bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of Poliovirus 3C Protease by the 2C Polypeptide
Authors: Banerjee Rajeev , Weidman Mary K. , Echeverri Angela , Kundu Pallob , Dasgupta Asim 
Published: August 2004

ABSTRACT

Poliovirus-encoded nonstructural polypeptide 2C is a multifunctional protein that plays an important role in viral RNA replication. 2C interacts with both intracellular membranes and virus-specific RNAs and has ATPase and GTPase activities. Extensive computer analysis of the 2C sequence revealed that in addition to the known ATPase-, GTPase-, membrane-, and RNA-binding domains it also contains several “serpin” (serine protease inhibitor) motifs. We provide experimental evidence suggesting that 2C is indeed capable of regulating virus-encoded proteases. The purified 2C protein inhibits 3C
pro
-catalyzed cleavage of cellular transcription factors at Q-G sites in vitro. It also inhibits cleavage of a viral precursor by the other viral protease, 2A
pro
. However, at least three cellular proteases appear not to be inhibited by 2C in vitro. The 2C-associated protease inhibitory activity can be depleted by anti-2C antibody. A physical interaction between 2C and His-tagged 3C
pro
can be demonstrated in vitro by coimmunoprecipitation of 2C with anti-His antibody. Deletion analysis suggests that the 2C central and C-terminal domains that include several serpin motifs are important for 3C
pro
-inhibitory activity. To examine the 2C protease inhibitory activity in vivo, stable HeLa cell lines were made that express 2C in an inducible fashion. Infection of 2C-expressing cells with poliovirus led to incomplete (or inefficient) processing of viral precursor polypeptides compared to control cell lines containing the vector alone. These results suggest that 2C can negatively regulate the viral protease 3C
pro
. The possible role of the 2C protease inhibitory activity in viral RNA replication is discussed.
Glycan-Controlled Epitopes of Prion Protein Include a Major Determinant of Susceptibility to Sheep Scrapie
Authors: Moudjou Mohammed , Treguer Eric , Rezaei Human , Sabuncu Elifsu , Neuendorf Erdi , Groschup Martin H. , Grosclaude Jeanne , Laude Hubert 
Published: August 2004

ABSTRACT

A key feature of prion encephalopathies is the accumulation of a misfolded form of the host glycoprotein PrP. Cell-free and cell culture studies have shown that the efficiency of conversion of PrP into the disease-associated form is influenced by its amino acid sequence and also by its carbohydrate moiety. Here, we characterize four novel glycoform-dependent monoclonal antibodies raised against prokaryotic recombinant sheep PrP. We demonstrate that these antibodies discriminate the PrP monoglycosylated species, since two of them recognize molecules that have the first Asn glycosylation site occupied (
mono1
) while the other two recognize molecules glycosylated at the second site (
mono2
). Remarkably, the recognition of PrP by the anti-
mono2
antibodies was strongly influenced by the amino acid present at position 171, i.e., either Gln or Arg. This polymorphism is known to be the main determinant of susceptibility and resistance to scrapie in sheep. Altogether, our findings lead us to propose that each glycan chain controls the accessibility of PrP determinants located close upstream from their attachment site. The monoglycoform-assigned and the allotype-restricted antibodies described here, the first to date, should provide further opportunities to investigate the involvement of each glycan chain in PrP conversion in relation to prion strain diversity and the basis of the resistance conferred by the Arg-171 amino acid.
Adaptive Immunity Is the Primary Force Driving Selection of Equine Infectious Anemia Virus Envelope SU Variants during Acute Infection
Authors: Mealey Robert H. , Leib Steven R. , Pownder Sarah L. , McGuire Travis C. 
Published: August 2004

ABSTRACTEquine infectious anemia virus (EIAV) is a lentivirus that causes persistent infection in horses. The appearance of antigenically distinct viral variants during recurrent viremic episodes is thought to be due to adaptive immune selection pressure. To test this hypothesis, we evaluated envelope SU cloned sequences from five severe combined immunodeficient (SCID) foals infected with EIAV. Within the SU hypervariable V3 region, 8.5% of the clones had amino acid changes, and 6.4% had amino acid changes within the known cytotoxic T lymphocyte (CTL) epitope Env-RW12. Of all the SU clones, only 3.1% had amino acid changes affecting potential N-linked glycosylation sites. In contrast, a much higher degree of variation was evident in SU sequences obtained from four EIAV-infected immunocompetent foals. Within V3, 68.8% of the clones contained amino acid changes, and 50% of the clones had amino acid changes within the Env-RW12 CTL epitope. Notably, 31.9% of the clones had amino acid changes affecting one or more glycosylation sites. Marked amino acid variation occurred in cloned SU sequences from an immune-reconstituted EIAV-infected SCID foal. Of these clones, 100% had amino acid changes within V3, 100% had amino acid changes within Env-RW12, and 97.5% had amino acid changes affecting glycosylation sites. Analysis of synonymous and nonsynonymous nucleotide substitutions revealed statistically significant differences between SCID and immunocompetent foals and between SCID foals and the reconstituted SCID foal. Interestingly, amino acid selection at one site occurred independently of adaptive immune status. Not only do these data indicate that adaptive immunity primarily drives the selection of EIAV SU variants, but also they demonstrate that other selective forces exist during acute infection.
Phylogenetic Analysis of Polyomavirus Simian Virus 40 from Monkeys and Humans Reveals Genetic Variation
Authors: Forsman Zac H. , Lednicky John A. , Fox George E. , Willson Richard C. , White Zoe S. , Halvorson Steven J. , Wong Connie , Lewis Andrew M. , Butel Janet S. 
Published: August 2004

ABSTRACT
A phylogenetic analysis of 14 complete simian virus 40 (SV40) genomes was conducted in order to determine strain relatedness and the extent of genetic variation. This analysis included infectious isolates recovered between 1960 and 1999 from primary cultures of monkey kidney cells, from contaminated poliovaccines and an adenovirus seed stock, from human malignancies, and from transformed human cells. Maximum-parsimony and distance methods revealed distinct SV40 clades. However, no clear patterns of association between genotype and viral source were apparent. One clade (clade A) is derived from strain 776, the reference strain of SV40. Clade B contains isolates from poliovaccines (strains 777 and Baylor), from monkeys (strains N128, Rh911, and K661), and from human tumors (strains SVCPC and SVMEN). Thus, adaptation is not essential for SV40 survival in humans. The C terminus of the T-antigen (T-ag-C) gene contains the highest proportion of variable sites in the SV40 genome. An analysis based on just the T-ag-C region was highly congruent with the whole-genome analysis; hence, sequencing of just this one region is useful in strain identification. Analysis of an additional 16 strains for which only the T-ag-C gene was sequenced indicated that further SV40 genetic diversity is likely, resulting in a provisional clade (clade C) that currently contains strains associated with human tumors and human strain PML-1. Four other polymorphic regions in the genome were also identified. If these regions were analyzed in conjunction with the T-ag-C region, most of the phylogenetic signal could be captured without complete genome sequencing. This report represents the first whole-genome approach to establishing phylogenetic relatedness among different strains of SV40. It will be important in the future to develop a more complete catalog of SV40 variation in its natural monkey host, to determine if SV40 strains from different clades vary in biological or pathogenic properties, and to identify which SV40 strains are transmissible among humans.
Biophysical and Mutational Analysis of the Putative bZIP Domain of Epstein-Barr Virus EBNA 3C
Authors: West Michelle J. , Webb Helen M. , Sinclair Alison J. , Woolfson Derek N. 
Published: August 2004

ABSTRACT
Epstein-Barr virus nuclear antigen 3C (EBNA 3C) is essential for B-cell immortalization and functions as a regulator of viral and cellular transcription. EBNA 3C contains glutamine-rich and proline-rich domains and a region in the N terminus consisting of a stretch of basic residues followed by a run of leucine residues spaced seven amino acids apart. This N-terminal domain is widely believed to represent a leucine zipper dimerization motif (bZIP). We have performed the first structural and functional analysis of this motif and demonstrated that this domain is not capable of forming stable homodimers. Peptides encompassing the EBNA 3C zipper domain are approximately 54 to 67% α-helical in solution but cannot form dimers at physiologically relevant concentrations. Moreover, the EBNA 3C leucine zipper cannot functionally substitute for another homodimerizing zipper domain in domain-swapping experiments. Our data indicate, however, that the EBNA 3C zipper domain behaves as an atypical bZIP domain and is capable of self-associating to form higher-order α-helical oligomers. Using directed mutagenesis, we also identified a new role for the bZIP domain in maintaining the interaction between EBNA 3C and RBP-Jκ in vivo. Disruption of the helical nature of the zipper domain by the introduction of proline residues reduces the ability of EBNA 3C to inhibit EBNA 2 activation and interact with RBP-Jκ in vivo by 50%, and perturbation of the charge on the basic region completely abolishes this function of EBNA 3C.
Kinetic Analysis of the Interactions between Vaccinia Virus Complement Control Protein and Human Complement Proteins C3b and C4b
Authors: Bernet John , Mullick Jayati , Panse Yogesh , Parab Pradeep B. , Sahu Arvind 
Published: August 2004

ABSTRACTThe vaccinia virus complement control protein (VCP) is an immune evasion protein of vaccinia virus. Previously, VCP has been shown to bind and support inactivation of host complement proteins C3b and C4b and to protect the vaccinia virions from antibody-dependent complement-enhanced neutralization. However, the molecular mechanisms involved in the interaction of VCP with its target proteins C3b and C4b have not yet been elucidated. We have utilized surface plasmon resonance technology to study the interaction of VCP with C3b and C4b. We measured the kinetics of binding of the viral protein to its target proteins and compared it with human complement regulators factor H and sCR1, assessed the influence of immobilization of ligand on the binding kinetics, examined the effect of ionic contacts on these interactions, and sublocalized the binding site on C3b and C4b. Our results indicate that (i) the orientation of the ligand is important for accurate determination of the binding constants, as well as the mechanism of binding; (ii) in contrast to factor H and sCR1, the binding of VCP to C3b and C4b follows a simple 1:1 binding model and does not involve multiple-site interactions as predicted earlier; (iii) VCP has a 4.6-fold higher affinity for C4b than that for C3b, which is also reflected in its factor I cofactor activity; (iv) ionic interactions are important for VCP-C3b and VCP-C4b complex formation; (v) VCP does not bind simultaneously to C3b and C4b; and (vi) the binding site of VCP on C3b and C4b is located in the C3dg and C4c regions, respectively.
Host Cell Gene Expression during Human Immunodeficiency Virus Type 1 Latency and Reactivation and Effects of Targeting Genes That Are Differentially Expressed in Viral Latency
Authors: Krishnan Vyjayanthi , Zeichner Steven L. 
Published: August 2004

ABSTRACTThe existence of reservoirs of cells latently infected with human immunodeficiency virus (HIV) is a major obstacle to the elimination of HIV infection. We studied the changes in cellular gene expression that accompany the reactivation and completion of the lytic viral cycle in cell lines chronically infected with HIV-1. We found that several genes exhibited altered expression in the chronically infected cells compared to the uninfected parental cells prior to induction into lytic replication. A number of gene classes showed increased expression in the chronically infected cells, notably including genes encoding proteasomes, histone deacetylases, and many transcription factors. Following induction of the lytic replication cycle, we observed ordered, time-dependent changes in the cellular gene expression pattern. Approximately 1,740 genes, many of which fall into 385 known pathways, were differentially expressed (P< 0.001), indicating that completion of the HIV replication cycle is associated with distinct, temporally ordered changes in host cell gene expression. Maximum changes were observed in the early and intermediate phases of the lytic replication cycle. Since the changes in gene expression in chronically infected cells suggested that cells latently infected with HIV have a different gene expression profile than corresponding uninfected cells, we studied the expression profiles of three different chronically infected cell lines to determine whether they showed similar changes in common cellular genes and pathways. Thirty-two genes showed significant differential expression in all cell lines studied compared to their uninfected parental cell lines. Notable among them werecdc42andlyn, which were downregulated and are required for HIV Nef binding and viral replication. Other genes previously unrelated to HIV latency or pathogenesis were also differentially expressed. To determine the effects of targeting products of the genes that were differentially expressed in latently infected cells, we treated the latently infected cells with a proteasome inhibitor, clastolactacystin-beta-lactone (CLBL), and an Egr1 activator, resveratrol. We found that treatment with CLBL and resveratrol stimulated lytic viral replication, suggesting that treatment of cells with agents that target cellular genes differentially expressed in latently infected cells can stimulate lytic replication. These findings may offer new insights into the interaction of the latently infected host cell and HIV and suggest therapeutic approaches for inhibiting HIV infection and for manipulating cells latently infected with HIV so as to trigger lytic replication.
Differential Roles of AC2 and AC4 of Cassava Geminiviruses in Mediating Synergism and Suppression of Posttranscriptional Gene Silencing
Authors: Vanitharani Ramachandran , Chellappan Padmanabhan , Pita Justin S. , Fauquet Claude M. 
Published: August 2004

ABSTRACT

Posttranscriptional gene silencing (PTGS) in plants is a natural defense mechanism against virus infection. In mixed infections, virus synergism is proposed to result from suppression of the host defense mechanism by the viruses. Synergistic severe mosaic disease caused by simultaneous infection with isolates of the Cameroon strain of
African cassava mosaic virus
(ACMV-[CM]) and
East African cassava mosaic Cameroon virus
(EACMCV) in cassava and tobacco is characterized by a dramatic increase in symptom severity and a severalfold increase in viral-DNA accumulation by both viruses compared to that in singly infected plants. Here, we report that synergism between ACMV-[CM] and EACMCV is a two-way process, as the presence of the DNA-A component of ACMV-[CM] or EACMCV in
trans
enhanced the accumulation of viral DNA of EACMCV and ACMV-[CM], respectively, in tobacco BY-2 protoplasts. Furthermore, transient expression of ACMV-[CM] AC4 driven by the
Cauliflower mosaic virus
35S promoter (p35S-AC4) enhanced EACMCV DNA accumulation by ∼8-fold in protoplasts, while p35S-AC2 of EACMCV enhanced ACMV-[CM] DNA accumulation, also by ∼8-fold. An
Agrobacterium
-based leaf infiltration assay determined that ACMV-[CM] AC4 and EACMCV AC2, the putative synergistic genes, were able to suppress PTGS induced by green fluorescent protein (GFP) and eliminated the short interfering RNAs associated with PTGS, with a correlated increase in GFP mRNA accumulation. In addition, we have identified AC4 of
Sri Lankan cassava mosaic virus
and AC2 of
Indian cassava mosaic virus
as suppressors of PTGS, indicating that geminiviruses evolved differently in regard to interaction with the host. The specific and different roles played by these AC2 and AC4 proteins of cassava geminiviruses in regulating anti-PTGS activity and their relation to synergism are discussed.
Human Cytomegalovirus Tegument Proteins ppUL82 (pp71) and ppUL35 Interact and Cooperatively Activate the Major Immediate-Early Enhancer
Authors: Schierling Karina , Stamminger Thomas , Mertens Thomas , Winkler Michael 
Published: August 2004

ABSTRACT
The tegument protein ppUL82 (pp71) of human cytomegalovirus (HCMV) has previously been shown to activate the immediate-early transcription of HCMV and to enhance the infectivity of viral DNA. This is concordant with its localization adjacent to promyelocytic leukemia oncogenic domains (PODs) immediately after infection. In a yeast two-hybrid screen, we identified the tegument protein ppUL35 as an interacting partner of ppUL82. The interaction could be confirmed in transfected and infected cells. The domain responsible for interaction was narrowed down to amino acids 447 to 516 within ppUL35, thus allowing both forms of ppUL35 to interact with ppUL82. Immunofluorescence experiments showed a relocalization of ppUL35 from a diffuse nuclear pattern when expressed alone to PODs when expressed together with ppUL82. In accordance with this observation and the role of ppUL82 as a transactivator, we observed a cooperative activation of the HCMV major immediate-early enhancer but not of heterologous viral enhancer elements. These results suggest an important role for this interaction in the stimulation of viral immediate-early gene expression and viral infection.
Pathogenesis of Acute Viral Disease Induced in Fish by Carp Interstitial Nephritis and Gill Necrosis Virus
Authors: Pikarsky Eli , Ronen Ariel , Abramowitz Julia , Levavi-Sivan Berta , Hutoran Marina , Shapira Yechiam , Steinitz Michael , Perelberg Ayana , Soffer Dov , Kotler Moshe 
Published: August 2004

ABSTRACT

A lethal disease of koi and common carp (species
Cyprinus carpio
) has afflicted many fish farms worldwide since 1998, causing severe financial losses. Morbidity and mortality are restricted to common carp and koi and appear in spring and autumn, when water temperatures are 18 to 28°C. We have isolated the virus causing the disease from sick fish, propagated it in koi fin cell culture, and shown that virus from a single clone causes lethal disease in carp and koi upon infection. Intraperitoneal virus injection or bathing the fish in virus-containing water kills 85 to 100% of the fish within 7 to 21 days. This virus is similar to the previously reported koi herpesvirus; however, it has characteristics inconsistent with the herpesvirus family, and thus we have called it carp interstitial nephritis and gill necrosis virus. We examined the pathobiology of this disease in carp by using immunohistochemistry and PCR. We found large amounts of the virus in the kidneys of sick fish and smaller amounts in liver and brain. A rapid increase in the viral load in the kidneys was detected by using both immunofluorescence and semiquantitative PCR. Histological analyses of fish at various times after infection revealed signs of interstitial nephritis as early as 2 days postinfection, which increased in severity up to 10 days postinfection. There was severe gill disease evidenced by loss of villi with accompanying inflammation in the gill rakers. Minimal focal inflammation was noted in livers and brains. This report describes the etiology and pathology of a recently described viral agent in fish.
Model Suggesting that Replication of Influenza Virus Is Regulated by Stabilization of Replicative Intermediates
Authors: Vreede Frank T. , Jung Tanis E. , Brownlee George G. 
Published: August 2004

ABSTRACT
The RNA-dependent RNA polymerase of influenza A virus is responsible for both transcription and replication of negative-sense viral RNA. It is thought that a “switching” mechanism regulates the transition between these activities. We demonstrate that, in the presence of preexisting viral RNA polymerase and nucleoprotein (NP), influenza A virus synthesizes both mRNA (transcription) and cRNA (replication) early in infection. We suggest that there may be no switch regulating the initiation of RNA synthesis and present a model suggesting that nascent cRNA is degraded by host cell nucleases unless it is stabilized by newly synthesized viral RNA polymerase and NP.
The importance of the past in public health
Authors: Scally Gabriel , Womack Justine 
Published: August 2004

Study objective:To explore the role of history in public health and its relevance to current practice and professional development.Design:An analysis of the issues surrounding the poor attention paid to the history of public health by its current practitioners.Setting:The paper is written from the perspective of practitioners in the UK but has wide applicability.Main results:The paper makes the case that the current neglect of public health history is to the detriment of public health practice.Conclusions:There is a strong case for more attention to be paid to public health history in professional formation, development, and communication.
IgA multiple myeloma presenting as non-obstructive jaundice
Authors: Arebi N , Patel B , Aqel N M , Pitcher M C L 
Published: August 2004

AbstractMultiple myeloma can occasionally present with jaundice. The underlying process may be pancreatic head myeloma infiltration causing obstructive jaundice or hepatic amyloid deposition resulting in cholestatic jaundice. A rare case of myeloma presenting as jaundice due to hepatic myeloma infiltration is reported.
Value of routine duodenal biopsy in diagnosing coeliac disease in patients with iron deficiency anaemia
Authors: Mandal A K , Mehdi I , Munshi S K , Lo T C N 
Published: August 2004

Abstract
Background: Iron deficiency anaemia (IDA) is a recognised feature of coeliac disease in adults and can be its only presentation.
Objective: To determine the yield of routine distal duodenal biopsies in diagnosing coeliac disease in adult and elderly patients with IDA whose endoscopy revealed no upper gastrointestinal cause of iron deficiency.
Study design: Prospective study in a teaching hospital endoscopy unit.
Method: Altogether 504 consecutive patients with IDA, aged 16–80 years, attending for endoscopy were included in this study. At least two distal duodenal biopsies were taken if endoscopy revealed no cause of iron deficiency.
Result: In nine (1.8%) patients duodenal biopsies revealed typical histological features of coeliac disease. Of these, five patients were above 65 years old.
Conclusion: In adult and elderly patients undergoing endoscopy for IDA, the endoscopist should take distal duodenal biopsies to exclude coeliac disease if no upper gastrointestinal cause of anaemia is found. Coeliac disease is not an uncommon cause of IDA in patients &gt;65 years of age and a history of chronic diarrhoea increases diagnostic yield in this age group.
Introduction to history taking and principles of sexual health
Authors: Jones R , Barton S 
Published: August 2004

Abstract
Sexual health has a profound influence over an individual’s physical and psychological wellbeing. There is an increasing need to develop effective strategies to reduce the incidence of sexually transmitted infections (STIs) globally. Many STIs are asymptomatic and yet, highly infectious. The sequelae of such infections may be catastrophic and hence, an integrated multidisciplinary and preventative approach to the control of STIs is clearly necessary. Sexual history taking holds the key to the practice of sexual health medicine. It provides the basis for treatment, prevention, education, and sexual health promotion.