Table 1.

Preferred codons and oligonucleotides in avian or human viruses

	Preferred in avian viruses	Preferred in human viruses
Codon	AAG, CAG, CUC, CUG, GCA, GCG, GUG, UCG, UUC	AAA, ACU, AGA, CAA, CCU, GUU, UCA, UUA, UUG, UUU
Di	AG, CG, CU, GA, GG	AA, UU
Tri	ACG, AGG, CAG, CCA, CGU, GAG, GCA, GCG, GGA, GUG, UCC, UCU	AAA, AUU, UAA, UCA, UUA, UUU
Tetra	ACGC, ACGG, AGAG, AGCG, CCAC, CGAG, CGGA, CGGC, CUUC, GACU, GAGC, GAGG, GCAG, GGAG, UCUU, UGUG, UUCG	AAAA, AAAU, AAGU, AUUA, AUUU, CAAA, CCAU, CUUU, GGCC, GGGG, UGUA, UGUU, UUAA, UUAU, UUCA, UUGU, UUUC, UUUG, UUUU

To specify the characteristic codon/oligonucleotide preference in the H1N1/09 strains, codons and oligonucleotides preferred in both H1N1/09 and avian strains are indicated in bold italic letters in the column ‘Preferred in avian viruses’. Similarly, those preferred in seasonal human viruses but not in H1N1/09 are indicated in bold italic letters in the column ‘Preferred in human viruses’.