Figure 1. Maximum likelihood phylogenetic tree representing the evolutionary relationships among the Papillomaviridae.

Maximum likelihood phylogenetic tree of the Papillomaviridae. This tree is based on a partitioned supermatrix derived from the E1, E2, L2 and L1 nucleotide sequences. Viruses indicated with a red clade do not contain a canonical E6 ORF, purple clades identify the avian/turtle viruses that contain a “single domain” E6 protein. Classification was based on¹⁸,¹⁹. The asterisk (*) indicates that some members of this clade have not yet been officially recognized as members of the Gammapapillomavirus genus. Colored nodes indicate bootstrap support (red = 100%, green >90%, blue >75%). The red triangle indicates the MRCA of Xi- and Gamma papillomaviruses. The arrowhead highlights CPV2, which was chosen to root the phylogenetic tree in Fig. 2.