bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vitro
Activities of Miltefosine and Antibacterial Agents from the Macrolide, Oxazolidinone, and Pleuromutilin Classes against Pythium insidiosum and Pythium aphanidermatum
Authors: Loreto Erico S. , Tondolo Juliana S. M. , Oliveira Daniele C. , Santurio Janio M. , Alves Sydney H. 
Published: January 2018

ABSTRACT

We tested 29 isolates of
Pythium insidiosum
and one isolate of
Pythium aphanidermatum
to investigate their susceptibility to miltefosine and antibacterial drugs from the macrolide, oxazolidinone, and pleuromutilin classes. We found that miltefosine, azithromycin, clarithromycin, josamycin, linezolid, sutezolid, retapamulin, tiamulin, and valnemulin had inhibitory and cidal activity against the pathogens at concentrations ranging from 0.25 to 64 μg/ml. Our results suggest that these antimicrobials are promising candidates for future studies on pythiosis in animals and humans.
Repurposing and Reformulation of the Antiparasitic Agent Flubendazole for Treatment of Cryptococcal Meningoencephalitis, a Neglected Fungal Disease
Authors: Nixon Gemma L. , McEntee Laura , Johnson Adam , Farrington Nicola , Whalley Sarah , Livermore Joanne , Natal Cristien , Washbourn Gina , Bibby Jaclyn , Berry Neil , Lestner Jodi , Truong Megan , Owen Andrew , Lalloo David , Charles Ian , Hope William 
Published: January 2018

ABSTRACT

Current therapeutic options for cryptococcal meningitis are limited by toxicity, global supply, and emergence of resistance. There is an urgent need to develop additional antifungal agents that are fungicidal within the central nervous system and preferably orally bioavailable. The benzimidazoles have broad-spectrum antiparasitic activity but also have
in vitro
antifungal activity that includes
Cryptococcus neoformans
. Flubendazole (a benzimidazole) has been reformulated by Janssen Pharmaceutica as an amorphous solid drug nanodispersion to develop an orally bioavailable medicine for the treatment of neglected tropical diseases such as onchocerciasis. We investigated the
in vitro
activity, the structure-activity-relationships, and both
in vitro
and
in vivo
pharmacodynamics of flubendazole for cryptococcal meningitis. Flubendazole has potent
in vitro
activity against
Cryptococcus neoformans
, with a modal MIC of 0.125 mg/liter using European Committee on Antimicrobial Susceptibility Testing (EUCAST) methodology. Computer models provided an insight into the residues responsible for the binding of flubendazole to cryptococcal β-tubulin. Rapid fungicidal activity was evident in a hollow-fiber infection model of cryptococcal meningitis. The solid drug nanodispersion was orally bioavailable in mice with higher drug exposure in the cerebrum. The maximal dose of flubendazole (12 mg/kg of body weight/day) orally resulted in an ∼2 log
10
CFU/g reduction in fungal burden compared with that in vehicle-treated controls. Flubendazole was orally bioavailable in rabbits, but there were no quantifiable drug concentrations in the cerebrospinal fluid (CSF) or cerebrum and no antifungal activity was demonstrated in either CSF or cerebrum. These studies provide evidence for the further study and development of the benzimidazole scaffold for the treatment of cryptococcal meningitis.
Investigation of Multiple Resistance Mechanisms in Voriconazole-Resistant Aspergillus flavus Clinical Isolates from a Chest Hospital Surveillance in Delhi, India
Authors: Sharma Cheshta , Kumar Rakesh , Kumar Nitin , Masih Aradhana , Gupta Dinesh , Chowdhary Anuradha 
Published: January 2018

ABSTRACT

Invasive and allergic infections by
Aspergillus flavus
are more common in tropical and subtropical countries. The emergence of voriconazole (VRC) resistance in
A. flavus
impacts the management of aspergillosis, as azoles are used as the first-line and empirical therapy. We screened 120 molecularly confirmed
A. flavus
isolates obtained from respiratory and sinonasal specimens in a chest hospital in Delhi, India, for azole resistance using the CLSI broth microdilution (CLSI-BMD) method. Overall, 2.5% (
n
= 3/120) of
A. flavus
isolates had VRC MICs above epidemiological cutoff values (>1 μg/ml). The whole-genome sequence analysis of three non-wild-type (WT)
A. flavus
isolates with high VRC MICs showed polymorphisms in azole target genes (
cyp51A
,
cyp51B
, and
cyp51C
). Further, four novel substitutions (S196F, A324P, N423D, and V465M) encoded in the
cyp51C
gene were found in a single non-WT isolate which also exhibited overexpression of
cyp51
(
cyp51A
, -
B
, and -
C
) genes and transporter genes, namely,
MDR1
,
MDR2
,
atrF
, and
mfs1
. The homology model of the non-WT isolate suggests that substitutions S196F and N423D exhibited major structural and functional effects on cyp51C drug binding. The substrate (drug) may not be able to bind to binding pocket due to changes in the pocket size or closing down or narrowing of cavities in drug entry channels. Notably, the remaining two VRC-resistant
A. flavus
isolates, including the one which had a pan-azole resistance phenotype (itraconazole and posaconazole), did not show upregulation of any of the analyzed target genes. These results suggest that multiple target genes and mechanisms could simultaneously contribute to azole resistance in
A. flavus
.
Pharmacokinetics of Telavancin at Fixed Doses in Normal-Body-Weight and Obese (Classes I, II, and III) Adult Subjects
Authors: Bunnell Kristen L. , Pai Manjunath P. , Sikka Monica , Bleasdale Susan C. , Wenzler Eric , Danziger Larry H. , Rodvold Keith A. 
Published: January 2018

ABSTRACT

A recommended total-body-weight (TBW) dosing strategy for telavancin may not be optimal in obese patients. The primary objective of this study was to characterize and compare the pharmacokinetics (PK) of telavancin across four body size groups: normal to overweight and obese classes I, II, and III. Healthy adult subjects (
n
= 32) received a single, weight-stratified, fixed dose of 500 mg (
n
= 4), 750 mg (
n
= 8), or 1,000 mg (
n
= 20) of telavancin. Noncompartmental PK analyses revealed that subjects with a body mass index (BMI) of ≥40 kg/m
2
had a higher volume of distribution (16.24 ± 2.7 liters) than subjects with a BMI of <30 kg/m
2
(11.71 ± 2.6 liters). The observed area under the concentration-time curve from time zero to infinity (AUC
0–∞
) ranged from 338.1 to 867.3 mg · h/liter, with the lowest exposures being in subjects who received 500 mg. AUC
0–∞
values were similar among obese subjects who received 1,000 mg. A two-compartment population PK model best described the plasma concentration-time profile of telavancin when adjusted body weight (ABW) was included as a predictive covariate. Fixed doses of 750 mg and 1,000 mg had similar target attainment probabilities for efficacy as doses of 10 mg/kg of body weight based on ABW and TBW, respectively. However, the probability of achieving a target area under the concentration-time curve from time zero to 24 h of ≥763 mg · h/liter in association with acute kidney injury was highest (19.7%) with TBW-simulated dosing and lowest (0.4%) at the 750-mg dose. These results suggest that a fixed dose of 750 mg is a safe and effective alternative to telavancin doses based on TBW or ABW for the treatment of obese patients with normal renal function and Staphylococcus
aureus
infections. (This study has been registered at ClinicalTrials.gov under identifier NCT02753855.)
Intraclade Variability in Toxin Production and Cytotoxicity of Bacillus cereus Group Type Strains and Dairy-Associated Isolates
Authors: Miller Rachel A. , Jian Jiahui , Beno Sarah M. , Wiedmann Martin , Kovac Jasna 
Published: January 2018

ABSTRACT

While some species in the
Bacillus cereus
group are well-characterized human pathogens (e.g.,
B. anthracis
and
B. cereus sensu stricto
), the pathogenicity of other species (e.g.,
B. pseudomycoides
) either has not been characterized or is presently not well understood. To provide an updated characterization of the pathogenic potential of species in the
B. cereus
group, we classified a set of 52 isolates, including 8 type strains and 44 isolates from dairy-associated sources, into 7 phylogenetic clades and characterized them for (i) the presence of toxin genes, (ii) phenotypic characteristics used for identification, and (iii) cytotoxicity to human epithelial cells. Overall, we found that
B. cereus
toxin genes are broadly distributed but are not consistently present within individual species and/or clades. After growth at 37°C, isolates within a clade did not typically show a consistent cytotoxicity phenotype, except for isolates in clade VI (
B. weihenstephanensis
/
B. mycoides
), where none of the isolates were cytotoxic, and isolates in clade I (
B. pseudomycoides
), which consistently displayed cytotoxic activity. Importantly, our study highlights that
B. pseudomycoides
is cytotoxic toward human cells. Our results indicate that the detection of toxin genes does not provide a reliable approach to predict the pathogenic potential of
B. cereus
group isolates, as the presence of toxin genes is not always consistent with cytotoxicity phenotype. Overall, our results suggest that isolates from multiple
B. cereus
group clades have the potential to cause foodborne illness, although cytotoxicity is not always consistently found among isolates within each clade.

IMPORTANCE
Despite the importance of the
Bacillus cereus
group as a foodborne pathogen, characterizations of the pathogenic potential of all
B. cereus
group species were lacking. We show here that
B. pseudomycoides
(clade I), which has been considered a harmless environmental microorganism, produces toxins and exhibits a phenotype consistent with the production of pore-forming toxins. Furthermore,
B. mycoides/B. weihenstephanensis
isolates (clade VI) did not show cytotoxicity when grown at 37°C, despite carrying multiple toxin genes. Overall, we show that the current standard methods to characterize
B. cereus
group isolates and to detect the presence of toxin genes are not reliable indicators of species, phylogenetic clades, or an isolate's cytotoxic capacity, suggesting that novel methods are still needed for differentiating pathogenic from nonpathogenic species within the
B. cereus
group. Our results also contribute data that are necessary to facilitate risk assessments and a better understanding as to which
B. cereus
group species are likely to cause foodborne illness.
Both Major Histocompatibility Complex Class I (MHC-I) and MHC-II Molecules Are Required, while MHC-I Appears To Play a Critical Role in Host Defense against Primary Coxiella burnetii Infection
Authors: Buttrum Laura , Ledbetter Lindsey , Cherla Rama , Zhang Yan , Mitchell William J. , Zhang Guoquan 
Published: January 2018

ABSTRACTTo understand the role of class I major histocompatibility complex (MHC-I) and class II MHC (MHC-II) antigen presentation pathways in host defense againstCoxiella burnetiiinfection, we examined whether MHC-I or MHC-II deficiency in mice would significantly influence their susceptibility to virulentC. burnetiiNine Mile phase I (NMI) infection. The results indicate that NMI infection induced more severe disease in both MHC-I-deficient and MHC-II-deficient mice than in wild-type (WT) mice, while only MHC-I-deficient mice developed a severe persistent infection and were unable to control bacterial replication. These results suggest that both MHC-I-restricted CD8+T cells and MHC-II-restricted CD4+T cells contribute to host defense against primaryC. burnetiiinfection, while MHC-I-restricted CD8+T cells appear to play a more critical role in controlling bacterial replication. Additionally, although NMI infection induced more severe disease in TAP1-deficient mice than in their WT counterparts, TAP1 deficiency in mice did not significantly influence their ability to eliminateC. burnetii. This suggests thatC. burnetiiantigen presentation to CD8+T cells by the MHC-I classical pathway may depend only partially on TAP1. Furthermore, granzyme B deficiency in mice did not significantly alter their susceptibility toC. burnetiiinfection, but perforin-deficient mice were unable to control host inflammatory responses during primaryC. burnetiiinfection. These results suggest that perforin, but not granzyme B, is required forC. burnetiiantigen-specific cytotoxic CD8+T cells to control primaryC. burnetiiinfection.
A Multimodal Strategy Used by a Large c-di-GMP Network
Authors: Dahlstrom Kurt M. , Collins Alan J. , Doing Georgia , Taroni Jaclyn N. , Gauvin Timothy J. , Greene Casey S. , Hogan Deborah A. , O'Toole George A. 
Published: January 2018

ABSTRACT

The
Pseudomonas fluorescens
genome encodes more than 50 proteins predicted to be involved in c-di-GMP signaling. Here, we demonstrated that, tested across 188 nutrients, these enzymes and effectors appeared capable of impacting biofilm formation. Transcriptional analysis of network members across ∼50 nutrient conditions indicates that altered gene expression can explain a subset of but not all biofilm formation responses to the nutrients. Additional organization of the network is likely achieved through physical interaction, as determined via probing ∼2,000 interactions by bacterial two-hybrid assays. Our analysis revealed a multimodal regulatory strategy using combinations of ligand-mediated signals, protein-protein interaction, and/or transcriptional regulation to fine-tune c-di-GMP-mediated responses. These results create a profile of a large c-di-GMP network that is used to make important cellular decisions, opening the door to future model building and the ability to engineer this complex circuitry in other bacteria.

IMPORTANCE
Cyclic diguanylate (c-di-GMP) is a key signaling molecule regulating bacterial biofilm formation, and many microbes have up to dozens of proteins that make, break, or bind this dinucleotide. A major open issue in the field is how signaling specificity is conferred in the unpartitioned space of a bacterial cell. Here, we took a systems approach, using mutational analysis, transcriptional studies, and bacterial two-hybrid analysis to interrogate this network. We found that a majority of enzymes are capable of impacting biofilm formation in a context-dependent manner, and we revealed examples of two or more modes of regulation (i.e., transcriptional control with protein-protein interaction) being utilized to generate an observable impact on biofilm formation.
ERK Is a Critical Regulator of JC Polyomavirus Infection
Authors: DuShane Jeanne K. , Wilczek Michael P. , Mayberry Colleen L. , Maginnis Melissa S. 
Published: January 2018

ABSTRACT

The human JC polyomavirus (JCPyV) infects the majority of the population worldwide and presents as an asymptomatic, persistent infection in the kidneys. In individuals who are immunocompromised, JCPyV can become reactivated and cause a lytic infection in the central nervous system resulting in the fatal, demyelinating disease progressive multifocal leukoencephalopathy (PML). Infection is initiated by interactions between the capsid protein viral protein 1 (VP1) and the α2,6-linked sialic acid on lactoseries tetrasaccharide c (LSTc), while JCPyV internalization is facilitated by 5-hydroxytryptamine 2 receptors (5-HT
2
Rs). The mechanisms by which the serotonin receptors mediate virus entry and the signaling cascades required to drive viral infection remain poorly understood. JCPyV was previously shown to induce phosphorylation of extracellular signal-regulated kinase (ERK), a downstream target of the mitogen-activated protein kinase (MAPK) pathway, upon virus entry. However, it remained unclear whether ERK activation was required for JCPyV infection. Both ERK-specific small interfering RNA (siRNA) and ERK inhibitor treatments resulted in significantly diminished JCPyV infection in both kidney and glial cells yet had no effect on the infectivity of the polyomavirus simian virus 40 (SV40). Experiments characterizing the role of ERK during steps in the viral life cycle indicate that ERK activation is required for viral transcription, as demonstrated by a significant reduction in production of large T antigen (TAg), a key viral protein associated with the initiation of viral transcription and viral replication. These findings delineate the role of the MAPK-ERK signaling pathway in JCPyV infection, elucidating how the virus reprograms the host cell to promote viral pathogenesis.

IMPORTANCE
Viral infection is dependent upon host cell factors, including the activation of cellular signaling pathways. These interactions between viruses and host cells are necessary for infection and play an important role in viral disease outcomes. The focus of this study was to determine how the human JC polyomavirus (JCPyV), a virus that resides in the kidney of the majority of the population and can cause the fatal, demyelinating disease progressive multifocal leukoencephalopathy (PML) in the brains of immunosuppressed individuals, usurps a cellular signaling pathway to promote its own infectious life cycle. We demonstrated that the activation of extracellular signal-regulated kinase (ERK), a component of the mitogen-activated protein kinase (MAPK) pathway, promotes JCPyV transcription, which is required for viral infection. Our findings demonstrate that the MAPK-ERK signaling pathway is a key determinant of JCPyV infection, elucidating new information regarding the signal reprogramming of host cells by a pathogenic virus.
HIV-1-Specific IgA Monoclonal Antibodies from an HIV-1 Vaccinee Mediate Galactosylceramide Blocking and Phagocytosis
Authors: Wills Saintedym , Hwang Kwan-Ki , Liu Pinghuang , Dennison S. Moses , Tay Matthew Zirui , Shen Xiaoying , Pollara Justin , Lucas Judith T. , Parks Robert , Rerks-Ngarm Supachai , Pitisuttithum Punnee , Nitayapan Sorachai , Kaewkungwal Jaranit , Thomas Rasmi , Kim Jerome H. , Michael Nelson L. , Robb Merlin L. , McRaven Mike , Montefiori David C. , Hope Thomas J. , Liao Hua-Xin , Moody M. Anthony , Ferrari Guido , Haynes Barton F. , Alam S. Munir , Bonsignori Mattia , Tomaras Georgia D. 
Published: January 2018

ABSTRACT
Vaccine-elicited humoral immune responses comprise an array of antibody forms and specificities, with only a fraction contributing to protective host immunity. Elucidation of antibody effector functions responsible for protective immunity against human immunodeficiency virus type 1 (HIV-1) acquisition is a major goal for the HIV-1 vaccine field. Immunoglobulin A (IgA) is an important part of the host defense against pathogens; however, little is known about the role of vaccine-elicited IgA and its capacity to mediate antiviral functions. To identify the antiviral functions of HIV-1-specific IgA elicited by vaccination, we cloned HIV-1 envelope-specific IgA monoclonal antibodies (MAbs) by memory B cell cultures from peripheral blood mononuclear cells from an RV144 vaccinee and produced two IgA clonal cell lines (HG129 and HG130) producing native, nonrecombinant IgA MAbs. The HG129 and HG130 MAbs mediated phagocytosis by monocytes, and HG129 blocked HIV-1 Env glycoprotein binding to galactosylceramide, an alternative HIV-1 receptor. These findings elucidate potential antiviral functions of vaccine-elicited HIV-1 envelope-specific IgA that may act to block HIV-1 acquisition at the portal of entry by preventing HIV-1 binding to galactosylceramide and mediating antibody Fc receptor-mediated virion phagocytosis. Furthermore, these findings highlight the complex and diverse interactions of vaccine-elicited IgA with pathogens that depend on IgA fine specificity and form (e.g., multimeric or monomeric) in the systemic circulation and mucosal compartments.

IMPORTANCE
Host-pathogen interactions
in vivo
involve numerous immune mechanisms that can lead to pathogen clearance. Understanding the nature of antiviral immune mechanisms can inform the design of efficacious HIV-1 vaccine strategies. Evidence suggests that both neutralizing and nonneutralizing antibodies can mediate some protection against HIV in animal models. Although numerous studies have characterized the functional properties of HIV-1-specific IgG, more studies are needed on the functional attributes of HIV-1-specific IgA, specifically for vaccine-elicited IgA. Characterization of the functional properties of HIV-1 Env-specific IgA monoclonal antibodies from human vaccine clinical trials are critical toward understanding the capacity of the host immune response to block HIV-1 acquisition.
Therapeutic Efficacy of Vectored PGT121 Gene Delivery in HIV-1-Infected Humanized Mice
Authors: Badamchi-Zadeh Alexander , Tartaglia Lawrence J. , Abbink Peter , Bricault Christine A. , Liu Po-Ting , Boyd Michael , Kirilova Marinela , Mercado Noe B. , Nanayakkara Ovini S. , Vrbanac Vladimir D. , Tager Andrew M. , Larocca Rafael A. , Seaman Michael S. , Barouch Dan H. 
Published: January 2018

ABSTRACT

Broadly neutralizing antibodies (bNAbs) are being explored for HIV-1 prevention and cure strategies. However, administration of purified bNAbs poses challenges in resource-poor settings, where the HIV-1 disease burden is greatest.
In vivo
vector-based production of bNAbs represents an alternative strategy. We investigated adenovirus serotype 5 (Ad5) and adeno-associated virus serotype 1 (AAV1) vectors to deliver the HIV-1-specific bNAb PGT121 in wild-type and immunocompromised C57BL/6 mice as well as in HIV-1-infected bone marrow-liver-thymus (BLT) humanized mice. Ad5.PGT121 and AAV1.PGT121 produced functional antibody
in vivo
. Ad5.PGT121 produced PGT121 rapidly within 6 h, whereas AAV1.PGT121 produced detectable PGT121 in serum by 72 h. Serum PGT121 levels were rapidly reduced by the generation of anti-PGT121 antibodies in immunocompetent mice but were durably maintained in immunocompromised mice. In HIV-1-infected BLT humanized mice, Ad5.PGT121 resulted in a greater reduction of viral loads than did AAV1.PGT121. Ad5.PGT121 also led to more-sustained virologic control than purified PGT121 IgG. Ad5.PGT121 afforded more rapid, robust, and durable antiviral efficacy than AAV1.PGT121 and purified PGT121 IgG in HIV-1-infected humanized mice. Further evaluation of vector delivery of HIV-1 bNAbs is warranted, although approaches to prevent the generation of antiantibody responses may also be required.

IMPORTANCE
Broadly neutralizing antibodies (bNAbs) are being explored for HIV-1 prevention and cure strategies, but delivery of purified antibodies may prove challenging. We investigated adenovirus serotype 5 (Ad5) and adeno-associated virus serotype 1 (AAV1) vectors to deliver the HIV-1-specific bNAb PGT121. Ad5.PGT121 afforded more rapid, robust, and durable antiviral efficacy than AAV1.PGT121 and purified PGT121 IgG in HIV-1-infected humanized mice.