Figure 1
Maximum likelihood phylogenetic tree of influenza A viruses included in the study. The phylogenetic tree is based on the hemagglutinin 1 (HA1) (A) and neuraminidase (NA) (B) amino acid sequences of the influenza A virus strains used for vaccination, challenge and serological assays. The vaccine strains and strains representative for the vaccine strains are colored in: magenta, TIV (Respiporc® FLU3); green, BIV (GRIPORK®); blue, MOV (Respiporc® FLUpan H1N1). The challenge virus is colored in red. The lineage of the HA and NA is indicated. H1 and H3 lineages include: 1A, classical swine H1; 1B, human-like H1; 1C, avian-like H1; 3.1970.1, European human-like H3; 3.2010.1, novel human-like H3. N1 and N2 lineages include: N1av, N1avian; N1pdm, N1pandemic; N1classical, N1classical; N2swSC94, H1N2 A/swine/Scotland/410440/94-like N2; N2swG84, H3N2 A/swine/Gent/1/84-like N2; N2it, N2 introduced from humans to Italian swine in 2000; N2.2002, N2 introduced from humans to North American swine in the early 2000s. *For A/swine/Olost/84, the avian-like H1N1 vaccine strain in BIV, no gene sequences are made publicly available. We therefore selected an avian-like H1N1 (1C.2.1-like) swIAV from 1983 as a substitute for the genetic and serological investigations.