Figure 3From: Avian influenza H9N2 seroprevalence among pig population and pig farm staff in Shandong, China Phylogenetic tree of HA genes of H9N2 avian influenza viruses isolated in Shandong from 2012 to 2013. Notes: The reference viruses are marked with a black triangle, and the used virus in this study (A/chicken/Shandongdong/1/2008) is marked with a black star.Back to article page