bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Two-Component Regulatory System TCS08 Is Involved in Cellobiose Metabolism ofStreptococcus pneumoniaeR6
Authors: McKessar Stuart J. , Hakenbeck Regine 
Published: February 2007

ABSTRACTThe two-component system TCS08 is one of the regulatory systems that is important for virulence ofStreptococcus pneumoniae. In order to investigate the TCS08 regulon, we have analyzed transcription profiles of mutants derived fromS. pneumoniaeR6 by microarray analysis. Since deletion mutants are often without a significant phenotype, we constructed a mutation in the histidine kinase HK08, T133P, in analogy to the phosphatase mutation T230P in the H box of theS. pneumoniaeCiaH kinase described recently (D. Zähner, K. Kaminski, M. van der Linden, T. Mascher, M. Merai, and R. Hakenbeck, J. Mol. Microbiol. Biotechnol. 4:211-216, 2002). In addition, a deletion mutation was constructed inrr08, encoding the cognate response regulator. The most heavily suppressed genes in thehk08mutant were spr0276 to spr0282, encoding a putative cellobiose phosphoenolpyruvate sugar phosphotransferase system (PTS). Whereas the R6 Smrparent strain and the Δrr08mutant readily grew on cellobiose, thehk08mutant and selected mutants with deletions in the PTS cluster did not, strongly suggesting that TCS08 is involved in the catabolism of cellobiose. Homologues of the TCS08 system were found in closely related streptococci and other gram-positive cocci. However, the genes spr0276 to spr0282, encoding the putative cellobiose PTS, represent a genomic island inS. pneumoniaeand homologues were found inStreptococcus gordoniionly, suggesting that this system might contribute to the pathogenicity potential of the pneumococcus.
The Plasminogen-Binding Group A Streptococcal M Protein-Related Protein Prp Binds Plasminogen via Arginine and Histidine Residues
Authors: Sanderson-Smith Martina L. , Dowton Mark , Ranson Marie , Walker Mark J. 
Published: February 2007

ABSTRACT

The migration of the human pathogen
Streptococcus pyogenes
(group A streptococcus) from localized to deep tissue sites may result in severe invasive disease, and sequestration of the host zymogen plasminogen appears crucial for virulence. Here, we describe a novel plasminogen-binding M protein, the
p
lasminogen-binding group A streptococcal M protein (PAM)-
r
elated
p
rotein (Prp). Prp is phylogenetically distinct from previously described plasminogen-binding M proteins of group A, C, and G streptococci. While competition experiments indicate that Prp binds plasminogen with a lower affinity than PAM (50% effective concentration = 0.34 μM), Prp nonetheless binds plasminogen with high affinity and at physiologically relevant concentrations of plasminogen (

K
d

= 7.8 nM). Site-directed mutagenesis of the putative plasminogen binding site indicates that unlike the majority of plasminogen receptors, Prp does not interact with plasminogen exclusively via lysine residues. Mutagenesis to alanine of lysine residues Lys
96
and Lys
101
reduced but did not abrogate plasminogen binding by Prp. Plasminogen binding was abolished only with the additional mutagenesis of Arg
107
and His
108
to alanine. Furthermore, mutagenesis of Arg
107
and His
108
abolished plasminogen binding by Prp despite the presence of Lys
96
and Lys
101
in the binding site. Thus, binding to plasminogen via arginine and histidine residues appears to be a conserved mechanism among plasminogen-binding M proteins.
Complete Genome of Acute Rheumatic Fever-Associated Serotype M5
Streptococcus pyogenes
Strain Manfredo
Authors: Holden Matthew T. G. , Scott Annabel , Cherevach Inna , Chillingworth Tracey , Churcher Carol , Cronin Ann , Dowd Linda , Feltwell Theresa , Hamlin Nancy , Holroyd Simon , Jagels Kay , Moule Sharon , Mungall Karen , Quail Michael A. , Price Claire , Rabbinowitsch Ester , Sharp Sarah , Skelton Jason , Whitehead Sally , Barrell Bart G. , Kehoe Michael , Parkhill Julian 
Published: February 2007

ABSTRACT

Comparisons of the 1.84-Mb genome of serotype M5
Streptococcus pyogenes
strain Manfredo with previously sequenced genomes emphasized the role of prophages in diversification of
S. pyogenes
and the close relationship between strain Manfredo and MGAS8232, another acute rheumatic fever-associated strain.
Five-Hour Diagnosis of Dermatophyte Nail Infections with Specific Detection ofTrichophyton rubrum
Authors: Brillowska-Dąbrowska Anna , Saunte Ditte Marie , Arendrup Maiken Cavling 
Published: February 2007

ABSTRACTA rapid two-step DNA extraction method and a multiplex PCR for the detection of dermatophytes in general andTrichophyton rubrumspecifically were developed and evaluated with DNA extracted from pure cultures and from clinically diseased nails. DNA from the following dermatophytes was used:Epidermophyton floccosum,Microsporum audouinii,Microsporum canis,Microsporum gypseum,Microsporum nanum,Trichophyton mentagrophytes,Trichophyton rubrum,Trichophyton schoenleinii,Trichophyton soudanense,Trichophyton terrestre,Trichophyton tonsurans,Trichophyton verrucosum, andTrichophyton violaceum. Human DNA and DNA from the following nondermatophyte fungi were included as controls:Alternaria,Aspergillus niger,Candida albicans,Candida glabrata,Candida krusei,Malassezia furfur,Saccharomyces cerevisiae, andScopulariopsis brevicaulis.A total of 118 nail samples received for routine microscopy and culture for dermatophytes were subsequently tested by the two PCRs separately and in a multiplex format. Using DNA extracted from pure cultures and the pan-dermatophyte PCR, theT. rubrum-specific PCR sequentially and in a multiplex format correctly detected all dermatophytes and additionally correctly identifiedT. rubrum.Comparison of the traditional diagnostic evaluation (microscopy and culture) of nail samples with PCR on DNA directly extracted from the nails showed excellent agreement between PCR and microscopy, but the number of samples with dermatophyte species identification was increased considerably from 22.9% to 41.5%, mainly due to the identification ofT. rubrumby PCR in microscopy-positive but culture-negative samples. In conclusion, this 5-hour diagnostic test was shown to increase not only the speed but also the sensitivity of investigation for nail dermatophytosis.
Evaluation of Disk Diffusion and Etest Compared to Broth Microdilution for Antifungal Susceptibility Testing of Posaconazole against Clinical Isolates of Filamentous Fungi
Authors: Messer Shawn A. , Diekema Daniel J. , Hollis Richard J. , Boyken Linda B. , Tendolkar Shailesh , Kroeger Jennifer , Pfaller Michael A. 
Published: February 2007

ABSTRACT
We performed Etest, disk diffusion, and broth microdilution susceptibility testing of posaconazole against 146 clinical isolates of filamentous fungi. By using provisional breakpoints for comparison purposes only, categorical agreement between the results of the agar-based methods and those of broth microdilution were 96 to 98%, with no very major errors. These agar-based methods hold promise as simple and reliable methods for determining the posaconazole susceptibilities of filamentous fungi.
MDA-5 Is Cleaved in Poliovirus-Infected Cells
Authors: Barral Paola M. , Morrison Juliet M. , Drahos Jennifer , Gupta Pankaj , Sarkar Devanand , Fisher Paul B. , Racaniello Vincent R. 
Published: February 2007

ABSTRACT

Infections with RNA viruses are sensed by the innate immune system through membrane-bound Toll-like receptors or the cytoplasmic RNA helicases RIG-I and MDA-5. It is believed that MDA-5 is crucial for sensing infections by picornaviruses, but there have been no studies on the role of this protein during infection with poliovirus, the prototypic picornavirus. Beginning at 4 h postinfection, MDA-5 protein is degraded in poliovirus-infected cells. Levels of MDA-5 declined beginning at 6 h after infection with rhinovirus type 1a or encephalomyocarditis virus, but the protein was stable in cells infected with rhinovirus type 16 or echovirus type 1. Cleavage of MDA-5 is not carried out by either poliovirus proteinase 2A
pro
or 3C
pro
. Instead, degradation of MDA-5 in poliovirus-infected cells occurs in a proteasome- and caspase-dependent manner. Degradation of MDA-5 during poliovirus infection correlates with cleavage of poly(ADP) ribose polymerase (PARP), a hallmark of apoptosis. Induction of apoptosis by puromycin leads to cleavage of both PARP and MDA-5. The MDA-5 cleavage product observed in cells treated with puromycin is ∼90 kDa, similar in size to the putative cleavage product observed in poliovirus-infected cells. Poliovirus-induced cleavage of MDA-5 may be a mechanism to antagonize production of type I interferon in response to viral infection.
Mutation in the Glycosylated Gag Protein of Murine Leukemia Virus Results in Reduced In Vivo Infectivity and a Novel Defect in Viral Budding or Release
Authors: Low Audrey , Datta Shoibal , Kuznetsov Yurii , Jahid Sohail , Kothari Nayantara , McPherson Alexander , Fan Hung 
Published: February 2007

ABSTRACT

All gammaretroviruses, including murine leukemia viruses (MuLVs), feline leukemia viruses, and gibbon-ape leukemia virus, encode an alternate, glycosylated form of Gag polyprotein (glyco-Gag or gPr80

gag

) in addition to the polyprotein precursor of the viral capsid proteins (Pr65

gag

). gPr80

gag

is translated from an upstream in-frame CUG initiation codon, in contrast to the AUG codon used for Pr65

gag

. The role of glyco-Gag in MuLV replication has been unclear, since gPr80

gag

-negative Moloney MuLV (M-MuLV) mutants are replication competent in vitro and pathogenic in vivo. However, reversion to the wild type is frequently observed in vivo. In these experiments, in vivo inoculation of a gPr80

gag

mutant, Ab-X-M-MuLV, showed substantially lower (2 log) initial infectivity in newborn NIH Swiss mice than that of wild-type virus, and revertants to the wild type could be detected by PCR cloning and DNA sequencing as early as 15 days postinfection. Atomic force microscopy of Ab-X-M-MuLV-infected producer cells or of the PA317 amphotropic MuLV-based vector packaging line (also gPr80

gag

negative) revealed the presence of tube-like viral structures on the cell surface. In contrast, wild-type virus-infected cells showed the typical spherical, 145-nm particles observed previously. Expression of gPr80

gag

in PA317 cells converted the tube-like structures to typical spherical particles. PA317 cells expressing gPr80

gag

produced 5- to 10-fold more infectious vector or viral particles as well. Metabolic labeling studies indicated that this reflected enhanced virus particle release rather than increased viral protein synthesis. These results indicate that gPr80

gag

is important for M-MuLV replication in vivo and in vitro and that the protein may be involved in a late step in viral budding or release.
The Large and Small Isoforms of Human Papillomavirus Type 16 E6 Bind to and Differentially Affect Procaspase 8 Stability and Activity
Authors: Filippova Maria , Johnson Melyssa M. , Bautista Marnelli , Filippov Valery , Fodor Nadja , Tungteakkhun Sandy S. , Williams Kadia , Duerksen-Hughes Penelope J. 
Published: February 2007

ABSTRACT
Human papillomavirus type 16 (HPV-16) has developed numerous ways to modulate host-initiated immune mechanisms. The HPV-16 E6 oncoprotein, for example, can modulate the cellular level, and consequently the activity, of procaspase 8, thus modifying the cellular response to cytokines of the tumor necrosis factor family. E6 from HPV-16, but not E6 from the low-risk types 6b and 11, alters the cellular level of procaspase 8 in a dose-dependent manner. Both the large and small (E6*) isoforms of E6, which originate by way of alternate splicing, can modulate procaspase 8 stability. Intriguingly, although both isoforms bind to procaspase 8, the large isoform accelerates the degradation of procaspase 8 while the small isoform stabilizes it. Binding leads to a change in the ability of procaspase 8 to bind either to itself or to FADD (Fas-associated death domain), with the large version of E6 able to inhibit this binding while the small isoform does not. Consistent with this model, knockdown of the large version of E6 by small interfering RNA leads to increases in the levels of procaspase 8 and its binding to both itself and FADD. Thus, these alternatively spliced isoforms can modulate both the level and the activity of procaspase 8 in opposite directions.
Emergence of Influenza A Virus Variants after Prolonged Shedding from Pheasants
Authors: Humberd Jennifer , Boyd Kelli , Webster Robert G. 
Published: February 2007

ABSTRACT
We previously demonstrated the susceptibility of pheasants to infection with influenza A viruses of 15 hemagglutinin (HA) subtypes: 13/23 viruses tested were isolated for ≥14 days, all in the presence of serum-neutralizing antibodies; one virus (H10) was shed for 45 days postinfection. Here we confirmed that 20% of pheasants shed low-pathogenic influenza viruses for prolonged periods. We aimed to determine why the antibody response did not clear the virus in the usual 3 to 10 days, because pheasants serve as a long-term source of influenza viruses in poultry markets. We found evidence of virus replication and histological changes in the large intestine, bursa of Fabricius, and cecal tonsil. The virus isolated 41 days postinfection was antigenically distinct from the parental H10 virus, with corresponding changes in the HA and neuraminidase. Ten amino acid differences were found between the parental H10 and the pheasant H10 virus; four were in potential antigenic sites of the HA molecule. Prolonged shedding of virus by pheasants results from a complex interplay between the diversity of virus variants and the host response. It is often argued that vaccination pressure is a mechanism that contributes to the generation of antigenic-drift variants in poultry. This study provided evidence that drift variants can occur naturally in pheasants after prolonged shedding of virus, thus strengthening our argument for the removal of pheasants from live-bird retail markets.
Dimer Initiation Signal of Human Immunodeficiency Virus Type 1: Its Role in Partner Selection during RNA Copackaging and Its Effects on Recombination
Authors: Moore Michael D. , Fu William , Nikolaitchik Olga , Chen Jianbo , Ptak Roger G. , Hu Wei-Shau 
Published: February 2007

ABSTRACT
Frequent human immunodeficiency virus type 1 (HIV-1) recombination occurs during DNA synthesis when portions of the two copackaged RNAs are used as templates to generate a hybrid DNA copy. Therefore, the frequency of copackaging of genomic RNAs from two different viruses (heterozygous virion formation) affects the generation of genotypically different recombinants. We hypothesized that the selection of copackaged RNA partners is largely determined by Watson-Crick pairing at the dimer initiation signal (DIS), a 6-nucleotide palindromic sequence at the terminal loop of stem-loop 1 (SL1). To test our hypothesis, we examined whether heterozygous virion formation could be encouraged by manipulation of the DIS. Three pairs of viruses were generated with compensatory DIS mutations, designed so that perfect DIS base pairing could only occur between RNAs derived from different viruses, not between RNAs from the same virus. We observed that vector pairs with compensatory DIS mutations had an almost twofold increase in recombination rates compared with wild-type viruses. These data suggest that heterozygous virion formation was enhanced in viruses with compensatory DIS mutations (from 50% to more than 90% in some viral pairings). The role of the SL1 stem in heterozygous virion formation was also tested; our results indicated that the intermolecular base pairing of the stem sequences does not affect RNA partner selection. In summary, our results demonstrate that the Watson-Crick pairing of the DIS is a major determinant in the selection of the copackaged RNA partner, and altering the base pairing of the DIS can change the proportion of heterozygous viruses in a viral population. These results also strongly support the hypothesis that HIV-1 RNA dimers are formed prior to encapsidation.
Susceptibility of CCR5-Deficient Mice to Genital Herpes Simplex Virus Type 2 Is Linked to NK Cell Mobilization
Authors: Thapa Manoj , Kuziel William A. , Carr Daniel J. J. 
Published: February 2007

ABSTRACTFollowing genital herpes simplex virus type 2 (HSV-2) exposure, NK cells and T cells are mobilized to sites of infection to control viral replication and spread. The present investigation sought to determine the role of the chemokine receptor CCR5 in this process. Mice deficient in CCR5 (CCR5−/−) displayed a significant reduction in cumulative survival following infection in comparison to wild-type, HSV-2-infected controls. Associated with decreased resistance to viral infection, CCR5−/−mice yielded significantly more virus and expressed higher levels of tumor necrosis factor alpha, CXCL1, CCL2, CCL3, and CCL5 in the vagina, spinal cord, and/or brain stem than did wild-type mice. Whereas there was no difference in absolute number of leukocytes (CD45high), CD4 T cells, or CD8 T cells residing in the draining lymph nodes, spleen, spinal cord, or brain stem comparing HSV-2-infected wild-type to CCR5−/−mice prior to or after infection, there were significantly more NK cells (NK1.1+CD3−) residing in the brain stem and spleen of infected wild-type mice. Functionally, NK activity from cells isolated from the brain stem of HSV-2-infected wild-type mice was greater than that from HSV-2-infected CCR5−/−mice. In addition, antibody-mediated depletion of NK cells resulted in an increase in HSV-2 levels in the vaginal, spinal cord, and brain stem tissue of wild-type but not CCR5−/−mice. Collectively, the absence of CCR5 expression significantly impacts the ability of the host to control genital HSV-2 infection, inflammation, and spread associated with a specific reduction in NK cell expansion, infiltration, and activity in the nervous system.
New Natural Intergenotypic (2/5) Recombinant of Hepatitis C Virus
Authors: Legrand-Abravanel Florence , Claudinon Julie , Nicot Florence , Dubois Martine , Chapuy-Regaud Sabine , Sandres-Saune Karine , Pasquier Christophe , Izopet Jacques 
Published: February 2007

ABSTRACT
A 9.2-kb sequence from a hepatitis C virus (HCV) strain found in southwest France was compared to sequences from reference strains in HCV sequence databases. We found a recombinant virus with genotype 2 at the 5′ end and genotype 5 at the 3′ end. The crossover point was located between genes NS2 and NS3. Recombination between HCV genotypes must now be considered in studies on HCV epidemiology and evolution and in predictions of the virus response to antiviral therapy. Knowing the location of the recombination point may also be useful for constructing infectious chimeric viruses.
Canine Distemper Virus Infection Requires Cholesterol in the Viral Envelope
Authors: Imhoff Heidi , von Messling Veronika , Herrler Georg , Haas Ludwig 
Published: February 2007

ABSTRACT
Cholesterol is known to play an important role in stabilizing particular cellular membrane structures, so-called lipid or membrane rafts. For several viruses, a dependence on cholesterol for virus entry and/or morphogenesis has been shown. Using flow cytometry and fluorescence microscopy, we demonstrate that infection of cells by canine distemper virus (CDV) was not impaired after cellular cholesterol had been depleted by the drug methyl-β-cyclodextrin. This effect was independent of the multiplicity of infection and the cellular receptor used for infection. However, cholesterol depletion of the viral envelope significantly reduced CDV infectivity. Replenishment by addition of exogenous cholesterol restored infectivity up to 80%. Thus, we conclude that CDV entry is dependent on cholesterol in the viral envelope. Furthermore, reduced syncytium formation was observed when the cells were cholesterol depleted during the course of the infection. This may be related to the observation that CDV envelope proteins H and F partitioned into cellular detergent-resistant membranes. Therefore, a role for lipid rafts during virus assembly and release as well is suggested.
Adeno-Associated Virus Type 2 p5 Promoter: a Rep-Regulated DNA Switch Element Functioning in Transcription, Replication, and Site-Specific Integration
Authors: Murphy Mary , Gomos-Klein Janette , Stankic Marko , Falck-Pedersen Erik 
Published: February 2007

ABSTRACT
The large Rep proteins, p68 and p78, function as master controllers of the adeno-associated virus type 2 (AAV2) life cycle, involved in transcriptional control, in latency, in rescue, and in viral DNA replication. The p5 promoter may be the nucleic acid complement to the large Rep proteins. It drives expression of the large Rep proteins, it undergoes autoregulation by Rep, it undergoes induction by helper virus, it is a target substrate for Rep-mediated site-specific integration (RMSSI), and it can function as a replicative origin. To better understand the relationship between each of the p5 functions, we have determined the effects of p5 promoter mutations (p5 integration efficiency element, or p5IEE) on transcription, integration, and replication using RMSSI transfection protocols in HeLa cells. The data demonstrate that the organization of the p5 promoter provides a unique platform for regulated AAV2 template transcription and subsequent repression by Rep through direct and indirect mechanisms. The elements of the p5IEE that define its function as a promoter also define its function as a highly optimized substrate for Rep-mediated site-specific integration and replication. The p5 Rep binding element (RBE) is essential in RMSSI and Rep-dependent replication; however, replacement of the p5 RBE with either the AAV2 inverted terminal repeat or the AAVS1 RBE sequence elements neither enhances nor severely compromises RMSSI activity of p5IEE. The RBE by itself or in combination with the YY1+1 initiator/terminal resolution sequence element does not mediate efficient site-specific integration. We found that replication and integration were highly sensitive to sequence manipulations of the p5 TATA/RBE/YY1+1 core structure in a manner that reflects the function of these elements in transcription. The data presented support a model where, depending on the state of the cell (Rep expression and helper virus influences), the p5IEE operates as a transcription/integration switch sequence element.