media after Heterologous Challenge
Authors: Kennedy Bobbie-Jo , Novotny Laura A. , Jurcisek Joseph A. , Lobet Yves , Bakaletz Lauren O. 
Published: July 2002

ABSTRACT

We recently determined that passive transfer of serum directed against a synthetic peptide called LB1 or a recombinant fusion protein immunogen [LPD-LB1(f)
2,1,3
] could prevent otitis media after challenge with a homologous nontypeable
Haemophilus influenzae
(NTHI) isolate. NTHI residing in the nasopharynx was rapidly cleared from this site, thus preventing it from ascending the eustachian tube and inducing otitis media in chinchillas compromised by an ongoing viral upper respiratory tract infection. While LB1 is based solely on one NTHI adhesin, the latter immunogen, LPD-LB1(f)
2,1,3
, was designed to incorporate two NTHI antigens shown to play a role in the pathogenesis of otitis media; lipoprotein D (LPD) and the P5-homologous fimbrin adhesin. The design of LPD-LB1(f)
2,1,3
also accommodated for the recently demonstrated existence of three major groupings, based on amino acid sequence diversity, in the third surface-exposed region of P5-fimbrin. LPD-LB1(f)
2,1,3
was thus designed to potentially confer broader protection against challenge by diverse strains of NTHI. Chinchillas were passively immunized here with serum specific for either LB1 or for LPD-LB1(f)
2,1,3
prior to challenge with a member of all three groups of NTHI relative to diversity in region 3. The transferred serum pools were also analyzed for titer, specificity, and several functional activities. We found that both serum pools had equivalent ability to mediate C′-dependent killing and to inhibit adherence of NTHI strains to human oropharyngeal cells. When passively transferred, both serum pools significantly inhibited the signs and incidence of otitis media (
P
≤ 0.01) induced by any of the three challenge isolates. Despite providing protection against disease, the ability of these antisera to induce total eradication of NTHI from the nasopharynx was not equivalent among NTHI groups. These data thus suggested that while early, complete eradication of NTHI from the nasopharynx was highly protective, reduction of the bacterial load to below a critical threshold level appeared to be similarly effective.
Identification of a Gene within a Pathogenicity Island of Enterotoxigenic
Escherichia coli
H10407 Required for Maximal Secretion of the Heat-Labile Enterotoxin
Authors: Fleckenstein James M. , Lindler Luther E. , Elsinghorst Eric A. , Dale James B. 
Published: July 2002

ABSTRACT

Studies of the pathogenesis of enterotoxigenic
Escherichia coli
(ETEC) have largely centered on extrachromosomal determinants of virulence, in particular the plasmid-encoded heat-labile (LT) and heat-stable enterotoxins and the colonization factor antigens. ETEC causes illnesses that range from mild diarrhea to severe cholera-like disease. These differences in disease severity are not readily accounted for by our current understanding of ETEC pathogenesis. Here we demonstrate that Tia, a putative adhesin of ETEC
H10407
, is encoded on a large chromosomal element of approximately 46 kb that shares multiple features with previously described
E. coli
pathogenicity islands. Further analysis of the region downstream from
tia
revealed the presence of several candidate open reading frames (ORFs) in the same transcriptional orientation as
tia
. The putative proteins encoded by these ORFs bear multiple motifs associated with bacterial secretion apparatuses. An in-frame deletion in one candidate gene identified here as
leoA
(labile enterotoxin output) resulted in marked diminution of secretion of the LT enterotoxin and lack of fluid accumulation in a rabbit ileal loop model of infection. Although previous studies have suggested that
E. coli
lacks the capacity to secrete LT, our studies show that maximal release of LT from the periplasm of
H10407
is dependent on one or more elements encoded on a pathogenicity island.
Antigenic Equivalence of Human T-Cell Responses to
Mycobacterium tuberculosis
-Specific RD1-Encoded Protein Antigens ESAT-6 and Culture Filtrate Protein 10 and to Mixtures of Synthetic Peptides
Authors: Arend Sandra M. , Geluk Annemieke , van Meijgaarden Krista E. , van Dissel Jaap T. , Theisen Michael , Andersen Peter , Ottenhoff Tom H. M. 
Published: July 2002

ABSTRACT

The early secreted antigenic target 6-kDa protein (ESAT-6) and culture filtrate protein 10 (CFP-10) are promising antigens for reliable immunodiagnosis of tuberculosis. Both antigens are encoded by RD1, a genomic region present in all strains of
Mycobacterium tuberculosis
and
M. bovis
but lacking in all
M. bovis
bacillus Calmette-Guérin vaccine strains. Production and purification of recombinant antigens are laborious and costly, precluding rapid and large-scale testing. Aiming to develop alternative diagnostic reagents, we have investigated whether recombinant ESAT-6 (rESAT-6) and recombinant CFP-10 (rCFP-10) can be replaced with corresponding mixtures of overlapping peptides spanning the complete amino acid sequence of each antigen. Proliferation of
M. tuberculosis
-specific human T-cell lines in response to rESAT-6 and rCFP-10 and that in response to the corresponding peptide mixtures were almost completely correlated (
r
= 0.96,
P
< 0.0001 for ESAT-6;
r
= 0.98,
P
< 0.0001 for CFP-10). More importantly, the same was found when gamma interferon production by peripheral blood mononuclear cells in response to these stimuli was analyzed (
r
= 0.89,
P
< 0.0001 for ESAT-6;
r
= 0.89,
P
< 0.0001 for CFP-10). Whole protein antigens and the peptide mixtures resulted in identical sensitivity and specificity for detection of infection with
M. tuberculosis
. The peptides in each mixture contributing to the overall response varied between individuals with different HLA-DR types. Interestingly, responses to CFP-10 were significantly higher in the presence of HLA-DR15, which is the major subtype of DR2. These results show that mixtures of synthetic overlapping peptides have potency equivalent to that of whole ESAT-6 and CFP-10 for sensitive and specific detection of infection with
M. tuberculosis
, and peptides have the advantage of faster production at lower cost.
Investigation of the Role of Type IV
Aeromonas
Pilus (Tap) in the Pathogenesis of
Aeromonas
Gastrointestinal Infection
Authors: Kirov Sylvia M. , Barnett Timothy C. , Pepe Cynthia M. , Strom Mark S. , Albert M. John 
Published: July 2002

ABSTRACT

Although there is substantial evidence that type IV pili purified from diarrhea-associated
Aeromonas
species (designated Bfp for bundle-forming pilus) are intestinal colonization factors (S. M. Kirov, L. A. O'Donovan, and K. Sanderson, Infect. Immun. 67:5447–5454, 1999), nothing is known regarding the function of a second family of
Aeromonas
type IV pili (designated Tap for type IV
Aeromonas
pilus), identified following the cloning of a pilus biogenesis gene cluster
tapABCD
. Related pilus gene clusters are widely conserved among gram-negative bacteria, but their significance for virulence has been controversial. To investigate the role of Tap pili in
Aeromonas
pathogenesis, mutants of
Aeromonas
strains (a fish isolate of
A. hydrophila
and a human dysenteric isolate of
A. veronii
bv. sobria) were prepared by insertional inactivation of the
tapA
gene which encodes the type IV pilus subunit protein, TapA. Exotoxic activities were unaffected by the mutation in
tapA
. Inactivation of
tapA
had no effect on the bacterial adherence of these two isolates to HEp-2 cells. For the
A. veronii
bv. sobria isolate, adhesion to Henle 407 intestinal cells and to human intestinal tissue was also unaffected. There was no significant effect on the duration of colonization or incidence of diarrhea when the
A. veronii
bv. sobria strain was tested in the removable intestinal tie adult rabbit diarrhea model or on its ability to colonize infant mice. Evidence was obtained that demonstrated that TapA was expressed by both
Aeromonas
species and was present on the cell surface, although if assembled into pili this pilus type appears to be an uncommon one under standard bacterial growth conditions. Further studies into factors which may influence Tap expression are required, but the present study suggests that Tap pili may not be as significant as Bfp pili for
Aeromonas
intestinal colonization.
Comparative Genomics ofHelicobacter pylori: Analysis of the Outer Membrane Protein Families
Authors: Alm Richard A. , Bina James , Andrews Beth M. , Doig Peter , Hancock Robert E. W. , Trust Trevor J. 
Published: July 2002

ABSTRACTThe two complete genomic sequences ofHelicobacter pyloriJ99 and 26695 were used to compare the paralogous families (related genes within one genome, likely to have related function) of genes predicted to encode outer membrane proteins which were present in each strain. We identified five paralogous gene families ranging in size from 3 to 33 members; two of these families contained members specific for eitherH. pyloriJ99 orH. pylori26695. Most orthologous protein pairs (equivalent genes between two genomes, same function) shared considerable identity between the two strains. The unusual set of outer membrane proteins and the specialized outer membrane may be a reflection of the adaptation ofH. pylorito the unique gastric environment where it is found. One subfamily of proteins, which contains both channel-forming and adhesin molecules, is extremely highly related at the sequence level and has likely arisen due to ancestral gene duplication. In addition, the largest paralogous family contained two essentially identical pairs of genes in both strains. The presence and genomic organization of these two pairs of duplicated genes were analyzed in a panel of independentH. pyloriisolates. While one pair was present in every strain examined, one allele of the other pair appeared partially deleted in several isolates.
Purification of Protease from a Mixture of Exfoliative Toxin and Newborn-Mouse Epidermis
Authors: Ninomiya Junya , Ito Yayoi , Takiuchi Iwao 
Published: July 2002

ABSTRACT
Although the role of exfoliative toxin in staphylococcal scalded-skin syndrome has been suggested to be that of a serine protease, it has not been demonstrated to show proteolytic activity. Our purpose was to purify a proteolytic enzyme from a mixture of exfoliative toxin and newborn-mouse epidermis. We used gel filtration and ion-exchange and hydroxyapatite chromatography with a high-pressure liquid chromatography system. A casein-hydrolyzing enzyme was isolated from the mixture. The molecular mass of the enzyme was confirmed to be 20 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Subcutaneous injection of the purified enzyme into newborn mice reproduced the epidermal splitting that is seen in staphylococcal scalded-skin syndrome. These results suggest that exfoliative toxin does not work as a protease itself but that some reaction between exfoliative toxin and an epidermal component(s) first produces a protease, after which epidermal splitting occurs.
Soluble CD14 Enhances Membrane CD14-Mediated Responses to Peptidoglycan: Structural Requirements Differ from Those for Responses to Lipopolysaccharide
Authors: Dziarski Roman , Viriyakosol Suganya , Kirkland Theo N. , Gupta Dipika 
Published: July 2002

ABSTRACTThe purpose of this study was to identify the functional significance of the binding of soluble CD14 (sCD14) to bacterial peptidoglycan (PGN) and to compare the structural requirements of sCD14 for the binding to PGN and lipopolysaccharide (LPS) and for sCD14-mediated enhancement of PGN- and LPS-induced cell responses. sCD14 did not facilitate the responses of membrane CD14 (mCD14)-negative pre-B 70Z/3 cells to PGN, although it facilitated the responses of these cells to LPS and although mCD14 facilitated the responses of 70Z/3 cells to PGN. sCD14 enhanced mCD14-mediated cell activation by both PGN and LPS, but only the responses to LPS, and not to PGN, were enhanced by LPS-binding protein. Four 4- or 5-amino-acid-long sequences within the 65-amino-acid N-terminal region of sCD14 were needed for binding to both PGN and LPS and for enhancement of cell activation by both PGN and LPS. However, deletions of individual sequences had different effects on the ability of sCD14 to bind to PGN and to LPS and on the ability to enhance the responses to PGN and to LPS. Thus, there are different structural requirements of sCD14 for binding to PGN and to LPS and for the enhancement of PGN- and LPS-induced cell activation.
Cytokine Responses toTreponema pectinovorumandTreponema denticolain Human Gingival Fibroblasts
Authors: Nixon Connie S. , Steffen Michelle J. , Ebersole Jeffrey L. 
Published: July 2002

ABSTRACTHuman gingival fibroblasts were challenged withTreponema pectinovorumandTreponema denticolato test three specific hypotheses: (i) these treponemes induce different cytokine profiles from the fibroblasts, (ii) differences in cytokine profiles are observed after challenge with live versus killed treponemes, and (iii) differences in cytokine profiles are noted from different gingival fibroblast cell lines when challenged with these treponemes. Three normal gingival fibroblast cell cultures were challenged withT. pectinovorumandT. denticolastrains, and the supernatants were analyzed for cytokine production (i.e., interleukin-1α [IL-1α], IL-1β, IL-6, IL-8, IL-10, gamma interferon, macrophage chemotactic protein 1 [MCP-1], platelet-derived growth factor, tumor necrosis factor alpha, and granulocyte-macrophage colony-stimulating factor). Unstimulated fibroblast cell lines produced IL-6, IL-8, and MCP-1.T. pectinovorumroutinely elicited the greatest production of these cytokines from the fibroblast cell lines, increasing 10- to 50-fold over basal production. WhileT. denticolaalso induced IL-6 and IL-8 production, these levels were generally lower than those elicited by challenge withT. pectinovorum. MCP-1 levels were significantly lower afterT. denticolachallenge, and the kinetics suggested that this microorganism actually inhibited basal production by the fibroblasts. No basal or stimulated production of the other cytokines was observed. Significant differences were noted in the responsiveness of the various cell lines with respect to the two species of treponemes and the individual cytokines produced. Finally, deadT. pectinovorumgenerally induced a twofold-greater level of IL-6 and IL-8 than the live bacteria. These results supported the idea that different species of oral treponemes can elicit proinflammatory cytokine production by gingival cells and that this stimulation did not require live microorganisms. Importantly, a unique difference was noted in the ability ofT. pectinovorumto induce a robust MCP-1 production, whileT. denticolaappeared to inhibit this activity of the fibroblasts. While the general cytokine profiles of the fibroblast cell cultures were similar, significant differences were noted in the quantity of individual cytokines produced, which could relate to individual patient variation in local inflammatory responses in the periodontium.
Immunity againstHelicobacter pylori: Significance of Interleukin-4 Receptor α Chain Status and Gender of Infected Mice
Authors: Aebischer Toni , Laforsch Stephanie , Hurwitz Robert , Brombacher Frank , Meyer Thomas F. 
Published: July 2002

ABSTRACTVaccination of interleukin-4 (IL-4) receptor α (IL-4Rα) chain-deficient BALB/c mice withHelicobacter pyloriurease and cholera toxin or with urease-expressing, live attenuatedSalmonella entericaserovar Typhimurium cells revealed that protection againstH. pyloriinfection is independent of IL-4- or IL-13-mediated signals. A comparison of male and female mice suggests a sexual dimorphism in the extent of bacterial colonization that is particularly evident in the absence of the IL-4Rα chain.
Essential Role for Estrogen in Protection against
Vibrio vulnificus
-Induced Endotoxic Shock
Authors: Merkel Sandra M. , Alexander Sarah , Zufall Eric , Oliver James D. , Huet-Hudson Yvette M. 
Published: July 2002

ABSTRACT

Little is known about the underlying mechanisms that result in a sexually dimorphic response to
Vibrio vulnificus
endotoxic shock.
V. vulnificus
is a gram-negative bacterium, considered one of the most invasive and rapidly fatal human pathogens known. However, 85% of individuals that develop endotoxic shock from
V. vulnificus
are males. Using the rat, we have developed a model for
V. vulnificus
endotoxic shock that mimics the sexually dimorphic response in humans. Gonadectomy in females results in increased mortality, and estrogen replacement results in decreased mortality in both gonadectomized males and females. These results demonstrate that estrogen is providing protection against
V. vulnificus
lipopolysaccharide-induced endotoxic shock.