bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absence of
Neisseria meningitidis
Serogroup C-Specific Antibodies during the First Year of Life in The Netherlands: an Age Group at Risk?
Authors: de Voer Richarda M. , van der Klis Fiona R. M. , Niers Laetitia E. M. , Rijkers Ger T. , Berbers Guy A. M. 
Published: August 2009

ABSTRACT

In The Netherlands, a single meningococcal serogroup C conjugate (MenCC) vaccination is administered to children at the age of 14 months. Here, we report the levels of MenC polysaccharide-specific antibodies in children at birth and at 3, 11, and 12 months of age and the presence of functional antibodies at 11 months of age, before infants receive their MenCC immunization. We observed a rapid decline in polysaccharide-specific antibodies after birth and no induction of naturally elicited polysaccharide-specific antibodies. Furthermore, at 11 months of age, no bactericidal antibodies are observed. These data indicate that these infants may be at risk in the period prior to MenCC immunization, if
Neisseria meningitidis
serogroup C starts to (re)circulate.
Clinical Evaluation of a (1,3)-β-
d
-Glucan Assay for Presumptive Diagnosis of
Pneumocystis jiroveci
Pneumonia in Immunocompromised Patients
Authors: Del Bono Valerio , Mularoni Alessandra , Furfaro Elisa , Delfino Emanuele , Rosasco Lorenzo , Miletich Franca , Viscoli Claudio 
Published: August 2009

ABSTRACT

(1,3)-β-
d
-Glucan (BG) is a component of the
Pneumocystis jiroveci
cell wall. Thirty-one immunocompromised patients with pneumonia (16 with presumptive pneumocystis pneumonia [PCP] and 15 with non-PCP) were evaluated for serum BG levels. Serum from all 16 presumptive PCP patients and from 2/15 patients with non-PCP was positive for BG. Results indicate that BG is a reliable marker for diagnosing PCP.
A Multifunctional, Synthetic
Gaussia princeps
Luciferase Reporter for Live Imaging of
Candida albicans
Infections
Authors: Enjalbert Brice , Rachini Anna , Vediyappan Govindsamy , Pietrella Donatella , Spaccapelo Roberta , Vecchiarelli Anna , Brown Alistair J. P. , d'Enfert Christophe 
Published: August 2009

ABSTRACT

Real-time monitoring of the spatial and temporal progression of infection/gene expression in animals will contribute greatly to our understanding of host-pathogen interactions while reducing the number of animals required to generate statistically significant data sets. Sensitive in vivo imaging technologies can detect low levels of light emitted from luciferase reporters in vivo, but the existing reporters are not optimal for fungal infections. Therefore, our aim was to develop a novel reporter system for imaging
Candida albicans
infections that overcomes the limitations of current luciferase reporters for this major fungal pathogen. This luciferase reporter was constructed by fusing a synthetic, codon-optimized version of the
Gaussia princeps
luciferase gene to
C. albicans PGA59
, which encodes a glycosylphosphatidylinositol-linked cell wall protein. Luciferase expressed from this
PGA59-gLUC
fusion (referred to as
gLUC59
) was localized at the
C. albicans
cell surface, allowing the detection of luciferase in intact cells. The analysis of fusions to strong (
ACT1
and
EFT3
), oxidative stress-induced (
TRX1
,
TRR1
, and
IPF9996
), and morphogenesis-dependent (
HWP1
) promoters confirmed that
gLUC59
is a convenient and sensitive reporter for studies of gene regulation in yeast or hyphal cells, as well as a flexible screening tool. Moreover, the
ACT1
-
gLUC59
fusion represented a powerful tool for the imaging of disease progression in superficial and subcutaneous
C. albicans
infections.
gLUC59
and related cell surface-exposed luciferase reporters might find wide applications in molecular biology, cell biology, pathobiology, and high-throughput screens.
The Membrane Localization Domain Is Required for Intracellular Localization and Autoregulation of YopE in
Yersinia pseudotuberculosis
Authors: Isaksson Elin L. , Aili Margareta , Fahlgren Anna , Carlsson Sara E. , Rosqvist Roland , Wolf-Watz Hans 
Published: August 2009

ABSTRACT

Recent work has shown that a domain of YopE of
Yersinia pseudotuberculosis
ranging from amino acids 54 to 75 (R. Krall, Y. Zhang, and J. T. Barbieri, J. Biol. Chem. 279:2747-2753, 2004) is required for proper localization of YopE after ectopic expression in eukaryotic cells. This domain, called the membrane localization domain (MLD), has not been extensively studied in
Yersinia
. Therefore, an in
cis
MLD deletion mutant of YopE was created in
Y. pseudotuberculosis
. The mutant was found to secrete and translocate YopE at wild-type levels. However, the mutant was defective in the autoregulation of YopE expression after the infection of HeLa cells. Although the mutant translocated YopE at wild-type levels, it showed a delayed HeLa cell cytotoxicity. This delay was not caused by a change in GTPase activating protein (GAP) activity, since the mutant showed wild-type YopE GAP activity toward Rac1 and RhoA. The MLD mutant displayed a changed intracellular localization pattern of YopE in HeLa cells after infection, and the YopEΔMLD protein was found to be dispersed within the whole cell, including the nucleus. In contrast, wild-type YopE was found to localize to the perinuclear region of the cell and was not found in the nucleus. In addition, the
yopE
ΔMLD mutant was avirulent. Our results suggest that YopE must target proteins other than RhoA and Rac1 and that the MLD is required for the proper targeting and hence virulence of YopE during infection. Our results raise the question whether YopE is a regulatory protein or a “true” virulence effector protein.
Streptolysin S Inhibits Neutrophil Recruitment during the Early Stages ofStreptococcus pyogenesInfection
Authors: Lin Ada , Loughman Jennifer A. , Zinselmeyer Bernd H. , Miller Mark J. , Caparon Michael G. 
Published: August 2009

ABSTRACTIn contrast to infection of superficial tissues,Streptococcus pyogenesinfection of deeper tissue can be associated with a significantly diminished inflammatory response, suggesting that this bacterium has the ability to both promote and suppress inflammation. To examine this, we analyzed the behavior of anS. pyogenesmutant deficient in expression of the cytolytic toxin streptolysin S (SLS−) and evaluated events that occur during the first few hours of infection by using several models including injection of zebrafish (adults, larvae, and embryos), a transepithelial polymorphonuclear leukocyte (PMN) migration assay, and two-photon microscopy of mice in vivo. In contrast to wild-typeS. pyogenes, the SLS−mutant was associated with the robust recruitment of neutrophils and significantly reduced lethal myositis in adult zebrafish. Similarly, the mutant was attenuated in embryos in its ability to cause lethality. Infection of larva muscle allowed an analysis of inflammation in real time, which revealed that the mutant had recruited PMNs to the infection site. Analysis of transepithelial migration in vitro suggested that SLS inhibited the host cells' production of signals chemotactic for neutrophils, which contrasted with the proinflammatory effect of an unrelated cytolytic toxin, streptolysin O. Using two-photon microscopy of mice in vivo, we showed that the extravasation of neutrophils during infection with SLS−mutant bacteria was significantly accelerated compared to infection with wild-typeS. pyogenes. Taken together, these data support a role for SLS in the inhibition of neutrophil recruitment during the early stages ofS. pyogenesinfection.
PspA Family Fusion Proteins Delivered by AttenuatedSalmonella entericaSerovar Typhimurium Extend and Enhance Protection againstStreptococcus pneumoniae
Authors: Xin Wei , Li Yuhua , Mo Hua , Roland Kenneth L. , Curtiss Roy 
Published: August 2009

ABSTRACTPneumococcal surface protein A (PspA) is highly immunogenic and can induce a protective immune response against pneumococcal infection. PspA is divided into two major families based on serological variability: family 1 and family 2. To provide broad protection, PspA proteins from pneumococcal strains Rx1 (family 1) and EF5668 (family 2) were combined to form two PspA fusion proteins, PspA/Rx1-EF5668 and PspA/EF5668-Rx1. Each protein was fused to a type II secretion signal and delivered by a recombinant attenuatedSalmonellavaccine (RASV). Both PspA/Rx1-EF5668 and PspA/EF5668-Rx1 were synthesized in the RASV and secreted into the periplasm and supernatant. The fusion proteins reacted strongly with both anti-PspA/Rx1 and anti-PspA/EF5668 antisera. Oral immunization of BALB/c mice with RASV synthesizing either PspA fusion protein elicited serum immunoglobulin G (IgG) and mucosal IgA responses against both families of PspA. Analysis of IgG isotypes (IgG2a and IgG1) indicated a strong Th1 bias to the immune responses to both proteins. Sera from mice immunized with RASV synthesizing PspA/Rx1-EF5668 bound to the surface and directed C3 complement deposition on representative strains from all five PspA clades. Immunization with RASV synthesizing either protein protected mice against intraperitoneal challenge withStreptococcus pneumoniaeWU2 strain (family 1), intravenous challenge withS. pneumoniae3JYP2670 strain (family 2), and intranasal challenge withS. pneumoniaeA66.1 (family 1). The PspA/Rx1-EF5668 protein elicited significantly greater protection than PspA/EF5668-Rx1, PspA/Rx1, or PspA/EF5668. These results indicate an RASV synthesizing a PspA fusion protein representing both PspA families constitutes an effective antipneumococcal vaccine, extending and enhancing protection against multiple strains ofS. pneumoniae.
Structural Determinants of Autoproteolysis of the
Haemophilus influenzae
Hap Autotransporter
Authors: Kenjale Roma , Meng Guoyu , Fink Doran L. , Juehne Twyla , Ohashi Tomoo , Erickson Harold P. , Waksman Gabriel , St. Geme Joseph W. 
Published: August 2009

ABSTRACT

Haemophilus influenzae
is a gram-negative bacterium that initiates infection by colonizing the upper respiratory tract. The
H. influenzae
Hap autotransporter protein mediates adherence, invasion, and microcolony formation in assays with respiratory epithelial cells and presumably facilitates colonization. The serine protease activity of Hap is associated with autoproteolytic cleavage and extracellular release of the Hap
S
passenger domain, leaving the Hap
β
C-terminal domain embedded in the outer membrane. Cleavage occurs most efficiently at the LN1036-37 peptide bond and to a lesser extent at three other sites. In this study, we utilized site-directed mutagenesis, homology modeling, and assays with a peptide library to characterize the structural determinants of Hap proteolytic activity and cleavage specificity. In addition, we used homology modeling to predict the S1, S2, and S4 subsite residues of the Hap substrate groove. Our results indicate that the P1 and P2 positions at the Hap cleavage sites are critical for cleavage, with leucine preferred over larger hydrophobic residues or other amino acids in these positions. The substrate groove is formed by L263 and N274 at the S1 subsite, R264 at the S2 subsite, and E265 at the S4 subsite. This information may facilitate design of approaches to block Hap activity and interfere with
H. influenzae
colonization.
Association of Malaria-Induced Murine Pregnancy Failure with Robust Peripheral and Placental Cytokine Responses
Authors: Poovassery Jayakumar , Moore Julie M. 
Published: August 2009

ABSTRACTMalarial infection in nonimmune pregnant women is a major risk factor for pregnancy failure. The biological mechanisms that underlie malaria-associated fetal loss, however, are poorly understood.Plasmodium chabaudiAS infection during early pregnancy results in midgestational embryonic loss in naive C57BL/6 mice. To define the immunopathogenesis of this malaria-induced pregnancy compromise, cytokine production in plasma, spleen, and placenta cell culture supernatants during the first 11 days of infection and gestation was studied. In infected pregnant mice, systemic interleukin-1β and both systemic and splenic gamma interferon levels were elevated relative to those in uninfected pregnant mice, and gamma interferon was also robustly produced within the placenta 1 to 2 days before malaria-induced fetal loss. Although circulating tumor necrosis factor production was not affected by pregnancy or infection, circulating soluble tumor necrosis factor receptor II was highest in infected pregnant mice, particularly those undergoing abortion, but decreased at the placental level preceding abortion. Systemic levels of interleukin-10 were also high in infected mice at this time point, but this cytokine was not detected at the placental level. Histological examination revealed that trophoblast giant cells of aborting mice phagocytosed infected red blood cells and hemozoin. Furthermore, in vitro-cultured trophoblast cells isolated from embryos on day 7 of gestation phagocytosedP. chabaudiAS-infected red blood cells and secreted tumor necrosis factor. These results suggest that systemic and placenta-level proinflammatory antimalarial immune responses, in the absence of adequate and sustained counterregulatory mechanisms, contribute to pregnancy loss in this model.
Ce-Duox1/BLI-3 Generates Reactive Oxygen Species as a Protective Innate Immune Mechanism in
Caenorhabditis elegans
Authors: Chávez Violeta , Mohri-Shiomi Akiko , Garsin Danielle A. 
Published: August 2009

ABSTRACT

Caenorhabditis elegans
was recently developed as a model system to study both pathogen virulence mechanisms and host defense responses. We previously demonstrated that
C. elegans
produces reactive oxygen species (ROS) in response to exposure to the important gram-positive nosocomial pathogen
Enterococcus faecalis
. We also presented evidence of oxidative stress and upregulation of stress responses after exposure to the pathogen. As in mammalian systems, this new work shows that production of ROS for innate immune functions occurs via an NADPH oxidase. Specifically, reducing expression of a dual oxidase, Ce-Duox1/BLI-3, causes a decrease in ROS production in response to
E. faecalis
. We also present evidence that reduction of expression of Ce-Duox1/BLI-3 increases susceptibility to this pathogen, specifically when expression is reduced in the intestine and the hypodermis. Ce-Duox1/BLI-3 was previously characterized as having a role in cuticle cross-linking. Two
C. elegans
mutants with point mutations in the peroxidase domain that exhibit severe cuticle defects were discovered to be unaffected in ROS production or pathogen susceptibility. These results demonstrate an important biological role for the peroxidase domain in cuticle cross-linking that is unrelated to ROS production. To further demonstrate the protective effects of the pathogen-induced ROS production, we show that antioxidants that scavenge ROS increase the sensitivity of the nematode to the infection, in stark contrast to their longevity-promoting effects under nonpathogenic conditions. In conclusion, we postulate that the generation of ROS by NADPH oxidases in the barrier epithelium is an ancient, highly conserved innate immune defense mechanism.
Identification of a Modular Pathogenicity Island That Is Widespread among Urease-Producing Uropathogens and Shares Features with a Diverse Group of Mobile Elements
Authors: Flannery Erika L. , Mody Lona , Mobley Harry L. T. 
Published: August 2009

ABSTRACT

Pathogenicity islands (PAIs) are a specific group of genomic islands that contribute to genomic variability and virulence of bacterial pathogens. Using a strain-specific comparative genomic hybridization array, we report the identification of a 94-kb PAI, designated ICE
Pm1
, that is common to
Proteus mirabilis
,
Providencia stuartii
, and
Morganella morganii
. These organisms are highly prevalent etiologic agents of catheter-associated urinary tract infections (caUTI), the most common hospital acquired infection. ICE
Pm1
carries virulence factors that are important for colonization of the urinary tract, including a known toxin (
Proteus
toxic agglutinin) and the high pathogenicity island of
Yersinia
spp. In addition, this PAI shares homology and gene organization similar to the PAIs of other bacterial pathogens, several of which have been classified as mobile integrative and conjugative elements (ICEs). Isolates from this study were cultured from patients with caUTI and show identical sequence similarity at three loci within ICE
Pm1
, suggesting its transfer between bacterial genera. Screening for the presence of ICE
Pm1
among
P. mirabilis
colonizing isolates showed that ICE
Pm1
is more prevalent in urine isolates compared to
P. mirabilis
strains isolated from other body sites (
P
< 0.0001), further suggesting that it contributes to niche specificity and is positively selected for in the urinary tract.
A Periplasmic Thioredoxin-Like Protein Plays a Role in Defense against Oxidative Stress in
Neisseria gonorrhoeae
Authors: Achard Maud E. S. , Hamilton Amanda J. , Dankowski Tarek , Heras Begoña , Schembri Mark S. , Edwards Jennifer L. , Jennings Michael P. , McEwan Alastair G. 
Published: August 2009

ABSTRACT

Thioredoxin-like proteins of the TlpA/ResE/CcmG subfamily are known to face the periplasm in gram-negative bacteria. Using the
tlpA
gene of
Bradyrhizobium japonicum
as a query, we identified a locus (NGO1923) in
Neisseria gonorrhoeae
that encodes a thioredoxin-like protein (NG_TlpA). Bioinformatics analysis indicated that the predicted NG_TlpA protein contained a cleavable signal peptide at the N terminus, and secondary structure analysis identified a thioredoxin fold with a helical insertion (∼25 residues), similar to that found in
B. japonicum
TlpA but absent in cytoplasmic thioredoxins. Biochemical characterization of a recombinant form of NG_TlpA revealed a standard redox potential (E
0
′) of −206 mV. This property and the observation that the oxidized form of the protein exhibited greater thermal stability than the reduced species indicated that NG_TlpA is a reducing thioredoxin and not an oxidizing thiol-disulfide oxidoreductase like DsbA. The thioredoxin activity of NG_TlpA was confirmed in an insulin disulfide reduction assay. A
tlpA
mutant of
N. gonorrhoeae
strain 1291 was found to be highly sensitive to oxidative killing by paraquat and hydrogen peroxide, indicating an antioxidant role for the NG_TlpA in this bacterium. The
tlpA
mutant also exhibited reduced intracellular survival in human primary cervical epithelial cells.
Herpes Simplex Virus Type 1 Production Requires a Functional ESCRT-III Complex but Is Independent of TSG101 and ALIX Expression
Authors: Pawliczek Tobias , Crump Colin M. 
Published: August 2009

ABSTRACT
Herpes simplex virus type 1 (HSV-1) acquires its mature virus envelope by budding into the lumen of cytoplasmic membranous compartments carrying the viral glycoproteins. In a cellular context, a budding process with identical topology occurs during the formation of intraluminal vesicles in multivesicular bodies. The cellular machinery that mediates this budding process is composed of four protein complexes termed endosomal sorting complexes required for transport (ESCRTs) and several associated proteins, including the ATPase VPS4. We have recently shown that functional VPS4 is specifically required for the cytoplasmic envelopment of HSV-1. We now demonstrate that, consistent with a role of VPS4 in virus envelopment, dominant-negative ESCRT-III proteins potently block HSV-1 production. Retroviruses are known to recruit the ESCRT machinery by small peptide motifs termed late domains. These late domains interact with various ESCRT components and thereby promote ESCRT recruitment. The best-characterized late-domain interacting ESCRT proteins are ALIX and TSG101. The presence of potential ALIX and TSG101 binding sequence motifs in various structural HSV-1 proteins suggested a functional role of these proteins in HSV-1 envelopment. We therefore used a set of dominant-negative proteins, as well as RNA interference, to characterize the contribution of ALIX and TSG101 to HSV-1 production. Interestingly, despite the strict requirement for a functional ESCRT-III complex, our data suggest that HSV-1 production is independent of ALIX and TSG101 expression. In line with these data, we also find that ESCRT-III proteins and VPS4A/B are specifically incorporated into mature HSV-1 virions.
Biological Signature Characteristics of Primary Isolates from Human Immunodeficiency Virus Type 1 Group O in Ex Vivo Human Tonsil Histocultures
Authors: Geuenich Silvia , Kaderali Lars , Allespach Ina , Sertel Serkan , Keppler Oliver T. 
Published: August 2009

ABSTRACT
Human immunodeficiency virus type 1 (HIV-1) group M viruses have achieved a global distribution, while HIV-1 group O viruses are endemic only in particular regions of Africa. Here, we evaluated biological characteristics of group O and group M viruses in ex vivo models of HIV-1 infection. The replicative capacity and ability to induce CD4 T-cell depletion of eight group O and seven group M primary isolates were monitored in cultures of human peripheral blood mononuclear cells and tonsil explants. Comparative and longitudinal infection studies revealed HIV-1 group-specific activity patterns: CCR5-using (R5) viruses from group M varied considerably in their replicative capacity but showed similar levels of cytopathicity. In contrast, R5 isolates from group O were relatively uniform in their replicative fitness but displayed a high and unprecedented variability in their potential to deplete CD4 T cells. Two R5 group O isolates were identified that cause massive depletion of CD4 T cells, to an extent comparable to CXCR4-using viruses and not documented for any R5 isolate from group M. Intergroup comparisons found a five- to eightfold lower replicative fitness of isolates from group O than for isolates from group M yet a similar overall intrinsic pathogenicity in tonsil cultures. This study establishes biological ex vivo characteristics of HIV-1 group O primary isolates. The current findings challenge the belief that a grossly reduced replicative fitness or inherently impaired cytopathicity of viruses from this group underlies their low global prevalence.
A Gammaherpesvirus Ubiquitin-Specific Protease Is Involved in the Establishment of Murine Gammaherpesvirus 68 Infection
Authors: Gredmark-Russ Sara , Isaacson Marisa K. , Kattenhorn Lisa , Cheung Evelyn J. , Watson Nicki , Ploegh Hidde L. 
Published: August 2009

ABSTRACT
Murine gammaherpesvirus 68 (MHV-68) contains a ubiquitin (Ub)-specific cysteine protease (USP) domain embedded within the large tegument protein ORF64, as do all other herpesviruses. The biological role of this protease is still unclear, but for the alphaherpesvirus Marek's disease virus, its USP is involved in T-cell lymphoma formation. We here study the role of the MHV-68 USP, encoded by ORF64. By constructing a mutant virus with a single cysteine-to-alanine replacement in the active site of ORF64, we demonstrate that the USP activity of ORF64 is abolished. The mutant virus replicates less efficiently in vitro, and plaque size is reduced compared to that of a revertant virus. Electron microscopy of infected cells did not reveal any obvious differences in virion morphogenesis or differences in egress for the mutant and revertant viruses. Intraperitoneal infection of C57/BL6 mice demonstrates that the mutant virus is generally cleared by day 7, indicating a role for the USP in the persistence of MHV-68 infection or efficient replication. However, the USP activity in MHV-68 is unlikely to be involved in the establishment of latency or reactivation, since we observed no significant difference in viral DNA genome copy number in the spleen or in the number of cells that reactivate MHV-68 from latency. Our results for MHV-68 ORF64 are consistent with an enzymatic function of the tegument protein that is beneficial to the virus during acute infection, particularly in vivo.