The amino acid sequences of HA and NA were obtained from the NCBI (National Center for Biotechnology Information) Influenza Resource (http://www.ncbi.nlm.nih.gov/genomes/ FLU, accessed 15th March 2012) [5] . To fully understand the distributed regularity of the glycosites in each subtype, we downloaded the 29 sets of HA and NA with the customized definition ''.{serotype} {strain} {segname}'' using the following combinations: H1Nx,H17Nx and HyN1,HyN10 (where x and y represent ''any'' by default), in addition to the HA and NA from the H5N1 virus.