Fig. 1

Midpoint rooted phylogenetic tree of the EIV H3N8 hemagglutinin 1 (HA1) subunit of the hemagglutinin gene conducted in MEGA11 [30] using Maximum Likelihood method and Tamura-Nei model [31]. The tree with the highest log likelihood (− 3160.56) is shown. The percentage of trees in which the associated taxa clustered together is shown next to the branches supported by 1 K bootstrap test replicates. Red triangles indicate sequences from this study forming a separate cluster with EIV from England and Scotland 2015–2016 suggesting a common ancestor. Solid color circles indicated strains indicated by OIE-ESP to be included in the vaccines [32]. Empty circles indicate strains available as EI vaccines in Egypt. Florida clade 2 subgroup 144V (FC2-144V) indicated in red color, Florida clade 2 subgroup 179V (FC2-179V) indicated in dark red color, and Florida clade 2 Asian subgroup (FC2-Asian) indicated in orange color. Florida clade 1 (FC1) indicated in purple color, Eurasian EIV in light blue color and finally pre-divergent EIV in navy color. Initial tree(s) were obtained automatically by applying Neighbor-Join and BioNJ algorithms to a matrix of pairwise distances estimated using the Tamura-Nei model followed by selection of the topology with superior log likelihood value. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. This analysis involved 58 nucleotide sequences, each with a total of 975 nucleotides (Additional file 1: Table S1)