Coronavirus RNAs have a 5′ cap and a 3′ poly(A) tail. In our model, SUD associates with the 40S/80S ribosome and enhances the PABP:Paip1 interaction to stimulate the host translation machinery. Meanwhile, coronaviral Nsp1 specifically cleaves host mRNAs (green) but not viral RNAs (Kamitani et al, 2006; Huang et al, 2011). Also, viral Nsp1 blocks host mRNA binding to the 40S ribosome. As a result, SARS-CoV could increase the viral RNA translation but inhibit host mRNA translation.  