bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcutaneous Immunization with Bacterial ADP-Ribosylating Exotoxins, Subunits, and Unrelated Adjuvants
Authors: Scharton-Kersten Tanya , Yu Jian-mei , Vassell Russell , O'Hagan Derek , Alving Carl R. , Glenn Gregory M. 
Published: July 2002

ABSTRACTWe have recently described a needle-free method of vaccination, transcutaneous immunization, consisting of the topical application of vaccine antigens to intact skin. While most proteins themselves are poor immunogens on the skin, we have shown that the addition of cholera toxin (CT), a mucosal adjuvant, results in cellular and humoral immune responses to the adjuvant and coadministered antigens. The present study explores the breadth of adjuvants that have activity on the skin, using diphtheria toxoid (DTx) and tetanus toxoid as model antigens. Heat-labile enterotoxin (LT) displayed adjuvant properties similar to those of CT when used on the skin and induced protective immune responses against tetanus toxin challenge when applied topically at doses as low as 1 μg. Interestingly, enterotoxin derivatives LTR192G, LTK63, and LTR72 and the recombinant CT B subunit also exhibited adjuvant properties on the skin. Consistent with the latter finding, non-ADP-ribosylating exotoxins, including an oligonucleotide DNA sequence, as well as several cytokines (interleukin-1β [IL-1β] fragment, IL-2, IL-12, and tumor necrosis factor alpha) and lipopolysaccharide also elicited detectable anti-DTx immunoglobulin G titers in the immunized mice. These results indicate that enhancement of the immune response to topical immunization is not restricted to CT or the ADP-ribosylating exotoxins as adjuvants. This study also reinforces earlier findings that addition of an adjuvant is important for the induction of robust immune responses to vaccine antigens delivered by topical application.
Random Transposon Mutagenesis of
Campylobacter jejuni
Authors: Golden Neal J. , Camilli Andrew , Acheson David W. K. 
Published: July 2002

ABSTRACT

Genetic studies of
Campylobacter jejuni
have been limited due to the lack of a transposon mutagenesis method. Here, we describe a novel technique for random transposon mutagenesis using a
mariner
-based transposon into
C. jejuni
strain 480. Insertions were random, as demonstrated by Southern blot analysis and insertional junction sequencing. We have demonstrated, for the first time, random in vivo transposon mutagenesis of
C. jejuni
.
Identity of Activation Molecule 3 on Superantigen-Stimulated Bovine Cells Is CD26
Authors: Lee Sang-Un , Ferens Witold , Davis William C. , Hamilton Mary Jo , Park Yong-Ho , Fox Lawrence K. , Naessens Jan , Bohach Gregory A. 
Published: July 2002

ABSTRACTMost CD8+T cells in cultures of bovine mononuclear cells stimulated with staphylococcal enterotoxin C1 develop an unusual phenotype characterized by expression of activation molecule 3 (ACT3). This superantigen-dependent phenotype may be relevant to immunopathogenesis mediated by certain microbial toxins. The size and N-terminal sequence of immunoprecipitated ACT3 indicate that ACT3 is the bovine orthologue of CD26.
Identification, Characterization, and Variable Expression of a Naturally Occurring Inhibitor Protein of IS
1106
Transposase in Clinical Isolates of
Neisseria
meningitidis
Authors: Salvatore Paola , Pagliarulo Caterina , Colicchio Roberta , Zecca Patrizia , Cantalupo Giuseppina , Tredici Maurizio , Lavitola Alfredo , Bucci Cecilia , Bruni Carmelo B. , Alifano Pietro 
Published: July 2002

ABSTRACT

Transposition plays a role in the epidemiology and pathogenesis of
Neisseria
meningitidis
. Insertion sequences are involved in reversible capsulation and insertional inactivation of virulence genes encoding outer membrane proteins. In this study, we have investigated and identified one way in which transposon IS
1106
controls its own activity. We have characterized a naturally occurring protein (Tip) that inhibits the transposase. The inhibitor protein is a truncated version of the IS
1106
transposase lacking the NH
2
-terminal DNA binding sequence, and it regulates transposition by competing with the transposase for binding to the outside ends of IS
1106
, as shown by gel shift and in vitro transposition assays. IS
1106
Tip mRNA is variably expressed among serogroup B meningococcal clinical isolates, and it is absent in most collection strains belonging to hypervirulent lineages.
Escherichia coli
Strain RDEC-1 AF/R1 Endogenous Fimbrial Glycoconjugate Receptor Molecules in Rabbit Small Intestine
Authors: Ryu Hyoik , Kim Young S. , Grange Philippe A. , Cassels Frederick J. 
Published: July 2002

ABSTRACT

Escherichia coli
strain RDEC-1 causes a diarrheagenic infection in rabbits with AF/R1 fimbriae, which have been identified as an important colonization factor in RDEC-1 adherence leading to disease. The AF/R1-mediated RDEC-1 adherence model has been used as a model systems for
E. coli
diarrheal diseases. In this study, RDEC-1 adhered specifically to small intestinal brush borders, with both sialic acid and β-galactosyl residues apparently involved. The AF/R1-mediated adherence activity of [
14
C]-labeled RDEC-1 was analyzed quantitatively by using 24-well plates coated with purified brush borders and purified microvilli. Two microvillus membrane proteins (130 and 140 kDa) were individually isolated, and chicken antibody raised to each protein inhibited bacterial adherence. These same two proteins, previously shown to be recognized by AF/R1, were individually digested with trypsin, and the amino acid sequences of peptides were determined by reversed-phase capillary liquid chromatography-mass spectrometry tandem mass spectrometry (LC-MS). This LC-MS analysis indicated that these proteins are subunits of the rabbit sucrase-isomaltase protein (SI) complex. Guinea pig serum raised to purified rabbit SI complex inhibited bacterial adherence to microvilli. Additionally, as determined by high-performance thin-layer chromatography and autoradiography, RDEC-1 adhered selectively, via AF/R1 fimbriae, to a glycolipid tentatively identified as galactosylceramide (Galβ1-1Cer) in the lipid extract of rabbit small intestinal brush borders. RDEC-1 adherence to Galβ1-1Cer was partially inhibited in the presence of galactose. These combined results indicate that the endogenous receptor molecule for AF/R1 fimbriae of RDEC-1 is each individual component of the SI complex, although binding to glycolipid may be responsible for an additional adherence mechanism.
HLA-A*01-Restricted Cytotoxic T-Lymphocyte Epitope from thePlasmodium falciparumCircumsporozoite Protein
Authors: Kumar Anita , Kumar Sanjai , Le Thong P. , Southwood Scott , Sidney John , Cohen Joe , Sette Alessandro , Hoffman Stephen L. 
Published: July 2002

ABSTRACTHere, we report the identification of a novel CD8+cytotoxic T-lymphocyte epitope on thePlasmodium falciparumcircumsporozoite protein (3D7; amino acids 310 to 319 [EPSDKHIKEY]) that is restricted by HLA-A*01 and is recognized by human volunteers immunized with irradiatedP. falciparumsporozoites. HLA-A*01 is the second most common HLA allele among Caucasians.
Comparison of the Fibronectin-Binding Protein FNE from
Streptococcus equi
Subspecies
equi
with FNZ from
S. equi
Subspecies
zooepidemicus
Reveals a Major and Conserved Difference
Authors: Lindmark Hans , Nilsson Martin , Guss Bengt 
Published: July 2002

ABSTRACT

The gene
fnz
from
Streptococcus equi
subspecies
zooepidemicus
encodes a cell surface protein that binds fibronectin (Fn). Fifty tested isolates of
S. equi
subspecies
equi
all contain DNA sequences with similarity to
fnz
. This work describes the cloning and sequencing of a gene, designated
fne
, with similarity to
fnz
from two
S. equi
subspecies
equi
isolates. The DNA sequences were found to be identical in the two strains, and sequence comparison of the
fne
and
fnz
genes revealed only minor differences. However, one base deletion was found in the middle of the
fne
gene and eight base pairs downstream of the altered reading frame there is a stop codon. An Fn-binding protein was purified from the growth medium of a subspecies
equi
culture. Determination of the NH
2
-terminal amino acid sequence and molecular mass, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, revealed that the purified protein is the gene product of the 5′-terminal half of
fne
. Fn-binding activity has earlier only been found in the COOH-terminal half of FNZ. By the use of a purified recombinant protein containing the NH
2
half of FNZ, we provide here evidence that this half of the protein also harbors an Fn-binding domain.
Association of Interleukin-10 Cytokine Expression Status with HLA Non-DRB1*02 andMycobacterium bovisBCG Scar-Negative Status in South Indian Pulmonary Tuberculosis Patients
Authors: Dheenadhayalan V. , Shanmugalakshmi S. , Vani S. , Muthuveeralakshmi P. , Arivarignan G. , Nageswari A. D. , Pitchappan R M. 
Published: July 2002

ABSTRACTHLA DRB1*02 and its subtypes predispose individuals for a far-advanced sputum-positive pulmonary tuberculosis transcending ethnic boundaries.Mycobacterium bovisBCG does not afford the desired protection against adult pulmonary tuberculosis, and a spectrum of immune reactivity exists in controls and hospital contacts. All of these findings have been identified and demonstrated in areas of endemicity. Skewing of immunity from protective to pathogenic may involve a shift in the Th1-Th2 paradigm. To elaborate these ideas, we studied gamma interferon (IFN-γ), interleukin-4 (IL-4), and IL-10 cytokine expression in 71 adult pulmonary tuberculosis patients and 74 controls from areas of endemicity in south India by 48-h microculture and reverse transcription-PCR. Most of the patients and controls expressed IFN-γ de novo, and in the presence of purified protein derivative (PPD), all of them expressed significantly higher levels of IFN-γ, suggesting a PPD-specific recall memory. HLA DRB1* allele-dependent IFN-γ expression was identified only in controls, suggesting a skewing of the immune response in patients. In contrast to the case for IFN-γ, only some patients and controls expressed IL-4 or IL-10 (Th2 profile); thus, the Th1 profile was identifiable only by a nonexpression of IL-4 or IL-10 in this area of endemicity. The Th2 profile was associated with HLA non-DRB1*02 and BCG scar-negative status in patients, attributing a significant risk (odds ratio = 2.074; 95% confidence interval = 0.612 to 7.07). It is possible thatMycobacterium tuberculosis(PPD)-specific IL-10 is expressed preemptively in unvaccinated (BCG scar-negative) individuals with a non-DR2 genetic background by chronic exposure in this area of endemicity and leads to pulmonary tuberculosis of adults.
Genetic Analysis of the
rgg-gtfG
Junctional Region and Its Role in
Streptococcus gordonii
Glucosyltransferase Activity
Authors: Vickerman M. M. , Minick P. E. 
Published: July 2002

ABSTRACT

Glucans synthesized by glucosyltransferase enzymes of oral streptococci facilitate bacterial accumulation on surfaces. The
Streptococcus gordonii
glucosyltransferase gene,
gtfG,
is positively regulated by
rgg,
which encodes a putative cytoplasmic protein. The
gtfG
promoter and ribosomal binding sequences are located within a DNA inverted repeat immediately downstream of
rgg
. Polycistronic
rgg-gtfG
as well as
rgg
- and
gtfG
-specific transcripts are associated with this chromosomal region. Previous studies have shown that the
rgg
product acts in
trans
near the
gtfG
promoter to increase the level of
gtfG
transcript, but it does not affect the level of
rgg-gtfG
transcript. To further analyze regulation by
rgg
, a series of strain Challis derivatives was constructed and glucosyltransferase activities were determined. Strains in which
rgg
was separated from
gtfG
by integrated vector sequences had decreased levels of glucosyltransferase activity; plasmid-borne
rgg
could not increase activity to parental levels. As expected, strains with chromosomal deletions involving the
rgg
structural gene and either the
rgg
or
gtfG
promoter also showed decreased glucosyltransferase activity. Plasmid-borne
rgg
could increase glucosyltransferase activity only in strains which had a 36-bp chromosomal region beginning 72 nucleotides upstream of the
gtfG
transcriptional start site. Results suggest that these nucleotides, located within the 3′ end of
rgg
, are necessary, either by direct involvement in binding or by indirectly affecting secondary structure, for Rgg to increase glucosyltransferase activity. Surprisingly, the presence of the
rgg
promoter upstream of this 36-bp region significantly increased the effects of plasmid-borne
rgg
. Implications for glucosyltransferase regulation and applicability to other
rgg
-like determinants are considered.
Antigen-Presenting Cell Function duringPlasmodium yoeliiInfection
Authors: Luyendyk James , Olivas O. Renee , Ginger Lisa A. , Avery Anne C. 
Published: July 2002

ABSTRACTAntigen-presenting cells (APC) play a key role in orchestrating immune responses. T-cell proliferative responses are inhibited during the erythrocyte stages of malaria infection, and a number of studies have suggested that APC are responsible for this phenomenon. In the present studies we examine individual components of the T-cell-activating function of APC: expression of costimulatory and major histocompatibility complex (MHC) class II proteins, the ability to process and present antigen to T cells, and the ability to support cytokine production. We find that during the acute phases ofPlasmodium yoeliierythrocyte stage infection, APC upregulate the expression of class II MHC and CD80, maintain expression of CD86, process and present antigen, and support gamma interferon production. However the CD11b+subpopulation produces a soluble factor or factors that specifically inhibit interleukin-2 (IL-2) production by responding CD4 T cells. This factor is distinct from prostaglandin E2, NO, or transforming growth factor β. The data suggest that IL-2 suppression observed during malaria infection is not due to functional defects of APC but is triggered by production of a factor(s) that actively suppresses production of IL-2 by T cells.
Mutually Exclusive Utilization of P
R
and P
RM
Promoters in Bacteriophage 434 O
R
Authors: Xu Jian , Koudelka Gerald B. 
Published: July 2002

ABSTRACT

Establishment and maintenance of a lysogen of the lambdoid bacteriophage 434 require that the 434 repressor both activate transcription from the P
RM
promoter and repress transcription from the divergent P
R
promoter. Several lines of evidence indicate that the 434 repressor activates initiation of P
RM
transcription by occupying a binding site adjacent to the P
RM
promoter and directly contacting RNA polymerase. The overlapping architecture of the P
RM
and P
R
promoters suggests that an RNA polymerase bound at P
R
may repress P
RM
transcription initiation. Hence, part of the stimulatory effect of the 434 repressor may be relief of interference between RNA polymerase binding to the P
RM
promoter and to the P
R
promoter. Consistent with this proposal, we show that the repressor cannot activate P
RM
transcription if RNA polymerase binds at P
R
prior to addition of the 434 repressor. However, unlike the findings with the related λ phage, formation of RNA polymerase promoter complexes at P
RM
and at P
R
apparently are mutually exclusive. We find that the RNA polymerase-mediated inhibition of repressor-stimulated P
RM
transcription requires the presence of an open complex at P
R
. Taken together, these results indicate that establishment of an open complex at P
R
directly prevents formation of an RNA polymerase-P
RM
complex.
DNA Polymerase I Is Essential for Growth of
Methylobacterium dichloromethanicum
DM4 with Dichloromethane
Authors: Kayser Martin F. , Stumpp Michael T. , Vuilleumier Stéphane 
Published: July 2002

ABSTRACT

Methylobacterium dichloromethanicum
DM4 grows with dichloromethane as the unique carbon and energy source by virtue of a single enzyme, dichloromethane dehalogenase–glutathione
S
-transferase. A mutant of the dichloromethane-degrading strain
M. dichloromethanicum
DM4, strain DM4-1445, was obtained by mini-Tn
5
transposon mutagenesis that was no longer able to grow with dichloromethane. Dichloromethane dehalogenase activity in this mutant was comparable to that of the wild-type strain. The site of mini-Tn
5
insertion in this mutant was located in the
polA
gene encoding DNA polymerase I, an enzyme with a well-known role in DNA repair. DNA polymerase activity was not detected in cell extracts of the
polA
mutant. Conjugation of a plasmid containing the intact DNA polymerase I gene into the
polA
mutant restored growth with dichloromethane, indicating that the
polA
gene defect was responsible for the observed lack of growth of this mutant with dichloromethane. Viability of the DM4-1445 mutant was strongly reduced upon exposure to both UV light and dichloromethane. The
polA′-lacZ
transcriptional fusion resulting from mini-Tn
5
insertion was constitutively expressed at high levels and induced about twofold after addition of 10 mM dichloromethane. Taken together, these data indicate that DNA polymerase I is essential for growth of
M. dichloromethanicum
DM4 with dichloromethane and further suggest an important role of the DNA repair machinery in the degradation of halogenated, DNA-alkylating compounds by bacteria.
DNA-Binding Proteins Possibly Involved in Regulation of the Post-Logarithmic-Phase Expression of Lipoprotein P35 in
Borrelia burgdorferi
Authors: Indest Karl J. , Philipp Mario T. 
Published: July 2002

ABSTRACT

Previously, we have shown that the transcription of
p35
, a lipoprotein gene of
Borrelia burgdorferi
, is upregulated or initiated during the post-logarithmic bacterial growth phase in vitro. To identify potential regulatory factors, we examined the formation of DNA-protein complexes by electromobility shift assay, using a 157-bp DNA fragment that spans the
p35
promoter region and cell-free extracts of spirochetes harvested from both logarithmic and stationary growth phases. The binding properties of the extracts with the promoter region of the
flaB
gene, a constitutively expressed, growth-phase-independent gene, were also compared. The results from these experiments demonstrate that
B. burgdorferi
stationary-phase cell-free extracts have a growth-phase-dependent DNA binding protein that interacts specifically with the
p35
promoter region. We show, in addition, that a segment from the 157-bp
p35
promoter region which contains both a T-rich stretch and an inverted repeat is able to compete off the stationary-phase-specific complex when the segment is present in molar excess.
Motility and Flagellum Synthesis in
Halobacillus halophilus
Are Chloride Dependent
Authors: Roeßler Markus , Wanner Gerhard , Müller Volker 
Published: July 2002

ABSTRACT

The motility of
Halobacillus halophilus
as observed on swarm agar plates was strictly dependent on the chloride concentration. Cl
−
was apparently not used as the coupling ion for flagellar rotation. Cells grown in the absence of chloride were devoid of flagella, but flagellation was restored upon the addition of chloride. These experiments indicate that chloride is involved in synthesis of flagella in
H. halophilus
.
Identification of an Extradiol Dioxygenase Involved in Tetralin Biodegradation: Gene Sequence Analysis and Purification and Characterization of the Gene Product
Authors: Andújar Eloísa , Hernáez María José , Kaschabek Stefan R. , Reineke Walter , Santero Eduardo 
Published: July 2002

ABSTRACT

A genomic region involved in tetralin biodegradation was recently identified in
Sphingomonas
strain TFA. We have cloned and sequenced from this region a gene designated
thnC
, which codes for an extradiol dioxygenase required for tetralin utilization. Comparison to similar sequences allowed us to define a subfamily of 1,2-dihydroxynaphthalene extradiol dioxygenases, which comprises two clearly different groups, and to show that ThnC clusters within group 2 of this subfamily. 1,2-Dihydroxy-5,6,7,8-tetrahydronaphthalene was found to be the metabolite accumulated by a
thnC
insertion mutant. The ring cleavage product of this metabolite exhibited behavior typical of a hydroxymuconic semialdehyde toward pH-dependent changes and derivatization with ammonium to give a quinoline derivative. The gene product has been purified, and its biochemical properties have been studied. The enzyme is a decamer which requires Fe(II) for activity and shows high activity toward its substrate (
V
max
, 40.5 U mg
−1
;

K
m

, 18.6 μM). The enzyme shows even higher activity with 1,2-dihydroxynaphthalene and also significant activity toward 1,2-dihydroxybiphenyl or methylated catechols. The broad substrate specificity of ThnC is consistent with that exhibited by other extradiol dioxygenases of the same group within the subfamily of 1,2-dihydroxynaphthalene dioxygenases.
Spirochaeta aurantia
Has Diacetyl Chloramphenicol Esterase Activity
Authors: Sohaskey Charles D. , Barbour Alan G. 
Published: July 2002

ABSTRACT

The free-living spirochete
Spirochaeta aurantia
was nearly as susceptible to diacetyl chloramphenicol, the product of chloramphenicol acetyltransferase, as it was to chloramphenicol itself. This unexpected susceptibility to diacetyl chloramphenicol was wholly or partly the consequence of intrinsic carboxylesterase activity, as indicated by high-performance liquid chromatography, thin-layer chromatography, and microbiological assays. The esterase converted the diacetate to chloramphenicol, thus inhibiting spirochete growth. The esterase activity was cell associated, reduced by proteinase K, eliminated by boiling, and independent of the presence of either chloramphenicol or diacetyl chloramphenicol.
S. aurantia
extracts also hydrolyzed other esterase substrates, and two of these, α-napthyl acetate and 4-methylumbelliferyl acetate, identified an esterase of approximately 75 kDa in a nondenaturing gel. Carboxylesterases occur in
Streptomyces
species, but in this study their activity was weaker than that of
S. aurantia
. The
S. aurantia
esterase could reduce the effectiveness of
cat
as either a selectable marker or a reporter gene in this species.
Stability of
Mycoplasma pneumoniae
Cytadherence-Accessory Protein HMW1 Correlates with Its Association with the Triton Shell
Authors: Balish Mitchell F. , Hahn Tae-Wook , Popham Phillip L. , Krause Duncan C. 
Published: July 2002

ABSTRACT

Mycoplasma pneumoniae
adsorbs to host respiratory epithelium primarily by its attachment organelle, the proper function of which depends upon mycoplasma adhesin and cytoskeletal proteins. Among the latter are the cytadherence-associated proteins HMW1 and HMW2, whose specific roles in this process are unknown. In the
M. pneumoniae
cytadherence mutant I-2, loss of HMW2 results in accelerated turnover of HMW1 and other cytadherence-accessory proteins, probably by proteolysis. However, both the mechanism of degradation and the means by which these proteins are rendered susceptible to it are not understood. In this study, we addressed whether HMW1 degradation is a function of its presence among specific subcellular fractions and established that HMW1 is a peripheral membrane protein that is antibody accessible on the outer surfaces of both wild-type and mutant I-2
M. pneumoniae
but to a considerably lesser extent in the mutant. Quantitation of HMW1 in Triton X-100-fractionated extracts from cells pulse-labeled with [
35
S]methionine indicated that HMW1 is synthesized in a Triton X-100-soluble form that exists in equilibrium with an insoluble (cytoskeletal) form. Pulse-chase analysis demonstrated that over time, HMW1 becomes stabilized in the cytoskeletal fraction and associated with the cell surface in wild-type
M. pneumoniae
. The less efficient transition to the cytoskeleton and mycoplasma cell surface in mutant I-2 leads to accelerated degradation of HMW1. These data suggest a role for HMW2 in promoting export of HMW1 to the cell surface, where it is stable and fully functional.