bluuebunny/crossref_metadata_2025_split huggingface dataset:
System for Expression of Microsporidian Methionine Amino Peptidase Type 2 (MetAP2) in the Yeast
Saccharomyces cerevisiae
Authors: Upadhya Rajendra , Zhang Hong Shan , Weiss Louis M. 
Published: September 2006

ABSTRACT

Microsporidia are parasitic protists of all classes of vertebrates and most invertebrates. They recently emerged as important infections in various immunosuppressed and immunocompetent patient populations. They are also important veterinary and agricultural pathogens. Current therapies for microsporidiosis include benzimidazoles, which bind tubulin-inhibiting microtubule assembly, and fumagillin and its derivatives, which bind and inhibit methionine amino peptidase type 2 (MetAP2). Benzimidazoles are not active against
Enterocytozoon bieneusi
, the most common cause of human microsporidiosis. Fumagillin is active against most microsporidia, including
E. bieneusi
, but thrombocytopenia has been a problem in clinical trials. There is a pressing need for more-specific microsporidian MetAP2 inhibitors. To expedite and facilitate the discovery of safe and effective MetAP2 inhibitors, we have engineered
Saccharomyces cerevisiae
to be dependent on
Encephalitozoon cuniculi
MetAP2 (EcMetAP2) for its growth, where EcMetAP2 is harbored on an episomal uracil-selectable tetracycline-regulated plasmid. We have also constructed a leucine-selectable tetracycline-regulated expression plasmid into which any MetAP2 gene can be cloned. By utilizing a 5-fluoroorotic acid-mediated plasmid shuffle in the EcMetAP2 yeast strain, a yeast strain can be generated whose growth is dependent on MetAP2 from any organism. The level of heterologous MetAP2 gene expression can be controlled by the addition of tetracycline to the growth medium. These yeast strains should permit high-throughput screening for the identification of new inhibitors with high specificity and activity toward microsporidian MetAP2.
In Vitro Susceptibility of Breakthrough
Candida
Bloodstream Isolates Correlates with Daily and Cumulative Doses of Fluconazole
Authors: Clancy Cornelius J. , Staley Benjamin , Nguyen M. Hong 
Published: September 2006

ABSTRACT

We determined MICs for 28
Candida
isolates recovered from patients who developed breakthrough candidemia while receiving fluconazole. MICs correlated with daily and cumulative doses of fluconazole. Patients receiving ≥2,000 mg cumulatively or >200 mg daily were more likely to be infected with isolates that were not fluconazole susceptible.
Comparative In Vitro Efficacies and Antimicrobial Durabilities of Novel Antimicrobial Central Venous Catheters
Authors: Hanna Hend , Bahna Paul , Reitzel Ruth , Dvorak Tanya , Chaiban Gassan , Hachem Ray , Raad Issam 
Published: September 2006

ABSTRACT

We investigated the efficacies and durability of novel antimicrobial central venous catheters (CVCs) in preventing the adherence of microbial organisms to the surfaces of the CVCs. Novel antimicrobial CVCs investigated in this in vitro study were impregnated with antibiotics (minocycline and rifampin), with Oligon agent (silver, platinum, and carbon black), with approved antiseptics (chlorhexidine and silver sulfadiazine), or with a novel antiseptic agent, gendine, which contains gentian violet and chlorhexidine. When tested against methicillin-resistant
Staphylococcus aureus
(MRSA) and
Pseudomonas aeruginosa
, gendine-coated CVC segments provided protection against bacterial adherence significantly more than all other types of tested CVCs (
P
< 0.05). Gendine-coated CVCs also provided better protection against
Candida albicans
and
Candida parapsilosis
than CVCs impregnated with antibiotics or with silver, platinum, and carbon (
P
< 0.02). After 28 days of being soaked in serum, the CVCs impregnated with chlorhexidine and silver sulfadiazine and the CVCs impregnated with silver, platinum, and carbon had lost antimicrobial activity against MRSA,
P. aeruginosa
, and
C. parapsilosis
, and the CVCs impregnated with minocycline and rifampin had lost activity against
P. aeruginosa
and
C. parapsilosis
. The CVCs impregnated with gendine maintained antimicrobial activities against MRSA,
P. aeruginosa
, and
C. parapsilosis
after 28 days of being soaked in serum. Central venous catheters impregnated with the novel investigational antiseptic gendine showed in vitro efficacy and provided protection against bacterial adherence more than other approved novel antimicrobial-coated CVCs.
Murine Model for Dengue Virus-Induced Lethal Disease with IncreasedVascular Permeability
Authors: Shresta Sujan , Sharar Kristin L. , Prigozhin Daniil M. , Beatty P. Robert , Harris Eva 
Published: September 2006

ABSTRACT
Lack
of an appropriate animal model for dengue virus (DEN), which causes
dengue fever and dengue hemorrhagic fever/dengue shock syndrome
(DHF/DSS), has impeded characterization of the mechanisms underlying
the disease pathogenesis. The cardinal feature of DHF/DSS, the severe
form of DEN infection, is increased vascular permeability. To develop a
murine model that is more relevant to DHF/DSS, a novel DEN strain,
D2S10, was generated by alternately passaging a non-mouse-adapted DEN
strain between mosquito cells and mice, thereby mimicking the natural
transmission cycle of the virus between mosquitoes and humans. After
infection with D2S10, mice lacking interferon receptors died early
without manifesting signs of paralysis, carried infectious virus in
both non-neuronal and neuronal tissues, and exhibited signs of
increased vascular permeability. In contrast, mice infected with the
parental DEN strain developed paralysis at late times after infection,
contained detectable levels of virus only in the central nervous
system, and displayed normal vascular permeability. In the mice
infected with D2S10, but not the parental DEN strain, significant
levels of serum tumor necrosis factor alpha (TNF-α) were
produced, and the neutralization of TNF-α activity prevented
early death of D2S10-infected mice. Sequence analysis comparing D2S10
to its parental strain implicated a conserved region of amino acid
residues in the envelope protein as a possible source for the D2S10
phenotype. These results demonstrate that D2S10 causes a more relevant
disease in mice and that TNF-α may be one of several key
mediators of severe DEN-induced disease in mice. This report represents
a significant advance in animal models for severe DEN disease, and it
begins to provide mechanistic insights into DEN-induced disease in
vivo.
Coactivator-Associated Arginine Methyltransferase 1 Enhances Transcriptional Activity ofthe Human T-Cell Lymphotropic Virus Type 1 Long Terminal Repeat through Direct Interactionwith Tax
Authors: Jeong Soo-Jin , Lu Hanxin , Cho Won-Kyung , Park Hyeon Ung , Pise-Masison Cynthia , Brady John N. 
Published: September 2006

ABSTRACT

In this study, we demonstrate that the coactivator-associated arginine
methyltransferase 1 (CARM1), which methylates histone H3 and other
proteins such as p300/CBP, is positively involved in the regulation of
Tax transactivation. First, transfection studies demonstrated that
overexpression of CARM1 wild-type protein resulted in increased Tax
transactivation of the human T-cell lymphotropic virus type 1 (HTLV-1)
long terminal repeat (LTR). In contrast, transfection of a
catalytically inactive CARM1 methyltransferase mutant did not enhance
Tax transactivation. CARM1 facilitated Tax transactivation of the
CREB-dependent cellular GEM promoter. A direct physical interaction
between HTLV-1 Tax and CARM1 was demonstrated using in vitro
glutathione
S
-transferase-Tax binding assays, in vivo
coimmunoprecipitation, and confocal microscopy experiments. Finally,
chromatin immunoprecipitation analysis of the activated HTLV-1 LTR
promoter showed the association of CARM1 and methylated histone H3 with
the template DNA. In vitro, Tax facilitates the binding of CARM1 to the
transcription complex. Together, our data provide evidence that CARM1
enhances Tax transactivation of the HTLV-1 LTR through a direct
interaction between CARM1 and Tax and this binding promotes methylation
of histone H3 (R2, R17, and
R26).
Infection of CD127+(Interleukin-7 Receptor+) CD4+Cells and Overexpression of CTLA-4 Are Linked to Loss of Antigen-Specific CD4 T Cells during Primary Human Immunodeficiency Virus Type 1 Infection
Authors: Zaunders John J. , Ip Susanna , Munier Mee Ling , Kaufmann Daniel E. , Suzuki Kazuo , Brereton Choechoe , Sasson Sarah C. , Seddiki Nabila , Koelsch Kersten , Landay Alan , Grey Pat , Finlayson Robert , Kaldor John , Rosenberg Eric S. , Walker Bruce D. , Fazekas de St. Groth Barbara , Cooper David A. , Kelleher Anthony D. 
Published: September 2006

ABSTRACTWe recently found that human immunodeficiency virus (HIV)-specific CD4+T cells express coreceptor CCR5 and activation antigen CD38 during early primary HIV-1 infection (PHI) but then rapidly disappear from the circulation. This cell loss may be due to susceptibility to infection with HIV-1 but could also be due to inappropriate apoptosis, an expansion of T regulatory cells, trafficking out of the circulation, or dysfunction. We purified CD38+++CD4+T cells from peripheral blood mononuclear cells, measured their level of HIV-1 DNA by PCR, and found that about 10% of this population was infected. However, a small subset of HIV-specific CD4+T cells also expressed CD127, a marker of long-term memory cells. Purified CD127+CD4+lymphocytes contained fivefold more copies of HIV-1 DNA per cell than did CD127-negative CD4+cells, suggesting preferential infection of long-term memory cells. We observed no apoptosis of antigen-specific CD4+T cells in vitro and only a small increase in CD45RO+CD25+CD127dimCD4+T regulatory cells during PHI. However, 40% of CCR5+CD38+++CD4+T cells expressed gut-homing integrins, suggesting trafficking through gut-associated lymphoid tissue (GALT). Furthermore, 80% of HIV-specific CD4+T cells expressed high levels of the negative regulator CTLA-4 in response to antigen stimulation in vitro, which was probably contributing to their inability to produce interleukin-2 and proliferate. Taken together, the loss of HIV-specific CD4+T cells is associated with a combination of an infection of CCR5+CD127+memory CD4+T cells, possibly in GALT, and a high expression of the inhibitory receptor CTLA-4.
Functional Interaction between Human Herpesvirus 6 Immediate-Early 2 Protein and Ubiquitin-Conjugating Enzyme 9 in the Absence of Sumoylation
Authors: Tomoiu Andru , Gravel Annie , Tanguay Robert M. , Flamand Louis 
Published: September 2006

ABSTRACT
The immediate-early 2 (IE2) protein of human herpesvirus 6 is a potent transactivator of cellular and viral promoters. To better understand the biology of IE2, we generated a LexA-IE2 fusion protein and screened, using the yeast two-hybrid system, a Jurkat T-cell cDNA library for proteins that could interact with IE2. The most frequently isolated IE2-interacting protein was the human ubiquitin-conjugating enzyme 9 (Ubc9), a protein involved in the small ubiquitin-like modifier (SUMO) conjugation pathway. Using deletion mutants of IE2, we mapped the IE2-Ubc9-interacting region to residues 989 to 1037 of IE2. The interaction was found to be of functional significance to IE2, as Ubc9 overexpression significantly repressed promoter activation by IE2. The C93S Ubc9 mutant exhibited a similar effect on IE2, indicating that the E2 SUMO-conjugating function of Ubc9 is not required for its repressive action on IE2. No consensus sumoylation sites or evidence of IE2 conjugation to SUMO could be demonstrated under in vivo or in vitro conditions. Moreover, expression levels and nuclear localization of IE2 were not altered by Ubc9 overexpression, suggesting that Ubc9's repressive function likely occurs at the transcriptional complex level. Overall, our results indicate that Ubc9 influences IE2's function and provide new information on the complex interactions that occur between herpesviruses and the sumoylation pathway.
JC Virus Evolution and Its Association with Human Populations
Authors: Shackelton Laura A. , Rambaut Andrew , Pybus Oliver G. , Holmes Edward C. 
Published: September 2006

ABSTRACT
The ubiquitous human polyomavirus JC (JCV) is a small double-stranded DNA virus that establishes a persistent infection, and it is often transmitted from parents to children. There are at least 14 subtypes of the virus associated with different human populations. Because of its presumed codivergence with humans, JCV has been used as a genetic marker for human evolution and migration. Codivergence has also been used as a basis for estimating the rate of nucleotide substitution in JCV. We tested the hypothesis of host-virus codivergence by (i) performing a reconciliation analysis of phylogenetic trees of human and JCV populations and (ii) providing the first estimate of the evolutionary rate of JCV that is independent from the assumption of codivergence. Strikingly, our comparisons of JCV and human phylogenies provided no evidence for codivergence, suggesting that this virus should not be used as a marker for human population history. Further, while the estimated nucleotide substitution rate of JCV has large confidence intervals due to limited sampling, our analysis suggests that this virus may evolve nearly two orders of magnitude faster than predicted under the codivergence hypothesis.
Neutralized Adenovirus-Immune Complexes Can Mediate Effective Gene Transfer via an Fc Receptor-Dependent Infection Pathway
Authors: Leopold Philip L. , Wendland Rebecca L. , Vincent Theresa , Crystal Ronald G. 
Published: September 2006

ABSTRACT
Neutralization of adenovirus (Ad) by anti-Ad neutralizing antibodies in serum involves formation of Ad-immune complexes that prevent the virus from interacting with target cells. We hypothesized that Ad-immune complexes likely contain viable Ad vectors which, although no longer capable of gaining access to receptors on target cells, may be able to express transgenes in cells bearing Fc receptors for immunoglobulins, i.e., that antibody-based “neutralization” of Ad vectors may be circumvented by the Fc receptor pathway. To test this hypothesis, we expressed the Fcγ receptor IIA (FcγR) in A549 lung epithelial cells or human dermal fibroblasts and evaluated gene transfer in the presence of human neutralizing anti-Ad serum. FcγR-expressing cells bound and internalized copious amounts of Ad, with a distinct population of internalized Ad trafficking to the nucleus. The dose-response curves for inhibition of gene transfer revealed that FcγR-expressing cells required a more-than-10-fold higher concentration of anti-Ad serum to achieve 50% inhibition of Ad-encoded β-galactosidase expression compared with non-FcγR-expressing cells. The discrepancy between neutralization of Ad during infection of FcγR-expressing cells and neutralization of Ad during infection of non-FcγR-expressing cells occurred with either heat-inactivated or non-heat-inactivated sera, was blocked by addition of purified Fc domain protein, and did not require the cytoplasmic domain of FcγR, suggesting that immune complex internalization proceeded via endocytosis rather than phagocytosis. FcγR-mediated infection by Ad-immune complexes did not require expression of the coxsackie virus-Ad receptor (CAR) since similar data were obtained when CAR-deficient human dermal fibroblasts were engineered to express FcγR. However, interaction of the Ad penton base with cell surface integrins contributed to the difference in neutralization between FcγR-expressing and non-FcγR-expressing cells. The data indicate that complexes formed from Ad and anti-Ad neutralizing antibodies, while compromised with respect to infection of non-FcγR-expressing target cells, maintain the potential to transfer genes to FcγR-expressing cells, with consequent expression of the transgene. The formation of Ad-immune complexes that can target viable virus to antigen-presenting cells may account for the success of Ad-based vaccines administered in the presence of low levels of neutralizing anti-Ad antibody.
Human T-Cell Responses to Vaccinia Virus Envelope Proteins
Authors: Tang Jie , Murtadha Mariam , Schnell Matthias , Eisenlohr Laurence C. , Hooper Jay , Flomenberg Phyllis 
Published: September 2006

ABSTRACT

One approach for a safer smallpox vaccine is to utilize recombinant subunits rather than live vaccinia virus (VACV). The products of the VACV envelope genes A27L, L1R, B5R, and A33R induce protective antibodies in animal models. We propose that proteins that elicit T-cell responses, as well as neutralizing antibodies, will be important to include in a molecular vaccine. To evaluate VACV-specific memory T-cell responses, peripheral blood mononuclear cells (PBMC) from four VACV vaccinees were tested against whole VACV and the individual envelope proteins A27, B5, L1, and A33, using gamma interferon enzyme-linked immunospot and cytokine flow cytometry assays. PBMC were stimulated with autologous dendritic cells infected with VACV or electroporated with individual VACV protein mRNAs. T-cell lines from all donors, vaccinated from 1 month to over 20 years ago, recognized all four VACV envelope proteins. Both CD4
+
and CD8
+
T-cell responses to each protein were detected. Further analysis focused on representative proteins B5 and A27. PBMC from a recent vaccinee exhibited high frequencies of CD4
+
and CD8
+
T-cell precursors to both B5 (19.8 and 20%, respectively) and A27 (6.8 and 3.7%). In comparison, B5- and A27-specific T-cell frequencies ranged from 0.4 to 1.3% in a donor vaccinated 3 years ago. Multiple CD4
+
and CD8
+
T-cell epitopes were identified from both A27 and B5, using overlapping 15-mer peptides. These data suggest that all four VACV envelope proteins may contribute to protective immunity, not only by inducing antibody responses, but also by eliciting T-cell responses.
Suppression of Proinflammatory Signal Transduction and Gene Expression by the DualNucleic Acid Binding Domains of the Vaccinia Virus E3L Proteins
Authors: Langland Jeffrey O. , Kash John C. , Carter Victoria , Thomas Matthew J. , Katze Michael G. , Jacobs Bertram L. 
Published: September 2006

ABSTRACT
Cells have evolved elaborate mechanisms to counteract the onslaught of viral
infections. To activate these defenses, the viral threat must be
recognized. Danger signals, or pathogen-associated molecular patterns,
that are induced by pathogens include double-stranded RNA (dsRNA),
viral single-stranded RNA, glycolipids, and CpG DNA. Understanding the
signal transduction pathways activated and host gene expression induced
by these danger signals is vital to understanding virus-host
interactions. The vaccinia virus E3L protein is involved in blocking
the host antiviral response and increasing pathogenesis, functions that
map to separate C-terminal dsRNA- and N-terminal Z-DNA-binding domains.
Viruses containing mutations in these domains allow modeling of the
role of dsRNA and Z-form nucleic acid in the host response to virus
infection. Deletions in the Z-DNA- or dsRNA-binding domains led to
activation of signal transduction cascades and up-regulation of host
gene expression, with many genes involved in the inflammatory
response. These data suggest that poxviruses actively
inhibit cellular recognition of viral danger signals and the subsequent
cellular response to the viral
threat.
Differential Enhancement of Dengue Virus Immune Complex Infectivity Mediated by Signaling-Competent and Signaling-Incompetent Human FcγRIA (CD64) or FcγRIIA (CD32)
Authors: Rodrigo W. W. Shanaka I. , Jin Xia , Blackley Shanley D. , Rose Robert C. , Schlesinger Jacob J. 
Published: September 2006

ABSTRACTFcγ receptor (FcγR)-mediated entry of infectious dengue virus immune complexes into monocytes/macrophages is hypothesized to be a key event in the pathogenesis of complicated dengue fever. FcγRIA (CD64) and FcγRIIA (CD32), which predominate on the surface of such dengue virus-permissive cells, were compared for their influence on the infectivity of dengue 2 virus immune complexes formed with human dengue virus antibodies. A signaling immunoreceptor tyrosine-based activation motif (ITAM) incorporated into the accessory γ-chain subunit that associates with FcγRIA and constitutively in FcγRIIA is required for phagocytosis mediated by these receptors. To determine whether FcγRIA and FcγRIIA activation functions are also required for internalization of infectious dengue virus immune complexes, we generated native and signaling-incompetent versions of each receptor by site-directed mutagenesis of ITAM tyrosine residues. Plasmids designed to express these receptors were transfected into COS-7 cells, and dengue virus replication was measured by plaque assay and flow cytometry. We found that both receptors mediated enhanced dengue virus immune complex infectivity but that FcγRIIA appeared to do so far more effectively. Abrogation of FcγRIA signaling competency, either by expression without γ-chain or by coexpression with γ-chain mutants, was associated with significant impairment of phagocytosis and of dengue virus immune complex infectivity. Abrogation of FcγRIIA signaling competency was also associated with equally impaired phagocytosis but had no discernible effect on dengue virus immune complex infectivity. These findings point to fundamental differences between FcγRIA and FcγRIIA with respect to their immune-enhancing capabilities and suggest that different mechanisms of dengue virus immune complex internalization may operate between these FcγRs.
Naïve T-Cell Depletion Related to Infection by X4 Human Immunodeficiency Virus Type 1 in Poor Immunological Responders to Highly Active Antiretroviral Therapy
Authors: Delobel Pierre , Nugeyre Marie-Thérèse , Cazabat Michelle , Sandres-Sauné Karine , Pasquier Christophe , Cuzin Lise , Marchou Bruno , Massip Patrice , Cheynier Rémi , Barré-Sinoussi Françoise , Izopet Jacques , Israël Nicole 
Published: September 2006

ABSTRACT

The reasons for poor CD4
+
T-cell recovery in some human immunodeficiency virus (HIV)-infected subjects despite effective highly active antiretroviral therapy (HAART) remain unclear. We recently reported that CXCR4-using (X4) HIV-1 could be gradually selected in cellular reservoirs during sustained HAART. Because of the differential expression of HIV-1 coreceptors CCR5 and CXCR4 on distinct T-cell subsets, the residual replication of R5 and X4 viruses could have different impacts on T-cell homeostasis during immune reconstitution on HAART. We examined this hypothesis and the mechanisms of CD4
+
T-cell restoration by comparing the virological and immunological features of 15 poor and 15 good immunological responders to HAART. We found a high frequency of X4 viruses in the poor immunological responders. But the levels of intrathymic proliferation of the two groups were similar regardless of whether they were infected by R5 or X4 virus. The frequency of recent thymic emigrants in the poor immunological responders was also similar to that found in the good immunological responders, despite their reduced numbers of naïve CD4
+
T cells. Our data, rather, suggest that the naïve T-cell compartment is drained by a high rate of mature naïve cell loss in the periphery due to bystander apoptosis or activation-induced differentiation. X4 viruses could play a role in the depletion of naïve T cells in poor immunological responders to HAART by triggering persistent T-cell activation and bystander apoptosis via gp120-CXCR4 interactions.