Global Distribution of Rubella Virus Genotypes
Figure 1. Phylogenetic trees. Unrooted tree was made by the maximum likelihood method in the Tree-Puzzle 5.0 program (25,000 puzzling steps for the tree in A; 10,000 puzzling steps for the tree in B) using the complete E1 gene sequence (1179 nt). Bootstrapping values (out of 100) for each node are given. The tree in A was constructed with half of the rubella genotype I (RGI) and all of the RGII sequences (to allow the reader to read the RGI virus designations); the tree in B is a blowup of the RGI node from a tree constructed with all of the sequences. In B, sequences used in the previous study (8) are designated by an (*), and sequences of viruses isolated before 1980 are in black. Branches are color-coded as follows: RGI Intercontinental (International) 1961–1986 and 1964–1981, black; RGI Europe 1972–1991, gold; RGI Europe 1986–1994 and Europe 1991–1998, green; RGI China, 1999, gold; RGI USA, 1990–2000, light blue; and branch containing sub-branches from Japan 1987–1991, Intercontinental (International) 1997–2000, Japan, Korea 1994–1996, New Zealand, 1991, and Japan-Philippines, 1997, dark blue. Of these, the black Intercontinental (International), green Europe, light-blue USA, and dark-blue branches were recognized in the previous study (the light-blue branch as US-Japan and the dark-blue branch as Japan-Hong Kong).