bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mycobacterial Antigens Exacerbate Disease Manifestations inMycobacterium tuberculosis-Infected Mice
Authors: Moreira Andre L. , Tsenova Liana , Haile Aman Melles , Bekker Linda-Gail , Freeman Sherry , Mangaliso Bande , Schröder Ulf , Jagirdar Jaishree , Rom William N. , Tovey Michael G. , Freedman Victoria H. , Kaplan Gilla 
Published: July 2002

ABSTRACTTo control tuberculosis worldwide, the burden of adult pulmonary disease must be reduced. Although widely used,Mycobacterium bovisBCG vaccination given at birth does not protect against adult pulmonary disease. Therefore, postexposure vaccination of adults with mycobacterial antigens is being considered. We examined the effect of various mycobacterial antigens on mice with priorM. tuberculosisinfection. Subcutaneous administration of live or heat-treated BCG with or without lipid adjuvants to infected mice induced increased antigen-specific T-cell proliferation but did not reduce the bacterial load in the lungs and caused larger lung granulomas. Similarly, additional mycobacterial antigen delivered directly to the lungs by aerosol infection with viableM. tuberculosismixed with heat-killedMycobacterium tuberculosis(1:1) also did not reduce the bacillary load but caused increased expression of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6), which was associated with larger granulomas in the lungs. WhenM. tuberculosis-infected mice were treated with recombinant BCG that secreted cytokines shown to reduce disease in a preinfection vaccine model, the BCG secreting TNF-α, and to a lesser extent, IL-2 and gamma interferon (IFN-γ), caused a significant increase in granuloma size in the lungs. Moreover, treatment ofM. tuberculosis-infected mice with recombinant murine TNF-α resulted in increased inflammation in the lungs and accelerated mortality without affecting the bacillary load. Taken together, these studies suggest that administration of mycobacterial antigens to mice with priorM. tuberculosisinfection leads to immune activation that may exacerbate lung pathology via TNF-α-induced inflammation without reducing the bacillary load.
NonviableBurkholderia malleiInduces a Mixed Th1- and Th2-Like Cytokine Response in BALB/c Mice
Authors: Amemiya Kei , Bush Gary V. , DeShazer David , Waag David M. 
Published: July 2002

ABSTRACTNonviable cell preparations ofBurkholderia mallei, the causative agent of glanders, were evaluated as potential vaccine candidates in a BALB/c murine model. Three differentB. malleicell preparations plus Alhydrogel were evaluated: a heat-killed preparation, an irradiation-inactivated preparation, and a preparation of a capsule-negative mutant strain which had been irradiation inactivated. BALB/c mice were vaccinated twice with the differentB. malleipreparations, and spleens and sera were collected to determine their cellular and humoral immune responses. All three bacterial cell preparations had essentially the same results in two cellular immune response assays. In a splenocyte proliferation assay, the amount of cell proliferation in response to the homologous immunogen, concanavalin A, or lipopolysaccharide was similar for all the cell preparations. Also, splenocytes from the inoculated mice expressed interleukin 2 (IL-2), gamma interferon, and small amounts of IL-4 and IL-5, and more IL-10 cytokine in the presence of the homologous antigen. When the immunoglobulin subclasses from these mice were examined, they all produced higher levels of IgG1 than IgG2a subclasses. The higher ratio of IgG1 to IgG2a was not due to the amount of the immunogen or the adjuvant (Alhydrogel) used in the BALB/c mice. The cell preparations did not protect the vaccinated mice from a live challenge (>300 50% lethal doses). Our results suggest that in BALB/c mice, a mixed T-helper-cell-like response to nonviableB. malleiis obtained, as demonstrated by a Th1- and Th2-like cytokine response and a Th2-like subclass immunoglobulin response. This may be the reason for the inability of theB. malleicells that were examined as candidate vaccines to protect the mice from a live challenge.
Gamma Interferon Fails To Induce Expression of Indoleamine 2,3-Dioxygenase and Does Not Control the Growth ofChlamydophila abortusin BeWo Trophoblast Cells
Authors: Entrican Gary , Wattegedera Sean , Chui Michelle , Oemar Lyn , Rocchi Mara , McInnes Colin 
Published: July 2002

ABSTRACTThe BeWo trophoblast cell line does not constitutively express the tryptophan degrading enzyme indolamine 2,3-dioxygenase (IDO), nor can IDO expression be induced by gamma interferon. This correlates with the inability of BeWo cells to control the growth ofChlamydophila abortus, in contrast to effects observed in HeLa cells treated with gamma interferon.
Differential Cytokine and Antibody Responses to Adult and Larval Stages ofOnchocerca volvulusConsistent with the Development of Concomitant Immunity
Authors: MacDonald Angus J. , Turaga Prasad S. D. , Harmon-Brown Carolyn , Tierney Tracy J. , Bennett Kristine E. , McCarthy Maggie C. , Simonek Scott C. , Enyong Peter A. , Moukatte Daniel W. , Lustigman Sara 
Published: July 2002

ABSTRACTThe possibility of concomitant immunity and its potential mechanisms inOnchocerca volvulusinfection were examined by analyzing cytokine and antibody responses to infective larval (third-stage larvae [L3] and molting L3 [mL3]), adult female worm (F-OvAg), and skin microfilaria (Smf) antigens in infected individuals in a region of hyperendemicity in Cameroon as a function of age. Peripheral blood mononuclear cell interleukin 5 (IL-5) responses to F-OvAg and Smf declined significantly with age (equivalent to years of exposure toO. volvulus). In contrast, IL-5 secretion in response to L3 and mL3 remained elevated with increasing age. Gamma interferon responses to L3, mL3, and F-OvAg were low or suppressed and unrelated to age, except for responses to Smf in older subjects. IL-10 levels were uniformly elevated, regardless of age, in response to L3, mL3, and F-OvAg but not to Smf, for which levels declined with age. A total of 49 to 60% of subjects had granulocyte-macrophage colony-stimulating factor responses to allO. volvulusantigens unrelated to age. Analysis of levels of stage-specific immunoglobulin G3 (IgG3) and IgE revealed a striking, age-dependent dissociation between antibody responses to larval antigens (L3 and a recombinant L3-specific protein,O. volvulusALT-1) which were significantly increased or maintained with age and antibody responses to F-OvAg, which decreased. Levels of IgG1 to L3 and F-OvAg were elevated regardless of age, and levels of IgG4 increased significantly with age, although not toO. volvulusALT-1, which may have unique L3-specific epitopes. Immunofluorescence staining of whole larvae showed that total anti-L3 immunoglobulin levels also increased with the age of the serum donor. The separate and distinct cytokine and antibody responses to adult and infective larval stages ofO. volvuluswhich are age related are consistent with the acquisition of concomitant immunity in infected individuals.
Analysis of Sequence Diversity at the Highly Polymorphic
Cpgp40
/
15
Locus among
Cryptosporidium
Isolates from Human Immunodeficiency Virus-Infected Children in South Africa
Authors: Leav Brett A. , Mackay Malanie R. , Anyanwu Akudo , O' Connor Roberta M. , Cevallos Ana Maria , Kindra Gurpreet , Rollins Nigel C. , Bennish Michael L. , Nelson Richard G. , Ward Honorine D. 
Published: July 2002

ABSTRACT

Cryptosporidium
sp. is a significant cause of diarrheal disease, particularly in human immunodeficiency virus (HIV)-infected patients in developing countries. We recently cloned and sequenced several alleles of the highly polymorphic single-copy
Cryptosporidium parvum
gene
Cpgp40
/
15.
This gene encodes a precursor protein that is proteolytically cleaved to yield mature cell surface glycoproteins gp40 and gp15, which are implicated in zoite attachment to and invasion of enterocytes. The most-striking feature of the
Cpgp40
/
15
alleles and proteins is their unprecedented degree of sequence polymorphism, which is far greater than that observed for any other gene or protein studied in
C. parvum
to date. In this study we analyzed nucleic acid and amino acid sequence polymorphism at the
Cpgp40
/
15
locus of 20
C. parvum
isolates from HIV-infected South African children. Fifteen isolates exhibited one of four previously identified genotype I alleles at the
Cpgp40
/
15
locus (Ia, Ib, Ic, and Id), while five displayed a novel set of polymorphisms that defined a new
Cpgp40
/
15
genotype I allele, designated genotype Ie. Surprisingly, only 15 of these isolates exhibited concordant type I alleles at the thrombospondin-related adhesive protein of
Cryptosporidium
and
Cryptosporidium
oocyst wall protein loci, while five isolates (all of which displayed
Cpgp40
/
15
genotype Ic alleles) displayed genotype II alleles at these loci. Furthermore, the last five isolates also manifested chimeric genotype Ic/Ib or Ic/II alleles at the
Cpgp40
/
15
locus, raising the possibility of sexual recombination within and between prototypal parasite genotypes. Lastly, children infected with isolates having genotype Ic alleles were significantly older than those infected with isolates displaying other genotype I alleles.
Sequence Diversity of
Pseudomonas aeruginosa
: Impact on Population Structure and Genome Evolution
Authors: Kiewitz Claudia , Tümmler Burkhard 
Published: July 2002

ABSTRACT

Comparative sequencing of
Pseudomonas aeruginosa
genes
oriC
,
citS
,
ampC
,
oprI
,
fliC
, and
pilA
in 19 environmental and clinical isolates revealed the sequence diversity to be about 1 order of magnitude lower than in comparable housekeeping genes of
Salmonella
. In contrast to the low nucleotide substitution rate, the frequency of recombination among different
P. aeruginosa
genotypes was high, leading to the random association of alleles. The
P. aeruginosa
population consists of equivalent genotypes that form a net-like population structure. However, each genotype represents a cluster of closely related strains which retain their sequence signature in the conserved gene pool and carry a set of genotype-specific DNA blocks. The codon adaptation index, a quantitative measure of synonymous codon bias of genes, was found to be consistently high in the
P. aeruginosa
genome irrespective of the metabolic category and the abundance of the encoded gene product. Such uniformly high codon adaptation indices of 0.55 to 0.85 fit the ubiquitous lifestyle of
P. aeruginosa
.
The Clp Proteases ofBacillus subtilisAre Directly Involved in Degradation of Misfolded Proteins
Authors: Krüger Elke , Witt Elke , Ohlmeier Steffen , Hanschke Renate , Hecker Michael 
Published: July 2002

ABSTRACTThe presence of the heat stress response-related ATPases ClpC and ClpX or the peptidase ClpP in the cell is crucial for tolerance of many forms of stress inBacillus subtilis. Assays for detection of defects in protein degradation suggest that ClpC, ClpP, and ClpX participate directly in overall proteolysis of misfolded proteins. Turnover rates for abnormal puromycyl peptides are significantly decreased inclpC,clpP, andclpXmutant cells. Electron-dense aggregates, most likely due to the accumulation of misfolded proteins, were noticed in studies of ultrathin cryosections inclpCandclpPmutant cells even under nonstress conditions. In contrast, in the wild type orclpXmutants such aggregates could only be observed after heat shock. This phenomenon supports the assumption thatclpCandclpPmutants are deficient in the ability to solubilize or degrade damaged and aggregated proteins, the accumulation of which is toxic for the cell. By using immunogold labeling with antibodies raised against ClpC, ClpP, and ClpX, the Clp proteins were localized in these aggregates, showing that the Clp proteins act at this level in vivo.
A Point Mutation in the
mma3
Gene Is Responsible for Impaired Methoxymycolic Acid Production in
Mycobacterium bovis
BCG Strains Obtained after 1927
Authors: Behr Marcel A. , Schroeder Benjamin G. , Brinkman Jacquelyn N. , Slayden Richard A. , Barry Clifton E. 
Published: July 2002

ABSTRACT

BCG vaccines are substrains of
Mycobacterium bovis
derived by attenuation in vitro. After the original attenuation (1908 to 1921), BCG strains were maintained by serial propagation in different BCG laboratories (1921 to 1961). As a result, various BCG substrains developed which are now known to differ in a number of genetic and phenotypic properties. However, to date, none of these differences has permitted a direct phenotype-genotype link. Since BCG strains differ in their abilities to synthesize methoxymycolic acids and since recent work has shown that the
mma3
gene is responsible for O-methylation of hydroxymycolate precursors to form methoxymycolic acids, we analyzed methoxymycolate production and
mma3
gene sequences for a genetically defined collection of BCG strains. We found that BCG strains obtained from the Pasteur Institute in 1927 and earlier produced methoxymycolates in vitro but that those obtained from the Pasteur Institute in 1931 and later all failed to synthesize methoxymycolates, and furthermore, the
mma3
sequence of the latter strains differs from that of
Mycobacterium tuberculosis
H37Rv by a point mutation at bp 293. Site-specific introduction of this guanine-to-adenine mutation into wild-type
mma3
(resulting in the replacement of glycine 98 with aspartic acid) eliminated the ability of this enzyme to produce O-methylated mycolic acids when the mutant was cloned in tandem with
mma4
into
Mycobacterium smegmatis
. These findings indicate that a point mutation in
mma3
occurred between 1927 and 1931, and that this mutant population became the dominant clone of BCG at the Pasteur Institute.
An Abundant DNA Binding Protein from the Hyperthermophilic Archaeon
Sulfolobus shibatae
Affects DNA Supercoiling in a Temperature-Dependent Fashion
Authors: Xue Hong , Guo Rong , Wen Yunfei , Liu Danxu , Huang Li 
Published: July 2002

ABSTRACT

The DNA binding protein Ssh10b, a member of the Sac10b family, has been purified from the hyperthermophilic archaeon
Sulfolobus shibatae
. Ssh10b constitutes about 4% of the cellular protein. Electrophoretic mobility shift assays showed that Ssh10b first bound a double-stranded DNA fragment with an estimated binding size of ∼∼12 bp, forming distinct shifts, until the DNA was coated with the protein. Binding of more Ssh10b resulted in the formation of smears of lower mobilities. The migration pattern of the smearing Ssh10b-DNA complexes was affected by temperature, whereas that of complexes associated with the distinct shifts was not. Interestingly, Ssh10b was capable of constraining negative DNA supercoils in a temperature-dependent fashion. While the ability of the protein to constrain supercoils was weak at 25°C, it was enhanced substantially at 45°C or higher temperatures (up to 80°C). Taken together, our data suggest that archaeal proteins of the Sac10b family may affect the topology of chromosomal DNA in thermophilic archaea at their growth temperatures.
Analysis of MinC Reveals Two Independent Domains Involved in Interaction with MinD and FtsZ
Authors: Hu Zonglin , Lutkenhaus Joe 
Published: July 2002

ABSTRACT

In
Escherichia coli
FtsZ assembles into a Z ring at midcell while assembly at polar sites is prevented by the
min
system. MinC, a component of this system, is an inhibitor of FtsZ assembly that is positioned within the cell by interaction with MinDE. In this study we found that MinC consists of two functional domains connected by a short linker. When fused to MalE the N-terminal domain is able to inhibit cell division and prevent FtsZ assembly in vitro. The C-terminal domain interacts with MinD, and expression in wild-type cells as a MalE fusion disrupts
min
function, resulting in a minicell phenotype. We also find that MinC is an oligomer, probably a dimer. Although the C-terminal domain is clearly sufficient for oligomerization, the N-terminal domain also promotes oligomerization. These results demonstrate that MinC consists of two independently functioning domains: an N-terminal domain capable of inhibiting FtsZ assembly and a C-terminal domain responsible for localization of MinC through interaction with MinD. The fusion of these two independent domains is required to achieve topological regulation of Z ring assembly.
Identification of aMycobacterium tuberculosisGene That Enhances Mycobacterial Survival in Macrophages
Authors: Wei Jun , Dahl John L. , Moulder James W. , Roberts Esteban A. , O'Gaora Peadar , Young Douglas B. , Friedman Richard L. 
Published: July 2002

ABSTRACTIntracellular survival plays a central role in the pathogenesis ofMycobacterium tuberculosis. To identifyM. tuberculosisgenes required for intracellular survival within macrophages, anM. tuberculosisH37Rv plasmid library was constructed by using the shuttle vector pOLYG. This plasmid library was electroporated intoMycobacterium smegmatis1-2c, and the transformants were used to infect the human macrophage-like cell line U-937. BecauseM. smegmatisdoes not readily survive within macrophages, any increased intracellular survival is likely due to clonedM. tuberculosisH37Rv DNA. After six sequential passages ofM. smegmatistransformants through U-937 cells, one clone (p69) was enriched more than 70% as determined by both restriction enzyme and PCR analyses. p69 demonstrated significantly enhanced survival compared to that of the vector control, ranging from 2.4- to 5.3-fold at both 24 and 48 h after infection. DNA sequence analysis revealed three open reading frames (ORFs) in the insert of p69. ORF2 (1.2 kb) was the only one which contained a putative promoter region and a ribosome-binding site. Deletion analysis of the p69 insert DNA showed that disruption of ORF2 resulted in complete loss of the enhanced intracellular survival phenotype. This gene was named the enhanced intracellular survival (eis) gene. By using an internal region ofeisas a probe for Southern analysis,eiswas found in the genomic DNA of variousM. tuberculosisstrains and ofMycobacterium bovisBCG but not in that ofM. smegmatisor 10 other nonpathogenic mycobacterial species. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis showed that allM. smegmatis eis-containing constructs expressed a unique protein of 42 kDa, the predicted size of Eis. The expression of this 42-kDa protein directly correlated to the enhanced survival ofM. smegmatisp69 in U-937 cells. These results suggest a possible role foreisand its protein product in the intracellular survival ofM. tuberculosis.
Mobilization of Poly(3-Hydroxybutyrate) inRalstonia eutropha
Authors: Handrick René , Reinhardt Simone , Jendrossek Dieter 
Published: July 2002

ABSTRACTRalstonia eutrophaH16 degraded (mobilized) previously accumulated poly(3-hydroxybutyrate) (PHB) in the absence of an exogenous carbon source and used the degradation products for growth and survival. Isolated native PHB granules of mobilizedR. eutrophacells released 3-hydroxybutyrate (3HB) at a threefold higher rate than did control granules of nonmobilized bacteria. No 3HB was released by native PHB granules of recombinantEscherichia coliexpressing the PHB biosynthetic genes. Native PHB granules isolated from chromosomal knockout mutants of an intracellular PHB (i-PHB) depolymerase gene ofR. eutrophaH16 and HF210 showed a reduced but not completely eliminated activity of 3HB release and indicated the presence of i-PHB depolymerase isoenzymes.
Cholic Acid Is Accumulated Spontaneously, Driven by Membrane ΔpH, in Many Lactobacilli
Authors: Kurdi Peter , van Veen Hendrik W. , Tanaka Hiroshi , Mierau Igor , Konings Wil N. , Tannock Gerald W. , Tomita Fusao , Yokota Atsushi 
Published: July 2002

ABSTRACT
Many lactobacilli from various origins were found to apparently lack cholic acid extrusion activity. Cholic acid was accumulated spontaneously, driven by the transmembrane proton gradient. Accumulation is a newly identified kind of interaction between intestinal microbes and unconjugated bile acids and is different from extrusion and modification, which have been described previously.
Regulatable Arabinose-Inducible Gene Expression System with Consistent Control in All Cells of a Culture
Authors: Khlebnikov Artem , Risa Øystein , Skaug Tove , Carrier Trent A. , Keasling J. D. 
Published: July 2002

ABSTRACT

The arabinose-inducible promoter

P
BAD

is subject to all-or-none induction, in which intermediate concentrations of arabinose give rise to subpopulations of cells that are fully induced and uninduced. To construct a host-vector expression system with regulatable control in a homogeneous population of cells, the
araE
gene of
Escherichia coli
was cloned into an RSF1010-derived plasmid under control of the isopropyl-β-
d
-thiogalactopyranoside-inducible

P
tac

and

P
taclac

promoters. This gene encodes the low-affinity, high-capacity arabinose transport protein and is controlled natively by an arabinose-inducible promoter. To detect the effect of arabinose-independent
araE
expression on population homogeneity and cell-specific expression, the
gfpuv
gene was placed under control of the arabinose-inducible
araBAD
promoter (

P
BAD

) on the pMB1-derived plasmid pBAD24. The transporter and reporter plasmids were transformed into
E. coli
strains with native arabinose transport systems and strains deficient in one or both of the arabinose transport systems (
araE
and/or
araFGH
). The effects of the arabinose concentration and arabinose-independent transport control on population homogeneity were investigated in these strains using flow cytometry. The
araE
, and
araE araFGH
mutant strains harboring the transporter and reporter plasmids were uniformly induced across the population at all inducer concentrations, and the level of gene expression in individual cells varied with arabinose concentration. In contrast, the parent strain, which expressed the native
araE
and
araFGH
genes and harbored the transporter and reporter plasmids, exhibited all-or-none behavior. This work demonstrates the importance of including a transport gene that is controlled independently of the inducer to achieve regulatable and consistent induction in all cells of the culture.
The Truncated Form of the Bacterial Heat Shock Protein ClpB/HSP100 Contributes to Development of Thermotolerance in the Cyanobacterium
Synechococcus
sp. Strain PCC 7942
Authors: Clarke Adrian K. , Eriksson Mats-Jerry 
Published: July 2002

ABSTRACT

ClpB is a highly conserved heat shock protein that is essential for thermotolerance in bacteria and eukaryotes. One distinctive feature of all bacterial
clpB
genes is the dual translation of a truncated 79-kDa form (ClpB-79) in addition to the full-length 93-kDa protein (ClpB-93). To investigate the currently unknown function of ClpB-79, we have examined the ability of the two different-sized ClpB homologues from the cyanobacterium
Synechococcus
sp. strain PCC 7942 to confer thermotolerance. We show that the ClpB-79 form has the same capacity as ClpB-93 to confer thermotolerance and that the ClpB-79 protein contributes ca. one-third of the total thermotolerance developed in wild-type
Synechococcus
, the first in vivo demonstration of a functional role for ClpB-79 in bacteria.