Normalized Tetranucleotide BLSOM for all influenza A and B virus genome sequences.
(A) NorTetra. Lattice points on NorTetra-BLSOM were colored as described in Figure 1A. Green dots and many black dots in the avian territory primarily corresponded to H5N1 strains isolated from humans. (B) Hum Sub. On the NorTetra-BLSOM, lattice points containing different human subtypes were differentially colored as described in Figure 1B. (Ci-v) Normalized occurrences of each tetranucleotide at individual lattice points were sorted and indicated, as described in Figure 1C. (D) Map locations of avian strains of special interests and human H7N9 strains. Avian strains listed in Table 1 were indicated by green dots and by a-f colored as presented in Table 1, the avian H5N1 strain isolated from turkey in Virginia was indicated by a blue dot specified by pink-colored h, and three human H7N9 strains recently isolated were indicated by blue dots specified by brown-colored i.