Open reading frames for the joint protein Orf8ab (or simply Orf8) in animal and early human SARS-CoV and splitted Orf 8a and Orf8b in the late human-adapted strains. The nucleotide sequence absent in the strains with splitted Orf8 is marked by arrows. Figure is from the work of Keng and Tan [14]. 2019-nCoV resembles upper variant, but lacks Orf9b and possess Orf10 right of gene N.