bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phagocyte-Derived Reactive Oxygen Species Do Not Influence the Progression of Murine Blood-Stage Malaria Infections
Authors: Potter S. M. , Mitchell A. J. , Cowden W. B. , Sanni L. A. , Dinauer M. , de Haan J. B. , Hunt N. H. 
Published: July 2005

ABSTRACTPhagocyte-derived reactive oxygen species have been implicated in the clearance of malaria infections. We investigated the progression of five different strains of murine malaria in gp91phox−/−mice, which lack a functional NADPH oxidase and thus the ability to produce phagocyte-derived reactive oxygen species. We found that the absence of functional NADPH oxidase in the gene knockout mice had no effect on the parasitemia or total parasite burden in mice infected with either resolving (Plasmodium yoeliiandPlasmodium chabaudiK562) or fatal (Plasmodium bergheiANKA,Plasmodium bergheiK173 andPlasmodium vinckei vinckei) strains of malaria. This lack of effect was apparent in both primary and secondary infections withP. yoeliiandP. chabaudi. There was also no difference in the presentation of clinical or pathological signs between the gp91phox−/−or wild-type strains of mice infected with malaria. Progression ofP. bergheiANKA andP. bergheiK173 infections was unchanged in glutathione peroxidase-1 gene knockout mice compared to their wild-type counterparts. The rates of parasitemia progression in gp91phox−/−mice and wild-type mice were not significantly different when they were treated withl-NG-methylarginine, an inhibitor of nitric oxide synthase. These results suggest that phagocyte-derived reactive oxygen species are not crucial for the clearance of malaria parasites, at least in murine models.
Prevention and Treatment of Cutaneous Leishmaniasis in Primates by Using Synthetic Type D/A Oligodeoxynucleotides Expressing CpG Motifs
Authors: Flynn Barbara , Wang Vivian , Sacks David L. , Seder Robert A , Verthelyi Daniela 
Published: July 2005

ABSTRACTOligodeoxynucleotides (ODN) containing CpG motifs mimic microbial DNA and are recognized by toll-like receptor 9 on immune cells. The resulting response limits the early spread of infectious organisms and promotes the development of adaptive immunity. In this regard, CpG ODN show promise as immunoprotective agents and as vaccine adjuvants. Previous studies of nonhuman primates showed that administration of CpG ODN type D (also known as type A) at the site of infection 3 days before and after a challenge withLeishmania majorenhanced host resistance and reduced the lesion's severity. In this study, we show that systemic administration of D/A ODN limits the size of lesions following an intradermal infection withL. major. Importantly, the reduced morbidity was not associated with a reduction in long-term immunity, as such treated macaques were still protected following a secondary challenge. Finally, administration of D/A ODN to macaques that had established cutaneous lesions reduced the severity of the lesions, suggesting a potential role for CpG ODN inL. majortreatment. Together, these findings support the development of clinical studies to assess the use of CpG ODN types D/A as immunoprotective and therapeutic agents.
Impaired Neutrophil Migration Associated with Specific Bovine CXCR2 Genotypes
Authors: Rambeaud M. , Pighetti G. M. 
Published: July 2005

ABSTRACTBovine mastitis continues to be the most detrimental factor for profitable dairying. Recent research conducted within our laboratory has identified a genetic marker in the CXCR2 gene associated with mastitis susceptibility. The objective of the present study was to evaluate the migratory ability of neutrophils from cows with different CXCR2 +777 genotypes. Neutrophils isolated from peripheral blood of 30 Holstein cows were tested for in vitro migration and adhesion molecule expression. Cows with the CC or GC genotype at CXCR2 +777 showed significantly lower neutrophil migration to recombinant human interleukin-8 (rhIL-8) than cows with the GG genotype (P< 0.05). Cows with the CC genotype at CXCR2 +777 also showed decreased neutrophil migration to zymosan-activated serum compared to these same cows (P< 0.05). Decreased upregulation of CD18 expression was observed after stimulation with rhIL-8 in cows expressing the CXCR2 +777 CC genotype compared to cows expressing the GG genotype (P< 0.05). A similar trend was observed for CD11b (P< 0.10). However, no difference in CD62 downregulation was observed with respect to genotype. These results provide initial evidence for a phenotypic association between a single nucleotide polymorphism and neutrophil function in dairy cows, as well as potential insight into specific mechanisms affected in cows more susceptible to mastitis.
Characterization of the Filamentous Hemagglutinin-Like Protein FhaS in
Bordetella bronchiseptica
Authors: Julio Steven M. , Cotter Peggy A. 
Published: July 2005

ABSTRACT

Filamentous hemagglutinin (FHA) is a large (>200 kDa), rod-shaped protein expressed by bordetellae that is both surface-associated and secreted. FHA mediates bacterial adherence to epithelial cells and macrophages in vitro and is absolutely required for tracheal colonization in vivo. The recently sequenced
Bordetella bronchiseptica
genome revealed the presence of a gene,
fhaS
, that is nearly identical to
fhaB
, the FHA structural gene. We show that although
fhaS
expression requires the BvgAS virulence control system, it is maximal only under a subset of conditions in which BvgAS is active, suggesting an additional level of regulation. We also show that, like FHA, FhaS undergoes a C-terminal proteolytic processing event and is both surface-associated and secreted and that export across the outer membrane requires the channel-forming protein FhaC. Unlike FHA, however, FhaS was unable to mediate adherence of
B. bronchiseptica
to epithelial cell lines in vitro and was not required for respiratory tract colonization in vivo. In a coinfection experiment, a Δ
fhaS
strain was out-competed by wild-type
B. bronchiseptica
, indicating that
fhaS
is expressed in vivo and that FhaS contributes to bacterial fitness in a manner revealed when the mutant must compete with wild-type bacteria. These data suggest that FHA and FhaS perform distinct functions during the
Bordetella
infectious cycle. A survey of various
Bordetella
strains revealed two distinct
fhaS
alleles that segregate according to pathogen host range and that
B. parapertussis
hu
most likely acquired its
fhaS
allele from
B. pertussis
horizontally, suggesting
fhaS
may contribute to host-species specificity.
Borrelia burgdorferi rel
Is Responsible for Generation of Guanosine-3′-Diphosphate-5′-Triphosphate and Growth Control
Authors: Bugrysheva Julia V. , Bryksin Anton V. , Godfrey Henry P. , Cabello Felipe C. 
Published: July 2005

ABSTRACT

The global transcriptional regulator (p)ppGpp (guanosine-3′-diphosphate-5′-triphosphate and guanosine-3′,5′-bisphosphate, collectively) produced by the
relA
and
spoT
genes in
Escherichia coli
allows bacteria to adapt to different environmental stresses. The genome of
Borrelia burgdorferi
encodes a single chromosomal
rel
gene (BB0198) (
B. burgdorferi rel
[

rel
Bbu

]) homologous to
relA
and
spoT
of
E. coli
. Its role in (p)ppGpp synthesis, bacterial growth, and modulation of gene expression has not been studied in detail. We constructed a

rel
Bbu

deletion mutant in an infectious
B. burgdorferi
297 strain and isolated an extrachromosomally complemented derivative of this mutant. The mutant did not synthesize

rel
Bbu

mRNA, Rel
Bbu
protein, or (p)ppGpp. This synthesis was restored in the complemented derivative, confirming that

rel
Bbu

is necessary and sufficient for (p)ppGpp synthesis and degradation in
B. burgdorferi
. The

rel
Bbu

mutant grew well during log phase in complete BSK-H but reached lower cell concentrations in the stationary phase than the wild-type parent, suggesting that (p)ppGpp may be an important factor in the ability of
B. burgdorferi
to adapt to stationary phase. Deletion of

rel
Bbu

did not eliminate the temperature-elicited OspC shift, nor did it alter
bmp
gene expression or
B. burgdorferi
antibiotic susceptibility. Although deletion of

rel
Bbu

eliminated
B. burgdorferi
virulence for mice, which was not restored by complementation, we suggest that

rel
Bbu

-dependent accumulation of (p)ppGpp may be important for in vivo survival of this pathogen.
Characterization of the
cciIR
Quorum-Sensing System in
Burkholderia cenocepacia
Authors: Malott Rebecca J. , Baldwin Adam , Mahenthiralingam Eshwar , Sokol Pamela A. 
Published: July 2005

ABSTRACT

Several transmissible
Burkholderia cenocepacia
strains that infect multiple cystic fibrosis patients contain a genomic island designated as the
c
eno
c
epacia
i
sland (cci). The cci contains a predicted
N-
acylhomoserine lactone (AHL) synthase gene,
cciI
, and a predicted response regulator gene,
cciR.
AHL production profiles indicated that CciI catalyzes the synthesis of
N
-hexanoyl-
l
-homoserine lactone and minor amounts of
N-
octanoyl-
l
-homoserine lactone. The
cciI
and
cciR
genes were found to be cotranscribed by reverse transcription-PCR analysis, and the expression of a
cciIR
::
luxCDABE
fusion in a
cciR
mutant suggested that the
cciIR
system negatively regulates its own expression.
B. cenocepacia
strains also have a
cepIR
quorum-sensing system. Expression of
cepI
::
luxCDABE
or
cepR
::
luxCDABE
fusions in a
cciR
mutant showed that CciR negatively regulates
cepI
but does not regulate
cepR.
Expression of the
cciIR
::
luxCDABE
fusion in a
cepR
mutant indicated that functional CepR is required for
cciIR
expression. Phylogenetic analysis suggested that the
cciIR
system was acquired by horizontal gene transfer from a distantly related organism and subsequently incorporated into the ancestral
cepIR
regulatory network. Mutations in
cciI
,
cciR
,
cepI cciI
, and
cepR cciR
were constructed in
B. cenocepacia
K56-2. The
cciI
mutant had greater protease activity and less swarming motility than the parent strain. The
cciR
mutant had less protease activity than the parent strain. The phenotypes of the
cepI cciI
and
cepR cciR
mutants were similar to
cepI
or
cepR
mutants, with less protease activity and swarming motility than the parent strain.
Characterization of Enterohemorrhagic
Escherichia coli
Strains Based on Acid Resistance Phenotypes
Authors: Bhagwat Arvind A. , Chan Lynn , Han Rachel , Tan Jasmine , Kothary Mahendra , Jean-Gilles Junia , Tall Ben D. 
Published: July 2005

ABSTRACT

Acid resistance is perceived to be an important property of enterohemorrhagic
Escherichia coli
strains, enabling the organisms to survive passage through the acidic environment of the stomach so that they may colonize the mammalian gastrointestinal tract and cause disease. Accordingly, the organism has developed at least three genetically and physiologically distinct acid resistance systems which provide different levels of protection. The glutamate-dependent acid resistance (GDAR) system utilizes extracellular glutamate to protect cells during extreme acid challenges and is believed to provide the highest protection from stomach acidity. In this study, the GDAR system of 82 pathogenic
E. coli
isolates from 34 countries and 23 states within the United States was examined. Twenty-nine isolates were found to be defective in inducing GDAR under aerobic growth conditions, while five other isolates were defective in GDAR under aerobic, as well as fermentative, growth conditions. We introduced
rpoS
on a low-copy-number plasmid into 26 isolates and were able to restore GDAR in 20 acid-sensitive isolates under aerobic growth conditions. Four isolates were found to be defective in the newly discovered LuxR-like regulator GadE (formerly YhiE). Defects in other isolates could be due to a mutation(s) in a gene(s) with an as yet undefined role in acid resistance since GadE and/or RpoS could not restore acid resistance. These results show that in addition to mutant alleles of
rpoS
, mutations in
gadE
exist in natural populations of pathogenic
E. coli
. Such mutations most likely alter the infectivity of individual isolates and may play a significant role in determining the infective dose of enterohemorrhagic
E. coli
.
Immunogenicity of the
Mycobacterium tuberculosis
PPE55 (Rv3347c) Protein during Incipient and Clinical Tuberculosis
Authors: Singh Krishna K. , Dong Yuxin , Patibandla Sai A. , McMurray David N. , Arora Vijay K. , Laal Suman 
Published: July 2005

ABSTRACT

Clinical tuberculosis (TB), whether noncavitary or cavitary, is the late stage of a chronic disease process, since
Mycobacterium tuberculosis
is a slowly growing organism. Our studies have shown that the profiles of antigenic proteins expressed by the in vivo bacteria that elicit antibodies differ in cavitary and noncavitary TB (K. Samanich, J. T. Belisle, and S. Laal, Infect. Immun.
69:
4600-4609, 2001). To gain insight into antigenic proteins expressed during incipient, subclinical TB, an expression library of
M. tuberculosis
genomic DNA was screened with sera obtained during subclinical TB from guinea pigs infected with aerosols of
M. tuberculosis
H37Rv. One of the proteins recognized by antibodies elicited during subclinical TB infection of guinea pigs is the 309-kDa PPE55 (Rv3347c) protein. Genomic hybridization studies suggest that the PPE55 gene is specific to the
M. tuberculosis
complex and is present in a majority of clinical isolates tested. Antibodies to the C-terminal, ∼100-kDa fragment of PPE55 (PPE-C) were detectable in sera from 29/30 (97%) human immunodeficiency virus-negative/TB-positive (HIV
−
TB
+
) patients and 17/24 (71%) HIV
+
TB
+
patients tested but not in sera from purified-protein derivative-positive healthy controls, suggesting that the in vivo expression of PPE55 protein correlates with active
M. tuberculosis
infection. Anti-PPE-C antibodies were also detected in retrospective sera obtained months prior to manifestation of clinical TB from 17/21 (81%) HIV
+
TB
+
individuals tested, providing evidence that the protein is expressed during incipient, subclinical TB in HIV-infected humans. Thus, PPE55 is a highly immunogenic protein that may be useful for differentiating between latent TB and incipient, subclinical TB.
Endocarditis-Associated Oral Streptococci Promote Rapid Differentiation of Monocytes into Mature Dendritic Cells
Authors: Hahn Chin-Lo , Schenkein Harvey A. , Tew John G. 
Published: July 2005

ABSTRACTEndocarditis is frequently attributable to oral streptococci, but mechanisms of pathogenesis are not well understood, although monocytes appear to be important. High titers of interleukin-12 (IL-12) are produced by peripheral blood mononuclear cells (PBMC) after engagingStreptococcus mutans, but monocytes in developing endocardial vegetations tend to disappear rather than become macrophages. These data prompted the hypothesis that streptococcus-infected monocytes differentiate into short-lived IL-12-producing dendritic cells (DCs) rather than macrophages. PBMC from healthy subjects were stimulated with six isolates of oral streptococci, three nonstreptococcal oral bacteria, or IL-4 plus granulocyte-macrophage colony-stimulating factor, and the appearance of cells with markers typical of mature DCs (CD83+, CD86+, CD11c+, and CD14−) was monitored. Supernatant fluids from the PBMC cultures were harvested and IL-12 p70 levels were determined.S. mutans-stimulated monocytes were analyzed for their ability to elicit allogeneic mixed-lymphocyte reactions. All streptococci examined, except one strain ofStreptococcus oralis(35037), rapidly induced up-regulation of CD83 and CD86 and a loss of CD14 in the CD11c+monocyte population within 20 h. Induction of IL-12 was CD14 dependent and correlated with streptococcal isolates that promoted the DC phenotype. Major histocompatibility complex (MHC) class II expression was up-regulated byS. mutans, and these cells were short-lived and elicited potent allogeneic mixed-lymphocyte reactions typical of DCs. In summary, monocytes stimulated with endocarditis-associated oral streptococci rapidly exhibited the DC phenotype and functions. These data suggest that the initiation of bacterial endocarditis by oral streptococci may involve monocyte-to-DC differentiation, and this may help explain the low levels of macrophages in the site.
Identification and Characterization of anSKN7Homologue inCryptococcus neoformans
Authors: Wormley F. L. , Heinrich G. , Miller J. L. , Perfect J. R. , Cox G. M. 
Published: July 2005

ABSTRACTCryptococcus neoformansis an encapsulated fungal pathogen that primarily infects the central nervous system of immunocompromised individuals, causing life-threatening meningoencephalitis. The capacity ofC. neoformansto subvert host defenses and disseminate by intracellular parasitism of alveolar macrophages in the immune-compromised host has led to studies to evaluate genes associated withC. neoformansresistance to oxidative stress. In the present study, we identify and characterize aC. neoformanshomologue toSKN7, a transcription factor inSaccharomyces cerevisiaethat regulates the oxidative stress response, cell cycle, and cell wall biosynthesis. To examine the contribution ofSKN7in the pathogenesis of fungal infections, we createdskn7mutants via targeted disruption. Theskn7mutants were observed to be more susceptible to reactive oxygen species in vitro and were significantly less virulent than the wild-type strain and a reconstituted strain as measured by cumulative survival in the mouse inhalational model. The Skn7 protein was observed to be important for expression of thioredoxin reductase in response to oxidative challenge. Interestingly,skn7mutants were also observed to flocculate following in vitro culture, a novel phenotype not observed inskn7mutants derived from other fungi. These findings demonstrate thatSKN7contributes to the virulence composite but is not required for pathogenicity inC. neoformans. In addition, flocculation ofC. neoformans skn7mutants suggests a potentially unique function ofSKN7not previously observed in other cryptococcal strains orskn7mutants.
Intranasal Delivery of Group B Meningococcal Native Outer Membrane Vesicle Vaccine Induces Local Mucosal and Serum Bactericidal Antibody Responses in Rabbits
Authors: Shoemaker David R. , Saunders Nancy B. , Brandt Brenda L. , Moran E. Ellen , LaClair Andrew D. , Zollinger Wendell D. 
Published: July 2005

ABSTRACT
We have previously shown that intranasal immunization of mice with meningococcal native outer membrane vesicles (NOMV) induces both a good local mucosal antibody response and a good systemic bactericidal antibody response. However, in the intranasal mouse model, some of the NOMV entered the lung and caused an acute granulocytic response. We therefore developed an alternate animal model using the rabbit. This model reduces the probability of lung involvement and more closely mimics intranasal immunization of humans. Rabbits immunized intranasally with doses of 100 μg of NOMV in 0.5 ml of saline developed serum bactericidal antibody levels comparable to those of rabbits immunized intramuscularly with 25-μg doses, particularly when the primary intranasal immunization was given daily for 3 days. Intranasal immunization also induced a local mucosal response as evidenced by immunoglobulin A antibody in saliva, nasal washes, and lung lavage fluids. NOMV from a capsule-deficient mutant induced higher serum bactericidal antibody responses than NOMV from the encapsulated parent. Meningococcal NOMV could be administered intranasally at 400 μg with no pyrogenic activity, but as little as 0.03 μg/kg of body weight administered intravenously or 25 μg administered intramuscularly induced a pyrogenic response. These data indicate that the rabbit is a useful model for preclinical testing of intranasal meningococcal NOMV vaccines, and this immunization regimen produces a safe and substantial systemic and local mucosal antibody response.
Scrub Typhus Vaccine Candidate Kp r56 Induces Humoral and Cellular Immune Responses in Cynomolgus Monkeys
Authors: Chattopadhyay Suchismita , Jiang Ju , Chan Teik-Chye , Manetz T. Scott , Chao Chien-Chung , Ching Wei-Mei , Richards Allen L. 
Published: July 2005

ABSTRACTA truncated recombinant 56-kDa outer membrane protein of the Karp strain ofOrientia tsutsugamushi(Kp r56) was evaluated in cynomolgus monkeys (Macaca fascicularis) for immunogenicity and safety as a vaccine candidate for the prevention of scrub typhus. This recombinant antigen induced strong humoral and cellular immune responses in two monkeys and was found to be well tolerated. Antigen-specific immunoglobulin M (IgM) and IgG were produced to almost maximal levels within 1 week of a single immunization. Peripheral blood mononuclear cells from vaccinated animals showed an induction of antigen-specific proliferation and gamma interferon production. The Kp r56 was not as efficient as infection with live organisms in preventing reinfection but was able to reduce the inflammation produced at the site of challenge. This report describes the results of the first systematic study of the immunogenicity of a recombinant scrub typhus vaccine candidate in a nonhuman primate model.
Experimental Infection withTrypanosoma cruziIncreases the Population of CD8+, but not CD4+, Immunoglobulin G Fc Receptor-Positive T Lymphocytes
Authors: Henriques-Pons Andrea , Olivieri Bianca P. , Oliveira Gabriel M. , Daëron Marc , de Araújo-Jorge Tania C. 
Published: July 2005

ABSTRACTIt is well established that activating-type Fc receptors for immunoglobulin G (FcγR), such as FcγRI and FcγRIII, are essential for inducing inflammatory responses. On the other hand, a unique inhibitory FcγR, FcγRIIB, inhibits intracellular signaling upon engagement of immunoglobulin G-immune complexes, suppressing inflammation and autoimmunity. The expression of FcγRIIB on B lymphocytes, natural killer cells, macrophages, mast cells, and a number of other cell types has been demonstrated for many years. However, the expression on T lymphocytes is probably restricted to activated cells in a narrow window of time. The controversy regarding the FcγR expression on T lymphocytes is attributable to considerable heterogeneity of cellular subpopulations and activation stages during immune responses in vivo. We addressed here this question by using mice experimentally infected withTrypanosoma cruzi, and we found an increase in the CD8+FcγR+population but not in the CD4+FcγR+population. Moreover, CD8+FcγR+T cells predominantly composed the cardiac inflammatory infiltration induced by the infection. These results indicate a novel pattern of FcγR expression on T cells in a pathological situation, and possible functional roles of this phenomenon are discussed.