10 Genes, Furiously Evolving

Viruses, numbering in the hundreds of millions and likely extant for centuries, are unique because of a process by which they cause host cells to produce more viruses. But it is reassortment – a phenomenon in which two viruses infecting the same cell combine to form a new virus – that likely leads to the evolution and proliferation of viruses. As one doctor noted, “Reassortment may be the major player in generating new seasonal viruses.” Indeed, the latest flu strain is a product of reassortment; that is, the flu is a combination of mammalian and avian viruses from the US and Europe that blended together in pigs, particularly suitable hosts for viral mixology. And it is this ability to mix and combine in a variety of hosts in a variety of locations that make flu viruses particularly suited to global transmission and regeneration. – YaleGlobal