Consensus maximum-likelihood tree of North American WNV ORFs, 1999–2012 (n = 870).

<p>WNV genotypes are color-coded as NY99 (black), INTermediate (orange), WN02 (blue), SW/WN03 (purple) and cluster MW/WN06 (red). All WNV sequences derived from this study are labeled by black diamonds, and Nodes 1 to 6 containing these sequences are highlighted in green and shown in detail. Taxon names correspond to GenBank accession numbers and years of collection. Node-specific amino acid substitutions are shown for each node (see also <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004717#pntd.0004717.s004" target="_blank">S4 Table</a>). For each node, states shown in red in the adjacent U.S. map are those from which strains have been isolated.