Figure 2.

Network of DR-associated mutations in the clade Beijing (Lineage 2). Polymorphic loci are shown as nodes titled by the respective gene name and the polymorphic codon number following the colon. Mutations known to cause DR are depicted by an orange color. Nodes linked exclusively by outgoing edges (prerequisite mutations) are shown in green, and those linked exclusively by incoming edges (final and compensatory mutations) are shown in pink, while intermediate mutations are shown in blue. Arrows show the relations between prerequisite and subordinate mutations, which in the case of direct association with the known DR mutations are highlighted by red and blue colors, respectively. The mutations linked to more than 20 subordinate mutations and having no prerequisite mutations were supposed as starting points of the DR evolution. They are depicted by a red stroke outline.