Sequences of selected anti-influenza macromolecules. Three representative classes are shown (siRNA, defensin and cathelicidin). Experimentally successful siRNA against influenza PA, PB1 and NP genes are shown in the upper box . For each siRNA, the location of the sequence in the original gene is indicated by nucleotide number; thus, PA-2087 indicates an siRNA in which the first nucleotide at position 2087 of the PA gene. The upper strand is written 5′to 3′; the two deoxythymidine (dT) at the 3′-end are presumed to stabilize the siRNA . The lower box shows the 37-mer peptide LL-37, written in single letter codes [92–94]. In the defensin family, note the abundance of Arg and Cys residues that are important for function .