ANALYSIS OF MUTATION RATES OF RNA VIRUSES.
Item
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Title
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ANALYSIS OF MUTATION RATES OF RNA VIRUSES.
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Identifier
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AAI8801747
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identifier
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8801747
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Creator
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PARVIN, JEFFREY DAVID.
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Contributor
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Peter Palese
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Microbiology
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Abstract
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Epidemiologic and genetic evidence suggests that influenza A viruses evolve more rapidly than other viruses in man. In this thesis the evolution of the influenza A virus nonstructural (NS) gene was studied by two approaches. First, the evolution of the gene derived from viruses isolated over a 50 year period was delineated by sequence analysis. We found that the NS gene evolved at a very high rate of 2 {dollar}\times{dollar} 10{dollar}\sp{lcub}-3{rcub}{dollar} substitutions/nucleotide/year and that this evolution was along a primary lineage. The lack of significant branching in the evolutionary tree suggested that selective pressures are involved in shaping the evolution. Second, we determined the mutation rate of this gene in tissue culture. Although high mutation rates are often implicated in generating rapid evolution, direct measurement of this parameter has not been previously determined for any animal virus. In this study, the rates of mutation of the NS gene of the influenza A virus and for the VP1 gene in poliovirus type 1 were measured by direct sequence analysis. Each gene was repeatedly sequenced in over one hundred viral clones which were descended from a single virion in one plaque generation. 108 NS genes of influenza virus were sequenced, and in the 91,708 nucleotides analyzed seven point changes were observed. 105 VP1 genes of poliovirus were sequenced and in the 95,688 nucleotides analyzed zero mutations were observed. We then calculated mutation rates of 1.5 {dollar}\times{dollar} 10{dollar}\sp{lcub}-5{rcub}{dollar} and less than 2.1 {dollar}\times{dollar} 10{dollar}\sp{lcub}-6{rcub}{dollar} mutations/nucleotide/infectious cycle for influenza virus and poliovirus, respectively. We suggest that the higher mutation rate of influenza A virus may promote the rapid evolution of this virus in nature.;Also described is the development of technologies which should facilitate future mutation rate analyses. Single point mutations in the NS gene of influenza virus were detected by electrophoresis of double stranded RNA heteroduplexes in denaturing gradient gels. The heteroduplex RNAs consist of virion RNA hybridized to SP6-derived RNA probes of varying length. Mutations located at different positions along the NS gene (890 nucleotides long) were all predictably detected. The method of heteroduplex analysis was also successfully used in detecting single point mismatches in DNA-RNA hybrids.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biomedical Sciences
