Strucutre-function studies of the venezuelan equine encephalitis virus 5'UTR promoter element and its role in attenuation of the virus

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Strucutre-function studies of the venezuelan equine encephalitis virus 5'UTR promoter element and its role in attenuation of the virus

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dc.contributor.advisor Vincent Hilser en_US
dc.creator Raghavendran Kulasegaran Shylini en_US
dc.date.accessioned 2011-12-20T16:04:58Z
dc.date.available 2010-09-28 en_US
dc.date.available 2011-12-20T16:04:58Z
dc.date.created 2009-07-19 en_US
dc.date.issued 2009-05-19 en_US
dc.identifier.other etd-07192009-155901 en_US
dc.identifier.uri http://hdl.handle.net/2152.3/169
dc.description.abstract RNA structural elements play critical roles in several viral processes. An \r\nattempt to elucidate the role of one such RNA structural element encoded by the 5’ \r\nUntranslated Region (5’UTR), in regulating virus replication and attenuation of \r\nVenezuelan equine encephalitis virus (VEEV) is described. VEEV is one of the \r\npathogenic members of the Alphavirus genus in the Togaviridae family. VEEV \r\ninfection causes debilitating illness complicated by neurological manifestations. The \r\nonly available vaccine for VEE infection, the attenuated strain VEEV TC-83 provides \r\nminimal protection against virulent strains, but the molecular basis for its attenuation \r\nremains poorly understood. Interestingly however, the attenuation of TC-83 was \r\nshown to strongly depend on two point mutations, one of which, the G3A mutation, \r\nwas found in the 5’UTR of the viral genome. \r\nResults from my biochemical and biophysical studies demonstrate that the \r\nG3A mutation strongly affects the structure of the VEEV 5’UTR. Further functional \r\nanalysis revealed that this change in 5’UTR RNA structure affects various processes \r\nin virus replication. The G3A mutation moderately enhanced translation of the \r\ndownstream polyprotein, and strongly increased replication of the viral genome, but \r\nled to a significant decrease in the synthesis of subgenomic RNA (sgRNA). Based on \r\nmy findings and those of others, I propose a model for attenuation of the vaccine \r\nstrain TC-83. The enhanced functionality of the TC-83 5’UTR in viral processes prompted further investigation into the structural requirements within the VEEV \r\n5’UTR for efficient virus replication. \r\nResults from these studies revealed that the sequence, secondary structure and \r\nstability of the stem-loop in this region are critical for virus replication. Mutations \r\naffecting any of the above resulted in pseudorevertants that either acquired \r\ncompensatory AU or AUG repeat sequences in the 5’UTR, or accumulated mutations \r\nin the VEEV non-structural proteins. Results from my mutational analyses thus \r\nprovide evidence that during the replication of the viral genome, the ends of the \r\ndsRNA replication intermediate stay single stranded and fold into individual stem- \r\nloops that are critical for virus replication, and the sequence and folding determines \r\nthe efficiency of the promoter in this region for genomic RNA synthesis. en_US
dc.format.medium electronic en_US
dc.language.iso eng en_US
dc.rights Copyright © is held by the author. Presentation of this material on the TDL web site by The University of Texas Medical Branch at Galveston was made possible under a limited license grant from the author who has retained all copyrights in the works. en_US
dc.subject virulence en_US
dc.subject venezuelan equine encephalitis virus en_US
dc.subject RNA structure en_US
dc.subject nt3 mutation en_US
dc.subject nmr en_US
dc.subject attenuation en_US
dc.subject 5' UTR en_US
dc.title Strucutre-function studies of the venezuelan equine encephalitis virus 5'UTR promoter element and its role in attenuation of the virus en_US
dc.type.material text en_US
dc.type.genre dissertation en_US
thesis.degree.name PhD en_US
thesis.degree.level Doctoral en_US
thesis.degree.grantor The University of Texas Medical Branch en_US
thesis.degree.department Biochemistry & Molecular Biology en_US
dc.contributor.committeeMember Stanley Watowich en_US
dc.contributor.committeeMember Krishna Rajarathnam en_US
dc.contributor.committeeMember Ilya Frolov en_US
dc.contributor.committeeMember Edward Nikonowicz en_US
dc.contributor.committeeMember David Gorenstein en_US

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