Using the first three SNPs shown on the left (SNP14676, 1642879, and 2935693), a strain is first typed into one of the four SNP types (1–4) and then subtyped using three or four markers shown at right/SNP type to give 16 subtypes (A–P). SNPs shown in blue are the same as those used for typing into type 1, 2, 3 & 4 (left side of the figure).
InDel: Insertion-deletion; SNP: Single nucleotide polymorphism.