bluuebunny/crossref_metadata_2025_split huggingface dataset:
c-Jun NH2-Terminal Kinase-Mediated Signaling Is Essential forPseudomonas aeruginosaExoS-Induced Apoptosis
Authors: Jia Jinghua , Alaoui-El-Azher Mounia , Chow Marie , Chambers Timothy C. , Baker Henry , Jin Shouguang 
Published: May 2003

ABSTRACTAs an opportunistic bacterial pathogen,Pseudomonas aeruginosamainly affects immunocompromised individuals as well as patients with cystic fibrosis. In a previous study, we showed that ExoS ofP.aeruginosa, when injected into host cells through a type III secretion apparatus, functions as an effector molecule to trigger apoptosis in various tissue culture cells. Here, we show that injection of the ExoS into HeLa cells activates c-Jun NH2-terminal kinase (JNK) phosphorylation while shutting down ERK1/2 and p38 phosphorylation. Inhibiting JNK activation by expression of a dominant negative JNK1 or with a specific JNK inhibitor abolishes ExoS-triggered apoptosis, demonstrating the requirement for JNK-mediated signaling. Following JNK phosphorylation, cytochromecis released into the cytosol, leading to the activation of caspase 9 and eventually caspase 3. Although c-Jun phosphorylation is also observed as a result of JNK activation, ongoing host protein synthesis is not essential for the apoptotic induction, suggesting that c-Jun- or other AP-1-driven activation of gene expression is dispensable in this process. Therefore, ExoS has opposing effects on different cellular pathways that regulate apoptosis: it shuts down host cell survival signal pathways by inhibiting ERK1/2 and p38 activation, and it activates proapoptotic pathways through activation of JNK1/2 leading ultimately to cytochromecrelease and activation of caspases. These results highlight the modulation of host cell signaling by the type III secretion system during interaction betweenP.aeruginosaand host cells.
Global Analysis of
Borrelia burgdorferi
Genes Regulated by Mammalian Host-Specific Signals
Authors: Brooks Chad S. , Hefty P. Scott , Jolliff Sarah E. , Akins Darrin R. 
Published: May 2003

ABSTRACT

Lyme disease is a tick-borne infection that can lead to chronic, debilitating problems if not recognized or treated appropriately.
Borrelia burgdorferi
, the causative agent of Lyme disease, is maintained in nature by a complex enzootic cycle involving
Ixodes
ticks and mammalian hosts. Many previous studies support the notion that
B. burgdorferi
differentially expresses numerous genes and proteins to help it adapt to growth in the mammalian host. In this regard, several studies have utilized a dialysis membrane chamber (DMC) cultivation system to generate “mammalian host-adapted” spirochetes for the identification of genes selectively expressed during mammalian infection. Here, we have exploited the DMC cultivation system in conjunction with microarray technology to examine the global changes in gene expression that occur in the mammalian host. To identify genes regulated by only mammal-specific signals and not by temperature, borrelial microarrays were hybridized with cDNA generated either from organisms temperature shifted in vitro from 23°C to 37°C or from organisms cultivated by using the DMC model system. Statistical analyses of the combined data sets revealed that 125 genes were expressed at significantly different levels in the mammalian host, with almost equivalent numbers of genes being up- or down-regulated by
B. burgdorferi
within DMCs compared to those undergoing temperature shift. Interestingly, during DMC cultivation, the vast majority of genes identified on the plasmids were down-regulated (79%), while the differentially expressed chromosomal genes were almost entirely up-regulated (93%). Global analysis of the upstream promoter regions of differentially expressed genes revealed that several share a common motif that may be important in transcriptional regulation during mammalian infection. Among genes with known or putative functions, the cell envelope category, which includes outer membrane proteins, was found to contain the most differentially expressed genes. The combined findings have generated a subset of genes that can now be further characterized to help define their role or roles with regard to
B. burgdorferi
virulence and Lyme disease pathogenesis.
Prior Exposure to LiveMycobacterium bovisBCG DecreasesCryptococcus neoformans-Induced Lung Eosinophilia in a Gamma Interferon-Dependent Manner
Authors: Walzl Gerhard , Humphreys Ian R. , Marshall Ben G. , Edwards Lorna , Openshaw Peter J. M. , Shaw Rory J. , Hussell Tracy 
Published: May 2003

ABSTRACTSome common childhood infections appear to prevent the development of atopy and asthma. In someMycobacterium bovisBCG-vaccinated populations, strong delayed-type hypersensitivity responses to mycobacterial antigens are associated with a reduced risk of atopy. Although BCG exposure decreases allergen-induced lung eosinophilia in animal models, little attention has been given to the effect of immunity to BCG on responses against live pathogens. We used the murineCryptococcus neoformansinfection model to investigate whether prior BCG infection can alter such responses. The present study shows that persistent pulmonary BCG infection of C57BL/6 mice induced an increase in gamma interferon, a reduction in interleukin-5, and a decrease in lung eosinophilia during subsequentCryptococcusinfection. This effect was long lasting, depended on the presence of live bacteria, and required persistence of mycobacterial infection in the lung. Reduction of eosinophilia was less prominent after infection with a mutant BCG strain (ΔhspR), which was rapidly cleared from the lungs. These observations have important implications for the development of vaccines designed to prevent Th2-mediated disease and indicate that prior lung BCG vaccination can alter the pattern of subsequent host inflammation.
Contribution of Proton-Translocating Proteins to the Virulence of
Salmonella enterica
Serovars Typhimurium, Gallinarum, and Dublin in Chickens and Mice
Authors: Turner A. K. , Barber L. Z. , Wigley P. , Muhammad S. , Jones M. A. , Lovell M. A. , Hulme S. , Barrow P. A. 
Published: May 2003

ABSTRACT

We investigated the attenuating effects of a range of respiratory chain mutations in three
Salmonella
serovars which might be used in the development of live vaccines. We tested mutations in
nuoG
,
cydA
,
cyoA
,
atpB
, and
atpH
in three serovars of
Salmonella enterica:
Typhimurium, Dublin, and Gallinarum. All three serovars were assessed for attenuation in their relevant virulence assays of typhoid-like infections. Serovar Typhimurium was assessed in 1-day-old chickens and the mouse. Serovar Gallinarum 9 was assessed in 3-week-old chickens, and serovar Dublin was assessed in 6-week-old mice. Our data show variation in attenuation for the
nuoG
,
cydA
, and
cyoA
mutations within the different serovar-host combinations. However, mutations in
atpB
and
atpH
were highly attenuating for all three serovars in the various virulence assays. Further investigation of the mutations in the
atp
operon showed that the bacteria were less invasive in vivo, showing reduced in vitro survival within phagocytic cells and reduced acid tolerance. We present data showing that this reduced acid tolerance is due to an inability to adapt to conditions rather than a general sensitivity to reduced pH. The data support the targeting of respiratory components for the production of live vaccines and suggest that mutations in the
atp
operon provide suitable candidates for broad-spectrum attenuation of a range of
Salmonella
serovars.
Disparity in Functional Activity between Serum Anticapsular Antibodies Induced in Adults by Immunization with an Investigational Group A and CNeisseria meningitidis-Diphtheria Toxoid Conjugate Vaccine and by a Polysaccharide Vaccine
Authors: Harris Shannon L. , Finn Adam , Granoff Dan M. 
Published: May 2003

ABSTRACTPolysaccharide-protein conjugate vaccines elicit higher concentrations of serum anticapsular antibody in infants and children than do unconjugated polysaccharide vaccines. The conjugate-induced antibodies also have higher avidity and complement-mediated bactericidal activity. Similar vaccine-related differences in the magnitude or functional activity of antibody are observed infrequently in immunized adults. We compared the antibody responses of adults immunized with an investigational group A and C meningococcal conjugate vaccine to those elicited by an unconjugated meningococcal polysaccharide vaccine. Although there were no significant differences between the respective geometric mean bactericidal titers of the two vaccine groups, it took, on average, three- to fourfold higher concentrations of polysaccharide-induced serum anticapsular antibody to achieve 50% complement-mediated bacteriolysis than conjugate-induced antibody (P< 0.001 for groups A and C). At limiting doses, the polysaccharide-induced anticapsular antibodies also were less effective in conferring passive protection against meningococcal bacteremia in infant rats challenged with a group C strain (P< 0.04). The avidity index of the group C antibodies was higher in the conjugate vaccine group than in the polysaccharide vaccine group (P< 0.005). The disparities in the functional activity of the anticapsular antibodies elicited in adults by the two vaccines imply fundamental differences in the respective B-cell populations stimulated.
Immunity Profiles of Wild-Type and Recombinant Shiga-Like Toxin-Encoding Bacteriophages and Characterization of Novel Double Lysogens
Authors: Allison Heather E. , Sergeant Martin J. , James Chloë E. , Saunders Jon R. , Smith Darren L. , Sharp Richard J. , Marks Trevor S. , McCarthy Alan J. 
Published: May 2003

ABSTRACT

The pathogenicity of Shiga-like toxin (stx)-producing
Escherichia coli
(STEC), notably serotype O157, the causative agent of hemorrhagic colitis, hemolytic-uremic syndrome, and thrombotic thrombocytopenic purpura, is based partly on the presence of genes (
stx
1
and/or
stx
2
) that are known to be carried on temperate lambdoid bacteriophages. Stx phages were isolated from different STEC strains and found to have genome sizes in the range of 48 to 62 kb and to carry either

stx
1

or

stx
2

genes. Restriction fragment length polymorphism patterns and sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profiles were relatively uninformative, but the phages could be differentiated according to their immunity profiles. Furthermore, these were sufficiently sensitive to enable the identification and differentiation of two different phages, both carrying the genes for Stx2 and originating from the same STEC host strain. The immunity profiles of the different Stx phages did not conform to the model established for bacteriophage lambda, in that the pattern of individual Stx phage infection of various lysogens was neither expected nor predicted. Unexpected differences were also observed among Stx phages in their relative lytic productivity within a single host. Two antibiotic resistance markers were used to tag a recombinant phage in which the
stx
genes were inactivated, enabling the first reported observation of the simultaneous infection of a single host with two genetically identical Stx phages. The data demonstrate that, although Stx phages are members of the lambdoid family, their replication and infection control strategies are not necessarily identical to the archetypical bacteriophage λ, and this could be responsible for the widespread occurrence of
stx
genes across a diverse range of
E. coli
serotypes.
Antigenic Composition of
Borrelia burgdorferi
during Infection of SCID Mice
Authors: Crother Timothy R. , Champion Cheryl I. , Wu Xiao-Yang , Blanco David R. , Miller James N. , Lovett Michael A. 
Published: May 2003

ABSTRACT

The general concept that during infection of mice the
Borrelia burgdorferi
surface protein composition differs profoundly from that of tick-borne or in vitro-cultivated spirochetes is well established. Specific knowledge concerning the differences is limited because the small numbers of spirochetes present in tissue have not been amenable to direct compositional analysis. In this report we describe novel means for studying the antigenic composition of host-adapted
Borrelia
(HAB). The detergent Triton X-114 was used to extract the detergent-phase HAB proteins from mouse ears, ankles, knees, and hearts. Immunoblot analysis revealed a profile distinct from that of in vitro-cultivated
Borrelia
(IVCB). OspA and OspB were not found in the tissues of SCID mice 17 days after infection. The amounts of antigenic variation protein VlsE and the relative amounts of its transcripts were markedly increased in ear, ankle, and knee tissues but not in heart tissue. VlsE existed as isoforms having both different unit sizes and discrete lower molecular masses. The hydrophobic smaller forms of VlsE were also found in IVCB. The amounts of the surface protein (OspC) and the decorin binding protein (DbpA) were increased in ear, ankle, knee, and heart tissues, as were the relative amounts of their transcripts. Along with these findings regarding VlsE, OspC, and DbpA, two-dimensional immunoblot analysis with immune sera also revealed additional details of the antigenic composition of HAB extracted from ear, heart, and joint tissues. A variety of novel antigens, including antigens with molecular masses of 65 and 30 kDa, were found to be upregulated in mouse tissues. Extraction of hydrophobic
B. burgdorferi
antigens from tissue provides a powerful tool for determining the antigenic composition of HAB.
Experimental Validation of Low Virulence in Field Strains of
Listeria monocytogenes
Authors: Roche S. M. , Gracieux P. , Albert I. , Gouali M. , Jacquet C. , Martin P. M. V. , Velge P. 
Published: May 2003

ABSTRACT

Several reports have described
Listeria monocytogenes
strains which were nonpathogenic or weakly pathogenic, but little is known about these low-virulence strains. We found that 9 field
L. monocytogenes
strains were hypovirulent and 17 were avirulent, based on the number of mice contaminated and the colonization of their spleens after subcutaneous inoculation. All these strains possessed the known virulence genes. We have now assessed the low virulence of these strains in other assays before determining how they differ from virulent strains. We have shown that the low-virulence strains exhibited a phenotypic stability and were not a mixture of virulent and avirulent bacteria. They did not recover virulence after many passages in mice and colonized the spleens of mice more poorly than virulent strains after i.v. inoculation. Their lethal capacities, determined by 50% lethal dose (LD
50
), were lower than those of virulent strains. Like
Listeria innocua
, 14 of 17 avirulent strains had no LD
50
and were eliminated by the lymph nodes after subcutaneous inoculation. The virulent, hypovirulent, and avirulent strains were always significantly different, whatever the tests of virulence used, confirming the importance of these low-virulence field strains in identifying the proteins involved in virulence.
Inhibition of Interleukin-17 Prevents the Development of Arthritis in Vaccinated Mice Challenged withBorrelia burgdorferi
Authors: Burchill Matthew A. , Nardelli Dean T. , England Douglas M. , DeCoster David J. , Christopherson John A. , Callister Steven M. , Schell Ronald F. 
Published: May 2003

ABSTRACTWe showed thatBorrelia burgdorferi-vaccinated interferon gamma-deficient (IFN-γ0) mice challenged with the Lyme spirochete developed a prominent chronic severe destructive osteoarthropathy. The immune response underlying the development of the severe destructive arthritis involves interleukin-17 (IL-17). Treatment of vaccinated IFN-γ0mice challenged withB. burgdorferiwith anti-IL-17 antibody delayed the onset of swelling of the hind paws but, more importantly, inhibited the development of arthritis. Histopathologic examination confirmed that treatment with anti-IL-17 antibody prevented the destructive arthropathy seen in vaccinated and challenged IFN-γ0mice. Similar preventive results were obtained when vaccinated and challenged IFN-γ0mice were treated with anti-IL-17 receptor antibody or sequentially with anti-IL-17 antibody followed by anti-IL-17 receptor antibody. By contrast, treatment of vaccinated and challenged IFN-γ0mice with recombinant IL-17 (rIL-17) did not alter the development and progression of arthritis found in vaccinated and challenged IFN-γ0mice without treatment with rIL-17. Therapeutic intervention may be a realistic approach to prevent arthritis, especially if IL-17 is involved in the perpetuation of chronic or intermittent arthritis.
Host Susceptibility to the Attaching and Effacing Bacterial PathogenCitrobacter rodentium
Authors: Vallance Bruce A. , Deng Wanyin , Jacobson Kevan , Finlay B. Brett 
Published: May 2003

ABSTRACTMany studies have shown that genetic susceptibility plays a key role in determining whether bacterial pathogens successfully infect and cause disease in potential hosts. Surprisingly, whether host genetics influence the pathogenesis of attaching and effacing (A/E) bacteria such as enteropathogenic and enterohemorrhagicEscherichia colihas not been examined. To address this issue, we infected various mouse strains withCitrobacter rodentium, a member of the A/E pathogen family. Of the strains tested, the lipopolysaccharide (LPS) nonresponder C3H/HeJ mouse strain experienced more rapid and extensive bacterial colonization than did other strains. Moreover, the high bacterial load in these mice was associated with accelerated crypt hyperplasia, mucosal ulceration, and bleeding, together with very high mortality rates. Interestingly, the basis for the increased susceptibility was not due to LPS hyporesponsiveness, as the genetically related but LPS-responsive C3H/HeOuJ and C3H/HeN mouse strains were also susceptible to infection. Analysis of the intestinal pathology in these susceptible strains revealed significant crypt epithelial cell apoptosis (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end label staining) as well as bacterial translocation to the mesenteric lymph nodes. Further studies with infection of SCID (T- and B-lymphocyte-deficient) C3H/HeJ mice demonstrated that loss of lymphocytes had no effect on bacterial numbers but did reduce crypt cell apoptosis and delayed mortality. These studies thus identify the adaptive immune system, crypt cell apoptosis, and bacterial translocation but not LPS responsiveness as contributing to the tissue pathology and mortality seen duringC.rodentiuminfection of highly susceptible mouse strains. Determining the basis for these strains' susceptibility to intestinal colonization by an A/E pathogen will be the focus of future studies.
Nontypeable
Haemophilus influenzae
Gene Expression Induced In Vivo in a Chinchilla Model of Otitis Media
Authors: Mason Kevin M. , Munson Robert S. , Bakaletz Lauren O. 
Published: May 2003

ABSTRACT

The gram-negative bacterium nontypeable
Haemophilus influenzae
(NTHI) is the predominant pathogen in chronic otitis media with effusion and, with
Streptococcus pneumoniae
and
Moraxella catarrhalis
, is a causative agent of acute otitis media. To identify potential virulence determinants, bacterial gene expression was monitored by differential fluorescence induction during early disease progression in one specific anatomical niche of a chinchilla model of NTHI-induced otitis media. Genomic DNA fragments from NTHI strain 86-028NP were cloned upstream of the promoterless
gfpmut3
gene. NTHI strain 86-028NP served as the host for the promoter trap library. Pools of 2,000 transformants were inoculated into the left and right middle ear cavities of chinchillas. Middle ear effusions were recovered by epitympanic tap at 24 and 48 h, and clones containing promoter elements that were induced in vivo and producing green fluorescent protein were isolated by two-color fluorescence-activated cell sorting. Insert DNA was sequenced and compared to the complete genome sequence of
H. influenzae
strain Rd. In a screen of 16,000 clones, we have isolated 44 clones that contain unique gene fragments encoding biosynthetic enzymes, metabolic and regulatory proteins, and hypothetical proteins of unknown function. An additional eight clones contain gene fragments unique to our NTHI isolate. Using quantitative reverse transcription-PCR, we have confirmed that 26 clones demonstrated increased gene expression in vivo relative to expression in vitro. These data provide insight into the response of NTHI bacteria as they sense and respond to the middle ear microenvironment during early events of otitis media.
AttenuatedYersinia pseudotuberculosisCarrier Vaccine for Simultaneous Antigen-Specific CD4 and CD8 T-Cell Induction
Authors: Rüssmann Holger , Gerdemann Ulrike , Igwe Emeka I. , Panthel Klaus , Heesemann Jürgen , Garbom Sara , Wolf-Watz Hans , Geginat Gernot 
Published: May 2003

ABSTRACTYersinia pseudotuberculosisemploys a type III secretion system for targeting of several virulence factors directly to the cytosol of eukaryotic cells. This protein translocation mechanism mediates the ability ofYersiniato resist phagocytosis and is required for sustained extracellular bacterial replication. In the present study, theYersiniaouter protein E (YopE) was used as a carrier molecule for type III-dependent secretion and translocation of listeriolysin O (LLO) fromListeria monocytogenes. In comparison to wild-typeYersinia, an attenuatedY.pseudotuberculosis yopK-null mutant strain hypertranslocates chimeric YopE/LLO into the cytosol of macrophages, resulting in enhanced major histocompatibility complex (MHC) class I-restricted antigen presentation of an LLO-derived CD8 T-cell epitope. Remarkably, T-cell activation assays also revealed a superior ability of translocated over secreted LLO to induce MHC class II-restricted antigen presentation. These in vitro observations were confirmed after immunization of mice with a single dose of theyopK-null mutant strain. Animals orally inoculated with recombinantYersiniaexpressing translocated chimeric YopE/LLO revealed high numbers of gamma interferon-producing LLO-specific CD4 and CD8 T cells. For the first time, it is shown that cytosolic antigen display mediated by an extracellular bacterial carrier vaccine results in simultaneous CD4 and CD8 T-cell priming, conferring protection against an intracellular pathogen.