Arenavirus genomics: novel insights into viral diversity, origin, and evolution.

Next-generation sequencing technologies have revolutionized our knowledge of virus diversity and evolution. In the case of arenaviruses, which are the focus of this review, metagenomic/metatranscriptomic approaches identified reptile-infecting and fish-infecting viruses, also showing that bi-segmented genomes are not a universal feature of the Arenaviridae family. Novel mammarenaviruses were described, allowing inference of their geographic origin and evolutionary dynamics. Extensive sequencing of Lassa virus (LASV) genomes revealed the zoonotic nature of most human infections and a Nigerian origin of LASV, which subsequently spread westward. Future efforts will likely identify many more arenaviruses and hopefully provide insight into the ultimate origin of the family, the pathogenic potential of its members, as well as the determinants of their geographic distribution.