Figure 1.

Maximum likelihood tree of PolB amino acid sequences from NCLDVs. Alignment was constructed with the use of T-Coffee. All the gap-containing amino acid residue sites were removed before tree construction. The phylogenetic tree was constructed using PhyML [38] available at Phylogeny.fr [39] using WAG matrix and gamma distribution. Branch labels indicate bootstrap percentages (≥ 50%) after 100 replicates. The tree is essentially an unrooted tree, albeit mid-point rooted only for presentation purpose. The same method was used for the phylogenetic trees in Fig. 2, Fig. 3 and in the additional file 3. HcDNAV and ASFV sequences are indicated by filled diamond marks. CeV: Chrysochromulina ericina virus; PoV: Pyramimonas orientalis virus; HaV: Heterosigma akashiwo virus.