Genetic trajectory of a fish virus over its history

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This fish virus suddenly appeared in the Laurentian Great Lakes, causing large mortality outbreaks in 2005 and 2006, and affecting >32 freshwater fish species. In this study, we conduct the largest whole genome sequencing analysis of VHSV-IVb to date, evaluating its evolutionary changes, comparing genomic and genetic variation, selection, and rates of sequence changes. Our overall findings indicate that the VHSV-IVb fish virus has undergone continued sequence change and a trend to lower virulence over its evolutionary history (2003 through present-day), which may facilitate its long-term persistence in fish host populations. Such evolutionary patterns characterize long-term pathogen adaptation to host populations.

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