Continued Evolution of West Nile Virus, Houston, Texas, USA, 2002–2012
Figure 1. . Bayesian-inferred, 50% majority-rule, coalescent phylogenetic tree of published, full-length West Nile virus isolates, Harris County, Texas, USA, 2002–2012. Novel 2010–2012 Harris County isolates cluster into 4 distinct monophyletic groups designated group 7 (red), group 8 (blue), group 9 (green), and group 10 (yellow). Strain names link geographic map code (e.g., B1, B2, M1, M2) with year of collection annotated in parentheses. Isolates sequenced in this study are indicated in boldface. Posterior probabilities ≥0.90 are indicated along branches to provide statistical support for inferred topologies. Scale bar indicates divergence time in years.