Fig. (1) Phylogenetic relationship of the HA gene of the swine H1N1 pandemic Italian isolate (A/sw/Italy/290271/2009 H1N1) with other Italian SIV and AIV viruses and database retrieved H1N1 and H1N2 swine and human viruses. The unrooted tree was created by maximum parsimony method and bootstrapped with 500 replicates. Only bootstrap values higher than 70% are shown.