Figure 2. Phylogenetic tree based on nucleotide sequences in the hemagglutinin gene. Sequence information corresponds to virus acronym/strain/GenBank accession number. Phylogenetic study was conducted using MEGA software version 4.0 (www.megasoftware.net). Genetic distances were calculated with the pairwise distance method. Phylogenetic tree were constructed with the neighbor-joining method. CPXV, cowpox virus; ECTV, ectromelia virus; VARV, variola virus; CMLV, camelpox virus; VACV, vaccinia virus; HSPV, horsepox virus; MPXV, monkeypox virus. Scale bar indicates genetic diversity at the nucleotide level.