FIG. 4.

Neighbor-joining tree of HERV-K(OLD) polymerase sequences and previously published HML polymerase sequences (21). The tree is rooted with a HML-6 sequence being the most distant of the six HML groups (21), but the HML6-3 and HML3-6 relation could not be resolved in this analysis. The distances were calculated using the Kimura two-parameter model with a transition/transversion ratio of 2. Support values (1,000 bootstrap replicates) are indicated on the corresponding branches. The scale bar represents a 10% evolutionary distance.