Fig. 1

Phylogenetic classification among the major capsid proteins (L1) of multiple types, and a structural comparison of HPV L1s. a Phylogenetic tree of HPV L1 proteins based on the amino acid sequences of 20 HPV types. The bar at the bottom provides a scale for the change in evolutionary lineages over time. Twenty HPV types were divided into seven groups based on evolutionary distance of their L1 proteins: Group 1 (blue): HPV33, -52 and -58; Group 2 (cyan): HPV16, -31 and -35; Group 3 (purple): HPV53, -56 and -66; Group 4 (yellow): HPV26, -51 and -69; Group 5 (orange): HPV39, -68 and -70; Group 6 (pink): HPV18, -45 and -59; and Group 7 (green): HPV6 and -11. b Structural comparison of loop structure among HPV types of HPV33, -58 (PDB code: 5Y9E), -52, -18 (PDB code: 2R5I), and -59 (PDB code: 5J6R). The loops are colored by type: HPV33 (light blue), HPV58 (deep blue), HPV52 (marine), HPV18 (light pink) and HPV59 (red). The loop sequence alignments among types are shown above the corresponding loop structure, with residue differences compared with HPV58 colored red