Table 1. Variations of M2e sequences among influenza A viruses.

No. of different amino acids	No. of influenza A virus strains
0	968
1	1663
2	1955
3	4796
4	998
5	166
6	5

10,551 M2e sequences of influenza A virus strains were obtained from NCBI. These sequences were aligned with PR8-M2e sequence as a reference.

*denoted conserved sequence among the M2e sequences.