Visualization of conserved regions in capsid and nucleocapsid. The capsid hexamer structure (PDB: 3H4E) is shown in top (A) and side (B) views, with the 6 capsid units (pink, blue), conserved NTD-NTD interaction domains (yellow) and conserved NTD-CTD interaction domains (red). Figure (C) shows the structural complex of nucleocapsid and RNA (left, PDB: 1A1T) and the structural complex of nucleocapsid and inhibitor CAA (right, PDB: 2M3Z). The first zinc-finger domain (nucleocapsid positions: 14–29, gag positions: 389–404) and the second zinc-finger domain (nucleocapsid positions: 35–50, gag positions: 410–425) are colored red and orange, respectively. Figures S5 and S6 in Additional file 2 provide detailed structures of conserved gag regions.