bluuebunny/crossref_metadata_2025_split huggingface dataset:
BCX4430, a Novel Nucleoside Analog, Effectively Treats Yellow Fever in a Hamster Model
Authors: Julander Justin G. , Bantia Shanta , Taubenheim Brian R. , Minning Dena M. , Kotian Pravin , Morrey John D. , Smee Donald F. , Sheridan William P. , Babu Yarlagadda S. 
Published: August 2014

ABSTRACT
No effective antiviral therapies are currently available to treat disease after infection with yellow fever virus (YFV). A Syrian golden hamster model of yellow fever (YF) was used to characterize the effect of treatment with BCX4430, a novel adenosine nucleoside analog. Significant improvement in survival was observed after treatment with BCX4430 at 4 mg/kg of body weight per day dosed intraperitoneally (i.p.) twice daily (BID). Treatment with BCX4430 at 12.5 mg/kg/day administered i.p. BID for 7 days offered complete protection from mortality and also resulted in significant improvement of other YF disease parameters, including weight loss, serum alanine aminotransferase levels (6 days postinfection [dpi]), and viremia (4 dpi). In uninfected hamsters, BCX4430 at 200 mg/kg/day administered i.p. BID for 7 days was well tolerated and did not result in mortality or weight loss, suggesting a potentially wide therapeutic index. Treatment with BCX4430 at 12 mg/kg/day i.p. remained effective when administered once daily and for only 4 days. Moreover, BCX4430 dosed at 200 mg/kg/day i.p. BID for 7 days effectively treated YF, even when treatment was delayed up to 4 days after virus challenge, corresponding with peak viral titers in the liver and serum. BCX4430 treatment did not preclude a protective antibody response, as higher neutralizing antibody (nAb) concentrations corresponded with increasing delays of treatment initiation, and greater nAb responses resulted in the protection of animals from a secondary challenge with YFV. In summary, BCX4430 is highly active in a hamster model of YF, even when treatment is initiated at the peak of viral replication.
Safety and Pharmacokinetic Profiles of Phosphorodiamidate Morpholino Oligomers with Activity against Ebola Virus and Marburg Virus: Results of Two Single-Ascending-Dose Studies
Authors: Heald Alison E. , Iversen Patrick L. , Saoud Jay B. , Sazani Peter , Charleston Jay S. , Axtelle Tim , Wong Michael , Smith William B. , Vutikullird Apinya , Kaye Edward 
Published: August 2014

ABSTRACT

Two identical single-ascending-dose studies evaluated the safety and pharmacokinetics (PK) of AVI-6002 and AVI-6003, two experimental combinations of phosphorodiamidate morpholino oligomers with positive charges (PMO
plus
) that target viral mRNA encoding Ebola virus and Marburg virus proteins, respectively. Both AVI-6002 and AVI-6003 were found to suppress disease in virus-infected nonhuman primates in previous studies. AVI-6002 (a combination of AVI-7537 and AVI-7539) or AVI-6003 (a combination of AVI-7287 and AVI-7288) were administered as sequential intravenous (i.v.) infusions of a 1:1 fixed dose ratio of the two subcomponents. In each study, 30 healthy male and female subjects between 18 and 50 years of age were enrolled in six-dose escalation cohorts of five subjects each and received a single i.v. infusion of active study drug (0.005, 0.05, 0.5, 1.5, 3, and 4.5 mg/kg per component) or placebo in a 4:1 ratio. Both AVI-6002 and AVI-6003 were safe and well tolerated at the doses studied. A maximum tolerated dose was not observed in either study. The four chemically similar PMO
plus
components exhibited generally similar PK profiles. The mean peak plasma concentration and area under the concentration-time curve values of the four components exhibited dose-proportional PK. The estimated plasma half-life of all four components was 2 to 5 h. The safety of the two combinations and the PK of the four components were similar, regardless of the target RNA sequence.
Respiratory Flexibility in Response to Inhibition of Cytochrome
c
Oxidase in Mycobacterium tuberculosis
Authors: Arora Kriti , Ochoa-Montaño Bernardo , Tsang Patricia S. , Blundell Tom L. , Dawes Stephanie S. , Mizrahi Valerie , Bayliss Tracy , Mackenzie Claire J. , Cleghorn Laura A. T. , Ray Peter C. , Wyatt Paul G. , Uh Eugene , Lee Jinwoo , Barry Clifton E. , Boshoff Helena I. 
Published: August 2014

ABSTRACT

We report here a series of five chemically diverse scaffolds that have
in vitro
activities on replicating and hypoxic nonreplicating bacilli by targeting the respiratory
bc
1
complex in
Mycobacterium tuberculosis
in a strain-dependent manner. Deletion of the cytochrome
bd
oxidase generated a hypersusceptible mutant in which resistance was acquired by a mutation in
qcrB
. These results highlight the promiscuity of the
bc
1
complex and the risk of targeting energy metabolism with new drugs.
The Production of Reactive Oxygen Species Is a Universal Action Mechanism of Amphotericin B against Pathogenic Yeasts and Contributes to the Fungicidal Effect of This Drug
Authors: Mesa-Arango Ana Cecilia , Trevijano-Contador Nuria , Román Elvira , Sánchez-Fresneda Ruth , Casas Celia , Herrero Enrique , Argüelles Juan Carlos , Pla Jesús , Cuenca-Estrella Manuel , Zaragoza Oscar 
Published: August 2014

ABSTRACT

Amphotericin B (AMB) is an antifungal drug that binds to ergosterol and forms pores at the cell membrane, causing the loss of ions. In addition, AMB induces the accumulation of reactive oxygen species (ROS), and although these molecules have multiple deleterious effects on fungal cells, their specific role in the action mechanism of AMB remains unknown. In this work, we studied the role of ROS in the action mechanism of AMB. We determined the intracellular induction of ROS in 44 isolates of different pathogenic yeast species (
Candida albicans
,
Candida parapsilosis
,
Candida glabrata
,
Candida tropicalis
,
Candida krusei
,
Cryptococcus neoformans
, and
Cryptococcus gattii
). We also characterized the production of ROS in AMB-resistant isolates. We found that AMB induces the formation of ROS in all the species tested. The inhibition of the mitochondrial respiratory chain by rotenone blocked the induction of ROS by AMB and provided protection from the killing action of the antifungal. Moreover, this phenomenon was absent in strains that displayed resistance to AMB. These strains showed an alteration in the respiration rate and mitochondrial membrane potential and also had higher catalase activity than that of the AMB-susceptible strains. Consistently, AMB failed to induce protein carbonylation in the resistant strains. Our data demonstrate that the production of ROS by AMB is a universal and important action mechanism that is correlated with the fungicidal effect and might explain the low rate of resistance to the molecule. Finally, these data provide an opportunity to design new strategies to improve the efficacy of this antifungal.
Maternal Intravenous Administration of Azithromycin Results in Significant Fetal Uptake in a Sheep Model of Second Trimester Pregnancy
Authors: Kemp Matthew W. , Miura Yuichiro , Payne Matthew S. , Jobe Alan H. , Kallapur Suhas G. , Saito Masatoshi , Stock Sarah J. , Spiller O. Brad , Ireland Demelza J. , Yaegashi Nobuo , Clarke Michael , Hahne Dorothee , Rodger Jennifer , Keelan Jeffrey A. , Newnham John P. 
Published: August 2014

ABSTRACT
Treatment of intrauterine infection is likely key to preventing a significant proportion of preterm deliveries before 32 weeks of gestation. Azithromycin (AZ) may be an effective antimicrobial in pregnancy; however, few gestation age-approriate data are available to inform the design of AZ-based treatment regimens in early pregnancy. We aimed to determine whether a single intra-amniotic AZ dose or repeated maternal intravenous (i.v.) AZ doses would safely yield therapeutic levels of AZ in an 80-day-gestation (term is 150 days) ovine fetus. Fifty sheep carrying single pregnancies at 80 days gestation were randomized to receive either: (i) a single intra-amniotic AZ administration or (ii) maternal intravenous AZ administration every 12 h. Amniotic fluid, maternal plasma, and fetal AZ concentrations were determined over a 5-day treatment regimen. Markers of liver injury and amniotic fluid inflammation were measured to assess fetal injury in response to drug exposure. A single intra-amniotic administration yielded significant AZ accumulation in the amniotic fluid and fetal lung. In contrast, repeated maternal intravenous administrations achieved high levels of AZ accumulation in the fetal lung and liver and a statistically significant increase in the fetal plasma drug concentration at 120 h. There was no evidence of fetal injury in response to drug exposure. These data suggest that (i) repeated maternal i.v. AZ dosing yields substantial fetal tissue uptake, although fetal plasma drug levels remain low; (ii) transfer of AZ from the amniotic fluid is less than transplacental transfer; and (iii) exposure to high concentrations of AZ did not elicit overt changes in fetal white blood cell counts, amniotic fluid monocyte chemoattractant protein 1 concentrations, or hepatotoxicity, all consistent with an absence of fetal injury.
Characterization of Urinary Tract Infection-Associated Shiga Toxin-Producing Escherichia coli
Authors: Toval Francisco , Schiller Roswitha , Meisen Iris , Putze Johannes , Kouzel Ivan U. , Zhang Wenlan , Karch Helge , Bielaszewska Martina , Mormann Michael , Müthing Johannes , Dobrindt Ulrich 
Published: August 2014

ABSTRACT

Enterohemorrhagic
Escherichia coli
(EHEC), a subgroup of Shiga toxin (Stx)-producing
E. coli
(STEC), is a leading cause of diarrhea and hemolytic-uremic syndrome (HUS) in humans. However, urinary tract infections (UTIs) caused by this microorganism but not associated with diarrhea have occasionally been reported. We geno- and phenotypically characterized three EHEC isolates obtained from the urine of hospitalized patients suffering from UTIs. These isolates carried typical EHEC virulence markers and belonged to HUS-associated
E. coli
(HUSEC) clones, but they lacked virulence markers typical of uropathogenic
E. coli
. One isolate exhibited a localized adherence (LA)-like pattern on T24 urinary bladder epithelial cells. Since the glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) are well-known receptors for Stx but also for P fimbriae, a major virulence factor of extraintestinal pathogenic
E. coli
(ExPEC), the expression of Gb3Cer and Gb4Cer by T24 cells and in murine urinary bladder tissue was examined by thin-layer chromatography and mass spectrometry. We provide data indicating that Stxs released by the EHEC isolates bind to Gb3Cer and Gb4Cer isolated from T24 cells, which were susceptible to Stx. All three EHEC isolates expressed
stx
genes upon growth in urine. Two strains were able to cause UTI in a murine infection model and could not be outcompeted in urine
in vitro
by typical uropathogenic
E. coli
isolates. Our results indicate that despite the lack of ExPEC virulence markers, EHEC variants may exhibit in certain suitable hosts, e.g., in hospital patients, a uropathogenic potential. The contribution of EHEC virulence factors to uropathogenesis remains to be further investigated.
Influenza A Virus Alters Pneumococcal Nasal Colonization and Middle Ear Infection Independently of Phase Variation
Authors: Wren John T. , Blevins Lance K. , Pang Bing , King Lauren B. , Perez Antonia C. , Murrah Kyle A. , Reimche Jennifer L. , Alexander-Miller Martha A. , Swords W. Edward 
Published: August 2014

ABSTRACT

Streptococcus pneumoniae
(pneumococcus) is both a widespread nasal colonizer and a leading cause of otitis media, one of the most common diseases of childhood. Pneumococcal phase variation influences both colonization and disease and thus has been linked to the bacteria's transition from colonizer to otopathogen. Further contributing to this transition, coinfection with influenza A virus has been strongly associated epidemiologically with the dissemination of pneumococci from the nasopharynx to the middle ear. Using a mouse infection model, we demonstrated that coinfection with influenza virus and pneumococci enhanced both colonization and inflammatory responses within the nasopharynx and middle ear chamber. Coinfection studies were also performed using pneumococcal populations enriched for opaque or transparent phase variants. As shown previously, opaque variants were less able to colonize the nasopharynx.
In vitro
, this phase also demonstrated diminished biofilm viability and epithelial adherence. However, coinfection with influenza virus ameliorated this colonization defect
in vivo
. Further, viral coinfection ultimately induced a similar magnitude of middle ear infection by both phase variants. These data indicate that despite inherent differences in colonization, the influenza A virus exacerbation of experimental middle ear infection is independent of the pneumococcal phase. These findings provide new insights into the synergistic link between pneumococcus and influenza virus in the context of otitis media.
Localization of Burkholderia cepacia Complex Bacteria in Cystic Fibrosis Lungs and Interactions with Pseudomonas aeruginosa in Hypoxic Mucus
Authors: Schwab Ute , Abdullah Lubna H. , Perlmutt Olivia S. , Albert Daniel , Davis C. William , Arnold Roland R. , Yankaskas James R. , Gilligan Peter , Neubauer Heiner , Randell Scott H. , Boucher Richard C. 
Published: August 2014

ABSTRACT

The localization of
Burkholderia cepacia
complex (Bcc) bacteria in cystic fibrosis (CF) lungs, alone or during coinfection with
Pseudomonas aeruginosa
, is poorly understood. We performed immunohistochemistry for Bcc and
P. aeruginosa
bacteria on 21 coinfected or singly infected CF lungs obtained at transplantation or autopsy. Parallel
in vitro
experiments examined the growth of two Bcc species,
Burkholderia cenocepacia
and
Burkholderia multivorans
, in environments similar to those occupied by
P. aeruginosa
in the CF lung. Bcc bacteria were predominantly identified in the CF lung as single cells or small clusters within phagocytes and mucus but not as “biofilm-like structures.” In contrast,
P. aeruginosa
was identified in biofilm-like masses, but densities appeared to be reduced during coinfection with Bcc bacteria. Based on chemical analyses of CF and non-CF respiratory secretions, a test medium was defined to study Bcc growth and interactions with
P. aeruginosa
in an environment mimicking the CF lung. When test medium was supplemented with alternative electron acceptors under anaerobic conditions,
B. cenocepacia
and
B. multivorans
used fermentation rather than anaerobic respiration to gain energy, consistent with the identification of fermentation products by high-performance liquid chromatography (HPLC). Both Bcc species also expressed mucinases that produced carbon sources from mucins for growth. In the presence of
P. aeruginosa
in vitro
, both Bcc species grew anaerobically but not aerobically. We propose that Bcc bacteria (i) invade a
P. aeruginosa
-infected CF lung when the airway lumen is anaerobic, (ii) inhibit
P. aeruginosa
biofilm-like growth, and (iii) expand the host bacterial niche from mucus to also include macrophages.
NOD2 Stimulation by Staphylococcus aureus-Derived Peptidoglycan Is Boosted by Toll-Like Receptor 2 Costimulation with Lipoproteins in Dendritic Cells
Authors: Schäffler Holger , Demircioglu Dogan Doruk , Kühner Daniel , Menz Sarah , Bender Annika , Autenrieth Ingo B. , Bodammer Peggy , Lamprecht Georg , Götz Friedrich , Frick Julia-Stefanie 
Published: August 2014

ABSTRACT

Mutations in the nucleotide-binding oligomerization domain-containing protein 2 (NOD2) play an important role in the pathogenesis of Crohn's disease. NOD2 is an intracellular pattern recognition receptor (PRR) that senses bacterial peptidoglycan (PGN) structures, e.g., muramyl dipeptide (MDP). Here we focused on the effect of more-cross-linked, polymeric PGN fragments (PGNpol) in the activation of the innate immune system. In this study, the effect of combined NOD2 and Toll-like receptor 2 (TLR2) stimulation was examined compared to single stimulation of the NOD2 receptor alone. PGNpol species derived from a lipoprotein-containing
Staphylococcus aureus
strain (SA113) and a lipoprotein-deficient strain (SA113 Δ
lgt
) were isolated. While PGNpol constitutes a combined NOD2 and TLR2 ligand, lipoprotein-deficient PGNpolΔ
lgt
leads to activation of the immune system only via the NOD2 receptor. Murine bone marrow-derived dendritic cells (BMDCs), J774 cells, and Mono Mac 6 (MM6) cells were stimulated with these ligands. Cytokines (interleukin-6 [IL-6], IL-12p40, and tumor necrosis factor alpha [TNF-α]) as well as DC activation and maturation parameters were measured. Stimulation with PGNpolΔ
lgt
did not lead to enhanced cytokine secretion or DC activation and maturation. However, stimulation with PGNpol led to strong cytokine secretion and subsequent DC maturation. These results were confirmed in MM6 and J774 cells. We showed that the NOD2-mediated activation of DCs with PGNpol was dependent on TLR2 costimulation. Therefore, signaling via both receptors leads to a more potent activation of the immune system than that with stimulation via each receptor alone.
Use of Immunodampening To Overcome Diversity in the Malarial Vaccine Candidate Apical Membrane Antigen 1
Authors: Harris Karen S. , Adda Christopher G. , Khore Madhavi , Drew Damien R. , Valentini-Gatt Antonina , Fowkes Freya J. I. , Beeson James G. , Dutta Sheetij , Anders Robin F. , Foley Michael 
Published: August 2014

ABSTRACT

Apical membrane antigen 1 (AMA1) is a leading malarial vaccine candidate; however, its polymorphic nature may limit its success in the field. This study aimed to circumvent AMA1 diversity by dampening the antibody response to the highly polymorphic loop Id, previously identified as a major target of strain-specific, invasion-inhibitory antibodies. To achieve this, five polymorphic residues within this loop were mutated to alanine, glycine, or serine in AMA1 of the 3D7 and FVO
Plasmodium falciparum
strains. Initially, the corresponding antigens were displayed on the surface of bacteriophage, where the alanine and serine but not glycine mutants folded correctly. The alanine and serine AMA1 mutants were expressed in
Escherichia coli
, refolded
in vitro
, and used to immunize rabbits. Serological analyses indicated that immunization with a single mutated form of 3D7 AMA1 was sufficient to increase the cross-reactive antibody response. Targeting the corresponding residues in an FVO backbone did not achieve this outcome. The inclusion of at least one engineered form of AMA1 in a biallelic formulation resulted in an antibody response with broader reactivity against different AMA1 alleles than combining the wild-type forms of 3D7 and FVO AMA1 alleles. For one combination, this extended to an enhanced relative growth inhibition of a heterologous parasite line, although this was at the cost of reduced overall inhibitory activity. These results suggest that targeted mutagenesis of AMA1 is a promising strategy for overcoming antigenic diversity in AMA1 and reducing the number of variants required to induce an antibody response that protects against a broad range of
Plasmodium falciparum
AMA1 genotypes. However, optimization of the immunization regime and mutation strategy will be required for this potential to be realized.
Damage to the Blood-Brain Barrier during Experimental Cerebral Malaria Results from Synergistic Effects of CD8+T Cells with Different Specificities
Authors: Poh Chek Meng , Howland Shanshan W. , Grotenbreg Gijsbert M. , Rénia Laurent 
Published: August 2014

ABSTRACTCD8+T cells play a pathogenic role in the development of murine experimental cerebral malaria (ECM) induced byPlasmodium bergheiANKA (PbA) infection in C57BL/6 mice. Only a limited number of CD8+epitopes have been described. Here, we report the identification of a new epitope from the bergheilysin protein recognized by PbA-specific CD8+T cells. Induction and functionality of these specific CD8+T cells were investigated in parallel with previously reported epitopes, using new tools such as tetramers and reporter cell lines that were developed for this study. We demonstrate that CD8+T cells of diverse specificities induced during PbA infection share many characteristics. They express cytolytic markers (gamma interferon [IFN-γ], granzyme B) and chemokine receptors (CXCR3, CCR5) and damage the blood-brain barrierin vivo. Our earlier finding that brain microvessels in mice infected with PbA, but not with non-ECM-causing strains, cross-presented a shared epitope was generalizable to these additional epitopes. Suppressing the induction of specific CD8+T cells through tolerization with a high-dose peptide injection was unable to confer protection against ECM, suggesting that CD8+T cells of other specificities participate in this process. The tools that we developed can be used to further investigate the heterogeneity of CD8+T cell responses that are involved in ECM.
Role of the Oligopeptide Permease ABC Transporter of Moraxella catarrhalis in Nutrient Acquisition and Persistence in the Respiratory Tract
Authors: Jones Megan M. , Johnson Antoinette , Koszelak-Rosenblum Mary , Kirkham Charmaine , Brauer Aimee L. , Malkowski Michael G. , Murphy Timothy F. 
Published: August 2014

ABSTRACT

Moraxella catarrhalis
is a strict human pathogen that causes otitis media in children and exacerbations of chronic obstructive pulmonary disease in adults, resulting in significant worldwide morbidity and mortality.
M. catarrhalis
has a growth requirement for arginine; thus, acquiring arginine is important for fitness and survival.
M. catarrhalis
has a putative oligopeptide permease ABC transport operon (
opp
) consisting of five genes (
oppB
,
oppC
,
oppD
,
oppF
, and
oppA
), encoding two permeases, two ATPases, and a substrate binding protein. Thermal shift assays showed that the purified recombinant substrate binding protein OppA binds to peptides 3 to 16 amino acid residues in length regardless of the amino acid composition. A mutant in which the
oppBCDFA
gene cluster is knocked out showed impaired growth in minimal medium where the only source of arginine came from a peptide 5 to 10 amino acid residues in length. Whether methylated arginine supports growth of
M. catarrhalis
is important in understanding fitness in the respiratory tract because methylated arginine is abundant in host tissues. No growth of wild-type
M. catarrhalis
was observed in minimal medium in which arginine was present only in methylated form, indicating that the bacterium requires
l
-arginine. An
oppA
knockout mutant showed marked impairment in its capacity to persist in the respiratory tract compared to the wild type in a mouse pulmonary clearance model. We conclude that the Opp system mediates both uptake of peptides and fitness in the respiratory tract.