FIG 1.

Phylogenetic relationship of the RNA-dependent RNA polymerase (RdRp) genes of 1,259 astroviruses. Tree branches are colored based on host ecology to highlight cross-species transmission between and among ecological niches (key), determined by using FigTree (http://tree.bio.ed.ac.uk/software/figtree/). The scale bar indicates nucleotide substitutions per site. The tree was generated based on an alignment of 540 nucleotides of the most conserved region of the RdRp region, which is routinely used for the PCR diagnostics of RNA viruses. This final data set was curated from a preliminary analysis of all publicly available sequence data (∼4,300 sequences deposited in NCBI GenBank) and by picking the most conserved region with the highest numbers of sequences available. The capsid gene had greater representation than the selected RdRp region but was not considered because the genes had greater family-level variation and, hence, could not be unambiguously aligned.