| development & evaluation of biotinylated dna probe for clinical diagnosis of chikungunya infection in patients' acute phase serum & csf samples. | the resurgence of chikungunya virus (chikv) in the indian ocean islands and india has drawn worldwide attention due to its explosive nature, high morbidity and complex clinico-pathological manifestations. the early confirmatory diagnosis of chikv is essential for management as well as control of unprecedented epidemics. the present study describes the development and evaluation of a highly sensitive and specific e1 structural gene specific biotinylated dna probe for detection of chikungunya viru ... | 0 | 24056565 |
| hypervariable domain of nonstructural protein nsp3 of venezuelan equine encephalitis virus determines cell-specific mode of virus replication. | venezuelan equine encephalitis virus (veev) is one of the most pathogenic members of the alphavirus genus in the togaviridae family. this genus is divided into the old world and new world alphaviruses, which demonstrate profound differences in pathogenesis, replication, and virus-host interactions. veev is a representative member of the new world alphaviruses. the biology of this virus is still insufficiently understood, particularly the function of its nonstructural proteins in rna replication ... | 2013 | 23637407 |
| mhc class ii-alpha chain knockout mice support increased viral replication that is independent of their lack of mhc class ii cell surface expression and associated immune function deficiencies. | mhcii molecules are heterodimeric cell surface proteins composed of an α and β chain. these molecules are almost exclusively expressed on thymic epithelium and antigen presenting cells (apcs) and play a central role in the development and function of cd4 t cells. various mhc-ii knockout mice have been generated including mhc-iiaα(-/-) (i-aα(-/-)), mhc-iiaβ(-/-) (i-β(-/-)) and the double knockout (i-aαxβ(-/-)). here we report a very striking observation, namely that alphaviruses including the avi ... | 2013 | 23840854 |
| the role of innate versus adaptive immune responses in a mouse model of o'nyong-nyong virus infection. | o'nyong-nyong virus (onnv), an alphavirus closely related to chikungunya virus (chikv), has caused three major epidemics in africa since 1959. both onnv and chikv produce similar syndromes with fever, rash, and debilitating arthralgia. to determine the roles of the innate and adaptive immune responses, we infected different knockout mice with two strains of onnv (sg650 and mp30). wild-type, rag1 ko, and ifnγr ko mice showed no signs of illness or viremia. the stat1 ko and a129 mice exhibited 50- ... | 2013 | 23568285 |
| viruses and antiviral immunity in drosophila. | viral pathogens present many challenges to organisms, driving the evolution of a myriad of antiviral strategies to combat infections. a wide variety of viruses infect invertebrates, including both natural pathogens that are insect-restricted, and viruses that are transmitted to vertebrates. studies using the powerful tools in the model organism drosophila have expanded our understanding of antiviral defenses against diverse viruses. in this review, we will cover three major areas. first, we will ... | 2013 | 23680639 |
| a fully attenuated recombinant salmonid alphavirus becomes pathogenic through a single amino acid change in the e2 glycoprotein. | a recombinant sleeping disease virus (rsdv) was previously shown to be totally attenuated and provide long-term protection in trout (c. moriette, m. leberre, a. lamoureux, t. l. lai, m. brémont, j. virol. 80:4088-4098, 2006). sequence comparison of the rsdv to wild-type genomes exhibited a number of nucleotide changes. in the current study, we demonstrate that the virulent phenotype of sdv was essentially associated with two amino acid changes, v8a and m136t, in the e2 glycoprotein, with the v8a ... | 2013 | 23449806 |
| structural analyses at pseudo atomic resolution of chikungunya virus and antibodies show mechanisms of neutralization. | a 5.3 å resolution, cryo-electron microscopy (cryoem) map of chikungunya virus-like particles (vlps) has been interpreted using the previously published crystal structure of the chikungunya e1-e2 glycoprotein heterodimer. the heterodimer structure was divided into domains to obtain a good fit to the cryoem density. differences in the t = 4 quasi-equivalent heterodimer components show their adaptation to different environments. the spikes on the icosahedral 3-fold axes and those in general positi ... | 2013 | 23577234 |
| predictors of chikungunya rheumatism: a prognostic survey ancillary to the telechik cohort study. | long-lasting relapsing or lingering rheumatic musculoskeletal pain (rmsp) is the hallmark of chikungunya virus (chikv) rheumatism (chik-r). little is known on their prognostic factors. the aim of this prognostic study was to search the determinants of lingering or relapsing rmsp indicative of chik-r. | 2013 | 23302155 |
| diversity in glycosaminoglycan binding amongst hmpv g protein lineages. | we have previously shown that hmpv g protein (b2 lineage) interacts with cellular glycosaminoglycans (gags). in this study we examined subtypes a1, a2 and b1 for this interaction. gag-dependent infectivity of available hmpv strains was demonstrated using gag-deficient cells and heparin competition. we expressed the g protein ectodomains from all strains and analysed these by heparin affinity chromatography. in contrast to the b2 lineage, neither the a2 or b1 g proteins bound to heparin. sequence ... | 2012 | 23242371 |
| probing the early temporal and spatial interaction of the sindbis virus capsid and e2 proteins with reverse genetics. | a 7-å cryoelectron microscopy-based reconstruction of sindbis virus (sinv) was recently generated. fitting the crystal structure of the sinv capsid protein (cp) into the density map revealed that the f2-g2 loop of the cp was shifted away from cytoplasmic domain of e2 (cde2) in the 7-å reconstruction relative to its position in the cp crystal structure. furthermore, the reconstruction demonstrated that residue e395 in region i of the cytoplasmic domain of the e2 envelope protein (cde2-ri) and k25 ... | 2012 | 22951842 |
| chikungunya virus and prospects for a vaccine. | in 2004, chikungunya virus (chikv) re-emerged from east africa to cause devastating epidemics of debilitating and often chronic arthralgia that have affected millions of people in the indian ocean basin and asia. more limited epidemics initiated by travelers subsequently occurred in italy and france, as well as human cases exported to most regions of the world, including the americas where chikv could become endemic. because chikv circulates during epidemics in an urban mosquito-human cycle, con ... | 0 | 23151166 |
| interferon response factors 3 and 7 protect against chikungunya virus hemorrhagic fever and shock. | chikungunya virus (chikv) infections can produce severe disease and mortality. here we show that chikv infection of adult mice deficient in interferon response factors 3 and 7 (irf3/7(-/-)) is lethal. mortality was associated with undetectable levels of alpha/beta interferon (ifn-α/β) in serum, ∼50- and ∼10-fold increases in levels of ifn-γ and tumor necrosis factor (tnf), respectively, increased virus replication, edema, vasculitis, hemorrhage, fever followed by hypothermia, oliguria, thrombocy ... | 2012 | 22761364 |
| eilat virus, a unique alphavirus with host range restricted to insects by rna replication. | most alphaviruses and many other arboviruses are mosquito-borne and exhibit a broad host range, infecting many different vertebrates including birds, rodents, equids, humans, and nonhuman primates. consequently, they can be propagated in most vertebrate and insect cell cultures. this ability of arboviruses to infect arthropods and vertebrates is usually essential for their maintenance in nature. however, several flaviviruses have recently been described that infect mosquitoes but not vertebrates ... | 2012 | 22908261 |
| genomic characterization of a novel virus of the family tymoviridae isolated from mosquitoes. | the family tymoviridae comprises three plant virus genera, including tymovirus, marafivirus, and maculavirus, which are found in most parts of the world and cause severe agricultural losses. we describe a putatively novel member of the family tymoviridae, which is isolated from mosquitoes (culex spp.), referred to as cutlv. | 2012 | 22848363 |
| attenuation of chikungunya virus vaccine strain 181/clone 25 is determined by two amino acid substitutions in the e2 envelope glycoprotein. | chikungunya virus (chikv) is the mosquito-borne alphavirus that is the etiologic agent of massive outbreaks of arthralgic febrile illness that recently affected millions of people in africa and asia. the only chikv vaccine that has been tested in humans, strain 181/clone 25, is a live-attenuated derivative of southeast asian human isolate strain af15561. the vaccine was immunogenic in phase i and ii clinical trials; however, it induced transient arthralgia in 8% of the vaccinees. there are five ... | 2012 | 22457519 |
| early events in alphavirus replication determine the outcome of infection. | alphaviruses are a group of important human and animal pathogens. they efficiently replicate to high titers in vivo and in many commonly used cell lines of vertebrate origin. they have also evolved effective means of interfering with development of the innate immune response. nevertheless, most of the alphaviruses are known to induce a type i interferon (ifn) response in vivo. the results of this study demonstrate that the first hours postinfection play a critical role in infection spread and de ... | 2012 | 22345447 |
| glycogen synthase kinase 3β (gsk3β) modulates antiviral activity of zinc-finger antiviral protein (zap). | zinc-finger antiviral protein (zap) is a host factor that specifically inhibits the replication of certain viruses, including hiv-1, ebola virus, and sindbis virus. zap binds directly to specific viral mrnas and recruits cellular mrna degradation machinery to degrade the target rna. zap has also been suggested to repress translation of the target mrna. in this study, we report that zap is phosphorylated by glycogen synthase kinase 3β (gsk3β). gsk3β sequentially phosphorylated ser-270, ser-266, s ... | 2012 | 22514281 |
| genetic and anatomic determinants of enzootic venezuelan equine encephalitis virus infection of culex (melanoconion) taeniopus. | venezuelan equine encephalitis (vee) is a re-emerging, mosquito-borne viral disease with the potential to cause fatal encephalitis in both humans and equids. recently, detection of endemic vee caused by enzootic strains has escalated in mexico, peru, bolivia, colombia and ecuador, emphasizing the importance of understanding the enzootic transmission cycle of the etiologic agent, vee virus (veev). the majority of work examining the viral determinants of vector infection has been performed in the ... | 2012 | 22509419 |
| the three-dimensional structure of frozen-hydrated nudaurelia capensis beta virus, a t = 4 insect virus. | the three-dimensional structure of nudaurelia capensis beta virus (n beta v) was reconstructed to 3.2-nm resolution from images of frozen-hydrated virions. the distinctly icosahedral capsid (approximately 40-nm diameter) contains 240 copies of a single 61-kda protein subunit arranged with t = 4 lattice symmetry. the outer surface of unstained virions compares remarkably well with that previously observed in negatively stained specimens. inspection of the density map, volume estimates, and model ... | 0 | 1712620 |
| unfolded protein response in hepatitis c virus infection. | hepatitis c virus (hcv) is a single-stranded, positive-sense rna virus of clinical importance. the virus establishes a chronic infection and can progress from chronic hepatitis, steatosis to fibrosis, cirrhosis, and hepatocellular carcinoma (hcc). the mechanisms of viral persistence and pathogenesis are poorly understood. recently the unfolded protein response (upr), a cellular homeostatic response to endoplasmic reticulum (er) stress, has emerged to be a major contributing factor in many human ... | 2014 | 24904547 |
| the c-terminal repeat domains of nsp3 from the old world alphaviruses bind directly to g3bp. | the old world alphaviruses block stress granule assembly by sequestration of rasgap sh3-domain binding protein (g3bp). here, we show that the proline-rich sequences in the hypervariable domain of nonstructural protein 3 (nsp3) of both semliki forest virus and chikungunya virus were dispensable for binding to g3bp. nsp3 variants with or without this domain colocalized with g3bp. furthermore, we show that the c-terminal repeat motifs of nsp3 were sufficient for g3bp binding. | 2014 | 24623412 |
| enhanced production of chikungunya virus-like particles using a high-ph adapted spodoptera frugiperda insect cell line. | chikungunya virus-like particles (vlps) have potential to be used as a prophylactic vaccine based on testing in multiple animal models and are currently being evaluated for human use in a phase i clinical trial. the current method for producing these enveloped alphavirus vlps by transient gene expression in mammalian cells presents challenges for scalable and robust industrial manufacturing, so the insect cell baculovirus expression vector system was evaluated as an alternative expression techno ... | 2014 | 24713807 |
| interferon-stimulated genes: roles in viral pathogenesis. | interferon-stimulated genes (isgs) are critical for controlling virus infections. as new antiviral isgs continue to be identified and characterized, their roles in viral pathogenesis are also being explored in more detail. our current understanding of how isgs impact viral pathogenesis comes largely from studies in knockout mice, with isolated examples from human clinical data. this review outlines recent developments on the contributions of various isgs to viral disease outcomes in vivo. | 2014 | 24713352 |
| enhancement of antitumor immunity using a dna-based replicon vaccine derived from semliki forest virus. | a dna-based replicon vaccine derived from semliki forest virus, psvk-shfcg-gm/b7.1 (fig. 1a) was designed for tumor immunotherapy as previously constructed. the expression of the fusion tumor antigen (survivin and hcgβ-ctp37) and adjuvant molecular protein (granulocyte-macrophage colony-stimulating factor/ gm-csf/b7.1) genes was confirmed by immunofluorescence assay in vitro, and immunohistochemistry assay in vivo. in this paper, the immunological effect of this vaccine was determined using immu ... | 2014 | 24608380 |
| efficient transfection of dissociated mouse chromaffin cells using small-volume electroporation. | we have developed an improved procedure for isolating and transfecting a chromaffin cell-enriched population of primary cells from adult mouse adrenal glands. significantly, the parameters of a novel electroporation transfection technique were optimized to achieve an average transfection efficiency of 45 % on the small number of cells derived from the mouse glands. such transfection efficiency was previously unachievable with the electroporation protocols conventionally used with bovine chromaff ... | 2014 | 24549789 |
| relating structure to evolution in class ii viral membrane fusion proteins. | enveloped viruses must fuse their lipid membrane to a cellular membrane to deliver the viral genome into the cytoplasm for replication. viral envelope proteins catalyze this critical membrane fusion event. they fall into at least three distinct structural classes. class ii fusion proteins have a conserved three-domain architecture and are found in many important viral pathogens. until 2013, class ii proteins had only been found in flaviviruses and alphaviruses. however, in 2013 a class ii fusion ... | 2014 | 24525225 |
| the major cellular sterol regulatory pathway is required for andes virus infection. | the bunyaviridae comprise a large family of rna viruses with worldwide distribution and includes the pathogenic new world hantavirus, andes virus (andv). host factors needed for hantavirus entry remain largely enigmatic and therapeutics are unavailable. to identify cellular requirements for andv infection, we performed two parallel genetic screens. analysis of a large library of insertionally mutagenized human haploid cells and a sirna genomic screen converged on components (srebp-2, scap, s1p a ... | 2014 | 24516383 |
| interferon-stimulated poly(adp-ribose) polymerases are potent inhibitors of cellular translation and virus replication. | the innate immune response is the first line of defense against most viral infections. its activation promotes cell signaling, which reduces virus replication in infected cells and leads to induction of the antiviral state in yet-uninfected cells. this inhibition of virus replication is a result of the activation of a very broad spectrum of specific cellular genes, with each of their products usually making a small but detectable contribution to the overall antiviral state. the lack of a strong, ... | 2013 | 24335297 |
| salmonid alphavirus replication in mosquito cells: towards a novel vaccine production system. | salmonid alphavirus (sav) causes pancreas disease and sleeping disease in atlantic salmon (salmo salar) and rainbow trout (oncorhynchus mykiss) and confers a major burden to the aquaculture industry. a commercial inactivated whole virus vaccine propagated in a salmon cell line at low temperature provides effective protection against sav infections. alphaviruses (family togaviridae) are generally transmitted between vertebrate hosts via blood-sucking arthropod vectors, typically mosquitoes. sav i ... | 2014 | 24418177 |
| recent developments in preclinical dna vaccination. | the advantages of genetic immunization of the new vaccine using plasmid dnas are multifold. for example, it is easy to generate plasmid dnas, increase their dose during the manufacturing process, and sterilize them. furthermore, they can be stored for a long period of time upon stabilization, and their protein encoding sequences can be easily modified by employing various dna-manipulation techniques. although dna vaccinations strongly increase th1-mediated immune responses in animals, several pr ... | 2014 | 26344468 |
| the role of innate immunity in conditioning mosquito susceptibility to west nile virus. | arthropod-borne viruses (arboviruses) represent an emerging threat to human and livestock health globally. in particular, those transmitted by mosquitoes present the greatest challenges to disease control efforts. an understanding of the molecular basis for mosquito innate immunity to arbovirus infection is therefore critical to investigations regarding arbovirus evolution, virus-vector ecology, and mosquito vector competence. in this review, we discuss the current state of understanding regardi ... | 2013 | 24351797 |
| human bocavirus in patients with encephalitis, sri lanka, 2009-2010. | we identified human bocavirus (hbov) dna by pcr in cerebrospinal fluid from adults and children with encephalitis in sri lanka. hbov types 1, 2, and 3 were identified among these cases. phylogenetic analysis of hbov1 strain sequences found no subclustering with strains previously identified among encephalitis cases in bangladesh. | 0 | 24188380 |
| the amino-terminal domain of alphavirus capsid protein is dispensable for viral particle assembly but regulates rna encapsidation through cooperative functions of its subdomains. | venezuelan equine encephalitis virus (veev) is a pathogenic alphavirus, which circulates in the central, south, and north americas, including the united states, and represents a significant public health threat. in recent years, strong progress has been made in understanding the structure of veev virions, but the mechanism of their formation has yet to be investigated. in this study, we analyzed the functions of different capsid-specific domains and its amino-terminal subdomains in viral particl ... | 2013 | 24006447 |
| infectious bronchitis virus generates spherules from zippered endoplasmic reticulum membranes. | replication of positive-sense rna viruses is associated with the rearrangement of cellular membranes. previous work on the infection of tissue culture cell lines with the betacoronaviruses mouse hepatitis virus and severe acute respiratory syndrome coronavirus (sars-cov) showed that they generate double-membrane vesicles (dmvs) and convoluted membranes as part of a reticular membrane network. here we describe a detailed study of the membrane rearrangements induced by the avian gammacoronavirus i ... | 2013 | 24149513 |
| control of the rescue and replication of semliki forest virus recombinants by the insertion of mirna target sequences. | due to their broad cell- and tissue-tropism, alphavirus-based replication-competent vectors are of particular interest for anti-cancer therapy. these properties may, however, be potentially hazardous unless the virus infection is controlled. while the rna genome of alphaviruses precludes the standard control techniques, host mirnas can be used to down-regulate viral replication. in this study, target sites from ubiquitous mirnas and those of mirnas under-represented in cervical cancer cells were ... | 2013 | 24098728 |
| a fusion-inhibiting peptide against rift valley fever virus inhibits multiple, diverse viruses. | for enveloped viruses, fusion of the viral envelope with a cellular membrane is critical for a productive infection to occur. this fusion process is mediated by at least three classes of fusion proteins (class i, ii, and iii) based on the protein sequence and structure. for rift valley fever virus (rvfv), the glycoprotein gc (class ii fusion protein) mediates this fusion event following entry into the endocytic pathway, allowing the viral genome access to the cell cytoplasm. here, we show that p ... | 2013 | 24069485 |
| rig-i and mda-5 detection of viral rna-dependent rna polymerase activity restricts positive-strand rna virus replication. | type i interferons (ifn) are important for antiviral responses. melanoma differentiation-associated gene 5 (mda-5) and retinoic acid-induced gene i (rig-i) proteins detect cytosolic double-stranded rna (dsrna) or 5'-triphosphate (5'-ppp) rna and mediate ifn production. cytosolic 5'-ppp rna and dsrna are generated during viral rna replication and transcription by viral rna replicases [rna-dependent rna polymerases (rdrp)]. here, we show that the semliki forest virus (sfv) rna replicase can induce ... | 2013 | 24039580 |
| virus infection, antiviral immunity, and autoimmunity. | as a group of disorders, autoimmunity ranks as the third most prevalent cause of morbidity and mortality in the western world. however, the etiology of most autoimmune diseases remains unknown. although genetic linkage studies support a critical underlying role for genetics, the geographic distribution of these disorders as well as the low concordance rates in monozygotic twins suggest that a combination of other factors including environmental ones are involved. virus infection is a primary fac ... | 0 | 23947356 |
| imaging of the alphavirus capsid protein during virus replication. | alphaviruses are enveloped viruses with highly organized structures. the nucleocapsid (nc) core contains a capsid protein lattice enclosing the plus-sense rna genome, and it is surrounded by a lipid bilayer containing a lattice of the e1 and e2 envelope glycoproteins. capsid protein is synthesized in the cytoplasm and particle budding occurs at the plasma membrane (pm), but the traffic and assembly of viral components and the exit of virions from host cells are not well understood. to visualize ... | 2013 | 23785213 |
| magnetic fractionation and proteomic dissection of cellular organelles occupied by the late replication complexes of semliki forest virus. | alphavirus replicase complexes are initially formed at the plasma membrane and are subsequently internalized by endocytosis. during the late stages of infection, viral replication organelles are represented by large cytopathic vacuoles, where replicase complexes bind to membranes of endolysosomal origin. in addition to viral components, these organelles harbor an unknown number of host proteins. in this study, a fraction of modified lysosomes carrying functionally intact replicase complexes was ... | 2013 | 23864636 |
| presentation overrides specificity: probing the plasticity of alphaviral proteolytic activity through mutational analysis. | semliki forest virus (genus alphavirus) is an important model for studying regulated nonstructural (ns) polyprotein processing. in this study, we evaluated the strictness of the previously outlined cleavage rules, accounting for the timing and outcome of each of three cleavages within the ns polyprotein p1234, and assessed the significance of residues p6 to p4 within the cleavage sites using an alanine scanning approach. the processing of the 1/2 and 3/4 sites was most strongly affected followin ... | 2013 | 23864614 |
| a compact viral processing proteinase/ubiquitin hydrolase from the otu family. | turnip yellow mosaic virus (tymv)--a member of the alphavirus-like supergroup of viruses--serves as a model system for positive-stranded rna virus membrane-bound replication. tymv encodes a precursor replication polyprotein that is processed by the endoproteolytic activity of its internal cysteine proteinase domain (pro). we recently reported that pro is actually a multifunctional enzyme with a specific ubiquitin hydrolase (dub) activity that contributes to viral infectivity. here, we report the ... | 2013 | 23966860 |
| template rna length determines the size of replication complex spherules for semliki forest virus. | the replication complexes of positive-strand rna viruses are always associated with cellular membranes. the morphology of the replication-associated membranes is altered in different ways in different viral systems, but many viruses induce small membrane invaginations known as spherules as their replication sites. we show here that for semliki forest virus (sfv), an alphavirus, the size of the spherules is tightly connected with the length of the replicating rna template. cells with different mo ... | 2013 | 23760239 |
| characterization of an early-stage fusion intermediate of sindbis virus using cryoelectron microscopy. | the sequential steps in the alphavirus membrane fusion pathway have been postulated based on the prefusion and postfusion crystal structures of the viral fusion protein e1 in conjunction with biochemical studies. however, the molecular structures of the hypothesized fusion intermediates have remained obscure due to difficulties inherent in the dynamic nature of the process. we developed an experimental system that uses liposomes as the target membrane to capture sindbis virus, a prototypical alp ... | 2013 | 23898184 |
| virus replicon particle based chikungunya virus neutralization assay using gaussia luciferase as readout. | chikungunya virus (chikv) has been responsible for large epidemic outbreaks causing fever, headache, rash and severe arthralgia. so far, no specific treatment or vaccine is available. as nucleic acid amplification can only be used during the viremic phase of the disease, serological tests like neutralization assays are necessary for chikv diagnosis and for determination of the immune status of a patient. furthermore, neutralization assays represent a useful tool to validate the efficacy of poten ... | 2013 | 23855906 |
| knockdown of pirna pathway proteins results in enhanced semliki forest virus production in mosquito cells. | the exogenous sirna pathway is important in restricting arbovirus infection in mosquitoes. less is known about the role of the piwi-interacting rna pathway, or pirna pathway, in antiviral responses. viral pirna-like molecules have recently been described following infection of mosquitoes and derived cell lines with several arboviruses. the pirna pathway has thus been suggested to function as an additional small rna-mediated antiviral response to the known infection-induced sirna response. here w ... | 2013 | 23559478 |
| cross-inhibition of chikungunya virus fusion and infection by alphavirus e1 domain iii proteins. | alphaviruses are small enveloped rna viruses that include important emerging human pathogens, such as chikungunya virus (chikv). these viruses infect cells via a low-ph-triggered membrane fusion reaction, making this step a potential target for antiviral therapies. the e1 fusion protein inserts into the target membrane, trimerizes, and refolds to a hairpin-like conformation in which the combination of e1 domain iii (diii) and the stem region (diii-stem) pack against a core trimer composed of e1 ... | 2013 | 23637415 |
| reconstruction of h3n2 influenza virus based virosome in-vitro. | virosomes are virus like particles (vlp) assembled in-vitro. influenza virosomes maintain the cell binding and membrane fusion activity of the wild type virus but are devoid of viral genetic material or internal proteins. influenza virosomes mimic the natural antigen presentation route of the influenza virus. | 0 | 23825736 |
| comparative analysis of the genome sequences and replication profiles of chikungunya virus isolates within the east, central and south african (ecsa) lineage. | a comparative analysis of the genomic and replication profiles of different geographical chikungunya virus (chikv) isolates of the east, central and south african (ecsa) lineage was performed. | 2013 | 23721429 |
| role for subgenomic mrna in host translation inhibition during sindbis virus infection of mammalian cells. | sindbis virus subgenomic mrna is efficiently translated in infected vertebrate cells whereas host translation is shut-off. deletions in the 5'utr of the subgenomic mrna were made to investigate its role in viral gene expression. deletion of nucleotides 1-10 and 11-20 caused a small plaque phenotype, reduced levels of subgenomic mrna and structural proteins, and increased expression of nonstructural proteins. whereas deletion 1-10 virus inhibited cellular protein synthesis, deletion 11-20 did so ... | 2013 | 23601784 |
| a key interaction between the alphavirus envelope proteins responsible for initial dimer dissociation during fusion. | alphaviruses such as semliki forest virus (sfv) are enveloped viruses whose surface is covered by an organized lattice composed of trimers of e2-e1 heterodimers. the e1 envelope protein, a class ii fusion protein, contains the hydrophobic fusion loop and refolds to drive virus fusion with the endosome membrane. the e2 protein is synthesized as a precursor p62, whose processing by furin primes the heterodimer for dissociation during virus entry. dissociation of the e2-e1 heterodimer is an essenti ... | 2013 | 23325694 |
| statistical analysis of sizes and shapes of virus capsids and their resulting elastic properties. | from the analysis of sizes of approximately 130 small icosahedral viruses we find that there is a typical structural capsid protein, having a mean diameter of 5 nm and a mean thickness of 3 nm, with more than two thirds of the analyzed capsid proteins having thicknesses between 2 nm and 4 nm. to investigate whether, in addition to the fairly conserved geometry, capsid proteins show similarities in the way they interact with one another, we examined the shapes of the capsids in detail. we classif ... | 2013 | 23860870 |
| recruitment and retention of b cells in the central nervous system in response to alphavirus encephalomyelitis. | sindbis virus (sinv) infection of neurons results in nonfatal viral encephalomyelitis and provides a model system for understanding recovery from virus infection of the central nervous system (cns). infection is followed by clearance of infectious virus, a gradual decrease in viral rna, and then long-term maintenance of low levels of viral rna. antibody to the e2 glycoprotein is important for virus clearance, and b cells enter the cns along with cd4(+) and cd8(+) t cells during the early clearan ... | 2012 | 23255791 |
| intrathecal humoral immunity to encephalitic rna viruses. | the nervous system is the target for acute encephalitic viral infections, as well as a reservoir for persisting viruses. intrathecal antibody (ab) synthesis is well documented in humans afflicted by infections associated with neurological complications, as well as the demyelinating disease, multiple sclerosis. this review focuses on the origin, recruitment, maintenance, and biological relevance of ab-secreting cells (asc) found in the central nervous system (cns) following experimental neurotrop ... | 2013 | 23435240 |
| structure and antimicrobial properties of monensin a and its derivatives: summary of the achievements. | in this paper structural and microbiological studies on the ionophorous antibiotic monensin a and its derivatives have been collected. monensin a is an ionophore which selectively complexes and transports sodium cation across lipid membranes, and therefore it shows a variety of biological properties. this antibiotic is commonly used as coccidiostat and nonhormonal growth promoter. the paper focuses on both the latest and earlier achievements concerning monensin a antimicrobial activity. the acti ... | 2013 | 23509771 |
| bst-2/tetherin-mediated restriction of chikungunya (chikv) vlp budding is counteracted by chikv non-structural protein 1 (nsp1). | chikungunya virus (chikv) is a re-emerging alphavirus transmitted by aedes mosquitoes. infection with chikv elicits a type i interferon response that facilities virus clearance, probably through the action of down-stream effectors such as antiviral ifn-stimulated genes (isgs). bone marrow stromal antigen 2 (bst-2) is an isg shown to restrict hiv-1 replication by preventing the infection of bystander cells by tethering progeny virions on the surface of infected cells. here we show that enrichment ... | 2013 | 23411007 |
| dicer-2 processes diverse viral rna species. | rna silencing pathways play critical roles in gene regulation, virus infection, and transposon control. rna interference (rnai) is mediated by small interfering rnas (sirnas), which are liberated from double-stranded (ds)rna precursors by dicer and guide the rna-induced silencing complex (risc) to targets. although principles governing small rna sorting into risc have been uncovered, the spectrum of rna species that can be targeted by dicer proteins, particularly the viral rnas present during an ... | 2013 | 23424633 |
| pseudoinfectious venezuelan equine encephalitis virus: a new means of alphavirus attenuation. | venezuelan equine encephalitis virus (veev) is a reemerging virus that causes a severe and often fatal disease in equids and humans. in spite of a continuous public health threat, to date, no vaccines or antiviral drugs have been developed for human use. experimental vaccines demonstrate either poor efficiency or severe adverse effects. in this study, we developed a new strategy of alphavirus modification aimed at making these viruses capable of replication and efficient induction of the immune ... | 2012 | 23221545 |
| hypervariable domains of nsp3 proteins of new world and old world alphaviruses mediate formation of distinct, virus-specific protein complexes. | alphaviruses are a group of single-stranded rna viruses with genomes of positive polarity. they are divided into two geographically isolated groups: the old world and the new world alphaviruses. despite their similar genome organizations and virion structures, they differ in many aspects of pathogenesis and interaction with the host cell. here we present new data highlighting previously unknown differences between these two groups. we found that nsp3 proteins of sindbis virus (sinv) and venezuel ... | 2012 | 23221551 |
| o'nyong nyong virus molecular determinants of unique vector specificity reside in non-structural protein 3. | o'nyong nyong virus (onnv) and chikungunya virus (chikv) are two closely related alphaviruses with very different infection patterns in the mosquito, anopheles gambiae. onnv is the only alphavirus transmitted by anopheline mosquitoes, but specific molecular determinants of infection of this unique vector specificity remain unidentified. fifteen distinct chimeric viruses were constructed to evaluate both structural and non-structural regions of the genome and infection patterns were determined th ... | 2013 | 23359824 |
| attenuation of semliki forest virus neurovirulence by microrna-mediated detargeting. | artificial target sequences for tissue-specific mirnas have recently been introduced as a new means for altering the tissue tropism of viral replication. this approach can be used to improve the safety of oncolytic viruses for cancer virotherapy by restricting their replication in unwanted tissues, such as the liver. semliki forest virus (sfv) is a positive-strand rna virus and, similar to the related alphaviruses, like sindbis virus, has potential as a gene therapy vector and an oncolytic virot ... | 2012 | 23077310 |
| construction and organization of a bsl-3 cryo-electron microscopy laboratory at utmb. | a unique cryo-electron microscopy facility has been designed and constructed at the university of texas medical branch (utmb) to study the three-dimensional organization of viruses and bacteria classified as select agents at biological safety level (bsl)-3, and their interactions with host cells. a 200kev high-end cryo-electron microscope was installed inside a bsl-3 containment laboratory and standard operating procedures were developed and implemented to ensure its safe and efficient operation ... | 2012 | 23274136 |
| sequestration of g3bp coupled with efficient translation inhibits stress granules in semliki forest virus infection. | dynamic, mrna-containing stress granules (sgs) form in the cytoplasm of cells under environmental stresses, including viral infection. many viruses appear to employ mechanisms to disrupt the formation of sgs on their mrnas, suggesting that they represent a cellular defense against infection. here, we report that early in semliki forest virus infection, the c-terminal domain of the viral nonstructural protein 3 (nsp3) forms a complex with ras-gap sh3-domain-binding protein (g3bp) and sequesters i ... | 2012 | 23087212 |
| crystal structure of aura virus capsid protease and its complex with dioxane: new insights into capsid-glycoprotein molecular contacts. | the nucleocapsid core interaction with endodomains of glycoproteins plays a critical role in the alphavirus life cycle that is essential to virus budding. recent cryo-electron microscopy (cryo-em) studies provide structural insights into key interactions between capsid protein (cp) and trans-membrane glycoproteins e1 and e2. cp possesses a chymotrypsin-like fold with a hydrophobic pocket at the surface responsible for interaction with glycoproteins. in the present study, crystal structures of th ... | 2012 | 23251484 |
| activation of double-stranded rna-activated protein kinase (pkr) by interferon-stimulated gene 15 (isg15) modification down-regulates protein translation. | the ubiquitin-like molecule isg15 (ucrp) and protein modification by isg15 (isgylation) are strongly induced by interferon, genotoxic stress, and pathogen infection, suggesting that isg15 plays an important role in innate immune responses. however, how isgylation contributes to innate immune responses is not clear. the dsrna-dependent protein kinase (pkr) inhibits translation by phosphorylating eif2α to exert its anti-viral effect. isg15 and pkr are induced by interferon, suggesting that a relat ... | 2012 | 23229543 |
| screening of dengue virus antiviral activity of marine seaweeds by an in situ enzyme-linked immunosorbent assay. | dengue is a significant public health problem worldwide. despite the important social and clinical impact, there is no vaccine or specific antiviral therapy for prevention and treatment of dengue virus (denv) infection. considering the above, drug discovery research for dengue is of utmost importance; in addition natural marine products provide diverse and novel chemical structures with potent biological activities that must be evaluated. in this study we propose a target-free approach for dengu ... | 2012 | 23227238 |
| the dna virus invertebrate iridescent virus 6 is a target of the drosophila rnai machinery. | rna viruses in insects are targets of an rna interference (rnai)-based antiviral immune response, in which viral replication intermediates or viral dsrna genomes are processed by dicer-2 (dcr-2) into viral small interfering rnas (vsirnas). whether dsdna virus infections are controlled by the rnai pathway remains to be determined. here, we analyzed the role of rnai in dna virus infection using drosophila melanogaster infected with invertebrate iridescent virus 6 (iiv-6) as a model. we show that d ... | 2012 | 23151511 |
| phenoloxidase activity acts as a mosquito innate immune response against infection with semliki forest virus. | several components of the mosquito immune system including the rna interference (rnai), jak/stat, toll and imd pathways have previously been implicated in controlling arbovirus infections. in contrast, the role of the phenoloxidase (po) cascade in mosquito antiviral immunity is unknown. here we show that conditioned medium from the aedes albopictus-derived u4.4 cell line contains a functional po cascade, which is activated by the bacterium escherichia coli and the arbovirus semliki forest virus ... | 2012 | 23144608 |
| virotherapy, gene transfer and immunostimulatory monoclonal antibodies. | malignant cells are susceptible to viral infection and consequent cell death. virus-induced cell death is endowed with features that are known to stimulate innate and adaptive immune responses. thus danger signals emitted by cells succumbing to viral infection as well as viral nucleic acids are detected by specific receptors, and tumor cell antigens can be routed to professional antigen-presenting cells. the anticancer immune response triggered by viral infection is frequently insufficient to er ... | 0 | 23243597 |
| dsrna-dependent protein kinase pkr and its role in stress, signaling and hcv infection. | the double-stranded rna-dependent protein kinase pkr plays multiple roles in cells, in response to different stress situations. as a member of the interferon (ifn)‑stimulated genes, pkr was initially recognized as an actor in the antiviral action of ifn, due to its ability to control translation, through phosphorylation, of the alpha subunit of eukaryotic initiation factor 2 (eif2a). as such, pkr participates in the generation of stress granules, or autophagy and a number of viruses have designe ... | 2012 | 23202496 |
| gcn2 has inhibitory effect on human immunodeficiency virus-1 protein synthesis and is cleaved upon viral infection. | the reversible phosphorylation of the alpha-subunit of eukaryotic translation initiation factor 2 (eif2alpha) is a well-characterized mechanism of translational control in response to a wide variety of cellular stresses, including viral infection. beside pkr, the eif2alpha kinase gcn2 participates in the cellular response against viral infection by rna viruses with central nervous system tropism. pkr has also been involved in the antiviral response against hiv-1, although this antiviral effect i ... | 2012 | 23110064 |
| an attenuating mutation in a neurovirulent sindbis virus strain interacts with the ips-1 signaling pathway in vivo. | the ar86 strain of sindbis virus causes lethal neurologic disease in adult mice. previous studies have identified a virulence determinant at nonstructural protein (nsp) 1 position 538 that regulates neurovirulence, modulates clearance from the cns, and interferes with the type i interferon pathway. the studies herein demonstrate that in the absence of type i interferon signaling, the attenuated mutant exhibited equivalent virulence to s300 virus. furthermore, both s300 and nsp1 t538i viruses dis ... | 2012 | 23084425 |
| prime-boost approaches to tuberculosis vaccine development. | four individuals die from active tb disease each minute, while at least 2 billion are latently infected and at risk for disease reactivation. bcg, the only licensed tb vaccine, is effective in preventing childhood forms of tb; however its poor efficacy in adults, emerging drug-resistant tb strains and tedious chemotherapy regimes, warrant the development of novel prophylactic measures. designing safe and effective vaccines against tb will require novel approaches on several levels, including the ... | 0 | 23176655 |
| chikungunya virus nsp3 blocks stress granule assembly by recruitment of g3bp into cytoplasmic foci. | chikungunya virus nonstructural protein nsp3 has an essential but unknown role in alphavirus replication and interacts with ras-gap sh3 domain-binding protein (g3bp). here we describe the first known function of nsp3, to inhibit stress granule assembly by recruiting g3bp into cytoplasmic foci. a conserved sh3 domain-binding motif in nsp3 is essential for both nsp3-g3bp interactions and viral rna replication. this study reveals a novel role for nsp3 as a regulator of the cellular stress response. | 2012 | 22837213 |
| structural and functional insights into alphavirus polyprotein processing and pathogenesis. | alphaviruses, a group of positive-sense rna viruses, are globally distributed arboviruses capable of causing rash, arthritis, encephalitis, and death in humans. the viral replication machinery consists of four nonstructural proteins (nsp1-4) produced as a single polyprotein. processing of the polyprotein occurs in a highly regulated manner, with cleavage at the p2/3 junction influencing rna template use during genome replication. here, we report the structure of p23 in a precleavage form. the pr ... | 2012 | 23010928 |
| oncolytic virotherapy for ovarian cancer. | in the past two decades, more than 20 viruses with selective tropism for tumor cells have been developed as oncolytic viruses (ovs) for treatments of a variety of malignancies. of these viruses, eleven have been tested in human ovarian cancer models in preclinical studies. so far, nine phase i or ii clinical trials have been conducted or initiated using four different types of ovs in patients with recurrent ovarian cancers. in this article, we summarize the different ovs that are being assessed ... | 0 | 25977900 |
| convergent evolution of argonaute-2 slicer antagonism in two distinct insect rna viruses. | rna interference (rnai) is a major antiviral pathway that shapes evolution of rna viruses. we show here that nora virus, a natural drosophila pathogen, is both a target and suppressor of rnai. we detected viral small rnas with a signature of dicer-2 dependent small interfering rnas in nora virus infected drosophila. furthermore, we demonstrate that the nora virus vp1 protein contains rnai suppressive activity in vitro and in vivo that enhances pathogenicity of recombinant sindbis virus in an rna ... | 2012 | 22916019 |
| a specific domain of the chikungunya virus e2 protein regulates particle formation in human cells: implications for alphavirus vaccine design. | virus-like particles (vlps) can be generated from chikungunya virus (chikv), but different strains yield variable quantities of particles. here, we define the genetic basis for these differences and show that amino acid 234 in e2 substantially affects vlp production. this site is located within the acid-sensitive region (asr) known to initiate a major conformational change in e1/e2. selected other mutations in the asr, or changes in ph, also increased vlp yield. these results demonstrate that th ... | 2012 | 22647698 |
| orthobunyavirus entry into neurons and other mammalian cells occurs via clathrin-mediated endocytosis and requires trafficking into early endosomes. | la crosse virus (lacv) is a leading cause of pediatric encephalitis and aseptic meningitis in the midwestern and southern united states, where it is considered an emerging human pathogen. no specific therapies or vaccines are available for lacv or any other orthobunyaviruses. inhibition of lacv entry into cells is a potential target for therapeutic intervention, but this approach is limited by our current knowledge of the entry process. here, we determined that clathrin-mediated endocytosis is t ... | 2012 | 22623766 |
| herpes simplex virus 2 infection impacts stress granule accumulation. | interference with stress granule (sg) accumulation is gaining increased appreciation as a common strategy used by diverse viruses to facilitate their replication and to cope with translational arrest. here, we examined the impact of infection by herpes simplex virus 2 (hsv-2) on sg accumulation by monitoring the localization of the sg components t cell internal antigen 1 (tia-1), ras-gtpase-activating sh3-domain-binding protein (g3bp), and poly(a)-binding protein (pabp). our results indicate tha ... | 2012 | 22623775 |
| new parp gene with an anti-alphavirus function. | alphaviruses represent a highly important group of human and animal pathogens, which are transmitted by mosquito vectors between vertebrate hosts. the hallmark of alphavirus infection in vertebrates is the induction of a high-titer viremia, which is strongly dependent on the ability of the virus to interfere with host antiviral responses on both cellular and organismal levels. the identification of cellular factors, which are critical in orchestrating virus clearance without the development of c ... | 2012 | 22623789 |
| an assembly model of rift valley fever virus. | rift valley fever virus (rvfv) is a bunyavirus endemic to africa and the arabian peninsula that infects humans and livestock. the virus encodes two glycoproteins, gn and gc, which represent the major structural antigens and are responsible for host cell receptor binding and fusion. both glycoproteins are organized on the virus surface as cylindrical hollow spikes that cluster into distinct capsomers with the overall assembly exhibiting an icosahedral symmetry. currently, no experimental three-di ... | 2012 | 22837754 |
| lack of interference with immunogenicity of a chimeric alphavirus replicon particle-based influenza vaccine by preexisting antivector immunity. | antivector immunity has been recognized as a potential caveat of using virus-based vaccines. in the present study, an alphavirus-based replicon particle vaccine platform, which has demonstrated robust immunogenicity in animal models, was tested for effects of antivector immunity on immunogenicity against hemagglutinin of influenza virus as a target antigen and efficacy for protection against lethal challenge with the virus. chimeric alphavirus-based replicon particles, comprising venezuelan equi ... | 2012 | 22623651 |
| photodynamic inactivation of mammalian viruses and bacteriophages. | photodynamic inactivation (pdi) has been used to inactivate microorganisms through the use of photosensitizers. the inactivation of mammalian viruses and bacteriophages by photosensitization has been applied with success since the first decades of the last century. due to the fact that mammalian viruses are known to pose a threat to public health and that bacteriophages are frequently used as models of mammalian viruses, it is important to know and understand the mechanisms and photodynamic proc ... | 2012 | 22852040 |
| determinants in the maturation of rubella virus p200 replicase polyprotein precursor. | rubella virus (rubv), a positive-strand rna virus, replicates its rna within membrane-associated replication complexes (rcs) in the cytoplasm of infected cells. rna synthesis is mediated by the nonstructural proteins (nsps) p200 and its cleavage products, p150 and p90 (n and c terminal within p200, respectively), which are processed by a protease residing at the c terminus of p150. in this study of nsp maturation, we found that early nsp localization into foci appeared to target the membranes of ... | 2012 | 22491463 |
| new insights into control of arbovirus replication and spread by insect rna interference pathways. | arthropod-borne (arbo) viruses are transmitted by vectors, such as mosquitoes, to susceptible vertebrates. recent research has shown that arbovirus replication and spread in mosquitoes is not passively tolerated but induces host responses to control these pathogens. small rna-mediated host responses are key players among these antiviral immune strategies. studies into one such small rna-mediated antiviral response, the exogenous rna interference (rnai) pathway, have generated a wealth of informa ... | 2012 | 26466541 |
| induction of gadd34 is necessary for dsrna-dependent interferon-β production and participates in the control of chikungunya virus infection. | nucleic acid sensing by cells is a key feature of antiviral responses, which generally result in type-i interferon production and tissue protection. however, detection of double-stranded rnas in virus-infected cells promotes two concomitant and apparently conflicting events. the dsrna-dependent protein kinase (pkr) phosphorylates translation initiation factor 2-alpha (eif2α) and inhibits protein synthesis, whereas cytosolic dexd/h box rna helicases induce expression of type i-ifn and other cytok ... | 2012 | 22615568 |
| accumulation of autophagosomes in semliki forest virus-infected cells is dependent on expression of the viral glycoproteins. | autophagy is a cellular process that sequesters cargo in double-membraned vesicles termed autophagosomes and delivers this cargo to lysosomes to be degraded. it is enhanced during nutrient starvation to increase the rate of amino acid turnover. diverse roles for autophagy have been reported for viral infections, including the assembly of viral replication complexes on autophagic membranes and protection of host cells from cell death. here, we show that autophagosomes accumulate in semliki forest ... | 2012 | 22438538 |
| amp-activated kinase restricts rift valley fever virus infection by inhibiting fatty acid synthesis. | the cell intrinsic innate immune responses provide a first line of defense against viral infection, and often function by targeting cellular pathways usurped by the virus during infection. in particular, many viruses manipulate cellular lipids to form complex structures required for viral replication, many of which are dependent on de novo fatty acid synthesis. we found that the energy regulator ampk, which potently inhibits fatty acid synthesis, restricts infection of the bunyavirus, rift valle ... | 2012 | 22532801 |
| innate antiviral immunity in drosophila. | the study of drosophila, and other genetically tractable insects, has expanded our understanding of innate immunity and more recently antiviral innate mechanisms. the drosophila antiviral program includes inflammatory signaling cascades as well as antiviral rna silencing and autophagy. this review will highlight the recent discoveries in antiviral immunity in insects and will reveal some of the lessons learned. | 0 | 20137906 |
| oncolytic viruses for cancer therapy: overcoming the obstacles. | targeted therapy of cancer using oncolytic viruses has generated much interest over the past few years in the light of the limited efficacy and side effects of standard cancer therapeutics for advanced disease. in 2006, the world witnessed the first government-approved oncolytic virus for the treatment of head and neck cancer. it has been known for many years that viruses have the ability to replicate in and lyse cancer cells. although encouraging results have been demonstrated in vitro and in a ... | 0 | 20543907 |
| virus-based technologies for investigating function and pathology of the nervous system. | | 2010 | 20126637 |
| viralorfeome: an integrated database to generate a versatile collection of viral orfs. | large collections of protein-encoding open reading frames (orfs) established in a versatile recombination-based cloning system have been instrumental to study protein functions in high-throughput assays. such 'orfeome' resources have been developed for several organisms but in virology, plasmid collections covering a significant fraction of the virosphere are still needed. in this perspective, we present viralorfeome 1.0 (http://www.viralorfeome.com), an open-access database and management syste ... | 2009 | 20007148 |
| culturing thick brain slices: an interstitial 3d microperfusion system for enhanced viability. | brain slice preparations are well-established models for a wide spectrum of in vitro investigations in the neuroscience discipline. however, these investigations are limited to acute preparations or thin organotypic culture preparations due to the lack of a successful method that allows culturing of thick organotypic brain slices. thick brain slice cultures suffer necrosis due to ischemia deep in the tissue resulting from a destroyed circulatory system and subsequent diffusion-limited supply of ... | 2009 | 19443039 |
| impact of protein kinase pkr in cell biology: from antiviral to antiproliferative action. | the double-stranded rna-dependent protein kinase pkr is a critical mediator of the antiproliferative and antiviral effects exerted by interferons. not only is pkr an effector molecule on the cellular response to double-stranded rna, but it also integrates signals in response to toll-like receptor activation, growth factors, and diverse cellular stresses. in this review, we provide a detailed picture on how signaling downstream of pkr unfolds and what are the ultimate consequences for the cell fa ... | 0 | 17158706 |
| cubic phases in phosphatidylcholine-cholesterol mixtures: cholesterol as membrane "fusogen". | x-ray diffraction reveals that mixtures of some unsaturated phosphatidylcholines (pcs) with cholesterol (chol) readily form inverted bicontinuous cubic phases that are stable under physiological conditions. this effect was studied in most detail for dioleoyl pc/chol mixtures with molar ratios of 1:1 and 3:7. facile formation of im3m and pn3m phases with lattice constants of 30-50 nm and 25-30 nm, respectively, took place in phosphate-buffered saline, in sucrose solution, and in water near the te ... | 2006 | 16829556 |
| interferon-inducible antiviral effectors. | since the discovery of interferons (ifns), considerable progress has been made in describing the nature of the cytokines themselves, the signalling components that direct the cell response and their antiviral activities. gene targeting studies have distinguished four main effector pathways of the ifn-mediated antiviral response: the mx gtpase pathway, the 2',5'-oligoadenylate-synthetase-directed ribonuclease l pathway, the protein kinase r pathway and the isg15 ubiquitin-like pathway. as discuss ... | 0 | 18575461 |
| intercellular extensions are induced by the alphavirus structural proteins and mediate virus transmission. | alphaviruses are highly organized enveloped rna viruses with an internal nucleocapsid surrounded by a membrane containing the e2 and e1 transmembrane proteins. alphavirus budding takes place at the plasma membrane and requires the interaction of the cytoplasmic domain of e2 with the capsid protein. here we used wt alphaviruses and sindbis virus in which e2 was fused to a fluorescent protein to characterize virus exit from host cells. our results show that alphavirus infection induced striking mo ... | 2016 | 27977778 |
| chikungunya virus infectivity, rna replication and non-structural polyprotein processing depend on the nsp2 protease's active site cysteine residue. | chikungunya virus (chikv), genus alphavirus, family togaviridae, has a positive-stand rna genome approximately 12 kb in length. in infected cells, the genome is translated into non-structural polyprotein p1234, an inactive precursor of the viral replicase, which is activated by cleavages carried out by the non-structural protease, nsp2. we have characterized chikv nsp2 using both cell-free and cell-based assays. first, we show that cys478 residue in the active site of chikv nsp2 is indispensable ... | 2016 | 27845418 |
| inactivation of the type i interferon pathway reveals long double-stranded rna-mediated rna interference in mammalian cells. | rna interference (rnai) elicited by long double-stranded (ds) or base-paired viral rna constitutes the major mechanism of antiviral defence in plants and invertebrates. in contrast, it is controversial whether it acts in chordates. rather, in vertebrates, viral rnas induce a distinct defence system known as the interferon (ifn) response. here, we tested the possibility that the ifn response masks or inhibits antiviral rnai in mammalian cells. consistent with that notion, we find that sequence-sp ... | 2016 | 27815315 |