Location of amino acid substitutions incurred after HeLa cell passage. (a) ZIKV genome organization showing the non-synonymous nucleotide changes occurring after in vitro HeLa cell passaging at positions 732 and 2797 (dark blue vertical lines), and after in vivo mouse passaging of HeLa-P6 at 1181 and 2242 (light blue vertical lines). (b) Cartoon representation of the location of prM amino acid 87 in the pr peptide domain, which is cleaved by furin protease during maturation. (c) Top view of the NS1 protein dimer structure [9] shows the location of residue 103 (green spheres) in the wing domain (yellow). (d) Side view of of the cryo-EM [10] of three M–E proteins showing E 68 in cyan in domain 2 and E 422 in magenta in the stem region. One M and one E protein are shown in color (red—E domain 1, yellow—E domain 2, green—fusion loop, dark blue—E domain 3, marine blue—E stem and transmembrane, orange—M transmembrane).