bluuebunny/crossref_metadata_2025_split huggingface dataset:
CD8+T Cells Participate in the Memory Immune Response toMycobacterium tuberculosis
Authors: Serbina Natalya V. , Flynn JoAnne L. 
Published: July 2002

ABSTRACTThe contribution of CD8+T cells to the control of tuberculosis has been studied primarily during acute infection in mouse models. Memory or recall responses in tuberculosis are less well characterized, particularly with respect to the CD8 T-cell subset. In fact, there are published reports that CD8+T cells do not participate in the memory immune response toMycobacterium tuberculosis. We examined the CD8+T-cell memory and local recall response toM. tuberculosis. To establish a memory immunity model, C57BL/6 mice were infected withM. tuberculosis, followed by treatment with anti-mycobacterial drugs and prolonged rest. The lungs of memory immune mice contained CD4+and CD8+T cells with the cell surface phenotype characteristic of memory cells (CD69lowCD25lowCD44high). At 1 week postchallenge withM. tuberculosisvia aerosol, ≥30% of both CD4+and CD8+T cells in the lungs of immune mice expressed the activation marker CD69 and could be restimulated to produce gamma interferon (IFN-γ). In contrast, <6% of T cells in the lungs of naive challenged mice were CD69+at 1 week postchallenge, and IFN-γ production was not observed at this time point. CD8+T cells from the lungs of both naive and memory mice after challenge were cytotoxic towardM. tuberculosis-infected macrophages. Our data indicate that memory and recall immunity toM. tuberculosisis comprised of both CD4+and CD8+T lymphocytes and that there is a rapid response of both subsets in the lungs following challenge.
Salmonella-Induced Cell Death Is Not Required for Enteritis in Calves
Authors: Santos Renato L. , Tsolis Renée M. , Zhang Shuping , Ficht Thomas A. , Bäumler Andreas J. , Adams L. Garry 
Published: July 2002

ABSTRACTSalmonellaenterica serovar Typhimurium causes cell death in bovine monocyte-derived and murine macrophages in vitro by asipB-dependent mechanism. During this process, SipB binds and activates caspase-1, which in turn activates the proinflammatory cytokine interleukin-1β through cleavage. We used bovine ileal ligated loops to address the role of serovar Typhimurium-induced cell death in induction of fluid accumulation and inflammation in this diarrhea model. Twelve perinatal calves had 6- to 9-cm loops prepared in the terminal ileum. They were divided into three groups: one group received an intralumen injection of Luria-Bertani broth as a control in 12 loops. The other two groups (four calves each) were inoculated with 0.75 × 109CFU of either wild-type serovar Typhimurium (strain IR715) or asopBmutant per loop in 12 loops. Hematoxylin and eosin-stained sections were scored for inflammation, and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells were detected in situ. Fluid accumulation began at 3 h postinfection (PI). Inflammation was detected in all infected loops at 1 h PI. The area of TUNEL-labeled cells in the wild-type infected loops was significantly higher than that of the controls at 12 h PI, when a severe inflammatory response and tissue damage had already developed. ThesopBmutant induced the same amount of TUNEL-positive cells as the wild type, but it was attenuated for induction of fluid secretion and inflammation. Our results indicate that serovar Typhimurium-induced cell death is not required to trigger an early inflammatory response and fluid accumulation in the ileum.
Distribution of Quorum-Sensing Genes in the
Burkholderia cepacia
Complex
Authors: Lutter E. , Lewenza S. , Dennis J. J. , Visser M. B. , Sokol P. A. 
Published: July 2002

ABSTRACT

The distribution of quorum-sensing genes among strains from seven genomovars of the
Burkholderia cepacia
complex was examined by PCR.
cepR
and
cepI
were amplified from
B. cepacia
genomovars I and III,
B. stabilis
, and
B. vietnamiensis. cepR
was also amplified from
B. multivorans
and
B. cepacia
genomovar VI.
bviIR
were amplified from
B. vietnamiensis
. All genomovars produced
N
-octanoyl-
l
-homoserine lactone and
N
-hexanoyl-
l
-homoserine lactone.
B. vietnamiensis
and
B. cepacia
genomovar VII produced additional
N
-acyl-
l
-homoserine lactones.
Susceptibility of Mice to Vaginal Infection withChlamydia trachomatisMouse Pneumonitis Is Dependent on the Age of the Animal
Authors: Pal Sukumar , Peterson Ellena M. , de la Maza Luis M. 
Published: July 2002

ABSTRACTMice from three strains, BALB/c (H-2d), C3H (H-2k), and C57BL/6 (H-2b), ranging from 5 to 14 weeks of age, were inoculated intravaginally with different doses of theChlamydia trachomatismouse pneumonitis serovar. Vaginal swabs taken at weekly intervals showed that the percentage of animals with positive cultures and the number of inclusion-forming units recovered per mouse were higher in the younger animals. Furthermore, vaginal shedding lasted longer in the young mice than in the older mice. In addition, following mating higher rates of infertility and a decrease in the number of embryos were observed in the infected young mice. In conclusion, susceptibility to a chlamydial vaginal infection is dependent on the age of the mice, with the older animals being more resistant.
T-Cell Reactivity against Streptococcal Antigens in the Periphery Mirrors Reactivity of Heart-Infiltrating T Lymphocytes in Rheumatic Heart Disease Patients
Authors: Guilherme Luiza , Oshiro Sandra E. , Faé Kellen C. , Cunha-Neto Edécio , Renesto Guilherme , Goldberg Anna C. , Tanaka Ana C. , Pomerantzeff Pablo M. A , Kiss Maria H. , Silva Clóvis , Guzman Fanny , Patarroyo Manuel E. , Southwood Scott , Sette Alessandro , Kalil Jorge 
Published: July 2002

ABSTRACTT-cell molecular mimicry between streptococcal and heart proteins has been proposed as the triggering factor leading to autoimmunity in rheumatic heart disease (RHD). We searched for immunodominant T-cell M5 epitopes among RHD patients with defined clinical outcomes and compared the T-cell reactivities of peripheral blood and intralesional T cells from patients with severe RHD. The role of HLA class II molecules in the presentation of M5 peptides was also evaluated. We studied the T-cell reactivity against M5 peptides and heart proteins on peripheral blood mononuclear cells (PBMC) from 74 RHD patients grouped according to the severity of disease, along with intralesional and peripheral T-cell clones from RHD patients. Peptides encompassing residues 1 to 25, 81 to 103, 125 to 139, and 163 to 177 were more frequently recognized by PBMC from RHD patients than by those from controls. The M5 peptide encompassing residues 81 to 96 [M5(81–96) peptide] was most frequently recognized by PBMC from HLA-DR7+DR53+patients with severe RHD, and 46.9% (15 of 32) and 43% (3 of 7) of heart-infiltrating and PBMC-derived peptide-reactive T-cell clones, respectively, recognized the M5(81–103) region. Heart proteins were recognized more frequently by PBMC from patients with severe RHD than by those from patients with mild RHD. The similar pattern of T-cell reactivity found with both peripheral blood and heart-infiltrating T cells is consistent with the migration of M-protein-sensitized T cells to the heart tissue. Conversely, the presence of heart-reactive T cells in the PBMC of patients with severe RHD also suggests a spillover of sensitized T cells from the heart lesion.
Rapid Activation of Protein Tyrosine Kinase and Phospholipase C-γ2 and Increase in Cytosolic Free Calcium Are Required byEhrlichia chaffeensisfor Internalization and Growth in THP-1 Cells
Authors: Lin Mingqun , Zhu Michael X. , Rikihisa Yasuko 
Published: July 2002

ABSTRACTEhrlichia chaffeensis, a bacterium that cannot survive outside the eukaryotic cell, proliferates exclusively in human monocytes and macrophages. In this study, signaling events required for ehrlichial infection of human monocytic cell line THP-1 were characterized. Entry and proliferation ofE. chaffeensisin THP-1 cells were significantly blocked by various inhibitors that can regulate calcium signaling, including 8-(diethylamino)octyl-3,4,5-trimethoxybenzoate and 2-aminoethoxydiphenyl borate (intracellular calcium mobilization inhibitors), verapamil and 1-{β-[3-(4-methoxyphenyl)propyl]-4-methoxyphenethyl}-1H-imidazole (SKF-96365) (calcium channel inhibitors), neomycin and 1-(6-{[17β-3-methoxyestra-1,3,5(10)-trien-17-yl]amino}hexyl)-1H-pyrrole-2,5-dione (U-73122) (phospholipase C [PLC] inhibitors), monodansylcadaverine (a transglutaminase [TGase] inhibitor), and genistein (a protein tyrosine kinase [PTK] inhibitor). Addition ofE. chaffeensisresulted in rapid increases in the level of inositol 1,4,5-trisphosphate (IP3) and the level of cytosolic free calcium ([Ca2+]i) in THP-1 cells, which were prevented by pretreatment of THP-1 cells with inhibitors of TGase, PTK, and PLC.E. chaffeensisinduced rapid tyrosine phosphorylation of PLC-γ2, and the presence of a PLC-γ2 antisense oligonucleotide in THP-1 cells significantly blocked ehrlichial infection. Furthermore, tyrosine-phosphorylated proteins and PLC-γ2 were colocalized with ehrlichial inclusions, as determined by double-immunofluorescence labeling. The heat-sensitive component of viableE. chaffeensiscells was essential for these signaling events.E. chaffeensis, therefore, can recruit interacting signal-transducing molecules and induce the following signaling events required for the establishment of infection in host cells: protein cross-linking by TGase, tyrosine phosphorylation, PLC-γ2 activation, IP3production, and an increase in [Ca2+]i.
Cross-Reactive Polyclonal Antibodies to the Inner Core of Lipopolysaccharide from
Neisseria meningitidis
Authors: Andersen Svein Rune , Guthrie Terry , Guile Geoffrey R. , Kolberg Jan , Hou Sam , Hyland Lisa , Wong Simon Y. C. 
Published: July 2002

ABSTRACT

Sera from mice immunized with native or detergent-extracted outer membrane vesicles derived from lipopolysaccharide (LPS) mutant 44/76
Mu-4
of
Neisseria meningitidis
were analyzed for antibodies to LPS. The carbohydrate portion of 44/76
Mu-4
LPS consists of the complete inner core, Glcβ1→4[GlcNAc α1→2Hep α1→3]Hep α1→5KDO[4→2αKDO]. Immunoblot analysis revealed that some sera contained antibodies to wild-type LPS which has a fully extended carbohydrate chain of immunotype L3,7, as well as to the homologous LPS. Sera reacted only weakly to LPS from 44/76
Mu-3
, which lacks the terminal glucose of the inner core. No binding to more truncated LPS was observed. Consequently, the cross-reactive epitopes are expressed mainly by the complete inner core. Dephosphorylation of wild-type LPS abolished antibody binding to LPS in all but one serum. Thus, at least two specificities of cross-reactive antibodies exist: one is dependent on phosphoethanolamine groups in LPS, and one is not. Detection of these cross-reactive antibodies strongly supports the notion that epitopes expressed by meningococcal LPS inner core are also accessible to antibodies when the carbohydrate chain is fully extended. Also, these inner core epitopes are sufficiently immunogenic to induce antibody levels detectable in polyclonal antibody responses. Meningococci can escape being killed by antibodies to LPS that bind only to a specific LPS variant, by altering the carbohydrate chain length. Cross-reactive antibodies may prevent such escape. Therefore, inner core LPS structures may be important antigens in future vaccines against meningococcal disease.
Influence of the Alternative σ
28
Factor on Virulence and Flagellum Expression of
Legionella pneumophila
Authors: Heuner Klaus , Dietrich Claudia , Skriwan Carina , Steinert Michael , Hacker Jörg 
Published: July 2002

ABSTRACT

The
fliA
gene of
Legionella pneumophila
encoding the alternative σ
28
factor was inactivated by introducing a kanamycin resistance cassette. Electron microscopy and Western blot analysis revealed that the
fliA
mutant strain is aflagellate and expresses no flagellin. Reporter gene assays indicated that the
flaA
promoter is not active in the
fliA
mutant strain. The
fliA
mutant strain multiplied less effectively in coculture with amoebae than the wild-type strain and was not able to replicate in coculture with
Dictyostelium discoideum
.
Extended Repertoire of Genes Encoding Variable Surface Lipoproteins in
Mycoplasma bovis
Strains
Authors: Nussbaum Sarit , Lysnyansky Inessa , Sachse Konrad , Levisohn Sharon , Yogev David 
Published: July 2002

ABSTRACT

A genomic cluster of
vsp
genes was previously shown to mediate high-frequency phenotypic switching of surface lipoprotein antigens in the bovine pathogen
Mycoplasma bovis
. This study revealed that field strains of
M. bovis
possess modified versions of the
vsp
gene complex in which extensive sequence variations occur primarily in the reiterated coding sequences of the
vsp
structural genes. These findings demonstrate that there is a vastly expanded potential for antigenic variation within populations of this organism.
A Superoxide-HypersusceptibleSalmonella entericaSerovar Typhimurium Mutant Is Attenuated but Regains Virulence in p47phox−/−Mice
Authors: van Diepen Angela , van der Straaten Tahar , Holland Steven M. , Janssen Riny , van Dissel Jaap T. 
Published: July 2002

ABSTRACTSalmonella entericaserovar Typhimurium is a gram-negative, facultative intracellular pathogen that predominantly invades mononuclear phagocytes and is able to establish persistent infections. One of the innate defense mechanisms of phagocytic cells is the production of reactive oxygen species, including superoxide.S. entericaserovar Typhimurium has evolved mechanisms to resist such radicals, and these mechanisms could be decisive in its ability to survive and replicate within macrophages. Recently, we described a superoxide-hypersusceptibleS. entericaserovar Typhimurium mutant strain, DLG294, that carries a transposon insspJ, resulting in the lack of expression of SspJ, which is necessary for resistance against superoxide and replication within macrophages. Here we show that DLG294, which is a 14028s derivative, hardly induced any granulomatous lesions in the livers upon subcutaneous infection of C3H/HeN (Ityr) mice with 3 × 104bacteria and that its bacterial counts were reduced by 3 log units compared to those of wild-typeS. entericaserovar Typhimurium 14028s on day 5 after infection. In contrast, DLG294 replicated like wild-typeS. entericaserovar Typhimurium 14028s and induced a phenotypically similar liver pathology in p47phox−/−mice, which are deficient in the p47phoxsubunit of the NADPH oxidase complex and which do not produce superoxide. Consistent with these results, DLG294 reached bacterial counts identical to those of wild-typeS. entericaserovar Typhimurium 14028s in bone marrow-derived macrophages from p47phox−/−mice and in X-CGD PLB-985 cells at 24 h after challenge. These results indicate that SspJ plays a role in the bacterium's resistance to oxidative stress and in the survival and replication ofS. entericaserovar Typhimurium both in vitro and in vivo.
A Glutamine Transport Gene,
glnQ
, Is Required for Fibronectin Adherence and Virulence of Group B Streptococci
Authors: Tamura Glen S. , Nittayajarn Aphakorn , Schoentag Deborah L. 
Published: July 2002

ABSTRACT

Group B streptococci (GBS) are a leading cause of neonatal sepsis and meningitis. GBS adhere to fibronectin when it is attached to a solid phase. We isolated a Tn
917
transposon mutant, COH1-GT1, which shows decreased adherence to fibronectin. COH1-GT1 also shows decreased adherence to and invasion of respiratory epithelial cells in vitro and decreased virulence in vivo. COH1-GT1 contains a Tn
917
insertion in a homolog of
glnQ
, a gene from
Escherichia coli
which is required for glutamine transport and codes for a cytoplasmic ATP-binding cassette protein. To confirm that the decreased fibronectin adherence of COH1-GT1 was due to the mutation in
glnQ
, we constructed COH1-GT2, a strain with a nonpolar site-directed mutation in
glnQ.
COH1-GT2 showed decreased binding to fibronectin. We also demonstrated that complementation of
glnQ
in
trans
restored fibronectin adherence to COH1-GT1. COH1-GT1 shows decreased uptake of radiolabeled glutamine and is resistant to the toxic glutamine analog γ-
l
-glutamylhydrazide, demonstrating that the
glnQ
gene is required for glutamine transport in GBS.
glnQ
lacks a signal sequence and is a cytoplasmic protein in
E. coli
and thus is unlikely to act as a fibronectin adhesin.
glnQ
is transcribed in an operon with a putative glutamine permease gene,
glnP
, which has a novel predicted structure containing three distinct domains linked in a single gene. The first two domains are putative glutamine binding domains with homology to the
E. coli
periplasmic glutamine binding gene
glnH
. The third is a putative permease domain with homology to the
E. coli
glutamine permease gene
glnP.
RT-PCR analysis demonstrated that
glnP
and
glnQ
are contained within a single transcript. Transcription of
scpB
, encoding the only known fibronectin-binding adhesin of GBS, is unaffected. We speculate that
glnQ
may regulate expression of fibronectin adhesins by affecting cytoplasmic glutamine levels and that regulation may be posttranscriptional.
Environmental Regulation of
Bacillus subtilis
ς
D
-Dependent Gene Expression
Authors: Mirel D. B. , Estacio W. F. , Mathieu M. , Olmsted E. , Ramirez J. , Márquez-Magaña L. M. 
Published: July 2002

ABSTRACT

The ς
D
regulon of
Bacillus subtilis
is composed of genes encoding proteins for flagellar synthesis, motility, and chemotaxis. Concurrent analyses of ς
D
protein levels and flagellin mRNA demonstrate that
sigD
expression and ς
D
activity are tightly coupled during growth in both complex and minimal media, although they exhibit different patterns of expression. We therefore used the ς
D
-dependent flagellin gene (
hag
) as a model gene to study the effects of different nutritional environments on ς
D
-dependent gene expression. In complex medium, the level of expression of a
hag-lacZ
fusion increased exponentially during the exponential growth phase and peaked early in the transition state. In contrast, the level of expression of this reporter remained constant and high throughout growth in minimal medium. These results suggest the existence of a nutritional signal(s) that affects
sigD
expression and/or ς
D
activity. This signal(s) allows for nutritional repression early in growth and, based on reconstitution studies, resides in the complex components of sporulation medium, as well as in a mixture of mono-amino acids. However, the addition of Casamino Acids to minimal medium results in a dose-dependent decrease in
hag-lacZ
expression throughout growth and the postexponential growth phase. In work by others, CodY has been implicated in the nutritional repression of several genes. Analysis of a
codY
mutant bearing a
hag-lacZ
reporter revealed that flagellin expression is released from nutritional repression in this strain, whereas mutations in the transition state preventor genes
abrB
,
hpr
, and
sinR
failed to elicit a similar effect during growth in complex medium. Therefore, the CodY protein appears to be the physiologically relevant regulator of
hag
nutritional repression in
B. subtilis.
Sequencing, Cloning, and High-Level Expression of the
pfp
Gene, Encoding a PP
i
-Dependent Phosphofructokinase from the Extremely Thermophilic Eubacterium
Dictyoglomus thermophilum
Authors: Ding Yan-Huai R. , Ronimus Ron S. , Morgan Hugh W. 
Published: July 2002

ABSTRACT

The sequencing, cloning, and expression of the
pfp
gene from
Dictyoglomus thermophilum
, which consists of 1,041 bp and encodes a pyrophosphate-dependent phosphofructokinase, are described. A phylogenetic analysis indicates that the enzyme is closely related to the pyrophosphate-dependent enzyme from
Thermoproteus tenax
. The recombinant and native enzymes share a high degree of similarity for most properties examined.
Genetic Evidence that Transcription Activation by RhaS Involves Specific Amino Acid Contacts with Sigma 70
Authors: Bhende Prasanna M. , Egan Susan M. 
Published: July 2002

ABSTRACT

RhaS activates transcription of the
Escherichia coli rhaBAD
and
rhaT
operons in response to
l
-rhamnose and is a member of the AraC/XylS family of transcription activators. We wished to determine whether ς
70
might be an activation target for RhaS. We found that ς
70
K593 and R599 appear to be important for RhaS activation at both
rhaBAD
and
rhaT
, but only at truncated promoters lacking the binding site for the second activator, CRP. To determine whether these positively charged ς
70
residues might contact RhaS, we constructed alanine substitutions at negatively charged residues in the C-terminal domain of RhaS. Substitutions at four RhaS residues, E181A, D182A, D186A, and D241A, were defective at both truncated promoters. Finally, we assayed combinations of the RhaS and ς
70
substitutions and found that RhaS D241 and ς
70
R599 met the criteria for interacting residues at both promoters. Molecular modeling suggests that ς
70
R599 is located in very close proximity to RhaS D241; hence, this work provides the first evidence for a specific residue within an AraC/XylS family protein that may contact ς
70
. More than 50% of AraC/XylS family members have Asp or Glu at the position of RhaS D241, suggesting that this interaction with ς
70
may be conserved.
The Flagellar Filament of
Rhodobacter sphaeroides
: pH-Induced Polymorphic Transitions and Analysis of the
fliC
Gene
Authors: Shah Deepan S. H. , Perehinec Tania , Stevens Susan M. , Aizawa Shin-Ichi , Sockett R. Elizabeth 
Published: July 2002

ABSTRACT

Flagellar motility in
Rhodobacter sphaeroides
is notably different from that in other bacteria.
R. sphaeroides
moves in a series of runs and stops produced by the intermittent rotation of the flagellar motor.
R. sphaeroides
has a single, plain filament whose conformation changes according to flagellar motor activity. Conformations adopted during swimming include coiled, helical, and apparently straight forms. This range of morphological transitions is larger than that in other bacteria, where filaments alternate between left- and right-handed helical forms. The polymorphic ability of isolated
R. sphaeroides
filaments was tested in vitro by varying pH and ionic strength. The isolated filaments could form open-coiled, straight, normal, or curly conformations. The range of transitions made by the
R. sphaeroides
filament differs from that reported for
Salmonella enterica
serovar Typhimurium. The sequence of the
R. sphaeroides fliC
gene, which encodes the flagellin protein, was determined. The gene appears to be controlled by a ς
28
-dependent promoter. It encodes a predicted peptide of 493 amino acids. Serovar Typhimurium mutants with altered polymorphic ability usually have amino acid changes at the terminal portions of flagellin or a deletion in the central region. There are no obvious major differences in the central regions to explain the difference in polymorphic ability. In serovar Typhimurium filaments, the termini of flagellin monomers have a coiled-coil conformation. The termini of
R. sphaeroides
flagellin are predicted to have a lower probability of coiled coils than are those of serovar Typhimurium flagellin. This may be one reason for the differences in polymorphic ability between the two filaments.