Fig. 4.

A Neighbour-joining tree of 36 full-length HA nucleotide sequences of avian and swine H3N3 viruses determined the wild bird to swine transmission in Ontario. The blue dots at the nodes represented > 90% bootstrap support. B The loss of glycosylation at amino acid residue 499 (NGTY) appeared to have transmitted H3N3 virus to swine; however, it should be noted that the availability of a limited number of avian and swine H3N3 virus sequences restricted our ability to infer avian to swine spillover. C The PCA plot illustrated the occurrence of swine and avian H3N3 viruses globally