Figure 2. Phylogenetic tree constructed on the full-length amino acid (aa) sequence of the capsid protein. The tree was constructed by using a selection of norovirus (NoV) strains representative of genogroups (GG) I to V. Phylogenetic reconstruction was carried out with the p-distance correction and the neighbor-joining method, supported with bootstrapping >1,000 replications. Distance analysis and phylogenetic inference were carried out using the Mega 3.0 software package (www.megasoftware.net). Strain classification follows the outlines of Wang et al. (7) and Zheng et al. (8); strain designation follows the outlines of Green et al. (9). Bo, bovine; DE, Germany; UK, United Kingdom; Hu, human; JP, Japan; US, United States; Mu, murine; NLD, the Netherlands; Po, porcine.