bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of a Novel Cathelicidin Gene in the Rainbow Trout,Oncorhynchus mykiss
Authors: Chang Chin-I , Pleguezuelos Olga , Zhang Yong-An , Zou Jun , Secombes Christopher J. 
Published: July 2005

ABSTRACTWe report the cloning of a novel antimicrobial peptide gene, termedrtCATH_1, found in the rainbow trout,Oncorhynchus mykiss. The predicted 216-residuertCATH_1 prepropeptide consists of three domains: a 22-residue signal peptide, a 128-residue cathelin-like region containing two identifiable cathelicidin family signatures, and a predicted 66-residue C-terminal cationic antimicrobial peptide. This predicted mature peptide was unique in possessing features of different known (mammalian) cathelicidin subgroups, such as the cysteine-bridged family and the specific amino-acid-rich family. ThertCATH_1 gene comprises four exons, as seen in all known mammalian cathelicidin genes, and several transcription factor binding sites known to be of relevance to host defenses were identified in the 5′ flanking region. By Northern blot analysis, the expression ofrtCATH_1 was detected in gill, head kidney, and spleen of bacterially challenged fish. Primary cultures of head kidney leukocytes from rainbow trout stimulated with lipopolysaccharide or poly(I · C) also expressedrtCATH_1. A 36-residue peptide corresponding to the core part of the fish cathelicidin was chemically synthesized and shown to exhibit potent antimicrobial activity and a low hemolytic effect. Thus,rtCATH_1 represents a novel antimicrobial peptide gene belonging to the cathelicidin family and may play an important role in the innate immunity of rainbow trout.
Conditional Lethality Yields a New Vaccine Strain ofListeria monocytogenesfor the Induction of Cell-Mediated Immunity
Authors: Li Zhongxia , Zhao Xinyan , Higgins Darren E. , Frankel Fred R. 
Published: July 2005

ABSTRACTListeria monocytogenesis a gram-positive intracellular pathogen that can enter phagocytic and nonphagocytic cells and colonize their cytosols. Taking advantage of this property to generate an intracellular vaccine delivery vector, we previously described a mutant strain ofL. monocytogenes, ΔdalΔdat, which is unable to synthesize cell wall by virtue of deletions in two genes (dalanddat) required ford-alanine synthesis. This highly attenuated strain induced long-lived protective systemic and mucosal immune responses in mice when administered in the transient presence ofd-alanine. We have now increased the usefulness of this organism as a vaccine vector by use of an inducible complementation system that obviates the need for exogenousd-alanine administration. The strain expresses a copy of theBacillus subtilisracemase gene under the control of a tightly regulated isopropyl-β-d-thiogalactopyranoside (IPTG)-inducible promoter present on a multicopy plasmid. This bacterium demonstrates strict dose-dependent growth in the presence of IPTG. After removal of inducer, bacterial growth ceased within two replication cycles. Following infection of mice in the absence of IPTG ord-alanine, the bacterium survived in vivo for less than 3 days. Nevertheless, a single immunization elicited a state of long-lasting protective immunity against wild-typeL. monocytogenesand induced a subset of effector listeriolysin O-specific CD11a+CD8+T cells in spleen and other tissues that was strongly enhanced after secondary immunization. This improvedL. monocytogenesvector system may have potential use as a live vaccine against human immunodeficiency virus, other infectious diseases, and cancer.
Heme Transfer from Streptococcal Cell Surface Protein Shp to HtsA of Transporter HtsABC
Authors: Liu Mengyao , Lei Benfang 
Published: July 2005

ABSTRACTHuman pathogen group A streptococcus (GAS) can take up heme from host heme-containing proteins as a source of iron. Little is known about the heme acquisition mechanism in GAS. We recently identified a streptococcal cell surface protein (designated Shp) and the lipoprotein component (designated HtsA) of an ATP-binding cassette (ABC) transporter made by GAS as heme-binding proteins. In an effort to delineate the molecular mechanism involved in heme acquisition by GAS, heme-free Shp (apo-Shp) and HtsA (apo-HtsA) were used to investigate heme transfer from heme-containing proteins (holo proteins) to the apo proteins. In addition, the interaction between holo-Shp and holo-HtsA was examined using native polyacrylamide gel electrophoresis. Heme was efficiently transferred from holo-Shp to apo-HtsA but not from holo-HtsA to apo-Shp. Apo-Shp acquired heme from human hemoglobin, and holo-Shp and holo-HtsA were able to form a complex, suggesting that Shp actively relays heme from hemoglobin to apo-HtsA. These findings demonstrate for the first time complex formation and directional heme transfer between a cell surface heme-binding protein and the lipoprotein of a heme-specific ABC transporter in gram-positive bacteria.
Identification and Characterization ofNeospora caninumCyclophilin That Elicits Gamma Interferon Production
Authors: Tuo Wenbin , Fetterer Raymond , Jenkins Mark , Dubey J. P. 
Published: July 2005

ABSTRACTGamma interferon (IFN-γ) response is essential to the development of a host protective immunity in response to infections by intracellular parasites. Neosporosis, an infection caused by the intracellular protozoan parasiteNeospora caninum, is fatal when there is a complete lack of IFN-γ in the infected host. However, the mechanism by which IFN-γ is elicited by the invading parasite is unclear. This study has identified a microbial protein in theN. caninumtachyzoiteN. caninumcyclophilin (NcCyP) as a major component of the parasite responsible for the induction of IFN-γ production by bovine peripheral blood mononuclear cells (PBMC) and antigen-specific CD4+T cells. NcCyP has high sequence homology (86%) withToxoplasma gondii18-kDa CyP with a calculated molecular mass of 19.4 kDa. NcCyP is a secretory protein with a predicted signal peptide of 17 amino acids. Abundant NcCyP was detected in whole-cellN. caninumtachyzoite lysate antigen (NcAg) andN. caninumtachyzoite culture supernatant. InN. caninumtachyzoite culture supernatant, three NcCyP bands of 19, 22, and 24 kDa were identified. NcAg stimulated high levels of IFN-γ production by PBMC and CD4+T cells. The IFN-γ-inducing effect of NcAg was blocked by cyclosporine, a specific ligand for CyP, in a dose-dependent manner. Furthermore, cyclosporine abolished IFN-γ production by PBMC from naïve cows as well as PBMC and CD4+T cells from infected/immunized cows. These results indicate that theN. caninumtachyzoite naturally produces a potent IFN-γ-inducing protein, NcCyP, which may be important for parasite survival as well as host protection.
Inter-Alpha-Inhibitor Proteins Are Endogenous Furin Inhibitors and Provide Protection against Experimental Anthrax Intoxication
Authors: Opal Steven M. , Artenstein Andrew W. , Cristofaro Patricia A. , Jhung Jhung W. , Palardy John E. , Parejo Nicholas A. , Lim Yow-Pin 
Published: July 2005

ABSTRACTInter-alpha-inhibitor protein (IαIp) functions as an endogenous serine protease inhibitor in human plasma, and IαIp levels diminish rapidly during acute inflammatory states. One potential target for IαIp is furin, a cell-associated serine endopeptidase essential for the activation of protective antigen and the formation of anthrax lethal toxin (LT). IαIp blocks furin activity in vitro and provides significant protection against cytotoxicity for murine peritoneal macrophages exposed to up to 500 ng/ml LT. A monoclonal antibody (MAb), 69.31, that specifically blocks the enzymatic activity of IαIp eliminates its protective effect against LT-induced cytotoxicity. IαIp (30 mg/kg of body weight) administered to BALB/c mice 1 hour prior to an intravenous LT challenge resulted in 71% survival after 7 days compared with no survivors among the control animals (P< 0.001). We conclude that human IαIp may be an effective preventative or therapeutic agent against anthrax intoxication.
Establishment of Cloned
Anaplasma phagocytophilum
and Analysis of
p44
Gene Conversion within an Infected Horse and Infected SCID Mice
Authors: Lin Quan , Rikihisa Yasuko 
Published: July 2005

ABSTRACT

Diverse
p44
alleles at the
p44
expression locus (
p44E
s) encoding surface-exposed major membrane proteins, P44s, of
Anaplasma phagocytophilum
were hypothesized to be garnered by recombination to enact antigenic variation. However, this hypothesis has not been proven so far, due to inability to clone this obligate intragranulocytic rickettsia. To define the
p44E
recombination, we developed a novel method to clone
A. phagocytophilum
. This isogenic cloned population containing a defined
p44E
was used to infect a naive horse and severe combined immunodeficiency (SCID) mice. During a 58-day infection period in the blood of the horse,
p44E
conversion was evident in a total of 11 new
p44E
s, 48% (115/242) of the sequenced
p44E
population. During a 50-day infection period in the blood of SCID mice,
p44E
conversion was manifested in a total of 13 new
p44E
s, 42% (192/460) of the
p44E
population. Thus, similar levels of
p44E
convertants were detected in either the presence or absence of an acquired immune system, suggesting that T- and B-cell immune pressure was not essential for recombination and/or selection of the
p44E
variants. Analysis of sequentially changed
p44E
s revealed that the entire central hypervariable region of donor
p44
pseudogenes or of donor full-length
p44
s replaced the same region of the resident
p44E
as a cassette. Putative recombination points were detected within
p44
conserved regions flanking the central hypervariable region by the TOPALi analysis. Our results unambiguously demonstrated
p44E
recombination. The cloning method developed would facilitate precise analysis of the recombination process and the extent of diversity which the recombination creates in the antigenic repertoire.
Shiga Toxin 1 Induces Apoptosis in the Human Myelogenous Leukemia Cell Line THP-1 by a Caspase-8-Dependent, Tumor Necrosis Factor Receptor-Independent Mechanism
Authors: Lee Sang-Yun , Cherla Rama P. , Caliskan Isa , Tesh Vernon L. 
Published: July 2005

ABSTRACTShiga toxins (Stxs) induce apoptosis in a variety of cell types. Here, we show that Stx1 induces apoptosis in the undifferentiated myelogenous leukemia cell line THP-1 in the absence of tumor necrosis factor alpha (TNF-α) or death receptor (TNF receptor or Fas) expression. Caspase-8 and -3 inhibitors blocked, and caspase-6 and -9 inhibitors partially blocked, Stx1-induced apoptosis. Stx1 induced the mitochondrial pathway of apoptosis, as activation of caspase-8 triggered the (i) cleavage of Bid, (ii) disruption of mitochondrial membrane potential, and (iii) release of cytochromecinto the cytoplasm. Caspase-8, -9, and -3 cleavage and functional activities began 4 h after toxin exposure and peaked after 8 h of treatment. Caspase-6 may also contribute to Stx1-induced apoptosis by directly acting on caspase-8. It appears that functional Stx1 holotoxins must be transported to the endoplasmic reticulum to initiate apoptotic signaling through the ribotoxic stress response. These data suggest that Stxs may activate monocyte apoptosis via a novel caspase-8-dependent, death receptor-independent mechanism.
Hag Directly Mediates the Adherence ofMoraxella catarrhalisto Human Middle Ear Cells
Authors: Bullard Brian , Lipski Serena L. , Lafontaine Eric R. 
Published: July 2005

ABSTRACTMoraxella catarrhalisis a human pathogen that causes otitis media in young children and lung infections in patients with chronic obstructive pulmonary disease. In this study, the role of the surface protein Hag in the adherence of multipleM. catarrhalisstrains was examined. Thehaggenes of four clinical isolates were disrupted with a spectinomycin resistance cassette, and the binding of isogenic mutants to primary cultures of human middle ear epithelial cells (HMEE), as well as A549 pneumocytes, was measured. These experiments revealed that the attachment of most mutants to both cell types was 10-fold less than that of their wild-type progenitors. To determine whether Hag directly mediates adherence to human cells, thehaggenes from threeM. catarrhalisisolates were cloned and expressed in a nonadherentEscherichia colicloning strain. At least 17-fold moreE. colibacteria expressing Hag attached to HMEE cells than an adherence-negative control. Surprisingly, Hag expression did not increase the binding of recombinantE. colito A549 monolayers. Our data demonstrate that the involvement of Hag inM. catarrhalisadherence to A549 and HMEE cells is conserved among isolates and that Hag directly mediates binding to HMEE cells.
MyD88, but Not Toll-Like Receptors 4 and 2, Is Required for Efficient Clearance ofBrucella abortus
Authors: Weiss David S. , Takeda Kiyoshi , Akira Shizuo , Zychlinsky Arturo , Moreno Edgardo 
Published: July 2005

ABSTRACTIt is not clear how the host initially recognizes and responds to infection by gram-negative pathogenicBrucellaspp. It was previously shown (D. S. Weiss, B. Raupach, K. Takeda, S. Akira, and A. Zychlinsky, J. Immunol. 172:4463-4469, 2004) that the early macrophage response against gram-negative bacteria is mediated by Toll-like receptor 4 (TLR4), which signals in response to lipopolysaccharide (LPS).Brucella, however, has a noncanonical LPS which does not have potent immunostimulatory activity. We evaluated the kinetics of TLR4 activation and the cytokine response in murine macrophages afterBrucellainfection. We found that during infection of macrophages,Brucellaavoids activation of TLR4 at 6 h but activates TLR4, TLR2, and myeloid differentiation factor 88 (MyD88) at 24 h postinfection. Interestingly, even though its activation is delayed, MyD88 is important for host defense againstBrucellainfection in vivo, since MyD88−/−mice do not clear the bacteria as efficiently as wild-type, TLR4−/−, TLR2−/−, or TLR4/TLR2−/−mice.
4-1BB (CD137) Is Required for Rapid Clearance ofListeria monocytogenesInfection
Authors: Lee Sang-C. , Ju Seong-A. , Pack Ha-N. , Heo Sook-K. , Suh Jae-H. , Park Sang-M. , Choi Boem-K. , Kwon Byoung S. , Kim Byung S. 
Published: July 2005

ABSTRACT4-1BB (CD137), a member of the tumor necrosis factor receptor superfamily, is a T-cell-costimulatory receptor that is expressed on activated T cells, dendritic cells, and NK cells. Little has been reported about its role in early host defense against bacterial infection. In this study, we report that 4-1BB-deficient (4-1BB−/−) mice are much more susceptible toListeria monocytogenes(intracellular bacteria) infections than wild-type mice. UponL. monocytogenesinfection, 4-1BB−/−mice showed a lower survival rate, a higher bacterial burden in organs, and larger hepatic microabscesses than 4-1BB+/+mice. 4-1BB−/−mice also had impairment in clearance of bacteria from the bloodstream. Neutrophils from 4-1BB+/+mice constitutively expressed 4-1BB, which could be activated to induce intracellular Ca2+influx by ligation with anti-4-1BB antibody. On the other hand, neutrophils from 4-1BB−/−mice were defective in reactive oxygen species generation, phagocytic activities, and intracellular Ca2+mobilization. In addition, mice pretreated with anti-4-1BB monoclonal antibody were much more resistant toL. monocytogenesinfection than control antibody-treated mice. Our results support the notion that 4-1BB may play a major role in host defense against intracellular pathogens through neutrophil activation.
Experimental Ocular Toxoplasmosis in Genetically Susceptible and Resistant Mice
Authors: Lu Fangli , Huang Shiguang , Hu Mark S. , Kasper Lloyd H. 
Published: July 2005

ABSTRACTGenetic factors determining the pathogenesis and course of ocular toxoplasmosis are poorly understood. In this study, we explored the development of experimental ocular pathogenesis in genetically dissimilar mice infected with either the RH strain, the PLK strain, or the immunodominant surface antigen 1 (SAG1 [P30])-deficient mutant of the RH strain ofToxoplasma gondii. At 11 days postinfection, ocular infection of C57BL/6 mice with all of the strains of parasites resulted in severe inflammatory lesions and high numbers of parasites in eye tissue; less severe ocular lesions at earlier histopathology and prolonged survival were observed in this mouse strain infected with either the major surface antigen 1-deficient SAG1−/−strain or the less virulent PLK strain compared with RH infection. In contrast, both BALB/c and CBA/J mice had less severe lesions and low numbers of parasites in their eye tissue, and infection developed into the chronic stage in these mice. There were significantly higher serum levels of gamma interferon and tumor necrosis factor alpha in C57BL/6 mice than in BALB/c and CBA/J mice following ocular infection. These observations confirm earlier reports on systemic immunity to these parasites that the route ofToxoplasmainfection markedly influences survival of mice. Our data indicate that genetic factors of the host as well as the parasite strain are critical in determining susceptibility to experimental ocular toxoplasmosis in murine models.
Production and Characterization of Monoclonal Antibodies against
Enterocytozoon bieneusi
Purified from Rhesus Macaques
Authors: Zhang Quanshun , Singh Inderpal , Sheoran Abhineet , Feng Xiaochuan , Nunnari John , Carville Angela , Tzipori Saul 
Published: July 2005

ABSTRACT

Enterocytozoon bieneusi
spores derived from rhesus macaque feces were purified by serial salt-Percoll-sucrose-iodixanol centrifugation, resulting in two bands with different specific densities of 95.6% and 99.5% purity and with a recovery efficiency of 10.8%. An ultrastructural examination revealed typical
E. bieneusi
spores. Twenty-six stable hybridomas were derived from BALB/c mice immunized with spores and were cloned twice by limiting dilution or growth on semisolid medium. Four monoclonal antibodies (MAbs), reacting exclusively with spores, were further characterized. These MAbs specifically reacted with spores present in stools of humans and macaques, as visualized by immunofluorescence, and with spore walls, as visualized by immunoelectron microscopy. A blocking enzyme-linked immunosorbent assay and Western blotting revealed that the epitope recognized by 8E2 was different from those recognized by 7G2, 7H2, and 12G8, which identified the same 40-kDa protein. These MAbs will be valuable tools for diagnostics, for epidemiological investigations, for host-pathogen interaction studies, and for comparative genomics and proteomics.
Probiotics Reduce Enterohemorrhagic
Escherichia coli
O157:H7- and Enteropathogenic
E. coli
O127:H6-Induced Changes in Polarized T84 Epithelial Cell Monolayers by Reducing Bacterial Adhesion and Cytoskeletal Rearrangements
Authors: Sherman Philip M. , Johnson-Henry Kathene C. , Yeung Helen P. , Ngo Peter S. C. , Goulet Jacques , Tompkins Thomas A. 
Published: July 2005

ABSTRACT

The aim of this study was to determine if probiotics reduce epithelial injury following exposure to
Escherichia coli
O157:H7 and
E. coli
O127:H6. The pretreatment of intestinal (T84) cells with lactic acid-producing bacteria reduced the pathogen-induced drop in transepithelial electrical resistance. These findings demonstrate that probiotics prevent epithelial injury induced by attaching-effacing bacteria.
Factors Associated with Severe Granulomatous Pneumonia inMycobacterium tuberculosis-Infected Mice Vaccinated Therapeutically with hsp65 DNA
Authors: Taylor Jennifer L. , Ordway Diane J. , Troudt JoLynn , Gonzalez-Juarrero Mercedes , Basaraba Randall J. , Orme Ian M. 
Published: July 2005

ABSTRACTResistant C57BL/6 mice infected in the lungs withMycobacterium tuberculosisand then therapeutically vaccinated withMycobacterium leprae-derived hsp65 DNA develop severe granulomatous pneumonia and tissue damage. Analysis of cells accumulating in the lungs of these animals revealed substantial increases in T cells secreting tumor necrosis factor alpha and CD8 cells staining positive for granzyme B. Stimulation of lung cells ex vivo revealed very high levels of interleukin-10, some of which was produced by B-1 B cells. This was probably an anti-inflammatory response, since lung pathology was dramatically worsened in B-cell gene-disrupted mice.
Intracellular Survival of
Campylobacter jejuni
in Human Monocytic Cells and Induction of Apoptotic Death by Cytholethal Distending Toxin
Authors: Hickey Thomas E. , Majam Gary , Guerry Patricia 
Published: July 2005

ABSTRACT

Campylobacter jejuni
81-176 is capable of extensive replication within human monocytic cell vacuoles and induces apoptotic death via cytolethal distending toxin.
Biofilm Formation by
Salmonella enterica
Serovar Typhimurium and
Escherichia coli
on Epithelial Cells following Mixed Inoculations
Authors: Esteves Cristina L. C. , Jones Bradley D. , Clegg Steven 
Published: July 2005

ABSTRACT

Biofilms were formed by inoculations of
Salmonella enterica
serovar Typhimurium and
Escherichia coli
on HEp-2 cells. Inoculations of
S. enterica
serovar Typhimurium and
E. coli
resulted in the formation of an extensive biofilm of
S. enterica
serovar Typhimurium. In experiments where an
E. coli
biofilm was first formed followed by challenge with
S. enterica
serovar Typhimurium, there was significant biofilm formation by
S. enterica
serovar Typhimurium. The results of this study indicate that
S. enterica
serovar Typhimurium can outgrow
E. coli
in heterologous infections and displace
E. coli
when it forms a biofilm on HEp-2 cells.
Virulence Comparisons of
Aspergillus nidulans
Mutants Are Confounded by the Inflammatory Response of p47

phox

−/−
Mice
Authors: Bignell Elaine , Negrete-Urtasun Susana , Calcagno Ana Maria , Arst Herbert N. , Rogers Tom , Haynes Ken 
Published: July 2005

ABSTRACT

While investigating the requirement for phagosomal alkalinization in the host defense against pulmonary aspergillosis, we observed high morbidity of p47

phox

−/−
mice infected with pH-insensitive
Aspergillus nidulans
mutants despite a paucity of fungal growth. Fatal infection also resulted from a normally avirulent
p
-aminobenzoate auxotroph. This demonstrates that p47

phox

−/−
murine immunity contributes significantly to
A. nidulans
lethality. These data have wider implications for microbial virulence studies with p47

phox

−/−
mice.
Identification of Variant-Specific Surface Proteins in
Giardia muris
Trophozoites
Authors: Ropolo Andrea S. , Saura Alicia , Carranza Pedro G. , Lujan Hugo D. 
Published: July 2005

ABSTRACT

Giardia lamblia
undergoes antigenic variation, a process that might allow the parasite to evade the host's immune response and adapt to different environments. Here we show that
Giardia muris
, a related species that naturally infects rodents, possesses multiple variant-specific surface proteins (VSPs) and expresses VSPs on its surface, suggesting that it undergoes antigenic variation similar to that of
G. lamblia
.
Importance of
srtA
and
srtB
for Growth of
Bacillus anthracis
in Macrophages
Authors: Zink Steven D. , Burns Drusilla L. 
Published: July 2005

ABSTRACT

We examined the effect of mutation of two sortase genes of
Bacillus anthracis
,
srtA
and
srtB
, on the ability of the bacterium to grow in J774A.1 cells, a mouse macrophage-like cell line. While disruption of either
srtA
or
srtB
had no effect on the ability of the bacteria to grow in rich culture media, mutations in each of these genes dramatically attenuated growth of the bacterium in J774A.1 cells. Complementation of the mutation restored the ability of bacteria to grow in the cells. Since the initial events in inhalation anthrax are believed to be uptake of
B. anthracis
spores by alveolar macrophages followed by germination of the spores and growth of the bacteria within the macrophages, these results suggest that two sortases of
B. anthracis
may be critical in the early stages of inhalation anthrax.