Genetic Variability of West Nile Virus in US Blood Donors, 2002–2005
Figure 1. Phylogenetic analyses based on maximum parsimony comparing the 2,685-bp nucleotide sequence, including the complete structural and the 5′-untranslated region of prototype West Nile virus (WNV) strain WN-NY99 with 30 WNV isolates collected during the 2002–2005 epidemics in the United States. Values in parentheses show percentage of nucleotide sequence divergence from WN-NY99. Scale bar represents a 1-nt change.