HBV strain phylogeny. A bootstrap consensus tree based on JTT-estimates of amino acid replacements in surface proteins of HBV genotype D displays the surface protein of donor 4 carrying an occult infection in the outgroup position (left panel). The scale bar indicates 2% of evolutionary divergence. For phylogenetic analysis by maximum likelihood, the HBV type D strains were grouped according to their topological position, approximately and provided with labels as indicated next to the branches of the compressed topology tree (right panel, S). The corresponding values obtained for dN/dS are in between of the labels and strains columns; PatB means ''parameter at boundary''. Data on donor 4 are in bold-face. The three panels marked by P(olymerase), C(ore) and X were constructed in a similar fashion, but without mentioning GenBank IDs and clade/branch labels. In case of P and X, the donor 4 species was combined with its nearest neighbor in order to avoid deviation due to insufficient branch length.