bluuebunny/crossref_metadata_2025_split huggingface dataset:
Specific Serum Immunoglobulin G Response to Urease and CagA Antigens of
Helicobacter pylori
in Infected Children and Adults in a Country with High Prevalence of Infection
Authors: Torres Javier , Camorlinga-Ponce Margarita , Perez-Perez Guillermo , Muñoz Leopoldo , Muñoz Onofre 
Published: July 2002

ABSTRACT

Few studies have analyzed the immune response to
Helicobacter pylori
CagA and urease antigens across age groups in the same population. The aim of this study was to analyze the serologic immunoglobulin G (IgG) response to CagA and urease proteins in children and adults with gastrointestinal symptoms and belonging to the same population and similar socioeconomic levels. The serologic response was studied in 352 children and 293 adults with gastrointestinal symptoms. IgG antibodies against CagA and urease were tested by enzyme-linked immunosorbent assay methods using highly purified recombinant antigens.
H. pylori
infection was defined as a positive result in a serologic assay using whole-cell
H. pylori
extracts as the antigen. We found, in
H. pylori
-positive children, a seroprevalence of 46.9% to CagA and 16.2% to urease, whereas in
H. pylori
-positive adults, a seroprevalence of 78.9% to CagA and 59% to urease was found. In children, the magnitude of the response to CagA was significantly higher and the response to urease was significantly lower than those in adults. The kinetics of serologic response to CagA and to urease across age groups was contrastably different. Whereas CagA is a strong immunogen, urease is a poor immunogen during natural infection. These differences in the humoral response may be important for the short-term or long-term outcome of the infection. These results add to our knowledge of the epidemiology of
H. pylori
infection.
Animal Model ofMycoplasma pneumoniaeInfection Using Germfree Mice
Authors: Hayakawa Masayuki , Taguchi Haruhiko , Kamiya Shigeru , Fujioka Yasunori , Watanabe Hidehiro , Kawai Shin , Kobayashi Hiroyuki 
Published: July 2002

ABSTRACTWe have attempted to establish a gnotobiotic mouse model monoassociated withMycoplasma pneumoniaefollowing single or repeated infection to examine the mechanism of pathogenesis followingM. pneumoniaeinfection.M. pneumoniaeinoculated into germfree mice colonized equally well at 105CFU/lung in both single infection and repeated infection. In histopathological observation, repeatedly infected mice showed pneumonia with mild infiltration of mononuclear cells and macrophages. Antibody titers againstM. pneumoniaerose in the repeatedly infected mice but not in the singly infected mice. The percentage of CD4-positive, CD8-positive, and CD25-positive lymphocytes infiltrated in the lung was increased in the repeatedly infected mice. In contrast, the lymphocyte subset in the spleen was not significantly different among mock-, singly, and repeatedly infected mice. In the study of cytokine productivity of spleen cells, production of interleukin (IL)-4 and IL-10 was significantly increased and that of gamma interferon was remarkably increased in the mice following repeated infection. These results indicate that a gnotobiotic mouse model monoassociated withM. pneumoniaewas established and that immune mechanisms might be involved in the pathogenesis in pneumonia followingM. pneumoniaeinfection.
Use of Reverse Transcriptase PCR in Early Diagnosis of Rift Valley Fever
Authors: Sall A. A. , Macondo E. A. , Sène O. K. , Diagne M. , Sylla R. , Mondo M. , Girault L. , Marrama L. , Spiegel A. , Diallo M. , Bouloy M. , Mathiot C. 
Published: July 2002

ABSTRACT
Reverse transcriptase PCR (RT-PCR) for diagnosis of Rift Valley fever (RVF) was evaluated by using 293 human and animal sera sampled during an RVF outbreak in Mauritania in 1998. Results of the RT-PCR diagnostic method were compared with those of virus isolation (VI) and detection of immunoglobulin M (IgM) antibodies. Our results showed that RT-PCR is a specific, sensitive tool for RVF diagnosis in the early phase of the disease and that its results do not differ significantly from those obtained by VI. Moreover, the combined results of RT-PCR and IgM antibody detection were in 100% concordance with the results of VI.
Sequence Polymorphism, Predicted Secondary Structures, and Surface-Exposed Conformational Epitopes of
Campylobacter
Major Outer Membrane Protein
Authors: Zhang Qijing , Meitzler Jerrel C. , Huang Shouxiong , Morishita Teresa 
Published: July 2002

ABSTRACT

The major outer membrane protein (MOMP), a putative porin and a multifunction surface protein of
Campylobacter jejuni
, may play an important role in the adaptation of the organism to various host environments. To begin to dissect the biological functions and antigenic features of this protein, the gene (designated
cmp
) encoding MOMP was identified and characterized from 22 strains of
C. jejuni
and one strain of
C. coli
. It was shown that the single-copy
cmp
locus encoded a protein with characteristics of bacterial outer membrane proteins. Prediction from deduced amino acid sequences suggested that each MOMP subunit consisted of 18 β-strands connected by short periplasmic turns and long irregular external loops. Alignment of the amino acid sequences of MOMP from different strains indicated that there were seven localized variable regions dispersed among highly conserved sequences. The variable regions were located in the putative external loop structures, while the predicted β-strands were formed by conserved sequences. The sequence homology of
cmp
appeared to reflect the phylogenetic proximity of
C. jejuni
strains, since strains with identical
cmp
sequences had indistinguishable or closely related macrorestriction fragment patterns. Using recombinant MOMP and antibodies recognizing linear or conformational epitopes of the protein, it was demonstrated that the surface-exposed epitopes of MOMP were predominantly conformational in nature. These findings are instrumental in the design of MOMP-based diagnostic tools and vaccines.
Pathogenesis of Infection by Clinical and Environmental Strains of
Vibrio vulnificus
in Iron-Dextran-Treated Mice
Authors: Starks Angela M. , Schoeb Trenton R. , Tamplin Mark L. , Parveen Salina , Doyle Thomas J. , Bomeisl Philip E. , Escudero Gloria M. , Gulig Paul A. 
Published: July 2002

ABSTRACT

Vibrio vulnificus
is an opportunistic pathogen that contaminates oysters harvested from the Gulf of Mexico. In humans with compromising conditions, especially excess levels of iron in plasma and tissues, consumption of contaminated seafood or exposure of wounds to contaminated water can lead to systemic infection and disfiguring skin infection with extremely high mortality.
V. vulnificus
-associated diseases are noted for the rapid replication of the bacteria in host tissues, with extensive tissue damage. In this study we examined the virulence attributes of three virulent clinical strains and three attenuated oyster or seawater isolates in mouse models of systemic disease. All six
V. vulnificus
strains caused identical skin lesions in subcutaneously (s.c.) inoculated iron dextran-treated mice in terms of numbers of recovered CFU and histopathology; however, the inocula required for identical frequency and magnitude of infection were at least 350-fold higher for the environmental strains. At lethal doses, all strains caused s.c. skin lesions with extensive edema, necrosis of proximate host cells, vasodilation, and as many as 10
8
CFU/g, especially in perivascular regions. These data suggest that the differences between these clinical and environmental strains may be related to growth in the host or susceptibility to host defenses. In non-iron dextran-treated mice, strains required 10
5
-fold-higher inocula to cause an identical disease process as with iron dextran treatment. These results demonstrate that s.c. inoculation of iron dextran-treated mice is a useful model for studying systemic disease caused by
V. vulnificus.
Early Induction of Gamma Interferon and Interleukin-10 Production in Draining Lymph Nodes from Mice Infected withBorrelia burgdorferi
Authors: Ganapamo Frederic , Dennis Vida A. , Philipp Mario T. 
Published: July 2002

ABSTRACTLymph node (LN) cells from C3H/HeJ mice (Lyme disease susceptible) infected for 1 week withBorrelia burgdorferistrain JD1 produced higher levels of gamma interferon (IFN-γ) when stimulated in vitro withB. burgdorferispirochetes than equivalent cells fromB. burgdorferi-infected C57BL/6J mice (disease resistant). The interleukin-10 (IL-10) levels were comparable in the two strains, whereas the IL-4 levels were below detection limits.B. burgdorferi-stimulated LN cells from C57BL/6J mice produced significantly higher levels of IFN-γ in the presence of neutralizing anti-IL-10 antibody than cells cultured withB. burgdorferialone. No effect of IL-10 neutralization on IFN-γ production by LN cells from C3H/HeJ mice was observed. Neutralizing antibody to IFN-γ had no effect on the production of IL-10 by LN cells from C57BL/6J mice. A slight decrease in IL-10 production was detected in culture supernatants of equivalent cells from C3H/HeJ mice. The differential effect of IL-10 on IFN-γ production in C57BL/6J and C3H/HeJ mice suggests that IL-10 is probably involved in the regulation of IFN-γ production by LN cells during infection and may be at the root of the differential susceptibility to Lyme arthritis in these two strains of mice.
Analysis of a Gene Cluster ofEnterococcus faecalisInvolved in Polysaccharide Biosynthesis
Authors: Xu Yi , Singh Kavindra V. , Qin Xiang , Murray Barbara E. , Weinstock George M. 
Published: July 2002

ABSTRACTPreviously, we described a gene cluster ofEnterococcus faecalisOG1RF that produced an antigenic polysaccharide when cloned inEscherichia coli. The polysaccharide antigen was not detectable inE. faecalisstrains, however. Here, we show by reverse transcriptase-PCR that the 16 genes in this region are transcribed in OG1RF. Gene disruption oforfde4, encoding a putative glycosyl transferase, andorfde6, a putative dTDP-rhamnose biosynthesis gene, generated two OG1RF mutants. The mutants showed delayed killing and a higher 50% lethal dose in a mouse peritonitis model. In addition, two mucoidE. faecalisisolates from patients with chronic urinary tract infections were found to produce the polysaccharide antigen.
Identification of Novel Serine/Threonine Protein Phosphatases in
Trypanosoma cruzi
: a Potential Role in Control of Cytokinesis and Morphology
Authors: Orr George A. , Werner Craig , Xu Jun , Bennett Marcia , Weiss Louis M. , Takvorkan Peter , Tanowitz Herbert B. , Wittner Murray 
Published: July 2002

ABSTRACT

We cloned two novel
Trypanosoma cruzi
proteins by using degenerate oligonucleotide primers prepared against conserved domains in mammalian serine/threonine protein phosphatases 1, 2A, and 2B. The isolated genes encoded proteins of 323 and 330 amino acids, respectively, that were more homologous to the catalytic subunit of human protein phosphatase 1 than to those of human protein phosphatase 2A or 2B. The proteins encoded by these genes have been tentatively designated TcPP1α and TcPP1β. Northern blot analysis revealed the presence of a major 2.3-kb mRNA transcript hybridizing to each gene in both the epimastigote and metacyclic trypomastigote developmental stages. Southern blot analysis suggests that each protein phosphatase 1 gene is present as a single copy in the
T. cruzi
genome. The complete coding region for TcPP1β was expressed in
Escherichia coli
by using a vector, pTACTAC, with the
trp-lac
hybrid promoter. The recombinant protein from the TcPP1β construct displayed phosphatase activity toward phosphorylase
a
, and this activity was preferentially inhibited by calyculin A (50% inhibitory concentration [IC
50
], ∼2 nM) over okadaic acid (IC
50
, ∼100 nM). Calyculin A, but not okadaic acid, had profound effects on the in vitro replication and morphology of
T. cruzi
epimastigotes. Low concentrations of calyculin A (1 to 10 nM) caused growth arrest. Electron microscopic studies of the calyculin A-treated epimastigotes revealed that the organisms underwent duplication of organelles, including the flagellum, kinetoplast, and nucleus, but were incapable of completing cell division. At concentrations higher than 10 nM, or upon prolonged incubation at lower concentrations, the epimastigotes lost their characteristic elongated spindle shape and had a more rounded morphology. Okadaic acid at concentrations up to 1 μM did not result in growth arrest or morphological alterations to
T. cruzi
epimastigotes. Calyculin A, but not okadaic acid, was also a potent inhibitor of the dephosphorylation of
32
P-labeled phosphorylase
a
by
T. cruzi
epimastigotes and metacyclic trypomastigote extracts. These inhibitor studies suggest that in
T. cruzi
, type 1 protein phosphatases are important for the completion of cell division and for the maintenance of cell shape.
Assessing the Binding of FourPlasmodium falciparumT Helper Cell Epitopes to HLA-DQ and Induction of T-Cell Responses in HLA-DQ Transgenic Mice
Authors: Pimtanothai Nattiya , Parra Marcela , Johnson Armead H. , David Chella S. , Katovich Hurley Carolyn 
Published: July 2002

ABSTRACTA subunit vaccine forPlasmodium falciparummalaria will need to contain well-defined T helper cell epitopes that induce protective immune responses to the parasite. One major barrier to the use of subunit vaccines is the requirement for T helper cell epitopes to be presented by the HLA class II molecules that are present in the population being vaccinated. Since the majority of malaria studies have focused on HLA-DR, little information on the role of HLA-DQ in the binding and immune response to malarial epitopes is available. This study used an in vitro peptide-binding assay to predict the extent of HLA-DQ binding of four conserved T helper cell epitopes identified from asexual-stage malaria vaccine candidate antigens. Epstein-Barr virus (EBV)-transformed human B-cell lines expressing 14 different DQ molecules (DQ2.1, -2.2, -4.1, -4.2, -5.1 to -5.3, -6.1, -6.2, -6.4, -7.1, -7.3, -8, and -9) representing all broad serological specificities, including common DQ molecules present in populations in areas where malaria is endemic, were used in the binding assay. Moreover, an HLA-DQ transgenic mouse model was employed to evaluate the correlation between the in vitro DQ binding of the peptides and the generation of in vivo immune responses following peptide immunization. This study identified two broad DQ-binding peptides, ABRA#14 and SERA#9. ABRA#14 also induced T-cell proliferation and Th1-associated cytokine production in DQ8+transgenic mice. The combination of peptide binding to EBV-transformed cell lines and DQ transgenic mice provides a method for identifying additional T-cell epitopes for inclusion in a vaccine.
Characterization of
Porphyromonas gingivalis
-Induced Degradation of Epithelial Cell Junctional Complexes
Authors: Katz Jannet , Sambandam Vijaya , Wu John H. , Michalek Suzanne M. , Balkovetz Daniel F. 
Published: July 2002

ABSTRACT

Porphyromonas gingivalis
is considered among the etiological agents of human adult periodontitis. Although in vitro studies have shown that
P. gingivalis
has the ability to invade epithelial cell lines, its effect on the epithelial barrier junctions is not known. Immunofluorescence analysis of human gingival epithelial cells confirmed the presence of tight-junction (occludin), adherens junction (E-cadherin), and cell-extracellular matrix junction (β1-integrin) transmembrane proteins. These transmembrane proteins are expressed in Madin-Darby canine kidney (MDCK) cells. In addition, MDCK cells polarize and therefore serve as a useful in vitro model for studies on the epithelial cell barrier. Using the MDCK cell system, we examined the effect of
P. gingivalis
on epithelial barrier function. Exposure of the basolateral surfaces of MDCK cells to
P. gingivalis
(>10
9
bacteria/ml) resulted in a decrease in transepithelial resistance. Immunofluorescence microscopy demonstrated decreases in the amounts of immunoreactive occludin, E-cadherin, and β1-integrin at specific times which were related to a disruption of cell-cell junctions in MDCK cells exposed to basolateral
P. gingivalis
. Disruption of cell-cell junctions was also observed upon apical exposure to bacteria; however, the effects took longer than those seen upon basolateral exposure. Cell viability was not affected by either basolateral or apical exposure to
P. gingivalis
. Western blot analysis demonstrated hydrolysis of occludin, E-cadherin, and β1-integrin in lysates derived from MDCK cells exposed to
P. gingivalis
. Immunoprecipitated occludin and E-cadherin molecules from MDCK cell lysates were also degraded by
P. gingivalis
, suggesting a bacterial protease(s) capable of cleaving these epithelial junction transmembrane proteins. Collectively, these data suggest that
P. gingivalis
is able to invade the deeper structures of connective tissues via a paracellular pathway by degrading epithelial cell-cell junction complexes, thus allowing the spread of the bacterium. These results also indicate the importance of a critical threshold concentration of
P. gingivalis
to initiate epithelial barrier destruction.
Long-Term Immunological Memory Induced by Recombinant Oral
Salmonella
Vaccine Vectors
Authors: Kohler James J. , Pathangey Latha , Hasona Adnan , Progulske-Fox Ann , Brown Thomas A. 
Published: July 2002

ABSTRACT

We have previously shown that
Salmonella enterica
serovar Typhimurium expressing the
hagB
hemagglutinin gene from
Porphyromonas gingivalis
can induce primary and recall immune responses in serum and secretions in mice; however, the longevity of memory induced by oral
Salmonella
carriers has not been adequately demonstrated. In this study, we examined the capacity of mice to mount a recall response 52 weeks after primary immunization. Recall responses were seen in serum immunoglobulin G (IgG) and IgA following boosting at week 52, and in most cases, they were equal to or greater than the primary responses. Significant mucosal IgA recall responses in saliva and vaginal wash were also detected following boosting at week 52. In addition, there was a considerable residual response in secretions at week 51, prior to boosting. These results indicate that oral
Salmonella
vectors can induce long-term memory to recombinant HagB and are particularly effective at inducing long-lasting mucosal responses as well as at inducing the capacity for mucosal recall responses.
Yersinia pestis
YbtU and YbtT Are Involved in Synthesis of the Siderophore Yersiniabactin but Have Different Effects on Regulation
Authors: Geoffroy Valerie A. , Fetherston Jacqueline D. , Perry Robert D. 
Published: July 2002

ABSTRACT

One prerequisite for the virulence of
Yersinia pestis
, causative agent of bubonic plague, is the yersiniabactin (Ybt) siderophore-dependent iron transport system that is encoded within a high-pathogenicity island (HPI) within the
pgm
locus of the
Y. pestis
chromosome. Several gene products within the HPI have demonstrated functions in the synthesis or transport of Ybt. Here we examine the roles of
ybtU
and
ybtT
. In-frame mutations in
ybtT
or
ybtU
yielded strains defective in siderophore production. Mutant strains were unable to grow on iron-deficient media at 37°C but could be cross-fed by culture supernatants from a Ybt-producing strain of
Y. pestis
. The
ybtU
mutant failed to express four indicator Ybt proteins (HMWP1, HMWP2, YbtE, and Psn), a pattern similar to those for other
ybt
biosynthetic mutants. In contrast, strains carrying mutations in
ybtT
or
ybtS
(a previously identified gene required for Ybt biosynthesis) produced all four proteins at wild-type levels under iron-deprived conditions. To assess the effects of
ybtT
, -
U
, and -
S
mutations on transcription of
ybt
genes, reporter plasmids with
ybtP
or
psn
promoters controlling
lacZ
expression were introduced into these mutants. Normal iron-regulated β-galactosidase activity was observed in the
ybtT
and
ybtS
mutants, whereas a significant loss of expression occurred in the Δ
ybtU
strain. These results show that
ybtT
and
ybtU
genes are involved in the biosynthesis of the Ybt siderophore and that a
ybtU
mutation but not
ybtT
or
ybtS
mutations affects transcription from the
ybtP
and
psn
promoters.
Characterization of
Porphyromonas gingivalis
Insertion Sequence-Like Element IS
Pg5
Authors: Califano Joseph V. , Kitten Todd , Lewis Janina P. , Macrina Francis L. , Fleischmann Robert D. , Fraser Claire M. , Duncan Margaret J. , Dewhirst Floyd E. 
Published: July 2002

ABSTRACT

Porphyromonas gingivalis
, a black-pigmented, gram-negative anaerobe, is found in periodontitis lesions, and its presence in subgingival plaque significantly increases the risk for periodontitis. In contrast to many bacterial pathogens,
P. gingivalis
strains display considerable variability, which is likely due to genetic exchange and intragenomic changes. To explore the latter possibility, we have studied the occurrence of insertion sequence (IS)-like elements in
P. gingivalis
W83 by utilizing a convenient and rapid method of capturing IS-like sequences and through analysis of the genome sequence of
P. gingivalis
strain W83. We adapted the method of Matsutani et al. (S. Matsutani, H. Ohtsubo, Y. Maeda, and E. Ohtsubo, J. Mol. Biol. 196:445–455, 1987) to isolate and clone rapidly annealing DNA sequences characteristic of repetitive regions within a genome. We show that in
P. gingivalis
strain W83, such sequences include (i) nucleotide sequence with homology to tRNA genes, (ii) a previously described IS element, and (iii) a novel IS-like element. Analysis of the
P. gingivalis
genome sequence for the distribution of the least used tetranucleotide, CTAG, identified regions in many of the initial 218 contigs which contained CTAG clusters. Examination of these CTAG clusters led to the discovery of 11 copies of the same novel IS-like element identified by the repeated sequence capture method of Matsutani et al. This new 1,512-bp IS-like element, designated IS
Pg5
, has features of the IS
3
family of IS elements. When a recombinant plasmid containing much of IS
Pg5
was used in Southern analysis of several
P. gingivalis
strains, including clinical isolates, diversity among strains was apparent. This suggests that IS
Pg5
and other IS elements may contribute to strain diversity and can be used for strain fingerprinting.
Soluble Egg Antigen-Stimulated T Helper Lymphocyte Apoptosis and Evidence for Cell Death Mediated by FasL+T and B Cells during MurineSchistosoma mansoniInfection
Authors: Lundy Steven K. , Lerman Stephen P. , Boros Dov L. 
Published: July 2002

ABSTRACTGranuloma formation around schistosomal eggs is induced by soluble egg antigens (SEA) and mediated by the activity of CD4+Th lymphocytes and their cytokines. Regulation of the inflammatory Th cell response during infection is still insufficiently understood. The hypothesis of this study was that activation-induced cell death (AICD) of CD4+T cells is involved in the immune inflammatory response. This study investigated the dynamics of splenic and granuloma CD4+Th cell apoptosis and Fas ligand (FasL) expression during the acute and chronic stages of murine schistosomal infection. Enhanced apoptosis of freshly isolated CD4+Th lymphocytes commenced after egg deposition and persisted during the peak and modulated phases of granuloma formation. After oviposition, CD4+, CD8+, and CD19+splenocytes and granuloma cells expressed elevated levels of FasL but FasL expression declined during the downmodulated stage of infection. In culture, SEA induced splenic and granuloma CD4+T-cell apoptosis and stimulated expression of FasL on splenic but not granuloma CD4+T cells, CD8+T cells, and CD19+B cells. SEA-stimulated splenocytes and granuloma cells preferentially lysed a Fas-transfected target cell line. Depletion of B cells from SEA-stimulated splenic cultures decreased CD4+T cell apoptosis. Coculture of purified splenic B cells with CD4+T cells and adoptive transfer of purified B cells indicated that antigen-stimulated B cells can kill CD4+Th cells. However, CD4+T cells were the dominant mediators of apoptosis in the granuloma. This study indicates that AICD is involved in the apoptosis of CD4+T cells during schistosomal infection.