Several adaptations of SIVcpz have occurred following its spillover in humans, including Vpu antagonism of human tetherin/Bst2 (Lim et al., 2010; Sauter et al., 2009), a mutation in MA that allows infection of human tissues (Bibollet-Ruche et al., 2012), and the adaptation of Vif to antagonize one of the human polymorphisms in APOBEC3H (Zhang et al., 2017). The gene discussed is BST2; the disease is infection.