bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mutational Analysis of the
Rhizobium lupini
H13-3 and
Sinorhizobium meliloti
Flagellin Genes: Importance of Flagellin A for Flagellar Filament Structure and Transcriptional Regulation
Authors: Scharf Birgit , Schuster-Wolff-Bühring Henriette , Rachel Reinhard , Schmitt Rüdiger 
Published: July 2002

ABSTRACT

Complex flagellar filaments are unusual in their fine structure composed of flagellin dimers, in their right-handed helicity, and in their rigidity, which prevents a switch of handedness. The complex filaments of
Rhizobium lupini
H13-3 and those of
Sinorhizobium meliloti
are composed of three and four flagellin (Fla) subunits, respectively. The Fla-encoding genes, named
flaA
through
flaD
, are separately transcribed from ς
28
-specific promoters. Mutational analysis of the
fla
genes revealed that, in both species, FlaA is the principal flagellin and that FlaB, FlaC, and FlaD are secondary. FlaA and at least one secondary Fla protein are required for assembling a functional flagellar filament. Western analysis revealed a ratio close to 1 of FlaA to the secondary Fla proteins (= FlaX) present in wild-type extracts, suggesting that the complex filament is assembled from FlaA-FlaX heterodimers. Whenever a given mutant combination of Fla prevented the assemblage of an intact filament, the biosynthesis of flagellin decreased dramatically. As shown in
S. meliloti
by reporter gene analysis, it is the transcription of
flaA
, but not of
flaB
,
flaC
, or
flaD
, that was down-regulated by such abortive combinations of Fla proteins. This autoregulation of
flaA
is unusual. We propose that any combination of Fla subunits incapable of assembling an intact filament jams the flagellar export channel and thus prevents the escape of an (as yet unidentified) anti-ς
28
factor that antagonizes the ς
28
-dependent transcription of
flaA
.
The
Brucella suis
Homologue of the
Agrobacterium tumefaciens
Chromosomal Virulence Operon
chvE
Is Essential for Sugar Utilization but Not for Survival in Macrophages
Authors: Alvarez-Martinez Maria-Teresa , Machold Jan , Weise Christoph , Schmidt-Eisenlohr Heike , Baron Christian , Rouot Bruno 
Published: July 2002

ABSTRACT

Brucella
strains possess an operon encoding type IV secretion machinery very similar to that coded by the
Agrobacterium tumefaciens virB
operon. Here we describe cloning of the
Brucella suis
homologue of the
chvE-gguA-gguB
operon of
A. tumefaciens
and characterize the sugar binding protein ChvE (78% identity), which in
A. tumefaciens
is involved in virulence gene expression.
B. suis chvE
is upstream of the putative sugar transporter-encoding genes
gguA
and
gguB
, also present in
A. tumefaciens
, but not adjacent to that of a LysR-type transcription regulator. Although results of Southern hybridization experiments suggested that the gene is present in all
Brucella
strains, the ChvE protein was detected only in
B. suis
and
Brucella canis
with
A. tumefaciens
ChvE-specific antisera, suggesting that
chvE
genes are differently expressed in different
Brucella
species. Analysis of cell growth of
B. suis
and of its
chvE
or
gguA
mutants in different media revealed that ChvE exhibited a sugar specificity similar to that of its
A. tumefaciens
homologue and that both ChvE and GguA were necessary for utilization of these sugars. Murine or human macrophage infections with
B. suis chvE
and
gguA
mutants resulted in multiplication similar to that of the wild-type strain, suggesting that
virB
expression was unaffected. These data indicate that the ChvE and GguA homologous proteins of
B. suis
are essential for the utilization of certain sugars but are not necessary for survival and replication inside macrophages.
Complete Nucleotide Sequence of a 43-Kilobase Genomic Island Associated with the Multidrug Resistance Region ofSalmonella entericaSerovar Typhimurium DT104 and Its Identification in Phage Type DT120 and Serovar Agona
Authors: Boyd David , Peters Geoffrey A. , Cloeckaert Axel , Boumedine Karim Sidi , Chaslus-Dancla Elisabeth , Imberechts Hein , Mulvey Michael R. 
Published: July 2002

ABSTRACTThis study describes the characterization of the recently describedSalmonellagenomic island 1 (SGI1) (D. A. Boyd, G. A. Peters, L.-K. Ng, and M. R. Mulvey, FEMS Microbiol. Lett. 189:285–291, 2000), which harbors the genes associated with the ACSSuT phenotype in a Canadian isolate ofSalmonella entericaserovar Typhimurium DT104. A 43-kb region has been completely sequenced and found to contain 44 predicted open reading frames (ORFs) which comprised ∼87% of the total sequence. Fifteen ORFs did not show any significant homology to known gene sequences. A number of ORFs show significant homology to plasmid-related genes, suggesting, at least in part, a plasmid origin for the SGI1, although some with homology to phage-related genes were identified. The SGI1 was identified in a number of multidrug-resistant DT120 andS. entericaserovar Agona strains with similar antibiotic-resistant phenotypes. The G+C content suggests a potential mosaic structure for the SGI1. Emergence of the SGI1 in serovar Agona strains is discussed.
Complementation of a Nonmotile
flaB
Mutant of
Borrelia burgdorferi
by Chromosomal Integration of a Plasmid Containing a Wild-Type
flaB
Allele
Authors: Sartakova Marina L. , Dobrikova Elena Y. , Motaleb M. Abdul , Godfrey Henry P. , Charon Nyles W. , Cabello Felipe C. 
Published: July 2002

ABSTRACT

With the recent identification of antibiotic resistance phenotypes, the use of reporter genes, the isolation of null mutants by insertional inactivation, and the development of extrachromosomal cloning vectors, genetic analysis of
Borrelia burgdorferi
is becoming a reality. A previously described nonmotile, rod-shaped, kanamycin-resistant
B. burgdorferi flaB
::Km null mutant was complemented by electroporation with the erythromycin resistance plasmid pED3 (a pGK12 derivative) containing the wild-type
flaB
sequence and 366 bp upstream from its initiation codon. The resulting MS17 clone possessed erythromycin and kanamycin resistance, flat-wave morphology, and microscopic and macroscopic motility. Several other electroporations with plasmids containing wild-type
flaB
and various lengths (198, 366, or 762 bp) of sequence upstream from the
flaB
gene starting codon did not lead to functional restoration of the nonmotile
flaB
null mutant. DNA hybridization, PCR analysis, and sequencing indicated that the wild-type
flaB
gene in nonmotile clones was present in the introduced extrachromosomal plasmids, while the motile MS17 clone was a merodiploid containing single tandem chromosomal copies of mutated
flaB
::Km and wild-type
flaB
with a 366-bp sequence upstream from its starting codon. Complementation was thus achieved only when wild-type
flaB
was inserted into the borrelial chromosome. Several possible mechanisms for the failure of complementation for extrachromosomally located
flaB
are discussed.
TheBacillus subtilisSignaling Protein SpoIVB Defines a New Family of Serine Peptidases
Authors: Hoa Ngo T. , Brannigan James A. , Cutting Simon M. 
Published: July 2002

ABSTRACTThe protein SpoIVB plays a key role in signaling in the ςKcheckpoint ofBacillus subtilis. This regulatory mechanism coordinates late gene expression during development in this organism and we have recently shown SpoIVB to be a serine peptidase. SpoIVB signals by transiting a membrane, undergoing self-cleavage, and then by an unknown mechanism activating a zinc metalloprotease, SpoIVFB, which cleaves pro-ςKto its active form, ςK, in the outer mother cell chamber of the developing cell. In this work we have characterized the serine peptidase domain of SpoIVB. Alignment of SpoIVB with homologues from other spore formers has allowed site-specific mutagenesis of all potential active site residues within the peptidase domain. We have defined the putative catalytic domain of the SpoIVB serine peptidase as a 160-amino-acid residue segment at the carboxyl terminus of the protein. His236 and Ser378 are the most important residues for proteolysis, with Asp363 being the most probable third member of the catalytic triad. In addition, we have shown that mutations at residues Asn290 and His394 lead to delayed signaling in the ςKcheckpoint. The active site residues suggest that SpoIVB and its homologues from other spore formers are members of a new family of serine peptidases of the trypsin superfamily.
Isolation of
Legionella anisa
Using an Amoebic Coculture Procedure
Authors: La Scola Bernard , Mezi Lyazid , Weiller P. J. , Raoult Didier 
Published: July 2002

ABSTRACT

Conventional diagnostic tests for legionellosis were negative for a 61-year-old immunocompromised man with pneumonia. However, coculture of a sputum sample with
Acanthamoeba polyphaga
amoebae led to the recovery of
Legionella anisa
. This procedure may be a sensitive and convenient diagnostic method, especially for non-
Legionella pneumophila
species infections that can be diagnosed only by culture.
Geographical Heterogeneity between Far Eastern and Western Countries in Prevalence of the Virulence Plasmid, the SuperantigenYersinia pseudotuberculosis-Derived Mitogen, and the High-Pathogenicity Island amongYersinia pseudotuberculosisStrains
Authors: Fukushima Hiroshi , Matsuda Yuhou , Seki Ryotaro , Tsubokura Misao , Takeda Nobuaki , Shubin Felix Nikolaevich , Paik In Ki , Zheng Xue Bin 
Published: July 2002

ABSTRACTYersinia pseudotuberculosisproduces novel superantigenic toxins designated YPMa (Y. pseudotuberculosis-derived mitogen), YPMb, and YPMc and has a pathogenicity island termed HPI (high-pathogenicity island) and R-HPI (the right-hand part of the HPI with truncation in its left-hand part) on the chromosome. Analysis of the distribution of these virulence factors allowed for differentiation of speciesY. pseudotuberculosisinto six subgroups, thus reflecting the geographical spread of two main clones: the YPMa+HPI−Far Eastern systemic pathogenic type belonging to serotypes O1b, -2a, -2b, -2c, -3, -4a, -4b, -5a, -5b, -6, -10, and UT (untypeable) and the YPMs−HPI+European gastroenteric pathogenic type belonging to serotypes O1a and -1b. The YPMa+HPI+pathogenic type belonging to serotypes O1b, -3, -5a, -5b, and UT and the YPMb+HPI−nonpathogenic type belonging to non-melibiose-fermenting serotypes O1b, -5a, -5b, -6, -7, -9, -10, -11, and -12 were prevalent in the Far East. The YPMc+R-HPI+European low-pathogenicity type belonging to non-melibiose-fermenting serotype O3 and the YPMs−HPI−pathogenic type belonging to 15 serotypes were found to be prevalent all over the world. This new information is useful for a better understanding of the evolution and spread ofY. pseudotuberculosis.
Infected Branchial Cleft Cyst Due to
Bordetella bronchiseptica
in an Immunocompetent Patient
Authors: Lo Re Vincent , Brennan Patrick J. , Wadlin Jill , Weaver Robert , Nachamkin Irving 
Published: July 2002

ABSTRACT

A healthy 23-year-old man with fever and a tender mass in his right anterior neck was found to have a branchial cleft cyst infected with
Bordetella bronchiseptica
. Initial testing suggested a
Brucella
species, but further laboratory testing identified the organism definitively.
B. bronchiseptica
infection in healthy adults is an unusual event.
Invasive Fungal Sinusitis and Meningitis Due to
Arthrographis kalrae
in a Patient with AIDS
Authors: Chin-Hong Peter V. , Sutton Deanna A. , Roemer Marguerite , Jacobson Mark A. , Aberg Judith A. 
Published: July 2002

ABSTRACT

We report the first described case of
Arthrographis kalrae
pansinusitis and meningitis in a patient with AIDS. The patient was initially diagnosed with
Arthrographis kalrae
pansinusitis by endoscopic biopsy and culture. The patient was treated with itraconazole for approximately 5 months and then died secondary to
Pneumocytis carinii
pneumonia. Postmortem examination revealed invasive fungal sinusitis that involved the sphenoid sinus and that extended through the cribiform plate into the inferior surfaces of the bilateral frontal lobes. There was also an associated fungal meningitis and vasculitis with fungal thrombosis and multiple recent infarcts that involved the frontal lobes, right caudate nucleus, and putamen. Post mortem cultures were positive for
A. kalrae
.
Case of Synovitis Potentially Caused by
Dolosigranulum pigrum
Authors: Hall G. S. , Gordon S. , Schroeder S. , Smith K. , Anthony K. , Procop G. W. 
Published: July 2002

ABSTRACT

We report a case of synovitis in a 64-year-old man who developed the infection while on steroid therapy for rheumatoid arthritis.
Dolosigranulum pigrum,
a gram-positive catalase-negative coccus, was isolated from two sets of blood cultures prior to antibiotic therapy. The patient was treated with 4 weeks of appropriate antibiotics, and the synovial inflammation resolved. Although synovial aspirates were never positive for any bacteria or fungi, the timing of positive blood cultures and absence of other pathogens suggest the possible etiology as
D. pigrum
.
Pediatric Solid-Organ Transplant Recipients Carry Chronic Loads of Epstein-Barr Virus Exclusively in the Immunoglobulin D-Negative B-Cell Compartment
Authors: Rose Camille , Green Michael , Webber Steven , Ellis Demetrius , Reyes Jorges , Rowe David 
Published: July 2002

ABSTRACTSolid-organ transplant recipients are at risk for development of lymphoproliferative diseases. The purpose of this study was to examine the distribution of Epstein-Barr virus (EBV) load in the peripheral blood of pediatric transplant recipients who had become chronic viral load carriers (>8 copies/105lymphocytes for >2 months). A total of 19 patients with viral loads ranging from 20 to 5,000 viral genome copies/105lymphocytes were studied. Ten patients had no previous diagnosis of posttransplant lymphoproliferative disease (PT-LPD), while nine had recovered from a diagnosed case of PT-LPD. No portion of the peripheral blood viral load was detected in the cell-free plasma fraction. Viral DNA was found in a population of cells characterized as CD19hiand immunoglobulin D negative, a phenotype that is consistent with the virus being carried exclusively in the memory B-cell compartment of the peripheral blood. There was no difference in the compartmentalization based upon either the level of the viral load or the past diagnosis of an episode of PT-LPD. These results have implications for the design of tests to detect EBV infection and for the interpretation and use of positive EBV PCR assays in the management of transplant recipients.
Epidemiology of Tuberculosis in Hamburg, Germany: Long-Term Population-Based Analysis Applying Classical and Molecular Epidemiological Techniques
Authors: Diel Roland , Schneider Steffen , Meywald-Walter Karen , Ruf Christa-Maria , Rüsch-Gerdes Sabine , Niemann Stefan 
Published: July 2002

ABSTRACT

To determine a detailed picture of tuberculosis (TB) epidemiology in Hamburg, Germany, 423
Mycobacterium tuberculosis
complex isolates from 77.0% of all patients with culture-confirmed TB diagnosed from 1997 to 1999 in Hamburg were analyzed by IS
6110
DNA fingerprinting. IS
6110
restriction fragment length polymorphism (RFLP) clusters were assumed to have arisen from recent transmission. Results of contact tracing and additional patient interviews were used for further epidemiological analyses. Of the 423 cases, 398 were included in the cluster analysis, of which 135 (33.9%) were classified into 35 clusters ranging from 2 to 23 patients. Epidemiological links verifying recent transmission could be confirmed for 87 of the 135 clustered patients. Risk factors for recent transmission were calculated by a two-step procedure: first, based on patients with clustered isolates; and second, based on patients with clustered isolates and transmission links. In both analyses, alcohol abuse appeared to be the strongest predictor for recent transmission, followed by a history of previous contact tracing and unemployment. Homelessness, foreign ethnicity, sex, drug addiction, and human immunodeficiency virus positivity were not independent risk factors for clustering in multivariate analyses. Classical contact tracing performed prior to IS
6110
RFLP analysis identified only 24 of the 135 clustered patient. In conclusion, recent transmission seems to be frequent in Hamburg and was found to be strongly associated with alcohol abuse. Conventional contact tracing appears to be insufficient for the detection of recent transmission chains. The data presented also indicate that improved TB control strategies, including the use of RFLP for the detection of transmission chains, are needed for TB control in the setting of countries with a low incidence of TB.
Neisseria meningitidis
Serogroups W135 and A Were Equally Prevalent among Meningitis Cases Occurring at the End of the 2001 Epidemics in Burkina Faso and Niger
Authors: Taha Muhamed-Kheir , Parent du Chatelet Isabelle , Schlumberger Martin , Sanou Idrissa , Djibo Saacou , de Chabalier François , Alonso Jean-Michel 
Published: July 2002

ABSTRACT

Meningococcal infections occur as epidemics in the African meningitis belt.
Neisseria meningitidis
serogroup A is predominantly involved in these epidemics. We report here new data on the involvement of both serogroups A and W135 in meningitis cases in Burkina Faso and Niger at the end of the 2001 epidemic.
Distribution of Hepatitis B Virus Genotypes among American Blood Donors Determined with a PreS2 Epitope Enzyme-Linked Immunosorbent Assay Kit
Authors: Moriya Takashi , Kuramoto Isamu K. , Yoshizawa Hiroshi , Holland Paul V. 
Published: July 2002

ABSTRACTWe genotyped 418 sera from volunteer blood donors from two large, regional blood centers in the United States who were HBsAg positive by an enzyme-linked immunosorbent assay (ELISA). The HBV genotypes were determined by a serological method using a preS2 epitope ELISA kit (Institute of Immunology, Tokyo, Japan) with monoclonal antibodies. Of the 418 samples, the genotypes of 320 could be determined (76.6%). One hundred forty-three (34.2%) were genotyped as A (preS2 subtype su), 31 (7.4%) were genotyped as B (subtype m), 59 (14.1%) were genotyped as C (subtype ks), 83 (19.9%) were genotyped as D or E (subtype ksu), and 4 (1.0%) were genotyped as F (subtype k). This kit cannot differentiate genotypes D and E. For 98 (23.4%) of the 418 samples, the genotype could not be determined; 11 of these 98 samples were positive for at least one of the preS2 genotype-specific epitopes (m, k, s, and u), but the combinations of positive epitopes were different from those of samples that could be genotyped; 45 had only the common epitope (b). In the group with a high signal-to-cutoff (S/C) ratio, the HBV genotype could be determined for 199 (84%) of 237 samples; in contrast, in the low-S/C-ratio group, only 10 (20%) of 51 samples could be genotyped (P< 0.001). These findings may indicate the limitation of genotyping samples with low S/C ratios for HBsAg by ELISA or the existence of genotype G or other new HBV genotypes in HBsAg-positive blood donors in the United States. Of the genotyped samples, 201 were assayed for HBeAg; only 9 (4.5%) were positive for HBeAg. The frequency of genotype C in HBeAg-positive donor samples (5 of 9 or 56%) was higher than that in HBeAg-negative donor samples (33 of 192, or 17%) (P= 0.022).
Design and Intracellular Activity of a Human Single-Chain Antibody to Human Immunodeficiency Virus Type 1 Conserved gp41 Epitope
Authors: Legastelois Isabelle , Desgranges Claude 
Published: July 2002

ABSTRACTA human lymphoid cell line (F172-D8) excreting a human immunodeficiency virus type 1 (HIV-1) anti-gp41 monoclonal antibody was used to construct a plasmid containing the cDNA of the single-chain variable fragment (scFvD8) corresponding to this antibody. A stable human osteosarcoma cell line was obtained which expressed the scFvD8 protein in the cytoplasm. Whereas a cell line transfected with a control construct (pCI-neo) was readily and productively infected with laboratory (Ba-L) or primary HIV-1 isolates, the scFvD8 cell line did not support productive infection. Binding of the virus, internalization, and reverse transcription were not altered by scFvD8 expression, but gp160 expression was dramatically reduced. These data suggest that cytoplasmic expression of this artificial single-chain antibody can interfere with gp160 expression, thereby reducing the production of mature viral envelope proteins.
Prostaglandin E2Increases Bovine Leukemia VirustaxandpolmRNA Levels via Cyclooxygenase 2: Regulation by Interleukin-2, Interleukin-10, and Bovine Leukemia Virus
Authors: Pyeon Dohun , Diaz Francisco J. , Splitter Gary A. 
Published: July 2002

ABSTRACTProstaglandin E2(PGE2), produced by macrophages, has important immune regulatory functions, suppressing a type 1 immune response and stimulating a type 2 immune response. Type 1 cytokines (interleukin-2 [IL-2], IL-12, and gamma interferon) increase in freshly isolated peripheral blood mononuclear cells (PBMCs) of animals with an early disease stage of bovine leukemia virus (BLV) infection, while IL-10 increases in animals with a late disease stage. Although IL-10 has an immunosuppressive role in the host immune system, IL-10 also inhibits BLVtaxandpolmRNA levels in vitro. In contrast, IL-2 stimulates BLVtaxandpolmRNA and p24 protein expression in cultured PBMCs. The inhibitory effect of IL-10 on BLV expression depends on soluble factors secreted by macrophages. Thus, we hypothesized that PGE2, a cyclooxygenase 2 (COX-2) product of macrophages, may regulate BLV expression. Here, we show that the level of COX-2 mRNA was decreased in PBMCs treated with IL-10, while IL-2 enhanced the level of COX-2 mRNA. Addition of PGE2stimulated BLVtaxandpolmRNA levels and reversed the IL-10 inhibition of BLV mRNA. In addition, the specific COX-2 inhibitor, NS-398, inhibited the amount of BLV mRNA detected. Addition of PGE2increased BLVtaxmRNA regardless of NS-398 addition. PGE2inhibited antigen-specific PBMC stimulation, suggesting that stimulation of BLVtaxandpolmRNA levels by PGE2is independent of cell proliferation. These findings suggest that macrophage-derived COX-2 products, such as PGE2, regulate virus expression and disease progression in BLV infection.
Human Parechovirus 1 Utilizes Integrins αvβ3 and αvβ1 as Receptors
Authors: Triantafilou Kathy , Triantafilou Martha , Takada Yoshikazu , Fernandez Nelson 
Published: July 2002

ABSTRACT
Human parechovirus 1 (HPEV1) displays an arginine-glycine-aspartic acid (RGD) motif in the VP1 capsid protein, suggesting integrins as candidate receptors for HPEV1. A panel of monoclonal antibodies (MAbs) specific for integrins αvβ3, αvβ1, and αvβ5, which have the ability to recognize the RGD motif, and also a MAb specific for integrin α2β1, an integrin that does not recognize the RGD motif, were tested on A549 cells. Our results showed that integrin αv-specific MAb reduced infectivity by 85%. To specify which αv integrins the virus utilizes, we tested MAbs specific to integrins αvβ3 and αvβ1 which reduced infectivity significantly, while a MAb specific for integrin αvβ5, as well as the MAb specific for α2β1, showed no reduction. When a combination of MAbs specific for integrins αvβ3 and αvβ1 were used, virus infectivity was almost completely inhibited; this shows that integrins αvβ3 and αvβ1 are utilized by the virus. We therefore proceeded to test whether αv integrins' natural ligands fibronectin and vitronectin had an effect on HPEV1 infectivity. We found that vitronectin reduced significantly HPEV1 infectivity, whereas a combination of vitronectin and fibronectin abolished infection. To verify the use of integrins αvβ3 and αvβ1 as HPEV1 receptors, CHO cells transfected and expressing either integrin αvβ3 or integrin αvβ1 were used. It was shown that the virus could successfully infect these cells. However, in immunoprecipitation experiments using HPEV1 virions and allowing the virus to bind to solubilized A549 cell extract, we isolated and confirmed by Western blotting the αvβ3 heterodimer. In conclusion, we found that HPEV1 utilises both integrin αvβ3 and αvβ1 as receptors; however, in cells that express both integrins, HPEV1 may preferentially bind integrin αvβ3.