Author
Kurt Tobler
Other affiliations: Northwestern University
Bio: Kurt Tobler is an academic researcher from University of Zurich. The author has contributed to research in topics: Virus & Gene. The author has an hindex of 23, co-authored 70 publications receiving 1890 citations. Previous affiliations of Kurt Tobler include Northwestern University.
Topics: Virus, Gene, Genome, Herpes simplex virus, Helper virus
Papers published on a yearly basis
Papers
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TL;DR: Comparative amino acid sequence alignments revealed that PEDV is most closely related to human coronavirus (HCoV)-229E and transmissible gastroenteritis virus (TGEV) and less related to murine hepatitis virus (MHV), and infectious bronchitis virus(IBV).
Abstract: The sequence of the replicase gene of porcine epidemic diarrhoea virus (PEDV) has been determined. This completes the sequence of the entire genome of strain CV777, which was found to be 28,033 nucleotides (nt) in length (excluding the poly A-tail). A cloning strategy, which involves primers based on conserved regions in the predicted ORF1 products from other coronaviruses whose genome sequence has been determined, was used to amplify the equivalent, but as yet unknown, sequence of PEDV. Primary sequences derived from these products were used to design additional primers resulting in the amplification and sequencing of the entire ORF1 of PEDV. Analysis of the nucleotide sequences revealed a small open reading frame (ORF) located near the 5′ end (no 99–137), and two large, slightly overlapping ORFs, ORF1a (nt 297–12650) and ORF1b (nt 12605–20641). The ORF1a and ORF1b sequences overlapped at a potential ribosomal frame shift site. The amino acid sequence analysis suggested the presence of several functional motifs within the putative ORF1 protein. By analogy to other coronavirus replicase gene products, three protease and one growth factor-like motif were seen in ORF1a, and one polymerase domain, one metal ion-binding domain, and one helicase motif could be assigned within ORF1b. Comparative amino acid sequence alignments revealed that PEDV is most closely related to human coronavirus (HCoV)-229E and transmissible gastroenteritis virus (TGEV) and less related to murine hepatitis virus (MHV) and infectious bronchitis virus (IBV). These results thus confirm and extend the findings from sequence analysis of the structural genes of PEDV.
277 citations
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TL;DR: The capacity of generating infectious and replication-competent HSV-1 progeny following transfection into mammalian cells was restored after insertion of a pac signal into fHSV delta pac, and the resulting amplicon stocks are virtually free of contaminating helper virus.
Abstract: Herpes simplex virus type 1 (HSV-1)-based amplicon vectors contain only approximately 1% of the 152-kb HSV-1 genome, and consequently, replication and packaging into virions depends on helper functions. These helper functions have been provided conventionally by a helper virus, usually a replication-defective mutant of HSV-1, or more recently, by a set of five cosmids that overlap and represent the genome of HSV-1 deleted for DNA cleavage/packaging signals (pac). In the absence of pac signals, potential HSV-1 genomes that are reconstituted from the cosmids via homologous recombination are not packageable. The resulting amplicon stocks are, therefore, virtually free of contaminating helper virus. To simplify this packing system, the HSV-1 genome was cloned and maintained stably as a single-copy, F plasmid-based bacterial artificial chromosome in E. coli. Such a plasmid containing the HSV-1 genome deleted for the pac signals (fHSV delta pac) did not generate replication-competent progeny virus on transfection into mammalian cells, but rather, it was able to support the packaging of cotransfected amplicon DNA that contained a functional pac signal. The resulting amplicon vector stocks had titers of up to 10(7) transducing units per milliliter of culture medium and efficiently transduced neural cells in the rat brain, as well as hepatocytes in the rat. The capacity of generating infectious and replication-competent HSV-1 progeny following transfection into mammalian cells was restored after insertion of a pac signal into fHSV delta pac.
235 citations
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TL;DR: In this paper, cDNA clones covering the region between the nucleocapsid and the spike (S) protein genes were independently constructed and sequenced for the two virulent isolates Br1/87 and CV777.
106 citations
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TL;DR: High-resolution scanning and transmission electron microscopy proved the distortions to be related to enlargement of nuclear pores through which nuclear content including capsids protrudes into the cytoplasm, suggesting that capsid-membrane interaction of high identity to the budding process at the inner nuclear membrane.
Abstract: Herpesvirus capsids originating in the nucleus overcome the nucleocytoplasmic barrier by budding at the inner nuclear membrane. The fate of the resulting virions is still under debate. The fact that capsids approach Golgi membranes from the cytoplasmic side led to the theory of fusion between the viral envelope and the outer nuclear membrane, resulting in the release of capsids into the cytoplasm. We recently discovered a continuum from the perinuclear space to the Golgi complex implying (i) intracisternal viral transportation from the perinuclear space directly into Golgi cisternae and (ii) the existence of an alternative pathway of capsids from the nucleus to the cytoplasm. Here, we analyzed the nuclear surface by high-resolution microscopy. Confocal microscopy of MDBK cells infected with recombinant bovine herpesvirus 1 expressing green fluorescent protein fused to VP26 (a minor capsid protein) revealed distortions of the nuclear surface in the course of viral multiplication. High-resolution scanning and transmission electron microscopy proved the distortions to be related to enlargement of nuclear pores through which nuclear content including capsids protrudes into the cytoplasm, suggesting that capsids use impaired nuclear pores as gateways to gain access to the cytoplasmic matrix. Close examination of Golgi membranes, rough endoplasmic reticulum, and outer nuclear membrane yielded capsid-membrane interaction of high identity to the budding process at the inner nuclear membrane. These observations signify the ability of capsids to induce budding at any cell membrane, provided the fusion machinery is present and/or budding is not suppressed by viral proteins.
98 citations
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TL;DR: The nucleotide sequence of 1.7 kbp cDNA, comprising the region nearest the 3' end of the genome of the porcine epidemic diarrhoea virus (PEDV), has been independently determined for two European isolates of PEDV, and results confirm the earlier provisional classification of P EDV as a coronavirus.
Abstract: The nucleotide sequence of 1.7 kbp cDNA, comprising the region nearest the 3' end of the genome of the porcine epidemic diarrhoea virus (PEDV), has been independently determined for two European isolates of PEDV. Almost identical results were obtained for the two isolates, which were derived from cases of PEDV infection in Belgium and Britain in 1977 and 1987, respectively. The sequences contained a 1323 nucleotide (nt) open reading frame (ORF), which showed moderate identity to the nucleocapsid (N) gene of other coronaviruses. The greatest similarity at both the nucleic acid and protein levels was to the human coronavirus 229E. The PEDV N gene was, however, notably larger than that of the human 229E and porcine transmissible gastroenteritis viruses. This reflects the presence of a putative insertion of approximately 135 nt located towards the middle of the N gene. A second 336 nt ORF, which might encode a leucine-rich protein similar to, but shorter than, the bovine coronavirus internal protein was found within the PEDV N gene. Several RNA motifs typical of coronaviruses were also observed. These results confirm the earlier provisional classification of PEDV as a coronavirus.
82 citations
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01 Jan 2011
TL;DR: The sheer volume and scope of data posed by this flood of data pose a significant challenge to the development of efficient and intuitive visualization tools able to scale to very large data sets and to flexibly integrate multiple data types, including clinical data.
Abstract: Rapid improvements in sequencing and array-based platforms are resulting in a flood of diverse genome-wide data, including data from exome and whole-genome sequencing, epigenetic surveys, expression profiling of coding and noncoding RNAs, single nucleotide polymorphism (SNP) and copy number profiling, and functional assays. Analysis of these large, diverse data sets holds the promise of a more comprehensive understanding of the genome and its relation to human disease. Experienced and knowledgeable human review is an essential component of this process, complementing computational approaches. This calls for efficient and intuitive visualization tools able to scale to very large data sets and to flexibly integrate multiple data types, including clinical data. However, the sheer volume and scope of data pose a significant challenge to the development of such tools.
2,187 citations
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TL;DR: A new group 1 coronavirus, HCoV-NL63, was identified in a 7-month-old child suffering from bronchiolitis and conjunctivitis as discussed by the authors.
Abstract: Three human coronaviruses are known to exist: human coronavirus 229E (HCoV-229E), HCoV-OC43 and severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV). Here we report the identification of a fourth human coronavirus, HCoV-NL63, using a new method of virus discovery. The virus was isolated from a 7-month-old child suffering from bronchiolitis and conjunctivitis. The complete genome sequence indicates that this virus is not a recombinant, but rather a new group 1 coronavirus. The in vitro host cell range of HCoV-NL63 is notable because it replicates on tertiary monkey kidney cells and the monkey kidney LLC-MK2 cell line. The viral genome contains distinctive features, including a unique N-terminal fragment within the spike protein. Screening of clinical specimens from individuals suffering from respiratory illness identified seven additional HCoV-NL63-infected individuals, indicating that the virus was widely spread within the human population.
1,496 citations
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TL;DR: It is discussed that based on emerging species concepts derived from genome sequences, PV types could be promoted to the taxonomic level of species, but it is not recommended to implement this change at the current time.
1,496 citations
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TL;DR: Further vector refinement and/or development is required before gene therapy will become standard care for any individual disorder, and some clinical successes are over the horizon.
Abstract: Considered by some to be among the simpler forms of life, viruses represent highly evolved natural vectors for the transfer of foreign genetic information into cells. This attribute has led to extensive attempts to engineer recombinant viral vectors for the delivery of therapeutic genes into diseased tissues. While substantial progress has been made, and some clinical successes are over the horizon, further vector refinement and/or development is required before gene therapy will become standard care for any individual disorder.
1,374 citations
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TL;DR: It is suggested that NSC migration can be extensive, even in the adult brain and along nonstereotypical routes, if pathology is present, and the adjunctive use of inherently migratory NSCs as a delivery vehicle for targeting therapeutic genes and vectors to refractory, migratory, invasive brain tumors is suggested.
Abstract: One of the impediments to the treatment of brain tumors (e.g., gliomas) has been the degree to which they expand, infiltrate surrounding tissue, and migrate widely into normal brain, usually rendering them “elusive” to effective resection, irradiation, chemotherapy, or gene therapy. We demonstrate that neural stem cells (NSCs), when implanted into experimental intracranial gliomas in vivo in adult rodents, distribute themselves quickly and extensively throughout the tumor bed and migrate uniquely in juxtaposition to widely expanding and aggressively advancing tumor cells, while continuing to stably express a foreign gene. The NSCs “surround” the invading tumor border while “chasing down” infiltrating tumor cells. When implanted intracranially at distant sites from the tumor (e.g., into normal tissue, into the contralateral hemisphere, or into the cerebral ventricles), the donor cells migrate through normal tissue targeting the tumor cells (including human glioblastomas). When implanted outside the CNS intravascularly, NSCs will target an intracranial tumor. NSCs can deliver a therapeutically relevant molecule—cytosine deaminase—such that quantifiable reduction in tumor burden results. These data suggest the adjunctive use of inherently migratory NSCs as a delivery vehicle for targeting therapeutic genes and vectors to refractory, migratory, invasive brain tumors. More broadly, they suggest that NSC migration can be extensive, even in the adult brain and along nonstereotypical routes, if pathology (as modeled here by tumor) is present.
1,209 citations