The evolutionary phases of the NP (A), M (B), and NS (C) segments of the swPL01 virus were inferred using the method described above (see the legend in Figure 1). The sequences with more than 95% for NP and 60% for M and NS bootstrap scores among the evolution branches of the swTx/98 virus and those of reference were used for the final ML tree evaluation. Lineage definitions were indicated as: TRIG, triple-reassortant; CS, classical swine; EA, Eurasian avian-like; and pH1N1, 2009 pandemic influenza A H1N1. The colors represent the following viruses: pink, A/swine/Texas/4199-2/1998 (swTx/98); green, Korean swine H3N2; red, A/swine/Korea/PL01/2012 (swPL01); and blue, 2009 pandemic influenza H1N1 viruses.