Fig. 2. : analysis of the human respiratory syncytial virus (HRSV) F protein. (A) Maximum likelihood tree based on the JTT + G model. The bootstrap value is shown next to the branch (only greater than 50). The tree is drawn to scale, and the branch lengths are measured as the number of substitutions per site. This analysis involved 22 HRSV amino acid (aa) sequences, which are identified by their respective GenBank accession number and NCBI subgroup (in bold). The F protein from bovine respiratory syncytial virus and human metapneumovirus were used as outgroups. (B) Mean aa divergence (based on p-distance) found between the major clades HRSV-A and HRSV-B and the outgroup sequences from bovine respiratory syncytial virus (Bov RSV) and human metapneumovirus (Meta). The mean aa divergence found within the groups is shown in bold. (C) Amino acid sequence alignment of the palivizumab-specific antibody epitope (254-277 aa). One sequence from HRSV-A, HRSV-B, bovine respiratory syncytial virus and human metapneumovirus is represented in the alignment.