Figure 1From: Isolation and complete genomic characterization of H1N1 subtype swine influenza viruses in southern China through the 2009 pandemicPhylogenetic trees of the HA genes of influenza A viruses. Analysis was based on the nucleotide sequences in open reading frames of the HA genes. The subtypes of the viruses were marked in the brackets. The virus marked with black triangle is the swine H1N1 virus isolated and sequenced in this study.Back to article page