bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gene Discovery through Genomic Sequencing of
Brucella abortus
Authors: Sánchez Daniel O. , Zandomeni Ruben O. , Cravero Silvio , Verdún Ramiro E. , Pierrou Ester , Faccio Paula , Diaz Gabriela , Lanzavecchia Silvia , Agüero Fernán , Frasch Alberto C. C. , Andersson Siv G. E. , Rossetti Osvaldo L. , Grau Oscar , Ugalde Rodolfo A. 
Published: July 2002

ABSTRACT

Brucella abortus
is the etiological agent of brucellosis, a disease that affects bovines and human. We generated DNA random sequences from the genome of
B. abortus
strain 2308 in order to characterize molecular targets that might be useful for developing immunological or chemotherapeutic strategies against this pathogen. The partial sequencing of 1,899 clones allowed the identification of 1,199 genomic sequence surveys (GSSs) with high homology (BLAST expect value < 10
−5
) to sequences deposited in the GenBank databases. Among them, 925 represent putative novel genes for the
Brucella
genus. Out of 925 nonredundant GSSs, 470 were classified in 15 categories based on cellular function. Seven hundred GSSs showed no significant database matches and remain available for further studies in order to identify their function. A high number of GSSs with homology to
Agrobacterium tumefaciens
and
Rhizobium meliloti
proteins were observed, thus confirming their close phylogenetic relationship. Among them, several GSSs showed high similarity with genes related to nodule nitrogen fixation, synthesis of nod factors, nodulation protein symbiotic plasmid, and nodule bacteroid differentiation. We have also identified several
B. abortus
homologs of virulence and pathogenesis genes from other pathogens, including a homolog to both the Shda gene from
Salmonella enterica
serovar Typhimurium and the AidA-1 gene from
Escherichia coli
. Other GSSs displayed significant homologies to genes encoding components of the type III and type IV secretion machineries, suggesting that
Brucella
might also have an active type III secretion machinery.
Lipopolysaccharide ofBurkholderia cepaciaand Its Unique Character To Stimulate Murine Macrophages with Relative Lack of Interleukin-1β-Inducing Ability
Authors: Shimomura Hirofumi , Matsuura Motohiro , Saito Shinji , Hirai Yoshikazu , Isshiki Yasunori , Kawahara Kazuyoshi 
Published: July 2002

ABSTRACTLipopolysaccharide (LPS) ofBurkholderia cepaciawas purified by the conventional phenol-water extraction method (preparation BcLPS-1), followed by enzymatic treatments with DNase, RNase, trypsin, and proteinase K (preparation BcLPS-2), and finally by deoxycholate-phenol-water extraction (preparation BcLPS-3). Cells of LPS-hyporesponsive C3H/HeJ mice were activated by both the BcLPS-1 and the BcLPS-2 preparations but barely activated by BcLPS-3. When LPS-responsive C3H/HeN mice were used as targets, endotoxic activities such as lethal toxicity to galactosamine-sensitized mice, mitogenicity to spleen cells, and activation of macrophages to induce tumor necrosis factor alpha and interleukin-6 (IL-6) were strongly exhibited even by highly purified BcLPS-3 at levels comparable to those of the highly active enterobacterial LPS ofSalmonella entericaserovar Abortus-equi (SaeLPS), used as the control. The ability of BcLPS-3 to activate murine macrophages for induction of IL-1β was, however, much weaker than that of SaeLPS. Both accumulation of pro-IL-1β protein and expression of IL-1β mRNA in macrophages by stimulation with BcLPS-3 were much weaker than by stimulation with SaeLPS. These results indicate that LPS ofB. cepaciahas the potential to play a role as a pathogenic factor with strong activity comparable to that of usual enterobacterial LPS, but unlike the latter, this LPS has a relative lack of ability in the activation of murine macrophages to induce IL-1β. The lack of IL-1β-inducing ability appears to be caused by incomplete signal transduction somewhere in the upstream step(s) of IL-1β gene transcription.
Pyrogenicity and Cytokine-Inducing Properties ofStreptococcus pyogenesSuperantigens: Comparative Study of Streptococcal Mitogenic Exotoxin Z and Pyrogenic Exotoxin A
Authors: Müller-Alouf Heide , Proft Thomas , Zollner Thomas M. , Gerlach Dieter , Champagne Eric , Desreumaux Pierre , Fitting Catherine , Geoffroy-Fauvet Christiane , Alouf Joseph E. , Cavaillon Jean-Marc 
Published: July 2002

ABSTRACTStreptococcal mitogenic exotoxin Z (SMEZ), a superantigen derived fromStreptococcus pyogenes, provoked expansion of human lymphocytes expressing the Vβ 2, 4, 7 and 8 motifs of T-cell receptor. SMEZ was pyrogenic in rabbits and stimulated the expression of the T-cell activation markers CD69 and cutaneous lymphocyte-associated antigen. A variety of cytokines was released by human mononuclear leukocytes stimulated with SMEZ, which was 10-fold more active than streptococcal pyrogenic exotoxin A. Th2-derived cytokines were elicited only by superantigens and not by streptococcal cells.
Down-Modulation of L-Selectin by Lipopolysaccharide Is Not Required for Lipopolysaccharide-Induced Expression of CD14 in Mouse Bone Marrow Granulocytes
Authors: Pédron Thierry , Girard Robert , Chaby Richard 
Published: July 2002

ABSTRACTWe established in previous studies that a constitutive lipopolysaccharide (LPS) receptor of low affinity is present on mouse bone marrow granulocytes (BMG). This yet-unidentified receptor is involved in the LPS-induced expression of a second LPS receptor, CD14. Because it has been claimed that L-selectin (CD62L) is a low-affinity LPS receptor in mature granulocytes (polymorphonuclear leukocytes), it may be asked whether this molecule could be the constitutive LPS receptor in BMG. We show in this study thatl-selectin is constitutively present on BMG and is down-regulated after exposure of the cells to LPS. A phorbol ester induced a down-regulation of CD62L and blocked the LPS-induced expression of CD14. However, a metalloproteinase inhibitor (BB-3103) blocked the former but not the latter effect of PMA. We also observed an absence of cross-reactivity between LPS and a CD62L ligand (fucoidan) in binding studies with radiolabeled derivatives of the two agents. Furthermore, BMG froml-selectin-deficient mice expressed normal levels of CD14 in response to LPS. Taken together, these results demonstrate that in BMG,l-selectin is not the constitutive LPS receptor required for the LPS-induced expression of CD14.
In Situ Activation of Helper T Cells in the Lung
Authors: Raju Bindu , Tung Chung F. , Cheng Debbie , Yousefzadeh Nora , Condos Rany , Rom William N. , Tse Doris B. 
Published: July 2002

ABSTRACTTo better understand the lung and systemic responses of helper T cells mediating memory immunity toMycobacterium tuberculosis, we used three- and four-color flow cytometry to study the surface phenotype of CD4+lymphocytes. Bronchoalveolar lavage (BAL) fluid and peripheral blood (PB) samples were obtained from a total of 25 subjects, including 10 tuberculosis (TB)-infected subjects, 8 purified-protein-derivative-negative subjects, and 7 purified-protein-derivative-positive subjects. In marked contrast to CD4+lymphocytes from PB (9% ± 5% expressing CD45RA and CD29), the majority (55% ± 16%) of CD4+lymphocytes in BAL (ALs) simultaneously expressed CD45RA, a naı̈ve T-cell marker, and CD29, members of the very late activation family. Further evaluation revealed that CD4+ALs expressed both CD45RA and CD45RO, a memory T-cell marker. In addition, the proportion of CD4+lymphocytes expressing CD69, an early activation marker, was drastically increased in BAL fluid (83% ± 9%) compared to PB (1% ± 1%), whereas no significant difference was seen in the expression of CD25, the low-affinity interleukin 2 receptor (34% ± 15% versus 40% ± 16%). More importantly, we identified a minor population of CD69brightCD25brightCD4+lymphocytes in BAL (10% ± 6%) that were consistently absent from PB (1% ± 1%). Thus, CD4+lymphocytes in the lung paradoxically coexpress surface molecules characteristic of naı̈ve and memory helper T cells as well as surface molecules commonly associated with early and late stages of activation. No difference was observed for ALs obtained from TB-infected and uninfected lung segments in this regard. It remains to be determined if these surface molecules are induced by the alveolar environment or if CD4+lymphocytes coexpressing this unusual combination of surface molecules are selectively recruited from the circulation. Our data suggest that ex vivo experiments on helper T-cell subsets that display distinctive phenotypes may be pivotal to studies on the human immune response to potential TB vaccines.
Production ofNeisseria meningitidisTransferrin-Binding Protein B by RecombinantBordetella pertussis
Authors: Coppens Isabelle , Alonso Sylvie , Antoine Rudy , Jacob-Dubuisson Françoise , Renauld-Mongénie Geneviève , Jacobs Eric , Locht Camille 
Published: July 2002

ABSTRACTNeisseria meningitidisserogroup B infections are among the major causes of fulminant septicemia and meningitis, especially severe in young children, and no broad vaccine is available yet. Because of poor immunogenicity of the serogroup B capsule, many efforts are now devoted to the identification of protective protein antigens. Among those are PorA and, more recently, transferrin-binding protein B (TbpB). In this study, TbpB ofN. meningitidiswas genetically fused to the N-terminal domain of theBordetella pertussisfilamentous hemagglutinin (FHA), and thefha-tbpBhybrid gene was expressed inB. pertussiseither as a plasmid-borne gene or as a single copy inserted into the chromosome. The hybrid protein was efficiently secreted by the recombinant strains, despite its large size, and was recognized by both anti-FHA and anti-TbpB antibodies. A single intranasal administration of recombinant virulent or pertussis-toxin-deficient, attenuatedB. pertussisto mice resulted in the production of antigen-specific systemic immunoglobulin G (IgG), as well as local IgG and IgA. The anti-TbpB serum antibodies were of the IgG1, IgG2a, and IgG2b isotypes and were found to express complement-mediated bactericidal activity againstN. meningitidis. These observations indicate that recombinantB. pertussismay be a promising vector for the development of a mucosal vaccine against serogroup B meningococci.
Intermediate Subunit of the Gal/GalNAc Lectin of
Entamoeba histolytica
Is a Member of a Gene Family Containing Multiple CXXC Sequence Motifs
Authors: Cheng Xun-Jia , Hughes Molly A. , Huston Christopher D. , Loftus Brendan , Gilchrist Carol A. , Lockhart Lauren A. , Ghosh Salil , Miller-Sims Vanessa , Mann Barbara J. , Petri William A. , Tachibana Hiroshi 
Published: July 2002

ABSTRACT

Killing by
Entamoeba histolytica
requires parasite adherence to host galactose- and
N
-acetyl-
d
-galactosamine (Gal/GalNAc)-containing cell surface receptors. A 260-kDa heterodimeric
E. histolytica
Gal/GalNAc lectin composed of heavy (Hgl) and light (Lgl) subunits has been previously described. Here we present the cloning and characterization of Igl, a 150-kDa intermediate subunit of the Gal/GalNAc lectin. Igl, Hgl, and Lgl colocalized on the surface membrane of trophozoites. Two unlinked copies of genes encoding Igl shared 81% amino acid sequence identity (GenBank accession no.
AF337950
and
AF337951
). They encoded cysteine-rich proteins with amino- and carboxy-terminal hydrophobic signal sequences characteristic of glycosylphosphatidylinositol (GPI)-anchored membrane proteins. The
igl
genes lacked carbohydrate recognition domains but were members of a large family of amebic genes containing CXXC and CXC motifs. These data indicate that Igl is part of the parasite's multimolecular Gal/GalNAc adhesin required for host interaction.
The
Helicobacter pylori
Homologue of the Ferric Uptake Regulator Is Involved in Acid Resistance
Authors: Bijlsma Jetta J. E. , Waidner Barbara , Vliet Arnoud H. M. van , Hughes Nicky J. , Häg Stephanie , Bereswill Stefan , Kelly David J. , Vandenbroucke-Grauls Christina M. J. E. , Kist Manfred , Kusters Johannes G. 
Published: July 2002

ABSTRACT

The only known niche of the human pathogen
Helicobacter pylori
is the gastric mucosa, where large fluctuations of pH occur, indicating that the bacterial response and resistance to acid are important for successful colonization. One of the few regulatory proteins in the
H. pylori
genome is a homologue of the ferric uptake regulator (Fur). In most bacteria, the main function of Fur is the regulation of iron homeostasis. However, in
Salmonella enterica
serovar Typhimurium, Fur also plays an important role in acid resistance. In this study, we determined the role of the
H. pylori
Fur homologue in acid resistance. Isogenic
fur
mutants were generated in three
H. pylori
strains (1061, 26695, and NCTC 11638). At pH 7 there was no difference between the growth rates of mutants and the parent strains. Under acidic conditions, growth of the
fur
mutants was severely impaired. No differences were observed between the survival of the
fur
mutant and parent strain 1061 after acid shock. Addition of extra iron or removal of iron from the growth medium did not improve the growth of the
fur
mutant at acidic pH. This indicates that the phenotype of the
fur
mutant at low pH was not due to increased iron sensitivity. Transcription of
fur
was repressed in response to low pH. From this we conclude that Fur is involved in the growth at acidic pH of
H. pylori
; as such, it is the first regulatory protein implicated in the acid resistance of this important human pathogen.
Identification and Testing of
Porphyromonas gingivalis
Virulence Genes with a pPGIVET System
Authors: Wu Yi , Lee Seok-Woo , Hillman Jeffrey D. , Progulske-Fox Ann 
Published: July 2002

ABSTRACT

An in vivo expression technology (IVET) system was designed to identify previously unknown virulence genes of
Porphyromonas gingivalis.
Fourteen
ivi
(for in vivo induced) genes that are induced during infection in a mouse abscess model were identified in our study. Of these, seven had homology to genes in the NCBI database, and the rest had no homology to reported DNA sequences. In order to determine virulence-related properties of these genes, three mutant strains, deleted of
ivi
8 (no homology to genes in the database),
ivi
10 (homologous to a putative TonB-dependent outer membrane receptor protein), and
ivi
11 (an immunoreactive 33-kDa antigen PG125 in
P. gingivalis
), were created. The mutants were tested in a mouse abscess model for alterations in virulence relative to the wild type by a competition assay in BALB/c mice. After 5 days we observed the enrichment of the wild-type strain over mutant strains Δ
ivi
10 and Δ
ivi
11, which indicated that mutant strains Δ
ivi
10 and Δ
ivi
11 are less able to survive in this model than the wild-type strain, while Δ
ivi
8 survives as well as the wild-type strain. We propose that knockout of these
ivi
genes reduced the ability of the mutated
P. gingivalis
to survive and cause infection compared to the wild-type strain at the site of injection. Also, in separate experiments, groups of mice were challenged with subcutaneous injections of each individual mutant strain (Δ
ivi
8, Δ
ivi
10, and Δ
ivi
11) or with the wild-type strain alone and were then examined to assess their general health status. The results showed that knockout of these
ivi
genes conferred a reduction in virulence. The ability of the mutants to invade KB cells compared to the wild type was also determined. Interestingly, the CFU counts of the mutant strain Δ
ivi
10 recovered from KB cells were eight times lower than those of the wild type, indicating that this mutant has a lower capacity for invasion. These results demonstrate that IVET is a powerful tool in discovering virulence genes and the significant role that
ivi
genes play in the pathogenesis of this species.
Intracellular Induction of
Listeria monocytogenes actA
Expression
Authors: Shetron-Rama Lynne M. , Marquis Hélène , Bouwer H. G. Archie , Freitag Nancy E. 
Published: July 2002

ABSTRACT

Following entry into the host cytosol, the bacterial pathogen
Listeria monocytogenes
dramatically increases the expression of several key virulence factors. The expression of
actA
, whose protein product is required for
L
.
monocytogenes
actin-based intracellular motility, is increased by more than 200-fold in cytosolic bacteria in comparison to broth-grown cultures. Two distinct promoter elements have been reported to regulate
actA
expression. One promoter is located immediately upstream of
actA
coding sequences, while the second promoter is contributed by the upstream
mpl
gene via the generation of an
mpl-actA-plcB
transcript. A series of
L
.
monocytogenes
mutants were constructed to define the contributions of individual promoter elements to
actA
expression. The intracellular induction of
actA
expression was found to be dependent upon the
actA
proximal promoter; the
mpl
promoter appeared to contribute to the extracellular induction of
actA
but did not affect intracellular levels of expression. The
actA
promoter is dependent upon a regulatory factor known as PrfA for transcriptional activation; however, no increase in
actA
expression was detected following the introduction of a high-affinity PrfA binding site within the
actA
promoter. The presence of a mutationally activated form of PrfA, known as PrfA*, increased overall
actA
expression in broth-grown cultures of both wild-type and
actA
promoter mutant strains, but the levels of induction observed were still approximately 50-fold lower than those observed for intracellularly grown
L
.
monocytogenes
. Collectively, these results indicate that the dramatic induction of
actA
expression that occurs in the host cell cytosol is mediated through a single promoter element. Furthermore, intracellular induction of
actA
appears to require additional steps or factors beyond those necessary for the activation and binding of PrfA to the
actA
promoter.
Dendritic Cells Pulsed with a Recombinant Chlamydial Major Outer Membrane Protein Antigen Elicit a CD4+Type 2 Rather than Type 1 Immune Response That Is Not Protective
Authors: Shaw Jennifer , Grund Vernon , Durling Luke , Crane Debbie , Caldwell Harlan D. 
Published: July 2002

ABSTRACTChlamydia trachomatisis an obligate intracellular bacterium that infects the oculogenital mucosae.C. trachomatisinfection of the eye causes trachoma, the leading cause of preventable blindness. Infections of the genital mucosae are a leading cause of sexually transmitted diseases. A vaccine to prevent chlamydial infection is needed but has proven difficult to produce by using conventional vaccination approaches. Potent immunity to vaginal rechallenge in a murine model of chlamydial genital infection has been achieved only by infection or by immunization with dendritic cells (DC) pulsed ex vivo with whole inactivated organisms. Immunity generated by infection or ex vivo antigen-pulsed DC correlates with a chlamydia-specific interleukin 12 (IL-12)-dependent CD4+Th1 immune response. Because of the potent antichlamydial immunizing properties of DC, we hypothesized that DC could be a powerful vehicle for the delivery of individual chlamydial antigens that are thought to be targets for more conventional vaccine approaches. Here, we investigated the recombinant chlamydial major outer membrane protein (rMOMP) as a target antigen. The results demonstrate that DC pulsed with rMOMP secrete IL-12 and stimulate infection-sensitized CD4+T cells to proliferate and secrete gamma interferon. These immunological properties implied that rMOMP-pulsed DC would be potent inducers of MOMP-specific CD4+Th1 immunity in vivo; however, we observed the opposite result. DC pulsed ex vivo with rMOMP and adoptively transferred to naive mice generated a Th2 rather than a Th1 anti-MOMP immune response, and immunized mice were not protected following infectious challenge. We conclude from these studies that the immunological properties of ex vivo pulsed DC are not necessarily predictive of the immune response generated in vivo following adoptive transfer. These findings suggest that the nature of the antigen used to pulse DC ex vivo influences the Th1-Th2 balance of the immune response in vivo.
Clonal Diversity of
Escherichia coli
Colonizing Stools and Urinary Tracts of Young Girls
Authors: Schlager Theresa A. , Hendley J. Owen , Bell Alison L. , Whittam Thomas S. 
Published: July 2002

ABSTRACT

Intestinal carriage of
Escherichia coli
in prepubertal girls without a history of urinary tract infection was examined by collecting weekly stools and periurethral and urine samples over 3 to 4 weeks of study. Dominant and minor clones were defined by grouping 28
E. coli
isolates into clonal types. Multiple enteric clones of
E. coli
, which changed week to week, were found in the 13 girls during the study (median, 3 clones/girl; range, 1 to 16 clones/girl). Dominance of an enteric clone did not predict persistence in the stool. In only 10 (34%) of the 29 episodes in which a dominant clone present in one weekly sample could have been detected the following week did it persist as the dominant clone in the next weekly sample. In 5 (17%) of the 29 episodes, a dominant clone found in one weekly sample was classified as a minor clone the next week. Both dominant and minor clones were observed to colonize the urinary tract. However, when colonization of the periurethra or bladder urine occurred, it was brief and often did not reflect the dominant stool flora from the same week. In fact, in only 40% of episodes was a clone that was detected either on the periurethra or in the urine also recovered from the stool the same week. Our findings suggest that the intestinal flora of healthy girls is multiclonal with frequent fluctuations in composition.
Selective T-Cell Recognition of the N-Terminal Peptide of GroES in Tuberculosis
Authors: Chua-Intra Boosbun , Wilkinson Robert J. , Ivanyi Juraj 
Published: July 2002

ABSTRACTPeptides derived from the whole sequence of mycobacterial GroES heat shock proteins were tested for the ability to induce the proliferation of blood mononuclear cells from tuberculosis patients and sensitized healthy subjects. The response to the N-terminal peptide (residues 1 to 16) was found to be more frequent and stronger in tuberculosis patients. This finding is exceptional, considering that recognition of all other GroES peptides by patients was either diminished or not different from that of controls.
Discordance between T-Cell Receptor Expression and Effector Function in Mice Infected withHistoplasma capsulatum
Authors: Deepe George S. , Gibbons Reta S. , Ward Susan R. 
Published: July 2002

ABSTRACTVβ10+and Vβ14+T cells were selectively increased 7 to 14 days following infection in the lungs of naive mice infected withHistoplasma capsulatum. Following secondary challenge of immune mice, Vβ1+and Vβ8.1+cells were sporadically increased. Elimination of Vβ10+and Vβ14+cells from naive mice did not alter the course of infection over a period of 21 days. Thus, overexpression of Vβ families does not necessarily signify a key role in host defense.
Involvement of PhoP-PhoS Homologs in
Enterococcus faecalis
Virulence
Authors: Teng Fang , Wang Ling , Singh Kavindra V. , Murray Barbara E. , Weinstock George M. 
Published: July 2002

ABSTRACT

Eleven PhoP-PhoS homolog pairs were identified by searching the
Enterococcus faecalis
V583 genome sequence database at The Institute for Genomic Research with the
Bacillus subtilis
PhoP-PhoS sequences. Each pair appears to be a potential two-component system composed of a response regulator and a sensor kinase. Seven of the homologs were disrupted in
E. faecalis
strain OG1RF. TX10293, a mutant disrupted in one of these genes (
etaR
, the first gene of the gene pair designated
etaRS
), showed delayed killing and a higher 50% lethal dose in a mouse peritonitis model. The predicted EtaR protein sequence showed greatest similarity to LisR of
Listeria monocytogenes
(77%) and CsrR of
Streptococcus pyogenes
(70%); EtaS is 53% similar to LisK and 54% similar to CsrS. When grown in vitro, the TX10293 mutant was more sensitive to low pH (pH 3.4) and more resistant to high temperature (55°C) than wild-type OG1RF. In conclusion, many potential two-component systems are identified for
E. faecalis
, one of which, EtaRS, was shown to be involved in stress response and virulence.