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Joseluis Nieva - One of the best experts on this subject based on the ideXlab platform.
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entry of semliki forest Virus into cells effects of concanamycin a and nigericin on viral membrane fusion and infection
Virology, 1997Co-Authors: Alicia Irurzun, Joseluis NievaAbstract:Semliki forest Virus (SFV) was biosynthetically labeled with pyrene phospholipids and used to investigate two alternative routes of entry of SFV into BHK-21 cells: (1) receptor-mediated endocytosis followed by fusion of the viral envelope with the endosomal membrane and (2) direct fusion of SFV with the plasma membrane induced by low pH treatment. The selective inhibitor of the vacuolar proton-ATPase, concanamycin A, abolished fusion and subsequent infection only when the Virus utilized the endocytic route to enter cells. The inhibitory effect of this macrolide antibiotic was bypassed by low pH treatment of cells. However, the ionophore nigericin was inhibitory irrespective of the route used by the Virus to infect cells, suggesting the necessity of a transmembrane pH gradient for the entry process. According to our results, concanamycin A emerges as a suitable tool for selectively investigating the involvement of endosomal function in Animal Virus entry.
Howard L Lipton - One of the best experts on this subject based on the ideXlab platform.
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double stranded rna is detected by immunofluorescence analysis in rna and dna Virus infections including those by negative stranded rna Viruses
Journal of Virology, 2015Co-Authors: Kyung No Son, Zhiguo Liang, Howard L LiptonAbstract:Early biochemical studies of viral replication suggested that most Viruses produce double-stranded RNA (dsRNA), which is essential for the induction of the host immune response. However, it was reported in 2006 that dsRNA could be detected by immunofluorescence antibody staining in double-stranded DNA and positive-strand RNA Virus infections but not in negative-strand RNA Virus infections. Other reports in the literature seemed to support these observations. This suggested that negative-strand RNA Viruses produce little, if any, dsRNA or that more efficient viral countermeasures to mask dsRNA are mounted. Because of our interest in the use of dsRNA antibodies for Virus discovery, particularly in pathological specimens, we wanted to determine how universal immunostaining for dsRNA might be in Animal Virus infections. We have detected the in situ formation of dsRNA in cells infected with vesicular stomatitis Virus, measles Virus, influenza A Virus, and Nyamanini Virus, which represent Viruses from different negative-strand RNA Virus families. dsRNA was also detected in cells infected with lymphocytic choriomeningitis Virus, an ambisense RNA Virus, and minute Virus of mice (MVM), a single-stranded DNA (ssDNA) parvoVirus, but not hepatitis B Virus. Although dsRNA staining was primarily observed in the cytoplasm, it was also seen in the nucleus of cells infected with influenza A Virus, Nyamanini Virus, and MVM. Thus, it is likely that most Animal Virus infections produce dsRNA species that can be detected by immunofluorescence staining. The apoptosis induced in several uninfected cell lines failed to upregulate dsRNA formation. IMPORTANCE An effective antiviral host immune response depends on recognition of viral invasion and an intact innate immune system as a first line of defense. Double-stranded RNA (dsRNA) is a viral product essential for the induction of innate immunity, leading to the production of type I interferons (IFNs) and the activation of hundreds of IFN-stimulated genes. The present study demonstrates that infections, including those by ssDNA Viruses and positive- and negative-strand RNA Viruses, produce dsRNAs detectable by standard immunofluorescence staining. While dsRNA staining was primarily observed in the cytoplasm, nuclear staining was also present in some RNA and DNA Virus infections. The nucleus is unlikely to have pathogen-associated molecular pattern (PAMP) receptors for dsRNA because of the presence of host dsRNA molecules. Thus, it is likely that most Animal Virus infections produce dsRNA species detectable by immunofluorescence staining, which may prove useful in viral discovery as well.
Rosario Guinea - One of the best experts on this subject based on the ideXlab platform.
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Concanamycin A: a powerful inhibitor of enveloped Animal-Virus entry into cells.
Biochemical and Biophysical Research Communications, 1994Co-Authors: Rosario GuineaAbstract:Abstract Concanamycin A, a selective inhibitor of the vacuolar proton ATPase, blocks the infection of Animal cells by vesicular stomatitis Virus, Semliki Forest Virus and influenza Virus even when the drug is present at the low concentration of 5 nM. Nevertheless the antibiotic prevents neither the attachment, to cells, of Semliki Forest Virus nor its subsequent internalization. Under certain conditions, described in this communication, Virus entry is prevented even when the pH of the medium is low, thus suggesting that a pH gradient, rather than low pH per se , is required to drive the entry, into cells, of these enveloped Animal Viruses.
John E Johnson - One of the best experts on this subject based on the ideXlab platform.
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the structure of a thermophilic archaeal Virus shows a double stranded dna viral capsid type that spans all domains of life
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: George Rice, John E Johnson, Liang Tang, Kenneth M Stedman, Francisco F Roberto, Josh Spuhler, Eric Gillitzer, Trevor DouglasAbstract:Of the three domains of life (Eukarya, Bacteria, and Archaea), the least understood is Archaea and its associated Viruses. Many Archaea are extremophiles, with species that are capable of growth at some of the highest temperatures and extremes of pH of all known organisms. Phylogenetic rRNA-encoding DNA analysis places many of the hyperthermophilic Archaea (species with an optimum growth ≳80°C) at the base of the universal tree of life, suggesting that thermophiles were among the first forms of life on earth. Very few Viruses have been identified from Archaea as compared to Bacteria and Eukarya. We report here the structure of a hyperthermophilic Virus isolated from an archaeal host found in hot springs in Yellowstone National Park. The sequence of the circular double-stranded DNA viral genome shows that it shares little similarity to other known genes in Viruses or other organisms. By comparing the tertiary and quaternary structures of the coat protein of this Virus with those of a bacterial and an Animal Virus, we find conformational relationships among all three, suggesting that some Viruses may have a common ancestor that precedes the division into three domains of life >3 billion years ago.
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an Animal Virus derived peptide switches membrane morphology possible relevance to nodaviral transfection processes
Biochemistry, 1999Co-Authors: Andreas Janshoff, John E Johnson, Dennis Bong, Claudia Steinem, Reza M GhadiriAbstract:The N-terminal domain of the capsid protein cleavage product of the flock house Virus (FHV) consists of 21 residues and forms an amphipathic α-helix, which is thought to play a crucial role in permeabilizing biological membranes for RNA translocation in the host cell. We have found that the Met → Nle variant of this domain (denoted here as γ1) efficiently induces the formation of the interdigitated gel phase (LβI) of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) bilayers. In situ scanning force microscopy of solid supported bilayers and fluorescence spectroscopy of peptide-treated DPPC vesicles provide evidence for the formation of acyl chain interdigitated lipid domains. It could be shown by fluorescence spectroscopy that the peptide inserts in the DPPC matrix above the main transition temperature of the lipid, while the formation of domains with decreased thickness occurs after the sample is cooled to 25 °C. The orientation and secondary structure of the peptide in lipid bilayers were investig...
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structure based design of peptide presentation on a viral surface the crystal structure of a plant Animal Virus chimera at 2 8 a resolution
Acta Crystallographica Section A, 1996Co-Authors: Tianwei Lin, Claudine Porta, George P Lomonossoff, John E JohnsonAbstract:Backgound: We employed a genetically engineered icosahedral plant Virus, cowpea mosaic Virus (CPMV), as an expression and presentation system to display a 14 amino acid linear antigenic epitope found in a capsid protein of human rhinoVirus 14 (HRV14). Results Gram quantities of the CPMV/HRV14 chimera were made in plants and purified particles were crystallized in a form isomorphous with wild-type CPMV. The 2.8 a resolution structure of the chimera shows that the inserted loop is well ordered and that if the loop were intact, a phenylalanine residue of CPMV would be placed in a hydrophilic environment. The resultant strain may make the loop an attractive substrate for endogenous plant proteases, as roughly 80% of the inserted polypeptides are cleaved, allowing the phenylalanine to be partially buried. Altering the phenylalanine to an arginine could relieve the stress, reducing the propensity for cleavage and increasing the likelihood that the peptide will assume a structure closely similar to its structure in HRV14. Conclusion Successful crystallization of other CPMV chimeras in forms isomorphous with the native Virus suggests that this is a viable system for structure-based design of peptide presentation.
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functional implications of quasi equivalence in a t 3 icosahedral Animal Virus established by cryo electron microscopy and x ray crystallography
Structure, 1994Co-Authors: Holland R Cheng, Vijay S Reddy, Norman H Olson, Andrew J Fisher, Timothy S Baker, John E JohnsonAbstract:Abstract Background Studies of simple RNA Animal Viruses show that cell attachment, particle destabilization and cell entry are complex processes requiring a level of capsid sophistication that is difficult to achieve with a shell containing only a single gene product. NodaViruses [such as Flock House Virus (FHV)] are an exception. We have previously determined the structure of FHV at 3 a resolution, and now combine this information with data from cryo-electron microscopy in an attempt to clarify the process by which nodaViruses infect Animal cells. Results A difference map was computed in which electron density at 22 a resolution, derived from the 3.0 a resolution X-ray model of the FHV capsid protein, was subtracted from the electron density derived from the cryo-electron microscopy reconstruction of FHV at 22 a resolution. Comparisons of this density with the X-ray model showed that quasi-equivalent regions of identical polypeptide sequences have markedly different interactions with the bulk RNA density. Previously reported biphasic kinetics of particle maturation and the requirement of subunit cleavage for particle infectivity are consistent with these results. Conclusions On the basis of this study we propose a model for nodaVirus infection that is conceptually similar to that proposed for polioVirus but differs from it in detail. The constraints of a single protein type in the capsid lead to a noteworthy use of quasi-symmetry not only to control the binding of a ‘pocket factor' but also to modulate maturation cleavage and to release a pentameric helical bundle (with genomic RNA attached) that may further interact with the cell membrane.
Tanel Punga - One of the best experts on this subject based on the ideXlab platform.
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Complementation of the human adenoVirus type 5 VA RNAI defect by the Vaccinia Virus E3L protein and serotype-specific VA RNAIs
Virology, 2015Co-Authors: Raviteja Inturi, Göran Akusjärvi, Wael Kamel, Tanel PungaAbstract:Human adenoViruses (HAdVs) encode for multifunctional non-coding Virus-associated (VA) RNAs, which function as powerful suppressors of the cellular interferon (IFN) and RNA interference (RNAi) systems. In this study we tested the ability of various plant and Animal Virus encoded RNAi and IFN suppressor proteins to functionally substitute for the HAdV-5 VA RNAI. Our results revealed that only the Vaccinia Virus (VACV) E3L protein was able to substitute for the HAdV-5 VA RNAI functions in Virus-infected cells. Interestingly, the E3L protein rescues the translational defect but does not stimulate viral capsid mRNA accumulation observed with VA RNA. We further show that the E3L C-terminal region containing the dsRNA-binding domain is needed to enhance VA RNAI mutant Virus replication. Additionally, we show that the HAdV-4 and HAdV-37 VA RNAI are more effective than the HAdV-5 VA RNAI in rescuing Virus replication.