New insights into the evolutionary relationships between arenaviruses provided by comparative analysis of small and large segment sequences.

Arenaviruses are rodent-borne negative-stranded bisegmented RNA viruses. Five arenaviruses are etiologic agents of hemorrhagic fever in humans and are potential agents of bioterrorism. They are classified as Biosafety level 4 agents and listed in the category A of the Pathogen Agents edited by the Center for Disease Control and Prevention.

Phylogeny of New World arenaviruses based on the complete coding sequences of the small genomic segment identified an evolutionary lineage produced by intrasegmental recombination.

Previous studies suggested that the small genomic segments (S-RNA) of the South American arenaviruses (SA-AVs) represent three phylogenetic lineages (designated A, B, and C) and indicated that the S-RNA of Whitewater Arroyo virus (WWAV) (a North American arenavirus [NA-AV]) is a product of genetic recombination between a lineage A and lineage B virus. The purpose of this study was to extend our knowledge on the phylogenetic relationships between WWAV, the two other NA-AVs (Tamiami and bear canyon), and the 15 SA-AVs. Therefore, we determined the complete sequence of the S-RNA of nine arenaviruses previously uncharacterized or sequenced only partially.