Figure 1.

 Adamantanes resistance among influenza A viruses. M2 protein sequence analysis for influenza A viruses (A/H1 viruses on upper panel and A/H3 viruses on lower panel). The figure shows the consensus sequence from residues 11 to 70. Positions where a substitution can confer resistance to adamantanes (26 and 31) are boxed and when substituted their position is marked in bold. Number (n) of samples found for each of the strains with their percentage among the population (%), Ada is the susceptibility to adamantanes (R, resistant; S, susceptible).