Figure 2.

Phylogenetic analysis of orthoreovirus fiber proteins and comparisons of their polycistronic genome segments. (A) Diagrams of the fiber encoding S1 and S4 genome segments from the indicated orthoreovirus species, drawn to approximate scale. Numbers refer to mRNA length. Open reading frames are depicted by rectangles, labeled to indicate the protein product and color-coded to depict functional or evolutionary protein relationships: yellow—FAST protein; green—potential cell cycle inhibitory protein; pink—heterologous non-fusogenic protein of no defined function; purple outline—fiber protein. Shading within the fiber ORFs depicts the four main structural features of the fiber protein: N-terminal anchor region (light grey), heptad repeat region (dark grey), β-spiral repeats (black), and globular head (white). Numbers embedded in the shaded areas indicate the number of predicted or demonstrated heptad or β-spiral repeats. The location of the polymorphic indel region is indicated below the Mammalian orthoreovirus (MRV) and Piscine orthoreovirus (PRV) fiber protein ORFs. (B) Maximum likelihood unrooted phylogram of the fiber proteins of the seven indicated orthoreovirus species or proposed species and the MdRVn and classical Muscovy duck reovirus (MdRVc) subgroups of waterfowl ARV isolates. The tree with the highest log likelihood is shown and included 21 amino acid sequences. The virus isolates used for the analysis are indicated by their accession numbers. Bootstrap values (500 replicates) indicating the percentage of trees in which the associated taxa clustered together in <95% of the replicate trees are shown next to the branches. Branch lengths are to scale and measured in the number of substitutions per site. The locations of three indel events that generated the extant fiber proteins are indicated (red circles).