Tree topology.

<p>Phylogenetic tree was inferred from global alignment of complete and partial genome nucleotide sequences. Distinct variant lineages (i.e., termed A, B, and C) are classified according to the topology and nucleotide sequence differences from >1% to <10%; distinct sublineages (e.g., termed A1 and A2) were also inferred from the tree topology and nucleotide sequence differences in the >0.5% to <1% range <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100746#pone.0100746-Burk1" target="_blank">[22]</a>.