Start with the Simian Flu under the casual difficulty setting. Genes will not matter. The ATP boost might speed things up, but is not necessary. Choose either the USA or Saudi Arabia. Progress as usual, popping DNA bubbles, until you have enough to evolve the "Simian Neuro-Genesis", which should cost 15 DNA points at the "Abilities" screen. Afterwards you will get the option to Devolve it at the cost of more DNA points.