Evolution of increased survival in RNA viruses specialized on cancer-derived cells

Viruses and other pathogens can diverge in their evolved host-use strategies, due to exposure to different host types and conflicts between within-host reproduction and between-host survival. Most host-pathogen studies have emphasized the role of intra-host reproduction in the evolution of pathogen virulence, whereas the role of extra-host survival has received less attention. Here we examined the evolution of free-living virion survival in RNA virus populations differing in their histories of host-use. To do so, we used lineages of vesicular stomatitis virus (VSV) that were experimentally evolved in laboratory tissue culture for 100 generations on cancer-derived cells, non-cancerous cells, or alternating passages of the two host types. We observed that free-living survival improved when VSV populations specialized on human cancer-derived (HeLa) cells, whereas this trait was not associated with selection on non-cancer cells or combinations of the cell types. We attributed this finding t...