Figure 1. . . Maximum-likelihood phylogenetic tree of dengue virus type 1, including isolates from Key West, Florida, USA, and representative isolates from 5 genotypes with global geographic distribution. Solid circles, 8 Key West viruses (Monroe County) isolated during 2009–2010; solid diamonds, isolates from other Florida counties (Dade, Pinellas, Orange, and Broward Counties). Scale bar indicates nucleotide substitutions per site. Each taxon represents a single virus isolate and is labeled with the geographic origin and collection year. All Florida viruses were labeled with the county of origin. Boldface taxa labels indicate the Key West lineage and cases not associated with travel. Isolate KW-Monroe/2009/JQ425068 represents the 2009 Key West outbreak index case virus. Thirty-six envelope glycoprotein gene sequences obtained from GenBank were included to support tree topology and identify genotypes. All genotypes except the American–African genotype (V) have been collapsed. Taxa labels and GenBank accession numbers are available in Technical Appendix.