New clues to flavivirus replication

For the first time, researchers have found a promoter element in a flavivirus -- specifically, the dengue virus genome. The 5' location of the promoter, revealed in this month's Genes & Development, may explain why the genome of this mosquito-transmitted pathogen must form a loop before it can be copied, opening up new avenues for researchers to explore in developing antiviral therapeutics."There's this emerging concept in RNA virus replication in which the promoter for RNA synthesis sits on the 5' end of the genome and the genome sort of loops back into the 3' end of the genome to deliver [replication machinery]," said Raul Andino at the University of California, San Francisco. The paper employs a "very diverse set of approaches to very solidly demonstrate this elegant gymnastics" in a new class of viruses, he said.RNA-dependent RNA polymerases (RdRps) encoded in the genomes of certain RNA viruses help catalyze...