Internal genome constellations of the influenza C viruses for which the full genome was analyzed in this study. (A) Influenza C viruses circulating between 1947 and 1983 around the world are shown. (B) Influenza C viruses isolated in Japan from 1988 to 2014 are shown. Virus particles are indicated by hexagons containing triangles for the six internal gene segments (clockwise: PB2, PB1, P3, NP, M, and NS) and colored according to their lineage: white, Mississippi/80-related lineage; black, Yamagata/81-related lineage. Abbreviations in panel B: YA, Yamagata; MI, Miyagi; AI, Aichi; FU, Fukuoka; TK, Tokyo.