EVOLUTIONARY PATTERNS OF INFLUENZA A AND C VIRUSES IN MAN (NS GENE).
Item
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Title
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EVOLUTIONARY PATTERNS OF INFLUENZA A AND C VIRUSES IN MAN (NS GENE).
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Identifier
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AAI8629676
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identifier
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8629676
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Creator
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BUONAGURIO, DEBORAH A.
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Contributor
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Petere Palese
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Date
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1986
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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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The evolution of influenza A viruses was examined by comparative nucleotide sequencing of the NS gene of fifteen human viruses isolated over a 53 year period. Nucleotide substitutions are distributed throughout the NS gene and many base changes found in the earliest isolates are retained in subsequent strains. These data suggest a common evolutionary history for the NS genes of the viruses. Using the maximum parsimony method, a phylogenetic tree was constructed which allowed for the calculation of an evolutionary rate for the NS gene of influenza A viruses. The rapid rate of nucleotide change is approximately 2 x 10('-3) substitutions per site per year, a million-fold higher than DNA genes of the eukaryotic host. Additionally, the uniform rate of substitution in the NS gene represents a good molecular clock in nature. The observed pattern of sequence changes in the NS gene is consistent with an evolutionary model for influenza A viruses whereby variants emerge successively with time through rapid accumulation of genetic changes. We suggest that positive selection plays a significant role in the unusual and rapid evolution of influenza A viruses in nature.;The genetic variability of influenza C viruses was analyzed by nucleotide sequencing of the HA and NS genes of eight human viruses isolated between 1947 and 1983. The pattern of sequence changes observed in the influenza C virus genes is different from the influenza A viruses in that many of the base substitutions are not cumulative with time. The extent of nucleotide differences among the HA and NS genes of the influenza C viruses does not correlate with the isolation dates of the strains. An evolutionary model for influenza C viruses was proposed which states that influenza C variants belonging to multiple phylogenetic lineages appear to cocirculate in nature. The evolutionary pattern of influenza C viruses is therefore quite different from that of influenza A viruses, but similar to that of most other RNA and DNA viruses.;In summary, the influenza A viruses evolve sequentially over time by rapidly accumulating changes in their genomes. Influenza C viruses, in contrast, appear to cocirculate and to evolve more slowly in nature.
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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
