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Observation of positive selection within hypervariable regions of a newly identified DNA virus (SEN virus)(1)
Takeji Umemura1, Yasuhito Tanaka, Kendo Kiyosawa
1Department of Transfusion Medicine, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
Abstract:
To elucidate the evolution of SEN virus (SEN-V), serial sequences of chronically SEN-V-infected patients were analyzed. In the hypervariable regions, non-synonymous substitutions significantly predominated. This could be attributed to positive selection in evading immune surveillance of the hosts and to establish a persistent infection. On the basis of the sequences in the two open reading frames of SEN-V DNA, the rate of synonymous substitutions was 7.32 x 10(-4) per site per year. Since this rate is close to RNA viruses and higher than other DNA viruses, the SEN-V might be replicated by machinery with poor or no proofreading function.