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Peter Tattersall |
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| Professor of Laboratory Medicine and Genetics |
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* B.Sc. University of Glasgow, Scotland, 1968
* Ph.D. Imperial Cancer Research Fund&University College, London, England, 1971
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| Research Interests: | |
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* Molecular Genetics of Virus-Host Cell Interactions
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Parvoviruses are small icosahedral, non-enveloped animal viruses. They are unique among all viruses in that they have a linear single-stranded DNA genome. In order to establish productive infection, parvoviruses require their host cells to be of a particular differentiated phenotype and to be actively traversing the S-phase of the cell cycle. Our major efforts have been directed at understanding the molecular basis of viral gene expression, host cell take-over and DNA replication. We are currently applying this knowledge to the construction of parvovirus derivatives for targeting tumor cells.
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| Current Research: | |
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How non-enveloped parvoviruses get to the host cell nucleus.
Enveloped viruses deliver their virions into the host cell by fusing their envelope with the cellular plasma or endosomal membrane, a strategy not available to non-enveloped viruses, which must employ alternative methods to breach their host cell's outer membrane. We have shown that the compact, icosahedral parvoviral virion gains entry to the cytoplasm from endosomes by deploying a lipolytic enzyme, phospholipase A2 (PLA2) that is expressed at the N-terminus of VP1, the minor coat protein. This region of VP1 is normally sequestered within the viral shell, but is extruded during the entry process, as a capsid-tethered domain, through an 8Ĺ pore at the five-fold vertex. We are collaborating with Dr. Michael Hodsdon to determine the structure of this PLA2 domain by NMR spectroscopy. The extruded VP1 N-terminus also displays a number of small protein interaction domains predicted to be involved in endocytosis, vesicle trafficking and nuclear transport. We are using differential real-time PCR, directed genetics, sub-cellular fractionation and confocal microscopy to explore aspects of the trans-cytosolic trafficking and nuclear import of the murine parvovirus Minute Virus of Mice, MVM.
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Characterization the unique parvoviral chromatin complex.
The parvoviral DNA genome is unique in the biosphere, in that it is both single-stranded and linear. Despite this alien structure, the virus inveigles its host to replicate the viral chromosome to high copy numbers, instead of the cellular genome, during the S-phase following infection. In doing so, it generates intermediates that comprise long single strands, displaced by exclusively leading strand synthesis at the viral fork. These structures strongly trigger host DNA damage responses that we presume the virus must evade. Part of the virus’ replication strategy involves the elaboration of a unique form of chromatin that ChIP analysis suggests incorporates both cellular histones and many copies of NS1, the major viral non-structural protein, which binds rather promiscuously to degenerate sequence blocks represented some 40 times through the viral genome. Insertion of transgene sequences, which do not contain NS1 binding sites, is quite deleterious to the replication and packaging of parvoviral vectors. We are using 2D gel electrophoresis and nuclease protection assays to look for stalling or pausing of replication forks through the capsid region of an otherwise wildtype viral genome rendered artifically devoid of NS1 binding sites throughout its entire capsid gene. and to characterize packaging intermediates generated by mutant, compared to wildtype, virus.
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Manipulating parvoviral oncoselectivity in human tumor models.
Many of the rodent parvoviruses will initiate infection in human cells with high efficiency, but fail to generate progeny and spread through the culture unless the host cell is neoplastically transformed. This makes these viruses promising candidates as oncolytic agents. Our efforts are directed toward understanding the molecular basis of this phenomenon, and using such knowledge to improve the efficacy of the virus in tumor eridication. Since tumorigenesis normally involves loss of genomic integrity, most, if not all, tumor cells carry a myriad of mutations that are secondary to those causing the transformed phenotype. To avoid studying or selecting for viral traits that represent adaptations to such “collateral” transformed cell properties, we use as hosts cells that have been transformed in a stepwise fashion with defined oncogenes or tumor suppressor knock-downs. We are employing reverse genetics and random mutant promoter screens to examine the contribution of the viral initiating promoter to the discrimination between normal and transformed cells, and to explore strategies for selecting more oncotropic versions of this critical transcriptional element.
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| Representative Publications: | |
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Cotmore, S. F. & Tattersall, P. Encapsidation of Minute Virus of Mice DNA: aspects of the translocation mechanism revealed by the structure of partially-packaged genomes. Virology, 336:100-112, 2005.
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Farr, G., Zhang, L-G., & Tattersall, P. Parvoviral virions deploy a capsid-tethered lipolytic enzyme to breach the endosomal membrane during cell entry. Proc. Natl. Acad. Sci. U.S.A., 102:17148–53, 2005.
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F Cotmore S.F. and Tattersall P. Parvoviruses. Chapter 29 in "DNA replication and Human Disease". DePamphilis M., ed. Cold Spring Harbor Laboratory Press. Cold Spring Harbor, New York. pp 593-608, 2006.
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arr, G., Cotmore, S.F. & Tattersall, P. VP2 cleavage and a leucine ring at the base of the five-fold cylinder control pH-dependent externalization of both the VP1 N-terminus and the genome of Minute Virus of Mice. J. Virol., 80:161–171, 2006.
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Paglino, J., Burnett, E., and Tattersall, P. Exploring the contribution of distal P4 promoter elements to the oncoselectivity of Minute Virus of Mice. Virology 361:174-184, 2007.
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