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Biotech Week

University Of Puerto Rico; Adaptive Evolution May Contribute To Dengue Virus Expansion

November 19, 2003
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2003 NOV 19 - ( & -- Adaptive evolution may contribute to the dramatic expansion of the dengue virus.

According to published research from the University of Puerto Rico, "In the last four decades the incidence of dengue fever has increased 30-fold worldwide, and over half the world's population is now threatened with infection from one or more of four co-circulating viral serotypes (DEN-1 through DEN-4)."

"To determine the role of viral molecular evolution in emergent disease dynamics," S.N. Bennett and coauthors "sequenced 40% of the genome of 82 DEN-4 isolates collected from Puerto Rico over the 20 years since the onset of endemic dengue on the island."

"Isolates were derived from years with varying levels of DEN-4 prevalence," they noted. "Over our sampling period there were marked evolutionary shifts in DEN-4 viral populations circulating in Puerto Rico; viral lineages were temporally clustered and the most common genotype at a particular sampling time often arose from a previously rare lineage."

"Expressed changes in structural genes did not appear to drive this lineage turnover, even though these regions include primary determinants of viral antigenic properties. Instead, recent dengue evolution can be attributed in part to positive selection on the nonstructural gene 2A (NS2A), whose functions may include replication efficiency and antigenicity," according to the report. "During the latest and most severe DEN-4 epidemic in Puerto Rico, in 1998, viruses were distinguished by three amino acid changes in NS2A that were fixed far faster than expected by drift alone."

"Our study therefore demonstrates viral genetic turnover within a focal population and the potential importance of adaptive evolution in viral epidemic expansion," the researchers concluded.

Bennett and colleagues published their study in Molecular Biology and Evolution (Selection-driven evolution of emergent dengue virus. Mol Biol Evol, 2003;20(10):1650-1658).

For additional information, contact S.N. Bennett, University of Puerto Rico, Department of Biology, San Juan, PR 00936, USA.

The publisher of the journal Molecular Biology and Evolution can be contacted at: Oxford University Press, Great Clarendon St., Oxford OX2 6DP, UK.

The information in this article comes under the major subject areas of Infectious Disease and Viral Genomics & Genetics.

This article was prepared by Biotech Week editors from staff and other reports.

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