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. Author manuscript; available in PMC: 2021 Oct 15.
Published in final edited form as: Virus Res. 2020 Aug 13;288:198118. doi: 10.1016/j.virusres.2020.198118

Figure 2: Phylogenetic trees of H1 and H3 genes of swine influenza viruses in North America.

Figure 2:

Figure 2:

A) Phylogenetic tree of HA of H1 viruses; B) Phylogenetic tree of HA of H3 viruses. The trees were generated by software MEGA 4.1 with the distance-based neighbor-joining method. The reliability of the tree was assessed by bootstrap analysis with 1,000 replications. The H1 viruses have at least 7 genetically and antigenically distinct clades and the H3 viruses have 4 antigenically distinct clusters. The cluster IV H3 viruses have several genetically different (a-f) clades.