bluuebunny/crossref_metadata_2025_split huggingface dataset:
Moraxella catarrhalisBacterium without Endotoxin, a Potential Vaccine Candidate
Authors: Peng Daxin , Hong Wenzhou , Choudhury Biswa P. , Carlson Russell W. , Gu Xin-Xing 
Published: October 2005

ABSTRACTLipooligosaccharide (LOS) is a major surface component ofMoraxella catarrhalisand a possible virulence factor in the pathogenesis of human infections caused by this organism. The presence of LOS on the bacterium is an obstacle to the development of vaccines derived from whole cells or outer membrane components of the bacterium. AnlpxAgene encoding UDP-N-acetylglucosamine acyltransferase responsible for the first step of lipid A biosynthesis was identified by the construction and characterization of an isogenicM. catarrhalis lpxAmutant in strain O35E. The resulting mutant was viable despite the complete loss of LOS. The mutant strain showed significantly decreased toxicity by theLimulusamebocyte lysate assay, reduced resistance to normal human serum, reduced adherence to human epithelial cells, and enhanced clearance in lungs and nasopharynx in a mouse aerosol challenge model. Importantly, the mutant elicited high levels of antibodies with bactericidal activity and provided protection against a challenge with the wild-type strain. These data suggest that the null LOS mutant is attenuated and may be a potential vaccine candidate againstM. catarrhalis.
Dra/AfaE Adhesin of Uropathogenic Dr/Afa
+
Escherichia coli
Mediates Mortality in Pregnant Rats
Authors: Wroblewska-Seniuk K. , Selvarangan R. , Hart A. , Pladzyk R. , Goluszko P. , Jafari A. , du Merle L. , Nowicki S. , Yallampalli C. , Le Bouguénec C. , Nowicki B. 
Published: October 2005

ABSTRACT

Escherichia coli
bearing adhesins of the Dr/Afa family frequently causes urogenital infections during pregnancy in humans and has been associated with mortality in pregnant rats. Two components of the adhesin, Dra/AfaE and Dra/AfaD, considered virulence factors, are responsible for bacterial binding and internalization. We hypothesize that gestational mortality caused by Dr/Afa
+
E. coli
is mediated by one of these two proteins, Dra/AfaE or Dra/AfaD. In this study, using
afaE
and/or
afaD
mutants, we investigated the role of the
afaE
and
afaD
genes in the mortality of pregnant rats from intrauterine infection. Sprague-Dawley rats, on the 17th day of pregnancy, were infected with the
E. coli afaE
+
afaD
and
afaE afaD
+
mutants. The clinical
E. coli
strain (
afaE
+
afaD
+
) and the
afaE afaD
double mutant were used as positive and negative controls, respectively. The mortality rate was evaluated 24 h after infection. The highest maternal mortality was observed in the group infected with the
afaE
+
afaD
+
strain, followed by the group infected with the
afaE
+
afaD
strain. The mortality was dose dependent. The
afaE afaD
double mutant did not cause maternal mortality, even with the highest infection dose. The in vivo studies corresponded with the invasion assay, where the
afaE
+
strains were the most invasive (
afaE
+
afaD
strain >
afaE
+
afaD
+
strain), while the
afaE
mutant strains (
afaE afaD
+
and
afaE afaD
strains) seemed to be noninvasive. This study shows for the first time that the
afaE
gene coding for the AfaE subunit of Dr/Afa adhesin is involved in the lethal outcome of gestational infection in rats. This lethal effect associated with AfaE correlates with the invasiveness of
afaE
+
E. coli
strains in vitro.
Peptidoglycan ofStaphylococcus aureusUpregulates Monocyte Expression of CD14, Toll-Like Receptor 2 (TLR2), and TLR4 in Human Blood: Possible Implications for Priming of Lipopolysaccharide Signaling
Authors: Hadley J. S. , Wang J. E. , Foster S. J. , Thiemermann C. , Hinds C. J. 
Published: October 2005

ABSTRACTPrevious studies have indicated that peptidoglycan (PepG) from gram-positive bacteria can exert a priming effect on the innate immune response to lipopolysaccharide (LPS) from gram-negative bacteria. Here, we hypothesized that this priming effect may be preceded by enhanced expression of monocyte CD14, Toll-like receptor 2 (TLR2), and TLR4. In an ex vivo whole human blood model, we observed a substantial synergy between LPS and PepG in the release of tumor necrosis factor alpha and interleukin-1β (IL-1β) over the 24-h experimental period, whereas the effect on IL-8 and IL-10 release was more time dependent. The priming effect of PepG on cytokine release was preceded by a rapid upregulation of CD14, TLR2, and TLR4 expression on monocytes: at 3 hours there was a twofold increase in CD14 expression (P< 0.03), a fivefold increase in TLR2 expression (P< 0.03), and a twofold increase in TLR4 expression (P< 0.03). CD14 and TLR2 remained upregulated throughout the experimental period following exposure to PepG (P< 0.05). Only a transient upregulation of these monocyte receptors was observed following treatment with LPS or LPS plus PepG. In conclusion, the synergistic effect of LPS and PepG on cytokine release is preceded by a reciprocal upregulation of TLR2 and TLR4 by both bacterial cell wall components.
Aggravated Lyme Carditis in CD11a−/−and CD11c−/−Mice
Authors: Guerau-de-Arellano Mireia , Alroy Joseph , Bullard Daniel , Huber Brigitte T. 
Published: October 2005

ABSTRACTCD18 hypomorph mice expressing reduced levels of the common β2 integrin chain develop aggravated Lyme carditis, compared to that developed by wild-type (WT) mice, upon infection with the spirocheteBorrelia burgdorferi. The enhancement of Lyme carditis in these mice is characterized by increased macrophage infiltration, correlating with augmented expression of the monocyte/macrophage chemoattractant protein 1 (MCP-1). The lack of CD18 results in the deficiency of all β2 integrins, i.e., CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1/CR3), CD11c/CD18 (p150,95/CR4), and CD11d/CD18. To determine the roles of the various β2 integrins in controlling the development of aggravated Lyme carditis, disease induction was analyzed in CD11a−/−, CD11b−/−, and CD11c−/−mice. CD11a−/−and CD11c−/−mice, but not CD11b−/−mice, developed aggravated Lyme carditis after exposure toB. burgdorferi. Similarly to CD18 hypomorph mice, CD11c−/−mice expressed higher levels of MCP-1, compared to both WT and CD11a−/−mice, as determined by in vitro analysis of MCP-1 secretion by bone marrow-derived dendritic cells and in vivo analysis of MCP-1 mRNA expression inB. burgdorferi-infected hearts. On the other hand, CD11a deficiency was associated with heightened heartB. burgdorferiburden relative to that of WT mice. Overall, our results suggest that the increased severity of Lyme carditis in CD18 hypomorph mice is caused by deficiency in CD11a or CD11c, possibly via different mechanisms.
Role of Motility in the Colonization of Uropathogenic
Escherichia coli
in the Urinary Tract
Authors: Lane M. Chelsea , Lockatell Virginia , Monterosso Greta , Lamphier Daniel , Weinert Julia , Hebel J. Richard , Johnson David E. , Mobley Harry L. T. 
Published: October 2005

ABSTRACT

Uropathogenic
Escherichia coli
(UPEC) causes most uncomplicated urinary tract infections (UTIs) in humans. Flagellum-mediated motility and chemotaxis have been suggested to contribute to virulence by enabling UPEC to escape host immune responses and disperse to new sites within the urinary tract. To evaluate their contribution to virulence, six separate flagellar mutations were constructed in UPEC strain CFT073. The mutants constructed were shown to have four different flagellar phenotypes:
fliA
and
fliC
mutants do not produce flagella; the
flgM
mutant has similar levels of extracellular flagellin as the wild type but exhibits less motility than the wild type; the
motAB
mutant is nonmotile; and the
cheW
and
cheY
mutants are motile but nonchemotactic. Virulence was assessed by transurethral independent challenges and cochallenges of CBA mice with the wild type and each mutant. CFU/ml of urine or CFU/g bladder or kidney was determined 3 days postinoculation for the independent challenges and at 6, 16, 48, 60, and 72 h postinoculation for the cochallenges. While these mutants colonized the urinary tract during independent challenge, each of the mutants was outcompeted by the wild-type strain to various degrees at specific time points during cochallenge. Altogether, these results suggest that flagella and flagellum-mediated motility/chemotaxis may not be absolutely required for virulence but that these traits contribute to the fitness of UPEC and therefore significantly enhance the pathogenesis of UTIs caused by UPEC.
Uropathogenic
Escherichia coli
Flagella Aid in Efficient Urinary Tract Colonization
Authors: Wright Kelly J. , Seed Patrick C. , Hultgren Scott J. 
Published: October 2005

ABSTRACT

In the murine model of urinary tract infections (UTI), cystitis by uropathogenic
Escherichia coli
(UPEC) occurs through an intimate relationship with the bladder superficial umbrella cell entailing cycles of adherence, invasion, intracellular bacterial community (IBC) formation, and dispersal (fluxing) from the intracellular environment. IBC dispersal is a key step that results in the spread of bacteria over the epithelial surface to initiate additional rounds of IBC formation. We investigated the role of flagella in mediating adherence and motility during UTI, hypothesizing that the dispersion of the IBC would be incomplete in the absence of motility, thus interrupting the IBC pathway and attenuating the infection. Using
gfp
reporter fusions, the expression of the flagellar class I
flhDC
and class III
fliC
genes was monitored to track key points of regulation throughout the pathogenic cascade. In vitro, growth under conditions promoting motility resulted in the robust expression of both fusions. In contrast, only the class I fusion produced significant expression throughout early stages of IBC development including the dispersion stage. Thus, unlike in vitro modeling of motility, the regulatory cascade appeared incomplete in vivo. Throughout IBC formation, nonmotile Δ
fliC
mutants achieved the same number of IBCs as the wild-type (
wt
) strain, demonstrating that flagella are neither essential nor required for first- or second-generation IBC formation. However, in competition experiments between
wt
and Δ
fliC
strains, the
wt
was shown to have a fitness advantage in persisting throughout the urinary tract for 2 weeks, demonstrating a subtle but measurable role for flagella in virulence.
Cardiac Apoptosis in Severe Relapsing Fever Borreliosis
Authors: Londoño Diana , Bai Yunhong , Zückert Wolfram R. , Gelderblom Harald , Cadavid Diego 
Published: October 2005

ABSTRACTPrevious studies revealed that the heart suffers significant injury during experimental Lyme and relapsing fever borreliosis when the immune response is impaired (D. Cadavid, Y. Bai, E. Hodzic, K. Narayan, S. W. Barthold, and A. R. Pachner, Lab. Investig.84:1439-1450, 2004; D. Cadavid, T. O'Neill, H. Schaefer, and A. R. Pachner, Lab. Investig.80:1043-1054, 2000; and D. Cadavid, D. D. Thomas, R. Crawley, and A. G. Barbour, J. Exp. Med. 179:631-642, 1994). To investigate cardiac injury in borrelia carditis, we used antibody-deficient mice persistently infected with isogenic serotypes of the relapsing fever agentBorrelia turicatae. We studied infection in hearts 1 to 2 months after inoculation by TaqMan reverse transcription-PCR and immunohistochemistry (IHC) and inflammation by hematoxylin and eosin and trichrome staining, IHC, and in situ hybridization (ISH). We studied apoptosis by terminal transferase-mediated DNA nick end labeling assay and measured expression of apoptotic molecules by RNase protection assay, immunofluorescence, and immunoblot. All antibody-deficient mice, but none of the immunocompetent controls, developed persistent infection of the heart. Antibody-deficient mice infected with serotype 2 had more severe cardiac infection and injury than serotype 1-infected mice. The injury was more severe around the base of the heart and pericardium, corresponding to sites of marked infiltration by activated macrophages and upregulation of interleukin-6 (IL-6). Infected hearts showed evidence of apoptosis of macrophages and cardiomyocytes as well as significant upregulation of caspases, most notably caspase-1. We conclude that persistent infection with relapsing fever borrelias causes significant loss of cardiomyocytes associated with prominent infiltration by activated macrophages, upregulation of IL-6, induction of caspase-1, and apoptosis.
Exposure to Mycobacteria Primes the Immune System for Evolutionarily Diverse Heat Shock Proteins
Authors: Qazi Khaleda Rahman , Qazi Mousumi Rahman , Julián Esther , Singh Mahavir , Abedi-Valugerdi Manuchehr , Fernández Carmen 
Published: October 2005

ABSTRACTDuring stress conditions, such as infection, the synthesis of heat shock proteins (HSPs) in microorganisms is upregulated. Since a high degree of homology exists within each HSP family, we postulated that exposure to microorganisms could prime the immune system for evolutionarily diverse HSPs. We tested this hypothesis by priming mice with three microorganisms, namely,Mycobacterium bovisBCG,Mycobacterium vaccae, andChlamydia pneumoniae.After this, mice received a dose of the various HSPs. We found that BCG andM. vaccaebut notC. pneumoniaeprimed the immune system for the induction of secondary immunoglobulin G (IgG) responses to most of the HSPs tested. Analysis of the IgG1 and IgG2a profile and gamma interferon production induced against the HSPs revealed the induction of a mixture of responses. We also observed that sera from mice treated withM. vaccaeand HSP70 were cross-reactive, but no antibody complexes were observed in their kidneys, which frequently are targets for autoantibody reactions. Our findings add further support for the use of HSPs as effective vaccine adjuvants.
Intranasal Immunization Strategy To Impede Pilin-Mediated Binding ofPseudomonas aeruginosato Airway Epithelial Cells
Authors: Hsieh Jennifer C. , Tham Doris M. , Feng Weijun , Huang Fan , Embaie Selamawit , Liu Keyi , Dean Deborah , Hertle Ralf , FitzGerald David J. , Mrsny Randall J. 
Published: October 2005

ABSTRACTPrevention of pulmonaryPseudomonas aeruginosainfections represents a critical unmet medical need for cystic fibrosis (CF) patients. We have examined the tenet that a mucosal immunization approach can reduce interactions of a piliated form of this opportunistic pathogen with respiratory epithelial cells. Vaccinations were performed using ntPEpilinPAK, a protein chimera composed of a nontoxic form ofP. aeruginosaexotoxin A (ntPE), where the C-terminal loop amino acid sequence of the PAK strain pilin protein was inserted in place of the ntPE Ib domain. Intranasal (i.n.) immunization of BALB/c mice with ntPEpilinPAK generated both serum and saliva immune responses. A series of in vitro studies showed that diluted samples of saliva obtained from immunized mice reduced pilin-dependentP. aeruginosabinding to polarized human tracheal epithelial cells, protected human pulmonary epithelial cells from cytotoxic actions associated with bacterial challenge, and reduced exotoxin A toxicity. Overall, i.n. administration of ntPEpilinPAK induced mucosal and systemic immune responses that may be beneficial for blocking early stage adhesion and/or infection events of epithelial cell-P. aeruginosainteractions at oropharyngeal surfaces.
Vaccination with a Sindbis Virus-Based DNA Vaccine Expressing Antigen 85B Induces Protective Immunity against
Mycobacterium tuberculosis
Authors: Derrick Steven C. , Yang Amy Li , Morris Sheldon L. 
Published: October 2005

ABSTRACT

To improve DNA vaccination against
Mycobacterium tuberculosis
, we evaluated the effectiveness of a Sindbis virus-based DNA construct expressing the tuberculosis antigen 85B (Sin85B). The protective efficacy of Sin85B was initially assessed by aerogenically challenging immunized C57BL/6 mice with virulent
Mycobacterium tuberculosis
. At 1 and 7 months postinfection, the lung bacterial burdens were considerably reduced and the lung pathology was improved in vaccinated mice compared to naive controls. Furthermore, the mean survival period for Sin85B-immunized mice (305 ± 9 days) after the tuberculous challenge was extended 102 days relative to the naive mice (203 ± 13 days) and was essentially equivalent to the survival time of
Mycobacterium bovis
BCG-vaccinated mice (294 ± 15 days). The essential role of gamma interferon (IFN-γ) in Sin85B-mediated protection was established by showing that significantly increased levels of IFN-γ mRNA were present postinfection in lung cells from vaccinated mice relative to control mice and by demonstrating that IFN-γ depletion prior to challenge abolished the vaccine-induced protection. The substantial antituberculosis protective responses induced by Sin85B immunization of CD4
−/−
mice strongly suggested that CD8 cells partially mediate Sin85B-induced protective immunity. Interestingly, Sin85B vaccination did not protect RNase L
−/−
(a key enzyme in the innate antiviral response) mice while significant protection was detected in RNase L
−/−
mice immunized with either BCG or a conventional DNA plasmid expressing antigen 85B. These data show that immunization with Sin85B offers protection similar to BCG in a murine model of pulmonary tuberculosis and suggest that Sin85B-induced protection is dependent upon both innate and acquired immune mechanisms.
Whole-Body Imaging of Sequestration of
Plasmodium falciparum
in the Rat
Authors: Pettersson Fredrik , Vogt Anna M. , Jonsson Cathrine , Mok Bobo W. , Shamaei-Tousi Alireza , Bergström Sven , Chen Qijun , Wahlgren Mats 
Published: October 2005

ABSTRACT

The occlusion of vessels by packed
Plasmodium falciparum
-infected (iRBC) and uninfected erythrocytes is a characteristic postmortem finding in the microvasculature of patients with severe malaria. Here we have employed immunocompetent Sprague-Dawley rats to establish sequestration in vivo. Human iRBC cultivated in vitro and purified in a single step over a magnet were labeled with
99m
technetium, injected into the tail vein of the rat, and monitored dynamically for adhesion in the microvasculature using whole-body imaging or imaging of the lungs subsequent to surgical removal. iRBC of different lines and clones sequester avidly in vivo while uninfected erythrocytes did not. Histological examination revealed that a multiadhesive parasite adhered in the larger microvasculature, inducing extensive intravascular changes while CD36- and chondroitin sulfate A-specific parasites predominantly sequester in capillaries, inducing no or minor pathology. Removal of the adhesive ligand
Plasmodium falciparum
erythrocyte membrane protein 1 (PfEMP1), preincubation of the iRBC with sera to PfEMP1 or preincubation with soluble PfEMP1-receptors prior to injection significantly reduced the sequestration. The specificity of iRBC binding to the heterologous murine receptors was confirmed in vitro, using primary rat lung endothelial cells and rat lung cryosections. In offering flow dynamics, nonmanipulated endothelial cells, and an intact immune system, we believe this syngeneic animal model to be an important complement to existing in vitro systems for the screening of vaccines and adjunct therapies aiming at the prevention and treatment of severe malaria.
Development of a Ligand-Directed Approach To Study the Pathogenesis of Invasive Aspergillosis
Authors: Lionakis Michail S. , Lahdenranta Johanna , Sun Jessica , Liu Wei , Lewis Russell E. , Albert Nathaniel D. , Pasqualini Renata , Arap Wadih , Kontoyiannis Dimitrios P. 
Published: October 2005

ABSTRACTInvasive aspergillosis is a leading cause of infectious death in immunosuppressed patients. Here, we adapted a phage display library-based selection to screen and identify binding peptides to the surface ofAspergillus fumigatusconidia and hyphae. We identified a peptide (sequence CGGRLGPFC) that reliably binds to the surface ofAspergillus fumigatushyphae. Binding was notAspergillusstrain specific, as it was also observed in hyphae of otherAspergillusclinical isolates. Furthermore, CGGRLGPFC-displaying phage targetsAspergillus fumigatushyphae on formalin-fixed paraffin-embedded histopathology sections of lung tissue recovered from mice with invasive pulmonary aspergillosis. This approach may yield reagents such as peptidomimetics for novel diagnostic and therapeutic interventions in invasive aspergillosis.
Memory T Lymphocytes Generated byMycobacterium bovisBCG Vaccination Reside within a CD4 CD44loCD62 LigandhiPopulation
Authors: Kipnis Andre , Irwin Scott , Izzo Angelo A. , Basaraba Randall J. , Orme Ian M. 
Published: October 2005

ABSTRACTIn the lungs of mice vaccinated withMycobacterium bovisBCG, there was an accumulation of CD4 cells expressing the activated effector phenotype CD44hiCD62 ligandlo(CD62Llo) which were capable of secreting gamma interferon. Upon cell transfer, however, cells expressing a resting/naïve phenotype (CD44loCD62Lhi) were capable of protecting the recipients from a virulent challenge infection, suggesting the emergence of T-cell memory from within this subset.
Differential Use of the Two High-Oxygen-Affinity Terminal Oxidases of
Brucella suis
for In Vitro and Intramacrophagic Multiplication
Authors: Loisel-Meyer Séverine , de Bagüés Maria Pilar Jiménez , Köhler Stephan , Liautard Jean-Pierre , Jubier-Maurin Véronique 
Published: October 2005

ABSTRACT

Expression of the high-oxygen-affinity cytochrome
cbb3
and cytochrome
bd
ubiquinol oxidases of
Brucella suis
was studied in vitro and in the intramacrophagic niche, which was previously proposed to be oxygen limited. The cytochrome
cbb3
oxidase was exclusively expressed in vitro, whereas the cytochrome
bd
oxidase was preferentially used inside macrophages and contributed to intracellular bacterial replication.
Decreased Virulence of a
gls24
Mutant of
Enterococcus faecalis
OG1RF in an Experimental Endocarditis Model
Authors: Nannini Esteban C. , Teng Fang , Singh Kavindra V. , Murray Barbara E. 
Published: October 2005

ABSTRACT

In
the current study, the
gls24
disruption mutant TX10100,
previously shown to be more sensitive to bile salts and attenuated in a
mouse peritonitis model, showed an approximately fivefold higher 50%
infective dose than wild-type OG1RF in a rat endocarditis model. When
administered as a mixture, TX10100, unlike a downstream
glsB
mutant, was significantly outnumbered by OG1RF in vegetations, organs,
and blood, despite being inoculated in greater numbers. These results
indicate that
gls24
is important in the pathogenesis of
enterococcal
endocarditis.
Immunization with Recombinant
Streptococcus pneumoniae
Neuraminidase NanA Protects Chinchillas against Nasopharyngeal Colonization
Authors: Tong H. H. , Li D. , Chen S. , Long J. P. , DeMaria T. F. 
Published: October 2005

ABSTRACT

Immunization with recombinant
S. pneumoniae
neuraminidase NanA (rNanA) resulted in a significant reduction in pneumococcal colonization in the chinchilla model. The bacteria were eliminated from the nasopharynx 1 week earlier than that from the control cohort. Our data suggest that rNanA affords protection against pneumococcal nasopharyngeal colonization.
The IncP Island in the Genome of
Brucella suis
1330 Was Acquired by Site-Specific Integration
Authors: Lavigne Jean-Philippe , Vergunst Annette C. , Bourg Gisèle , O'Callaghan David 
Published: October 2005

ABSTRACT

An 18,228-bp region containing open reading frames predicted to be derived from the IncP plasmid or phage ancestors is present in the genomes of
Brucella suis
biovars 1 to 4,
B. canis
,
B. neotomae
, and strains isolated from marine mammals, but not in
B. melitensis
,
B. abortus
,
B. ovis
, and
B. suis
biovar 5. The presence of circular excision intermediates and the results of an analysis of sequenced bacterial genomes suggest that the region downstream of the
guaA
gene is a hotspot for site-specific integration of foreign DNA mediated by a CP4-like integrase.