West Nile Virus in Mexico: Evidence of Widespread Circulation since July 2002.
Figure 2. Phylogenetic tree, derived by maximum likelihood (ML) by using prM-E sequences for West Nile virus (WNV) isolates including the 2003 Mexican Raven isolate. Strains are indicated by country or abbreviated state (U.S.) followed by year and strain designation. GenBank accession nos. are in parentheses. A lineage 2 WNV strain (AY277251) was used to root the tree. Numbers indicate bootstrap values from 1,000 replicates.