Influenza A virus protein sequences were downloaded from NCBI (as of April 29 th ). Neuraminidases were identified by BLAST (E-value < 0.001) [19] using the representative NA of the new strain as query [Genbank: ACP41107.1 http://www.ncbi.nlm.nih.gov/protein/ 227809834]. Redundancy was removed with cd-hit at a level of maximal 90% sequence identity [20] , the remain-Domain architecture (drawn with http://au.expasy.org/tools/mydomains/) Figure 1 Domain architecture (drawn with http://au.expasy.org/tools/mydomains/). Besides the labelled domains (TM ... transmembrane), grey lollipops indicate known and putative glycosylation sites and the red lollipop marks the conserved cysteine shown in Figure 2 .