Relationships between European HPR0 and HPRΔ variants belonging to clades II and III.

The best-fitting nucleotide substitution model was used during maximum likelihood analysis and the tree was bootstrapped (50 000 quartet puzzling steps) in TREE_PUZZLE. The scale bar shows the number of nucleotide substitutions as a proportion of branch lengths. HPRΔ ISAV from farmed salmon in Norway (Black), HPR0 ISAV from salmonids in Norway (Red), ISAV from the Faeroe Islands (Green), and ISAV from Russia (Purple).