Figure 2. Phylogenetic tree showing genetic relationships between the eight genetic groups of measles virus associated with U.S. outbreaks and cases since 1988. The location and year of isolation is given for each virus. Viruses not assigned to one of the eight groups are labeled in brown. The unrooted tree is based on the sequence of the protein coding region of the H gene (1854 nt). Wt-Edmonston = low passage seed of the original Edmonston isolate. SSPE = sequences obtained from cases of subacute sclerosing panencephalitis.
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