Figure 2.

Mapping of viruses to hosts. (Top) a tree is drawn according to the hierarchical taxonomy of the hosts (from class to genus, based on NCBI taxonomy). The hosts that are unified at the suborder level are framed with an identical color. The four levels (A–D) represent the host grouping at the genus, suborder, order, and class levels, respectively. Below each host, the viruses that infect it are listed. (Bottom) for each taxonomy level, the virus-to-host mapping resulting from the tree is shown. Ambiguity in mapping of viruses to their hosts results from viruses that are annotated to infect a group of hosts that are not uniquely defined at the taxonomical level of interest (e.g., V5 not uniquely defined at level B). In this real-life example, V1–V7 are Mokola virus, Woodchuck hepatitis B virus, Hamster polyomavirus, Murine coronavirus, Sendai virus, Artic squirrel hepatitis virus, and Ground squirrel hepatitis virus, respectively.